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The snaplage residue presents itself as a potential alternative roughage source in finishing systems, owing to its high fiber concentration which aids in maintaining rumen health. Nevertheless, the performance of animals will hinge on both the allowance and the nutritive value it offers. This study aimed to evaluate different stocking rates of heifers grazing snaplage residue as an exclusive source of fiber on finishing phase performance. The treatments included two stocking rates (SR): i) low stocking rate (LS; 3.5 AU/ha) and ii) high stocking rate (HS; 7.0 AU/ha), which were obtained by modifying the size of the paddocks. Crossbred beef heifers ( n  = 48; initial body weight = 276 ± 23 kg) were assigned to 16 paddocks (3 heifers/paddock). The concentrate (87% of corn, 3.5% of soybean meal, 3.9% of cottonseed meal, 1.2% of urea, and 4% of mineral; DM basis) was fed ad libitum daily at 0600 hours. Data were analyzed using the MIXED procedure of SAS. There was no SR × time effect ( P  = 0.88) on residue mass. There was less ( P  < 0.01) total residue mass for HS than LS, and total mass decreased ( P  < 0.01) over time. There was no SR × time effect ( P  ≥ 0.16) for behavior characteristics. There was no difference between HS and LS for average residue intake ( P  = 0.34; 0.44 vs 0.48 kg/d, respectively), concentrate intake ( P  = 0.84; 7.72 vs 7.78 kg/d, respectively), and daily gain (ADG; P  = 0.94; 0.95 vs 0.95 kg/d, respectively), The HS treatment increased ( P  < 0.01) gain per area (618 vs 309 kg/ha) compared to LS. No differences between SR were observed for carcass characteristics ( P  ≥ 0.12 ). The meat's chemical composition was not different ( P  ≥ 0.37) between treatments. Overall, the snaplage residue stocking rate did not affect the finishing phase performance of beef heifers, but the greater stocking rate (7.0 AU/ha) increased gain per land area., Competing Interests: The authors declare no conflicts of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Numerous studies have shown genetic variation at the LCORL-NCAPG locus is strongly associated with growth traits in beef cattle. However, a causative molecular variant has yet to be identified. To define all possible candidate variants, 34 Charolais-sired calves were whole-genome sequenced, including 17 homozygous for a long-range haplotype associated with increased growth ( QQ ) and 17 homozygous for potential ancestral haplotypes for this region ( qq ). The Q haplotype was refined to an 814 kb region between chr6:37,199,897-38,014,080 and contained 218 variants not found in qq individuals. These variants include an insertion in an intron of NCAPG , a previously documented mutation in NCAPG (rs109570900), two coding sequence mutations in LCORL (rs109696064 and rs384548488), and 15 variants located within ATAC peaks that were predicted to affect transcription factor binding. Notably, rs384548488 is a frameshift variant likely resulting in loss of function for long isoforms of LCORL . To test the association of the coding sequence variants of LCORL with phenotype, 405 cattle from five populations were genotyped. The two variants were in complete linkage disequilibrium. Statistical analysis of the three populations that contained QQ animals revealed significant ( p < 0.05) associations with genotype and birth weight, live weight, carcass weight, hip height, and average daily gain. These findings affirm the link between this locus and growth in beef cattle and describe DNA variants that define the haplotype. However, further studies will be required to define the true causative mutation.

Strategic supplementation during late gestation has the potential to alter progeny performance. Mature fall-calving Simmental × Angus cows were used to evaluate the effects of late gestation supplementation of fatty acids to beef cows on cow performance, steer progeny growth performance during pre-weaning and backgrounding periods, and relative mRNA expression of genes associated with myogenesis and adipogenesis. Cows (n = 190; 4 pasture groups of cows/treatment) grazed endophyte-infected tall fescue and were supplemented during late gestation with calcium salts of either saturated fatty acid/monounsaturated fatty acid (SFA/MUFA), polyunsaturated fatty acid (PUFA), or an isocaloric and isonitrogenous control (CON). There were no differences ( p ≥ 0.11) in cow body weight (BW) or body condition scores from pre-supplementation to weaning or steer BW at birth, weaning, or at the end of the backgrounding period. Concentrations of C18:2n-6 in plasma were greater ( p = 0.01) in SFA/MUFA and PUFA cows compared to CON cows during supplementation. For mRNA expression in the longissimus muscle of steer progeny from birth to weaning: PAX7 decreased to a greater ( p < 0.01) extent for SFA/MUFA and PUFA steers; AGPAT1 and CPT1 increased to a greater ( p ≤ 0.02) extent for CON steers. The expression of MYH7 mRNA during the pre-weaning period was greater ( p = 0.01) in PUFA. In conclusion, late gestation fatty acid supplementation modified plasma relative concentrations of fatty acids for dams and progeny and modified mRNA expression of genes related to myogenesis and adipogenesis but had limited effects on progeny growth performance during pre-weaning and backgrounding periods.

This study investigated the effects of injectable vitamin C (VC) at weaning and prior to transit on growth performance and immune function in early-weaned beef steers. On day 0, 91 Angus × Simmental steers (92 ± 4 kg) were weaned (65 ± 11 d of age), given vaccination boosters, blocked by age, and randomly assigned to weaning (WEAN) treatments: intramuscular injections (20 mL per steer) of VC (250-mg sodium ascorbate per mL; 5 g per steer) or saline (SAL). From days 0 to 48, steers were housed at the Dixon Springs Agricultural Center (Simpson, IL) in pens (six pens; N = 14 to 16 steers per pen) equipped with two to three Vytelle bunks to measure individual daily feed disappearance. On day 49, half of the steers in each WEAN treatment were randomly assigned to an additional injection treatment (20 mL per steer) of VC or SAL prior to transport (TRANS). After administering pretransit injections, all steers were loaded onto a commercial livestock trailer with equal representation of treatments across compartments. Steers were transported for 6 h (approximately 480 km) to the Illinois Beef and Sheep Field Laboratory (Urbana, IL). Upon arrival, steers were sorted into pens (six pens; N = 13 to 17 steers per pen) with 2 Vytelle bunks per pen. Steers were weighed on days 0, 1, 14, 48, 49, 64, 78, 106, and 107. Blood was collected (WEAN = 24 steers per treatment; TRANS = 12 steers per treatment) on days 0, 1, 2, 14, 49 (pre- and posttransit), 50, and 51. Data were analyzed using the MIXED procedure of SAS 9.4 with fixed effects of age block, WEAN, TRANS, and WEAN × TRANS. Plasma ascorbate concentrations were greater (WEAN × time P < 0.01) on days 1 and 2 for steers that received VC at weaning. Similarly, for steers that received VC on day 49 pretransit, ascorbate concentrations were greater (TRANS × time P = 0.04) on days 49 posttransit, 50, and 51. Treatments did not affect (P ≥ 0.13) body weight, average daily gain, or gain to feed throughout the trial. Serum Bovine Viral Diarrhea Virus type 1 and 2 antibody titers on days 14 and 51 were not affected (P ≥ 0.32) by treatment. Injectable VC administered to early-weaned beef steers at the time of weaning or pretransit increased plasma ascorbate concentrations but did not improve growth performance or antibody response to vaccination booster., (© The Author(s) 2023. Published by Oxford University Press on behalf of the American Society of Animal Science.)

The objective was to determine the effects of injectable vitamin E (VE) before or after transit on feedlot cattle receiving performance, health, and blood parameters. Angus × Simmental steers (n = 196; body weight [BW] = 163 ± 29 kg) were utilized in a randomized complete block design. Steers were blocked by BW and randomly assigned to 1 of 3 treatments: intramuscular injections of saline pre- and post-transit (CON), intramuscular injections of VE (2,000 mg d-α-tocopherol) pre-transit and saline post-transit (PRE), or intramuscular injections of saline pre-transit and VE (2,000 mg d-α-tocopherol) post-transit (POST). Pre-transit injections were administered on day 0, and steers were transported on day 7 for approximately 4 h (348 km). After arrival, steers were fed a common corn silage-based diet in GrowSafe bunks. Final BW tended to be greater (P = 0.08) for CON steers compared with POST steers while PRE steers were intermediate. From days 7 to 63, treatment affected average daily gain (ADG) with PRE and CON steers exhibiting (P = 0.04) greater ADG compared with POST steers. Dry matter intake (DMI), water intake, and gain to feed from days 7 to 63 were not affected (P ≥ 0.17) by treatment. Day 0 serum α-tocopherol concentrations were considered marginal (2.3 ± 0.2 mg/l). A treatment × day interaction (P < 0.01) was observed for serum α-tocopherol concentrations. Serum α-tocopherol concentrations were greatest for PRE steers on day 7 (prior to and post-transit), but greater for POST steers on dys 10 and 14. Plasma ferric-reducing antioxidant potential concentrations increased (P = 0.04) for POST steers compared with CON steers and PRE steers being intermediate. Plasma non-esterified fatty acids (NEFA) concentrations exhibited a treatment × day interaction (P = 0.04) with CON and POST steers being 16% and 14% greater than PRE steers on day 14, respectively. On day 21, NEFA concentrations were greatest for POST steers compared with PRE steers and CON steers being intermediate. There was no main effect (P ≥ 0.14) of treatment on the number of bovine respiratory disease morbidity treatments. Hair cortisol concentrations were decreased (P < 0.01) 14 days after transit for PRE and POST steers compared with CON steers. Overall, injectable VE administered before or after transit increased serum tocopherol concentrations while reducing stress, but did not improve the growth performance of beef steers during the receiving phase., (© The Author(s) 2023. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The objective was to determine effects of old and new rubber matting in a slatted, indoor cattle feeding facility on cattle growth performance, locomotion, and carcass characteristics. In experiment 1, fall-born Angus × Simmental steers (N = 207; body weight = 222 ± 38 kg) were blocked by weight and assigned to 32 pens. Pens were randomly assigned to 1 of 4 treatments: no matting/concrete (CONC1), 12-yr-old Animat Pebble matting (OLD1), new Animat Maxgrip matting (MG), and new Animat Pebble matting (PEB1). Steers were fed a common diet for 209 d with a minimum stocking density of 3.40 m2 per animal. Final body weight (BW) and average daily gain (ADG) were affected (P = 0.02 and P < 0.01, respectively) by treatment with steers on PEB1 finishing heaviest with the greatest growth, MG and CONC1 intermediate, and OLD1 finishing at the lightest final BW with the least growth. Flooring treatment did not affect overall dry matter intake (DMI; P = 0.16) or gain to feed ratio (G:F; P = 0.94). Flooring treatment did not affect (P ≥ 0.19) any carcass traits. Locomotion scores (LS) were affected (P < 0.01) by flooring treatment with CONC1 having the worst mobility while OLD1, MG, and PEB1 were similar (P ≥ 0.24). Locomotion score had a day effect (P < 0.01) where cattle gait and mobility worsened as days on feed increased. In experiment 2, fall-born Angus × Simmental steers (N = 189; BW = 352 ± 43 kg) were blocked by weight and assigned to 21 pens. Pens were randomly assigned to 1 of 3 treatments: no matting/concrete (CONC2), 15-yr-old Animat Pebble matting (OLD2), and new Animat Pebble matting (PEB2). Steers were fed a common diet for 152 d with a stocking density of 2.65 m2 per steer. After 152 d on feed, flooring treatment did not affect (P ≥ 0.30) BW, ADG, or DMI nor did treatment affect (P ≥ 0.17) carcass traits. However, steers housed on OLD2 or PEB2 had improved locomotion scores (P = 0.02) compared with steers housed on CONC2. Locomotion score had a day effect (P < 0.01) as cattle gait and mobility worsened with greater number of days on feed, regardless of treatment. Overall, results suggest that new rubber matting increased ADG and HCW during a 209-d trial when cattle were stocked at 3.4 m2 in small pens and that rubber matting regardless of age improved cattle locomotion scores in slatted indoor feeding facilities., (© The Author(s) 2022. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The objectives were to analyze the effects of housing cow-calf pairs in drylots (DL) or pasture (PAST) on cow performance and reproduction as well as calf performance and behavior through feedlot receiving. Simmental × Angus (2 yr; 108/yr; 81 ± 15.3 d postpartum) spring-calving cows were stratified by age, body weight (BW), body condition score (BCS), and calf sex and allotted to six groups per year. Groups were randomly assigned to one of two treatments: DL or PAST. Cows in DL were limit-fed at maintenance and calves had ad libitum access to the cow diet in an adjacent pen. Pairs on PAST were rotationally grazed and calves received creep ad libitum 3 wk prior to weaning. On day 110, calves were fence-line weaned and behavior was observed on days 111 and 112. On day 116, calves were transported 272 km to a feedlot for a 42-d receiving period. Behavior was evaluated again on days 117 and 118. Data were analyzed using the MIXED procedure of SAS except reproductive data which was analyzed using the GLIMMIX procedure. Cows on DL had greater (P ≤ 0.01) BW and BCS at weaning. There were no differences (P ≥ 0.42) detected in reproductive data. Cows on DL had greater (P = 0.02) milk production. Calves on DL had greater BW (P ≤ 0.01) on day 55 and at weaning and greater preweaning average daily gain (ADG). There were treatment × time effects (P = 0.01) for lying and eating on days 111 and 112. More DL calves were eating in the morning and lying in the evening. More (P < 0.01) PAST calves were walking on day 111. Pasture calves vocalized more (P ≤ 0.01) on day 112. On day 117, more (P ≤ 0.05) pasture calves were lying and eating, and DL vocalized more. On day 118, treatment × time and treatment effects were detected (P ≤ 0.02) for lying and walking. More PAST calves were lying and more DL calves were walking. Drylot calves had greater (P ≤ 0.02) BW at the beginning and end of the receiving phase. Pasture calves had greater (P < 0.01) ADG and tended (P = 0.10) to have greater gain efficiency during feedlot receiving phase. In conclusion, housing cow-calf pairs in drylots improved BW, BCS, and milk production of cows but did not affect reproductive performance. Drylot calves had increased BW and ADG during the preweaning phase. Calf behavior at weaning and receiving was influenced by preweaning housing. Pasture calves had improved receiving phase ADG and feed efficiency but were still lighter than drylot calves after 42-d receiving phase., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Mature Simmental × Angus cows [ n = 147; body weight (BW) = 590 ± 72 kg] were used to evaluate the effects of early weaning on subsequent parity calf growth performance and carcass characteristics. Cows were assigned to one of two treatments based on their previous calf's weaning age: early wean (EW) or conventional wean (CW). Dams assigned to the EW treatment had calves previously weaned at 88 ± 6 d of age, whereas dams assigned to the CW treatment had calves previously weaned at 185 ± 6 d of age. Cow BW and body condition scores (BCS) were monitored during the experiment. All cows were managed as a common group from the onset of the experiment at breeding until final pregnancy check of their next production cycle 462 d later. All calves in the experiment were managed as one group and weaned at a single time point, then feedlot performance and carcass characteristics were evaluated. Initial cow BW was different ( P < 0.05), so it was included as a covariate for cow BW analysis. There was a treatment × date interaction ( P < 0.01) for cow BW and cow BCS. Cow BW was consistently greater for the EW treatment from day 39 to the end of the experiment ( P < 0.01). Cow BCS were not different at the onset of the experiment ( P = 0.20), although after breeding and throughout lactation, BCS diverged between treatments and the EW treatment consistently had greater ( P < 0.01) BCS than the CW treatment throughout the entire subsequent lactation. Gestation length was not different ( P = 0.21) between treatments, yet calf birth BW was greater ( P = 0.05) for the EW treatment. Neither artificially inseminated pregnancy percentage nor overall pregnancy percentage was different between treatments ( P ≥ 0.61). Despite the greater birth BW for the EW treatment and no difference ( P = 0.25) in milk production, weaning BW was not different ( P = 0.50) between treatments. Feedlot performance measures were not different ( P ≥ 0.13) between treatments, including feedlot arrival weight, final BW, average daily gain, dry matter intake, and gain to feed. Final carcass characteristics were not different ( P ≥ 0.33) between treatments, including dressing percentage, hot carcass weight, LM area, 12th rib fat thickness, kidney, pelvic, heart fat percentage, USDA yield grade, and marbling score. Thus, early weaning resulted in improved BW and BCS of cows as well as increased birth BW of subsequent calf, although that did not transpire into differences in postnatal growth performance or carcass traits., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society of Animal Science.)

The objective was to investigate the effects of feeding late gestational beef cows supplements differing in fatty acid profile on steer progeny finishing phase growth performance, carcass characteristics, and relative mRNA expression of myogenic and adipogenic genes. Seventy Angus-cross steers (initial body weight [BW] 273 ± 34 kg) born from dams supplemented with either 155 g DM/d EnerGII (CON, rich in palmitic and oleic acids) or 80 g DM/d Strata + 80 g DM/d Prequel (PUFA, rich in linoleic acid, eicosapentaenoic acid, and docosahexaenoic acid) for the last 77 ± 6 d prepartum were used. Longissimus muscle and subcutaneous adipose biopsies were collected to evaluate relative mRNA expression of genes related to myogenesis and adipogenesis. Steers were slaughtered at 423 ± 6 d of age. No treatment × time interaction or treatment effect ( p ≥ 0.21) was detected for steer finishing phase BW, while steers from PUFA supplemented dams tended ( p = 0.06) to have a greater gain to feed ratio (G:F). Neither carcass characteristics nor relative mRNA expression was different ( p ≥ 0.11). In conclusion, late gestation PUFA supplementation tended to increase steer progeny finishing phase G:F, but had no effects on finishing phase BW, carcass characteristics, or relative mRNA expression during the finishing phase.

Background: Maternal nutrition during gestation affects fetal development, which has long-term programming effects on offspring postnatal growth performance. With a critical role in protein and lipid metabolism, essential fatty acids can influence the development of muscle and adipose tissue. The experiment investigated the effects of late gestation supplements (77 d prepartum), either rich in saturated and monounsaturated fatty acids (CON; 155 g/cow/d EnerGII) or polyunsaturated fatty acids (PUFA; 80 g/cow/d Strata and 80 g/cow/d Prequel), on cow performance and subsequent calf growth performance as well as mRNA expression in longissimus muscle (LM) and subcutaneous adipose tissue at birth and weaning., Results: There was no difference (P ≥ 0.34) in cow body weight (BW) or body condition score from pre-supplementation through weaning. Relative concentrations of C18:3n-3 and C20:4n-6 decreased (P ≤ 0.05) to a greater extent from mid-supplementation to calving for PUFA compared with CON cows. Cow plasma C20:0, C20:5n-3, and C22:6n-3 were increased (P ≤ 0.01) in PUFA during supplementation period. At birth, PUFA steers had greater (P = 0.01) plasma C20:5n-3. No differences (P ≥ 0.33) were detected in steer birth BW or dam milk production, however, CON steers tended (P = 0.06) to have greater pre-weaning average daily gain and had greater (P = 0.05) weaning BW compared with PUFA. For mRNA expression in steers: MYH7 and C/EBPβ in LM increased (P ≤ 0.04) to a greater extent from birth to weaning for PUFA compared with CON; MYF5 in LM and C/EBPβ in adipose tissue tended (P ≤ 0.08) to decrease more from birth to weaning for CON compared with PUFA; SCD in PUFA adipose tissue tended (P = 0.08) to decrease to a greater extent from birth to weaning than CON. In addition, maternal PUFA supplementation tended (P = 0.08) to decrease MYOG mRNA expression in LM and decreased (P = 0.02) ZFP423 in adipose tissue during the pre-weaning stage., Conclusions: Late gestation PUFA supplementation decreased pre-weaning growth performance of the subsequent steer progeny compared with CON supplementation, which could have been a result of downregulated mRNA expression of myogenic genes during pre-weaning period.

The objective of this study was to investigate effects of maternal supplementation with an injectable trace mineral (Cu, Mn, Zn, and Se) on subsequent steer performance during the finishing phase. Seventy-six Angus cross steers (initial body weight 249 ± 41.5 kg) from dams administered either an injectable trace mineral (TM; Multimin 90) or sterilized physiological saline (CON) during prepartum stage were used. Individual feed intake during the finishing phase were recorded with GrowSafe feed bunks. Blood and liver biopsy samples were collected to evaluate trace mineral status. Steers were slaughtered at 413 ± 26 days of age and carcass data were obtained at a commercial abattoir. Growth performance or mineral status of the steers during the finishing phase was not affected ( p ≥ 0.14) by maternal treatments. Carcass characteristics were not different ( p ≥ 0.18), except steers from TM dams had greater ( p = 0.05) percentage of carcasses graded as Choice or greater. In conclusion, maternal supplementation of an injectable trace mineral increased the percentage of carcasses graded as Choice or greater, other than that, maternal supplementation had limited influence on finishing phase growth performance, trace mineral status, or carcass characteristics of the subsequent steer progeny.

This study evaluated the effect of heifer development system on body weight (BW), body condition score (BCS), fescue toxicosis symptoms, reproductive performance, and subsequent calf growth of fall-calving beef heifers. Angus × Simmental heifers [ n = 399; 240 ± 20.0 kg initial BW; age = 252 ± 20 d] were stratified by BW and BCS and assigned to 1 of 12 groups in each of the two production years. The study utilized a stratified randomized design. Pens were randomly assigned to four treatments: drylot (DL) development (fed ad-libitum diet consisting of 90% hay and 10% DDGS on a dry matter basis), grazing endophyte-infected fescue supplemented daily (2.3 kg as-fed/heifer/d; 50:50 mix of soybean hulls and DDGS; E+/S), grazing endophyte-infected fescue and supplemented from the midpoint of treatment period until breeding (4.5 kg as-fed/heifer/d; 50:50 mix of soybean hulls and DDGS; E+/LS), and grazing novel endophyte-infected fescue with no supplement (NE+/NS). Treatments ceased on d 168 [time of artificial insemination (AI)] and heifers were commingled and managed as a group through second breeding season. Heifers in DL had greatest ( P ≤ 0.05) BW and BCS from d 28 until d 254. Furthermore, E+/S heifers had greater ( P ≤ 0.05) BW and BCS than both E+/LS and NE+/NS from d 28 until d 168. On d 56 and 84, E+/LS heifers had lower ( P ≤ 0.05) BW and BCS compared to NE+/NS, but on d 148 treatments reranked and E+/LS remained at a greater ( P ≤ 0.05) BW and BCS compared to NE+/NS through the first breeding season. Drylot heifers had greatest ( P ≤ 0.05) percentage cycling and percentage of mature BW at AI (66.6%) and had greater ( P ≤ 0.05) AI and overall pregnancy rates compared to E+/LS and NE+/NS. The E+/S (55%) and E+/LS (53.7%) heifers were developed to a greater ( P < 0.01) percentage of mature BW than NE+/NS (49.3%). A greater ( P ≤ 0.02) percentage of DL and E+/S heifers were pregnant at the end of the first breeding season (89.3 and 85.1%; respectively) compared to NE+/NS (61.5%). In summary, DL heifers had the greatest BW and BCS at AI, percentage cycling, and AI pregnancy rate. However, this strategy did not result in differing overall pregnancy rates between DL, E+/S, and E+/LS and there were no differences in milk production, rebreeding reproductive performance, and calf performance between all treatments. Finally, the poorest AI and overall pregnancy rates of the NE+/NS heifers suggests this is not a viable development strategy for fall-born heifers., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science.)

This study evaluated how corn supplementation and age of female affected body weight (BW), body condition score (BCS), artificial insemination (AI) pregnancy rate, and blood metabolites (nonesterified fatty acid [NEFA], β-hydroxybutyrate [BHBA], and blood urea nitrogen [BUN]) when grazing lush spring pasture. Angus and Angus × Simmental beef females ( n = 361) were blocked by location, stratified by BW and BCS, and then were assigned to groups ( n = 8 groups/treatment combination; 9-14 females/group). The study utilized a stratified, randomized complete block design with a 2 × 2 factorial arrangement of treatments. The four treatment combinations were: yearling heifers receiving no supplement (CON-H); yearling heifers receiving supplement of dry-rolled corn (SUPP-H; 1.81 kg as-fed/heifer/d) for 42 d; 2-yr-old lactating cow-calf pairs receiving no supplement (CON-C); and 2-yr-old lactating cow-calf pairs receiving supplement of dry-rolled corn (SUPP-C; 1.81 kg as-fed/cow/d) for 42 d. Supplementation began at AI (end of April) when cows began grazing tall fescue ( Festuca arundinacea schreb )-red clover ( Trifolium pratense ) pastures. Pasture forage was collected weekly for analysis. Throughout the study, forage crude protein decreased ( P < 0.01) over time, but acid detergent fiber (ADF), neutral detergent fiber, dry matter, forage height, and forage mass all increased ( P < 0.01) over time. Females receiving SUPP tended ( P = 0.10) to have greater BW and greater BW change over the supplementation period. Supplementation × age effects for BCS were detected ( P = 0.04); SUPP-H had greater BCS than all other treatment combinations at d 42. Cow BHBA was greater ( P < 0.01) compared with heifers. Female NEFA increased ( P < 0.01) from d 12 to 42. Control females had greater ( P = 0.02) serum NEFA concentrations compared with SUPP females. Control females had greater ( P = 0.03) BUN concentrations compared with SUPP females. Cow BUN was greater ( P < 0.01) than heifer BUN. Supplementation effects were not detected ( P ≥ 0.25) for AI or overall pregnancy rate. In conclusion, there were no supplementation × age interactions excluding d 42 BCS. Supplementation regardless of female age tended to improve d 42 BW and BW change. Cow BHBA and BUN was greater compared with the heifers, whereas the supplemented females had decreased NEFA and BUN. Cows tended to have greater AI pregnancy rates than heifers, but supplementation did not affect AI or overall pregnancy rates., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science.)

This study evaluated the effects of offering growing bulls a diet with 40% modified wet distillers grains plus solubles (MWDGS; dry matter [DM] basis) on growth, composition, hoof scores, and reproductive performance. Simmental × Angus bulls ( n  = 28) were stratified by body weight (BW; 316 ± 29 kg), sire, and day 0 semen production (Y/N) and assigned into one of six pens. Pens were randomly assigned to one of two dietary treatments ( n  = 3 pens/treatment): 1) offered free-choice access to a corn-based diet with no MWDGS (CON) or 2) offered free-choice access to a diet with 40% MWDGS (DST; DM basis). Bulls were offered treatments for 140 d and, then, switched to a free-choice, common, low-energy diet for an additional 70 d. Bull BW, body condition score (BCS), hip height (HH), ultrasound (rump fat depth [RF], 12th rib fat thickness [BF], marbling score [MS], and longissimus muscle depth [MD]), hoof evaluations, breeding soundness examination (BSE), and semen evaluations were performed on days 0, 28, 56, 84, 112, 140, 175, and 210. There was a tendency ( P  < 0.09) for a treatment × time effect for BW. Bulls fed DST tended ( P  ≤ 0.10) to be heavier on days 28 and 56 than CON bulls. A treatment × time effect was detected ( P  < 0.01) for RF. Bulls fed DST had greater ( P  = 0.02) RF on day 84 than CON bulls. Treatment × time and treatment effects were detected ( P  ≤ 0.05) for BF, in which DST bulls had greater ( P ≤ 0 .05) BF on days 84, 112, and 175 and tended ( P  ≤ 0.10) to be greater on days 56 and 210 than CON bulls. A treatment × time effect was detected ( P  < 0.02) for percentage of major sperm defects. Bulls fed DST had a greater ( P  < 0.01) percentage of major sperm defects on day 140 than control bulls. There was a tendency ( P  = 0.09) for a treatment × time effect for percentage of sperm with proximal droplets. Bulls fed DST had a greater ( P  = 0.01) percentage of sperm with proximal droplets on day 140 than CON bulls. In conclusion, offering growing bulls a diet with 40% MWDGS (DM basis) resulted in heavier BW at days 28 and 56, increased RF at day 84, and increased BF and increases in both major sperm defects and sperm with proximal droplets at day 140. However, after 70 d on the common low-energy diet, there were no carryover effects for any growth, composition, hoof, or reproductive measures except for a tendency for BF., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Newly weaned, commercial Angus steers [body weight (BW) = 204 ± 19 kg; n = 24; 12 steers from dams administered an injectable trace mineral (MM; Mulimin90) and 12 steers from control (CON) dams] were utilized to determine the effects of maternal supplementation with an injectable trace mineral on the inflammatory response of subsequent steers subjected to a lipopolysaccharide (LPS) challenge at the initiation of a 42-d receiving period. On day -2 steers were weaned, and the following day, shipped 354 km to the Beef Cattle and Sheep Field Laboratory in Urbana, IL. On day 0, steers were administered an intravenous LPS challenge. Body temperature and blood samples were collected from steers prior to LPS administration (0 h) and again at 0.5, 1, 2, 3, 4, 5, and 6 h. Blood samples were analyzed for trace mineral and cortisol at 0 and 2 h and glucose, insulin, LPS-binding protein (LBP), interleukin-1β (IL-1β), interleukin-6 (IL-6), haptoglobin, ceruloplasmin, and fibrinogen at 0, 0.5, 1, 2, 3, 4, 5, and 6 h. Calf BW was collected at trial initiation and subsequently every 14 d. Dry matter intake was collected daily and average daily gain (ADG) and feed efficiency were assessed. Initial plasma Zn tended (P = 0.06) to be greater for MM steers. However, there was no difference (P ≥ 0.31) in trace mineral status or serum cortisol at any other time. Total area under the curve (TAUC) for body temperature was lesser (P > 0.01) for MM steers. Basal LBP concentrations and TAUC for LBP tended (P ≤ 0.10) to be greater for MM steers. Peak concentration of IL-6 tended (P = 0.09) to be reached earlier for CON steers. However, there was no difference (P ≥ 0.11) in glucose, insulin, IL-6, ceruloplasmin, haptoglobin, and fibrinogen concentrations between treatments. Calf performance and feed efficiency did not differ (P ≥ 0.17) between treatments except ADG from day 28 to 42, which was greater (P = 0.03) for CON steers. Maternal supplementation with an injectable trace mineral tended to improve steer plasma Zn status at 0 h and tended to increase basal concentrations of LBP and overall LBP production when steers were administered an LPS challenge. Additionally, MM steers exhibited a more favorable change in body temperature following LPS administration. However, injectable trace mineral supplementation of dams during gestation had minimal to no effect on cytokine and acute-phase protein concentrations, as well as overall calf performance and efficiency during a 42-d receiving period., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Nerve growth factor-β (NGF) is a seminal plasma protein associated with improved sperm membrane integrity and motility in mammalian species. The objective of this study was to compare post-thaw semen quality from both ejaculated and pididymal-collected bull sperm incubated with purified NGF prior to cryopreservation. Semen was obtained from Angus × Simmental crossbred bulls (n = 10) collected by electroejaculation, followed by castration and epididymal sperm collections 3 days later. Semen samples were incubated with extender having 0 ng/mL (CONT), 0.5 ng/mL (LOW), 5 ng/mL (MED), or 50 ng/mL (HIGH) of purified NGF prior to cryopreservation. Sperm motility was assessed in each sample prior to treatment and cryopreservation and at post-thaw. Flow cytometry was used for post-thaw assessment of sperm viability (SYBR-14/PI), acrosome integrity (FITC-PNA/PI), and chromatin stability (acridine orange). Values for post-thaw sperm motility and velocity variables were decreased, while linearity was increased in samples of the HIGH compared with CONT group (P < 0.01), but there were no differences in epididymal samples (P> 0.05). Samples from the HIGH group also had a lesser amplitude of lateral head displacement at 2.5 and 3 h post-thaw (P < 0.01). Post-thaw sperm viability, acrosome integrity, and DNA fragmentation index were not affected by NGF treatment in either ejaculated or epididymal sperm (P> 0.05). In conclusion, supplementation of freezing extender with NGF had minimal effects on post-thaw sperm quality in bulls. Results indicate NGF may have a function in preventing premature sperm hyperactivation in ejaculated, but not epididymal-collected spermatozoa. Fertility studies, both in vitro and in vivo, are warranted to ascertain the relevancy of these findings., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The objective of this experiment was to evaluate effects of extended-release eprinomectin on fescue toxicosis and impacts on performance and reproduction in fall-calving beef cows. Fall-calving Angus × Simmental multiparous cows [ n = 335; age = 5.8 ± 2.1 yr; 586.5 ± 6.0 kg body weight (BW); 5.48 ± 0.05 body condition score (BCS)] were stratified by BW, age, and BCS and randomly assigned to one of three treatments. Treatments included a spring injection of extended-release eprinomectin (SERE) on day 0, a fall injection of extended-release eprinomectin injection (FERE) on day 84, and a saline control (CON). All treatments were administered at a rate of 1 mL/50 kg BW. Prior to the experiment, all cows were treated with oral fenbendazole to minimize parasite load. Cows grazed endophyte-infected tall fescue. Hair coat score (HCS), BW, and BCS were recorded on all cattle. Fecal egg count (FEC), respiration rate (RR), horn fly and tick count, hematocrit (% packed cell volume, PCV), and serum prolactin were analyzed on a subset of cows (35/treatment). On day 194, cows were artificially inseminated (AI) and 11 d following AI were exposed to bulls for 51 d. Milk production was estimated on day 210 on a subset of 85 cow-calf pairs (28-29/treatment). There was a tendency for a treatment × time interaction ( P = 0.07) for FEC likely driven by an increase in FEC of the CON cattle at day 126 compared to SERE and FERE. There was a tendency for a treatment × time interaction ( P = 0.06) for cow BW, largely driven by time differences; however, there was no effect of treatment ( P = 0.84) on BW. There was no difference ( P ≥ 0.13) in cow PCV, fly and tick count, BCS, HCS, RR, and serum prolactin throughout the experiment. Additionally, there was no difference ( P ≥ 0.46) in Julian calving date, calf birth BW, or milk production between treatments. Interestingly, heifer calves born to FERE dams tended to have greater ( P = 0.06) weaning BW compared to heifer calves born to CON dams. In addition, there was no difference ( P ≥ 0.17) in heat patch scores, AI conception rates, or overall pregnancy rates between treatments. Extended-release eprinomectin did not impact cow growth performance, reproductive performance or fescue toxicity symptoms when grazing endophyte-infected tall fescue; however, calf weaning BW tended to be improved., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Residual feed intake (RFI) is a widely used measure of feed efficiency in cattle. Although the precise biologic mechanisms associated with improved feed efficiency are not well-known, most-efficient steers (i.e., with low RFI coefficient) downregulate abundance of proteins controlling protein degradation in skeletal muscle. Whether cellular mechanisms controlling protein turnover in ruminal tissue differ by RFI classification is unknown. The aim was to investigate associations between RFI and signaling through the mechanistic target of rapamycin (MTOR) and ubiquitin-proteasome pathways in ruminal epithelium. One hundred and forty-nine Red Angus cattle were allocated to 3 contemporary groups according to sex and herd origin. Animals were offered a finishing diet for 70 d to calculate the RFI coefficient for each. Within each group, the 2 most-efficient (n = 6) and least-efficient animals (n = 6) were selected. Compared with least-efficient animals, the most-efficient animals consumed less feed (P < 0.05; 18.36 vs. 23.39 kg/d DMI). At day 70, plasma samples were collected for insulin concentration analysis. Ruminal epithelium was collected immediately after slaughter to determine abundance and phosphorylation status of 29 proteins associated with MTOR, ubiquitin-proteasome, insulin signaling, and glucose and amino acid transport. Among the proteins involved in cellular protein synthesis, most-efficient animals had lower (P ≤ 0.05) abundance of MTOR, p-MTOR, RPS6KB1, EIF2A, EEF2K, AKT1, and RPS6KB1, whereas MAPK3 tended (P = 0.07) to be lower. In contrast, abundance of p-EEF2K, p-EEF2K:EEF2K, and p-EIF2A:EIF2A in most-efficient animals was greater (P ≤ 0.05). Among proteins catalyzing steps required for protein degradation, the abundance of UBA1, NEDD4, and STUB1 was lower (P ≤ 0.05) and MDM2 tended (P = 0.06) to be lower in most-efficient cattle. Plasma insulin and ruminal epithelium insulin signaling proteins did not differ (P > 0.05) between RFI groups. However, abundance of the insulin-responsive glucose transporter SLC2A4 and the amino acid transporters SLC1A3 and SLC1A5 also was lower (P ≤ 0.05) in most-efficient cattle. Overall, the data indicate that differences in signaling mechanisms controlling protein turnover and nutrient transport in ruminal epithelium are components of feed efficiency in beef cattle., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The objective of this experiment was to assess the effects of eprinomectin, an extended-release injectable parasiticide, on fescue toxicosis and its impacts on beef heifer performance and reproduction. Fall-born Angus × Simmental heifers (age = 246.3 ± 22.4 d; 264.8 ± 21.1 kg body weight [BW]) were randomly assigned to one of two treatments: extended-release eprinomectin injection (ERE; n = 100) or control (CON; saline; n = 99). Treatments were administered at a rate of 1 mL/50 kg BW. Prior to experiment, heifers were dosed with oral fenbendazole to minimize parasite load. All heifers grazed endophyte-infected tall fescue as a single group and were offered a 50:50 supplement mix of corn gluten feed and soybean hulls (2.7 kg as fed per heifer per day). Body condition scores (BCS), BW, hair coat score (HCS), blood, and fecal samples were collected throughout the experiment. A subset of 40 heifers were randomly selected (20 per treatment) to assess respiration rate (RR). On d 138, heifers began a 14-d controlled internal drug release + prostaglandin synchronization protocol. Following artificial insemination (AI), heifers were exposed to five bulls for 71 d. On d 214 and 291, AI and overall pregnancy rates, respectively, were determined. There was a treatment × time interaction ( P < 0.01) for BW, BCS, and average daily gain (ADG). The ERE heifers had greater ( P < 0.04) BW and BCS compared to CON heifers from d 55 and 112, respectively. In addition, ERE heifers had greater ( P ≤ 0.04) ADG from d 0 to 56, 56 to 112, 112 to 171, and 171 to 214; however CON heifers had greater ( P < 0.01) ADG from d 214 to 291. There was no treatment × time interaction or treatment difference ( P ≥ 0.27) for HCS, RR, and serum prolactin concentrations. However, serum prolactin decreased ( P < 0.01) in all heifers over time. There was a treatment × time interaction ( P< 0.01) for fecal egg counts (FEC). The FEC did not differ ( P ≥ 0.32) on d -1 or 55; however, ERE heifers had decreased ( P < 0.01) FEC compared with CON heifers on d 111 (1.52 vs. 13.56 eggs per gram). The ERE heifers tended ( P = 0.10) to have greater AI pregnancy rates (69% vs. 58%) and had greater ( P = 0.01) overall pregnancy rates (84% vs. 68%) than CON heifers. Spring administration of extended-release eprinomectin improved BW, ADG, BCS, and AI and overall pregnancy rates in fall-born beef heifers. However, the underlying mechanism is still unclear, as there were minimal to no differences in HCS, RR, serum prolactin, and FEC., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science.)

The objective was to evaluate the effects of two-stage weaning and injectable trace mineral ( ITM ) on receiving cattle growth performance and behavior. Angus and Simmental × Angus steers ( n = 136; body weight [BW] = 200 ± 26 kg) were utilized in a 2 × 2 factorial design. Calves were blocked by source, and assigned to one of four treatments: 1) two-stage weaning and ITM ( 2MM ), 2) two-stage weaning and saline injection ( 2SAL ), 3) abrupt weaning and ITM ( AbtMM ), or 4) abrupt weaning and saline injection ( AbtSAL ). On d-6, calves were weighed, plastic calf weaner devices (used to prevent calf from nursing) were inserted in two-stage weaned calves, and ITM or saline injections (1 mL/45.4 kg BW) were administered. On day 0, plastic calf weaner devices were removed, and calves were weighed and shipped 272 km to Urbana, IL. Steer behavior was observed the 2 d following separation from dam. Receiving period was day 0 to 42 and growing period was day 42 to 124. Data were analyzed using the MIXED procedure of SAS and pen (six per treatment) was the experimental unit. Abruptly weaned calves had greater ( P < 0.01) preweaning average daily gain (ADG) than two-stage weaned calves. Treatment did not affect ( P ≥ 0.16) ADG during the receiving or growing period; however, calves that received ITM tended ( P 0.06) to have greater ADG from day 0 to 124. During the receiving period, abruptly weaned calves tended ( P = 0.08) to eat more than two-stage calves and ITM calves ate more ( P = 0.03) than calves that received saline. There was a weaning strategy × ITM interaction ( P < 0.01) for dry matter intake (DMI) from day 0 to 124; 2MM calves ate more ( P < 0.01) than 2SAL, but DMI was not different ( P = 0.58) between AbtMM and AbtSAL calves. There was a weaning strategy × ITM interaction ( P < 0.01) for gain-to-feed ratio (G:F) from day 0 to 124; 2SAL calves had greater ( P = 0.05) G:F than AbtSAL, with 2MM and AbtMM calves being intermediate and not different ( P = 0.38) than each other. Two-stage weaning decreased ( P ≤ 0.02) the percentage of calves walking, standing, and vocalizing, and increased ( P ≤ 0.02) the percentage of calves lying and eating following separation from dam. Two-stage weaning decreased preweaning ADG and behavioral signs of stress at feedlot arrival, but had no effect on overall growth. In addition, ITM had no effect on calf BW or behavior, but increased overall DMI in two-stage weaned calves compared to abruptly weaned calves and tended to increase overall ADG regardless of weaning strategy., (© The Author(s) 2018. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Commercial Angus heifers ( n = 190; body weight (BW) = 315 ± 49.3 kg) were used to determine the effects of trace mineral injections during gestation on heifer and subsequent calf performance. Heifers received three previous subcutaneous trace mineral (Multimin 90 [ MM ]; n = 93) or sterilized physiological saline ( CON ; n = 97) injections approximately 90 d apart. These treatments were maintained and subsequent injections were given 205, 114, and 44 ± 26 d prepartum. Heifers were provided free-choice inorganic minerals. Heifer BW and body condition scores (BCS) were collected at trial initiation (296 ± 26 d prepartum) and 5- to 10-week intervals thereafter. Liver samples were collected at trial initiation, 5 and 176 ± 3 d postpartum from a subset of cows to determine trace mineral status. Milk production was assessed on 80 cow-calf pairs (40/treatment) at 71 ± 15 d postpartum. Cows were artificially inseminated (AI) 82 d postpartum and then exposed to bulls for 38 d. Data were reported from 174 calves ( n = 87 calves/treatment). Calf liver samples were collected 5 and 147 ± 3 d postpartum to determine trace mineral status. Calf weaning BW was collected at 159 ± 26 d postpartum. Calf performance including calving date, birth BW, weaning BW, average daily gain (ADG), and health data were collected. Heifer BW and BCS did not differ ( P ≥ 0.72) throughout the experiment. Multimin heifers tended ( P = 0.08) to have greater initial liver Se and tended to have decreased ( P = 0.08) initial liver Zn compared with CON. At calving, MM cows had increased ( P ≤ 0.01) liver Cu and Se. There was no difference ( P ≥ 0.47) in Julian calving date, calving percent, or unassisted births. Calf birth BW was lesser ( P = 0.02) for MM than CON calves, and MM calves had greater ( P = 0.03) liver Cu concentrations at birth than CON calves. Despite MM cows having increased ( P < 0.01) milk production, calf weaning BW and ADG were not different ( P ≥ 0.87). In addition, calf morbidity and mortality were not different ( P ≥ 0.43) between treatments. Calf mineral status was not different ( P ≥ 0.57) at the time of weaning regardless of treatment; however, MM cows had decreased ( P = 0.03) liver Zn. Multimin cows had decreased ( P = 0.05) AI pregnancy rates, yet there was no difference ( P = 0.34) in overall pregnancy rate. Supplementing an injectable trace mineral during heifer development and gestation increased cow milk production and resulted in decreased AI pregnancy rates; however, there was no effect on overall pregnancy rates or preweaning calf health or performance., (© The Author(s) 2018. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Background: Residual feed intake (RFI) describes an animal's feed efficiency independent of growth performance. The objective of this study was to determine differences in growth performance, carcass traits, major bacteria attached to ruminal solids-fraction, and ruminal epithelium gene expression between the most-efficient and the least-efficient beef cattle. One-hundred and forty-nine Red Angus cattle were allocated to three contemporary groups according to sex and herd origin. Animals were fed a finishing diet in confinement for 70 d to determine the RFI category for each. Within each group, the two most-efficient ( n  = 6; RFI coefficient = - 2.69 ± 0.58 kg dry matter intake (DMI)/d) and the two least-efficient animals ( n  = 6; RFI coefficient = 3.08 ± 0.55 kg DMI/d) were selected. Immediately after slaughter, ruminal solids-fraction and ruminal epithelium were collected for bacteria relative abundance and epithelial gene expression analyses, respectively, using real-time PCR., Results: The most-efficient animals consumed less feed ( P  = 0.01; 5.03 kg less DMI/d) compared with the least-efficient animals. No differences ( P  > 0.10) in initial body weight (BW), final BW, and average daily gain (ADG) were observed between the two RFI classes. There were no significant RFI × sex effects ( P  > 0.10) on growth performance. Compared with the least-efficient group, hot carcass weight (HCW), ribeye area (REA), and kidney, pelvic, and heart fat (KPH) were greater ( P  ≤ 0.05) in the most-efficient cattle. No RFI × sex effect ( P  > 0.10) for carcass traits was detected between RFI groups. Of the 10 bacterial species evaluated, the most-efficient compared with least efficient cattle had greater ( P  ≤ 0.05) relative abundance of Eubacterium ruminantium , Fibrobacter succinogenes , and Megasphaera elsdenii , and lower ( P  ≤ 0.05) Succinimonas amylolytica and total bacterial density. No RFI × sex effect on ruminal bacteria was detected between RFI groups. Of the 34 genes evaluated in ruminal epithelium, the most-efficient cattle had greater ( P  ≤ 0.05) abundance of genes involved in VFA absorption, metabolism, ketogenesis, and immune/inflammation-response. The RFI × sex interactions indicated that responses in gene expression between RFI groups were due to differences in sex. Steers in the most-efficient compared with least-efficient group had greater ( P  ≤ 0.05) expression of SLC9A1 , HIF1A , and ACO2 . The most-efficient compared with least-efficient heifers had greater ( P  ≤ 0.05) mRNA expression of BDH1 and lower expression ( P  ≤ 0.05) of SLC9A2 and PDHA1 ., Conclusions: The present study revealed that greater feed efficiency in beef cattle is associated with differences in bacterial species and transcriptional adaptations in the ruminal epithelium that might enhance nutrient delivery and utilization by tissues. The lack of RFI × sex interaction for growth performance and carcass traits indicates that sex may not play a major role in improving these phenotypes in superior RFI beef cattle. However, it is important to note that this result should not be considered a solid biomarker of efficient beef cattle prior to further examination due to the limited number of heifers compared with steers used in the study., Competing Interests: Ahmed A. Elolimy is PhD candidate, Department of Animal Sciences, University of Illinois, Urbana, Illinois, 61,801, USA. Mohamed K. Abdelmegeid is Lecturer in the Faculty of Veterinary Medicine, Kafrelsheikh University, Kafr El-Shaikh 33,516, Egypt. Joshua C. McCann is Assistant Professor in the Department of Animal Sciences, University of Illinois, Urbana, Illinois, 61,801, USA. Daniel W. Shike Loor is Associate Professor in the Department of Animal Sciences, University of Illinois, Urbana, Illinois, 61,801, USA. Juan J. Loor is Associate Professor in the Department of Animal Sciences, University of Illinois, Urbana, Illinois, 61,801, USA.All procedures for this study (protocol no. 12009) were approved by the Institutional Animal Care and Use Committee of the University of Illinois.Not applicable.The authors declare that they have no competing interests.

To determine the effects of repeated trace mineral injections on heifer development and reproductive performance, commercial Angus heifers (n = 290; 199 ± 34.3 kg; 221 ± 22 d of age) were utilized in a completely randomized design. Heifers were stratified by body weight (BW) and were administered an injectable trace mineral (MM; Multimin 90) or saline (CON) given subcutaneously, post-weaning at 221, 319, 401, and 521 ± 22 d of age. Throughout development, heifers grazed endophyte-infected fescue, red clover pastures and were supplemented with corn distillers grains (2.7 kg per heifer per day) and given access to free choice inorganic minerals. Heifer BW and body condition scores (BCS) were collected at trial initiation and 4- to 7-wk intervals thereafter. Hair coat scores (HCS) and respiration rates (n = 30 heifers per treatment) were collected at 269, 310, and 361 ± 22 d of age. Blood and liver samples were collected at trial initiation and estrous synchronization from 30 heifers per treatment to determine trace mineral status. At 319, 372, and 421 ± 22 d of age, antral follicle count and ovarian size were determined via ultrasonography. Two blood samples from all heifers were collected 10 d apart, concurrent with ultrasound dates, for cyclicity determination. Estrous synchronization was initiated, and reproductive tract scores (RTS) were collected at 421 ± 22 d of age, and heifers were bred via artificial insemination (AI) at 430 ± 22 d of age. Heifer BW, BCS, and HCS did not differ (P ≥ 0.12) throughout development, except at 268 ± 22 d of age when BCS was greater (P = 0.03) for MM than CON heifers. Respiratory rates were greater (P = 0.05) for MM than CON heifers at 269 ± 22 d of age but did not differ (P ≥ 0.66) at 310 and 361 ± 22 d of age. Plasma Mn and Zn concentrations did not differ (P ≥ 0.54). However, MM heifers had greater (P ≤ 0.01) plasma and liver concentrations of Cu and Se compared to CON. Interestingly, MM decreased (P = 0.02) liver Zn concentrations compared to CON, and there was no difference (P = 0.60) in liver Mn. Antral follicle count and ovarian size did not differ (P ≥ 0.51) due to treatment. Throughout development, number of heifers cycling was lesser (P < 0.01) for MM than CON heifers. However, there was no difference (P ≥ 0.19) in RTS, AI pregnancy rates, or overall pregnancy rates. Supplementing an injectable trace mineral increased heifer Cu and Se status; however, no effect was noted on ovarian development or pregnancy rates., (© The Author(s) 2018. Published by Oxford University Press on behalf of American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Our main objective was to evaluate the effects of feeding α-amylase (Amaize, Alltech Inc., Nicholasville, KY, USA) for 140 days on skeletal muscle and liver gene transcription in beef steers. Steers fed Amaize had lower average daily gain (p = .03) and gain:feed ratio (p = .05). No differences (p > .10) in serum metabolites or carcass traits were detected between the two groups but Amaize steers tended (p < .15) to have increased 12th rib fat depth. Microarray analysis of skeletal muscle revealed 21 differentially expressed genes (DEG), where 14 were up-regulated and seven were down-regulated in Amaize-fed steers. The bioinformatics analysis indicated that metabolic pathways involved in fat formation and deposition, stress response, and muscle function were activated, while myogenesis was inhibited in Amaize-fed steers. The quantitative PCR results for liver revealed a decrease (p < .01) in expression of fatty acid binding protein 1 (FABP1) and 3-hydroxybutyrate dehydrogenase 1 (BDH1) with Amaize. Because these genes are key for intracellular fatty acid transport, oxidation and ketone body production, data suggest a reduction in hepatic lipid catabolism. Future work to investigate potential positive effects of Amaize on cellular stress response, muscle function, and liver function in beef cattle appears warranted., (© 2018 Japanese Society of Animal Science.)

The objective was to evaluate the interaction of a trace mineral (TM) injection (Multimin 90) and a supranutritional concentration of dietary vitamin E (VITE) on performance, carcass characteristics, and color stability of strip steaks from feedlot heifers. Prior to trial initiation, Angus × Simmental cross heifers (N = 48) were managed on a common diet supplemented to meet the NRC recommendations. Heifers were stratified by BW and allotted to a 2 × 2 factorial arrangement: 1) no supplemental vitamin E and saline injection (CONT + SAL), 2) 1,000 IU vitamin E·heifer-1·d-1 and saline injection (VITE + SAL), 3) no supplemental vitamin E and TM injection (CONT + MM), or 4) vitamin E and TM injection (VITE + MM). Trace mineral injection contained 15, 10, 5, and 60 mg/mL of Cu, Mn, Se, and Zn, respectively, and TM injection or saline injection (1 mL/68 kg BW) were given on day 0 of the 89-d finishing period. All heifers were fed a common diet containing a basal concentration of 19.8 IU/kg DM vitamin E. Heifers were slaughtered and loins sections were collected. Strip steaks were cut and placed in overwrap trays for evaluation of color stability for 16 d. Data were analyzed using the MIXED procedure of SAS. Color stability data were analyzed as repeated measures. Neither TM injection nor VITE had an effect on final BW, DMI, or G:F (P ≥ 0.12). There was a tendency (P = 0.09) for TM injection to increase ADG. A tendency (P = 0.08) was observed for TM injection to increase DMI of heifers receiving supranutritional VITE. Trace mineral injection and VITE had no effect on HCW, yield grade, 12th-rib backfat thickness, or ribeye area (P ≥ 0.34). Marbling scores tended to increase (P = 0.08) in VITE heifers compared with control-fed heifers. Vitamin E supplementation decreased final lipid oxidation (1.00 vs. 1.97 µg malondialdehyde/g fat, P = 0.03) and total visual discoloration (15.82% vs. 33.96%, P = 0.04) of steaks compared with steaks from nonsupplemented heifers. Heifers fed supranutritional VITE produced steaks that maintained retail color longer shown by lower hue angle values (38.17° vs. 38.66°, P < 0.01) than nonsupplemented heifers. A TM injection × vitamin E × day interaction (P < 0.01) revealed by day 16 steaks from the CONT + MM heifers exhibited greater discoloration than VITE + SAL and VITE + MM steaks with CONT + SAL intermediate. Overall, VITE improved color stability and TM injection appeared to increase discoloration of strip steaks from feedlot heifers after day 14 of display.

Mature Simmental × Angus cows (214 cows; 635 ± 7 kg) were utilized to determine the effects of late gestation and early postpartum supplementation of methionine hydroxy analog (MHA) on cow BW, BCS, milk production, milk composition, reproduction, and calf performance until weaning in a fall-calving, cool-season grazing system. Cows were stratified by BW, age, AI sire, and assigned to 1 of 12 pastures (17 or 18 cows·pasture). Pastures were randomly allotted to 1 of 2 treatments: control (0.45 kg·cow·d of wheat midd-based pellets, = 6) or supplement including MHA (0.45 kg·cow·d of wheat midd-based pellets including 10 g MHA supplied as MFP (Novus International, Inc., St. Charles, MO; = 6). Treatments were fed 23 ± 7 d prepartum through 73 ± 7 d postpartum. Cow BW was collected at postcalving (27 ± 7 d postpartum), end of supplementation (73 ± 7 d postpartum), AI, pregnancy check, and end of trial (192 and 193 ± 7 d postpartum). At 73 ± 7 d postpartum, a subset of cow-calf pairs was used in a weigh-suckle-weigh procedure to determine milk production, and milk samples were taken to determine milk composition ( = 45·treatment). Serum from blood was collected at 73 ± 7 and 83 ± 7 d postpartum to determine cow cyclicity and concentrations of 2-hydroxy4-(methylthio) butanoic acid (HMTBa) and L-Methionine. After supplementation, all cow-calf pairs were managed as a common group until weaning (193 ± 7 d of age). Cows were bred via AI at 97 ± 7 d postpartum and clean-up bulls were turned out 11 d post-AI for a 55-d breeding season. Cows fed MHA had greater ( < 0.01) serum concentrations of HMTBa. Cow BW and BCS were not different ( ≥ 0.10) at any time points between treatments. There was no treatment effect ( ≥ 0.17) on calf birth BW, calf weaning BW (193 ± 7 d of age), or calf ADG. Calculated 24-h milk production, milk composition and component production did not differ ( ≥ 0.21). There were no differences ( ≥ 0.50) in percentage of cows cycling, AI conception rate, and overall pregnancy rate between treatments. Post-trial nutritional modeling suggests cows experienced several nutritional deficiencies beyond methionine (Met) that limited the response to Met supplementation. Although supplementation of MHA during late gestation through estimated peak lactation increased serum HMTBa concentrations, it did not affect cow performance, cow milk production, or calf performance when fall-calving cows grazed cool-season forages.

Three experiments were conducted at separate locations to determine the effects of a trace mineral injection (TMI), Multimin 90, on heifer performance and reproduction. In Exp. 1, [spring-born, Angus, n = 93, body weight (BW) = 428 ± 45.2 kg], Exp. 2 (spring-born, Angus × Simmental, n = 120, BW = 426 ± 54.0 kg), and Exp. 3 (fall-born, commercial Angus, n = 199, BW = 345 ± 39.7 kg) heifers were stratified by BW within experiment and assigned to 1 of 2 treatments: a control, saline injection, or TMI at a dose of 1 mL/68 kg BW. Free choice mineral, containing Cu, Mn, Se, and Zn formulated to meet or exceed NRC recommendations, was supplemented to heifers. Injections were given 33 d prior to breeding at the initiation of a 14-d controlled internal drug release (CIDR)-prostaglandin protocol. There was no difference ( P ≥ 0.37) in BW during Exp. 1. Additionally, there was no difference ( P ≥ 0.52) in body condition score (BCS) at initiation or at artificial insemination (AI) and final pregnancy confirmation in Exp. 1; however, a greater ( P = 0.03) BCS was noted for control heifers at breeding. Pregnancy rates to timed AI and overall pregnancy rates were also similar ( P ≥ 0.74) regardless of treatment. During Exp. 2, BCS and BW did not differ ( P ≥ 0.44) across treatments. There was a tendency ( P = 0.07) for TMI heifers to have an increased AI pregnancy rate (62 vs. 45%) compared with control heifers despite no difference ( P = 0.51) in overall pregnancy rate. In Exp. 3, BW was not different ( P ≥ 0.39) across all time points. Also, BCS did not differ ( P ≥ 0.45) at initiation, AI, or final pregnancy conformation. Interestingly, there was a tendency ( P = 0.10) for TMI heifers to have an increased BCS at the time of breeding compared with control heifers. However, there were no differences ( P ≥ 0.50) in AI and overall pregnancy rates. In 1 of 3 experiments, an injectable trace mineral administered 33 d prior to the breeding season in conjunction with a 14-d CIDR protocol, tended to increased AI conception rates of heifers even when adequate trace mineral supplement was provided. The variable response observed across experiments may be caused by differences in breed, calving season, mineral sources, and management strategies.

Five ruminally fistulated steers were used in a 5 × 5 Latin square design to determine the effects of increasing dietary fat and sulfur from condensed distiller's solubles (CDS) on the ruminal microbiome. Treatments included a corn-based control (CON) and 4 levels of CDS (0, 10, 19, and 27%) in a coproduct-based (corn gluten feed and soybean hulls) diet. Fat concentrations were 1.79, 4.43, 6.80, and 8.91% for diets containing 0, 10, 19, and 27% CDS, respectively. Steers were fed for ad libitum intake once daily. After feeding each diet for 18 d, ruminal samples were collected 3 h after feeding on d 19. Samples were separated into solid and liquid fractions. Microbial DNA was extracted for bacterial analysis using paired-end sequencing of the V3 through V4 region of the 16S rRNA gene on the MiSeq Illumina platform and quantitative PCR of selected species. Orthogonal contrasts were used to determine linear and quadratic effects of CDS inclusion. Increasing CDS inclusion decreased (linear, < 0.05) α-diversity and species richness in the liquid fraction. Analysis of Bray-Curtis similarity indicated a treatment effect ( = 0.01) in the liquid fraction. At the phyla level, relative abundance of Bacteroidetes decreased in steers fed increasing dietary inclusion of CDS as Firmicutes increased to 82% of sequences for the 27% CDS treatment. Family Ruminococcaceae increased (linear, < 0.01) 2-fold in the liquid fraction when feeding CDS increased from 0 to 27% CDS, yet genera tended ( = 0.09) to decrease in steers fed greater CDS. The most abundant family of sulfate-reducing bacteria, Desulfovibrionaceae, increased ( < 0.03) in the solid and liquid fraction in steers fed additional dietary CDS and sulfur. Relative abundance of family Veillonellaceae and were increased (linear, ≤ 0.02) in the solid fraction as steers were fed increasing CDS. There were no effects ( > 0.10) of feeding increasing dietary fat from CDS on fibroylytic genus in either fraction. Results demonstrate increasing fat and sulfur from CDS in a coproduct-based diet markedly alters the liquid fraction ruminal microbiome but does not elicit negative effects on relative abundance of identified fiber-fermenting bacteria.

Crossbred calves ( = 30; age = 95 ± 1.7 d; BW = 179 ± 18 kg) were fed 1 of 5 growing diets: 1) corn-based control, 2) low-fat, low-protein coproduct blend, 3) high-fat, low-protein coproduct blend, 4) low-fat, high-protein coproduct blend, and 5) high-fat, high-protein coproduct blend for 112 d (growing phase) followed by a common corn-based finishing diet (additional 112 d; finishing phase). Calves were biopsied at 0, 112, and 224 d for transcriptional analysis via real-time quantitative PCR of 14 genes associated with adipogenesis and lipogenesis within the muscle. Serum was collected at d 0, 112, and 224 and analyzed for leptin, IGF-1, and GH concentration. Treatments were arranged in a 2 × 2 factorial. Data were analyzed using the MIXED procedures of SAS (SAS Inst. Inc., Cary, NC) to ascertain the effects of 2 protein levels, 2 fat levels, time, and any interactions. Increased protein and decreased fat in the growing diet resulted in a carryover effect that increased ( 0.01) gene expression of PPARγ, insulin-induced gene 1, thyroid hormone responsive SPOT14 protein, ATP citrate lyase, adiponectin, diacylglycerol O-acyltransferase homologue 2, fatty acid binding protein 4, fatty acid synthase, phosphoenolpyruvate carboxykinase 1, and stearoyl-CoA desaturase as well as serum leptin concentrations between d 112 and 224. Expression of sterol regulatory element binding transcription factor 1 was increased ( 0.01) at d 112 in steers fed high-protein, high-fat diets compared to those fed high-protein, low-fat diets. A fat × day interaction ( 0.01) occurred for the expression of adiponectin receptor 2 and CCAAT/enhancer binding protein alpha, resulting in a carryover effect wherein low-fat diets fed during the growing phase increased expression of both genes at the end of the finishing phase (d 224). After slaughter, cattle fed the control during the growing phase tended ( 0.09) to have greater marbling scores, whereas other carcass parameters were not different ( ≥ 0.13). These data indicate that feeding differing levels of dietary fat and protein during the growing phase does affect i.m. adipogenesis at the transcriptional level, but differences in gene expression were not sufficient to affect carcass quality among cattle fed coproducts.

Background: Single nucleotide polymorphism (SNP) arrays for domestic cattle have catalyzed the identification of genetic markers associated with complex traits for inclusion in modern breeding and selection programs. Using actual and imputed Illumina 778K genotypes for 3887 U.S. beef cattle from 3 populations (Angus, Hereford, SimAngus), we performed genome-wide association analyses for feed efficiency and growth traits including average daily gain (ADG), dry matter intake (DMI), mid-test metabolic weight (MMWT), and residual feed intake (RFI), with marker-based heritability estimates produced for all traits and populations., Results: Moderate and/or large-effect QTL were detected for all traits in all populations, as jointly defined by the estimated proportion of variance explained (PVE) by marker effects (PVE ≥ 1.0%) and a nominal P-value threshold (P ≤ 5e-05). Lead SNPs with PVE ≥ 2.0% were considered putative evidence of large-effect QTL (n = 52), whereas those with PVE ≥ 1.0% but < 2.0% were considered putative evidence for moderate-effect QTL (n = 35). Identical or proximal lead SNPs associated with ADG, DMI, MMWT, and RFI collectively supported the potential for either pleiotropic QTL, or independent but proximal causal mutations for multiple traits within and between the analyzed populations. Marker-based heritability estimates for all investigated traits ranged from 0.18 to 0.60 using 778K genotypes, or from 0.17 to 0.57 using 50K genotypes (reduced from Illumina 778K HD to Illumina Bovine SNP50). An investigation to determine if QTL detected by 778K analysis could also be detected using 50K genotypes produced variable results, suggesting that 50K analyses were generally insufficient for QTL detection in these populations, and that relevant breeding or selection programs should be based on higher density analyses (imputed or directly ascertained)., Conclusions: Fourteen moderate to large-effect QTL regions which ranged from being physically proximal (lead SNPs ≤ 3Mb) to fully overlapping for RFI, DMI, ADG, and MMWT were detected within and between populations, and included evidence for pleiotropy, proximal but independent causal mutations, and multi-breed QTL. Bovine positional candidate genes for these traits were functionally conserved across vertebrate species.

Very little is known regarding the effects of cow exposure to toxic ergot alkaloids in late gestation and the subsequent, long-term effects on progeny. Therefore, the objectives were to determine the effects of grazing toxic endophyte-infected tall fescue () or novel endophyte-infected tall fescue during late gestation on cow BW, BCS, hair coat score (HCS), respiration rates, milk production, and reproduction and on growth performance and carcass characteristics of progeny. Eighty gestating, Angus × Simmental cows (age = 6.68 ± 0.32 yr; 588 ± 16 kg initial BW; initial BCS = 5.66 ± 0.28) were stratified by initial BW and allocated into 8 pasture groups (10 cows/group) with 4 groups per treatment. Each group was allotted to 1 of 2 grazing treatments: toxic endophyte-infected tall fescue ('Kentucky-31'; E+) or novel endophyte-infected tall fescue ('Jesup MaxQ'; NOV). Cows were placed on grazing treatments at 110 ± 6 d prepartum (May 28, 2014) and remained on treatment until the end of the calving period (October 8, 2014; 23 ± 6 d postpartum). Cow BW and BCS did not diverge ( ≥ 0.15) at any time point among grazing treatments. However, cows grazing E+ had increased ( < 0.05) respiration rates and HCS and reduced ( < 0.05) prolactin concentration compared with cows grazing NOV. Calf birth BW, Julian calving date, milk production, AI conception rate, and overall pregnancy rate did not differ ( ≥ 0.23) by grazing treatment. In a subsequent grazing period of the progeny, dam grazing treatment did not affect ( ≥ 0.14) respiration rates, HCS, or prolactin concentration of the progeny when all progeny grazed E+ pastures. However, progeny born to dams grazing NOV tended ( > 0.06 to ≤0.10) to have increased BW at 70 ± 6 d of age, 205 d (adjusted weaning BW), and throughout the postweaning calf grazing period. Despite a tendency for BW to differ throughout the postweaning calf grazing period, finishing phase performance and carcass characteristics of progeny did not differ ( ≥ 0.20) between dam grazing treatment. In conclusion, results indicate that by the time progeny enter the feedlot and are finished on a high-grain diet, any fetal programming effects are minimal.

Objectives of this experiment were to: 1) determine appropriate test length, timing, and repeatability of DMI, ADG, and efficiency over different biological time points; 2) determine the efficacy of using decoupled performance and intake data to generate accurate feed efficiency measures; and 3) determine the relationship between forage-and grain-feed efficiency measures. Over 2 yr, Charolais crossbred heifers ( = 308) and steers ( = 320) were fed for two 70 d periods and DMI, ADG, and 12th rib fat thickness were recorded. Steers were fed grain-based diets during the growing and finishing periods to determine the effects of test period and timing on DMI and feed efficiency. Heifers were fed forage during the growing period and grain during the finishing period to test the effect of diet type on measures of DMI and feed efficiency. For each 70 d test period, individual DMI was recorded using the GrowSafe (Airdrie, AB) system. Residual feed intake (RFI) was calculated for each test period. Total feeding period ADG (FP&#95;ADG) was calculated for steers by regressing all weights taken from feedlot arrival to final BW, which was calculated by dividing HCW by a standard dressing percentage (63%). Dry matter intake and RFI were correlated (r 0.56; < 0.01, and 0.63; < 0.01, respectively) for the growing and finishing periods of grain-fed steers. Average daily gain was not repeatable ( = 0.11; 0.06) across both test periods for steers. However, growing and finishing ADG were correlated ( = 0.58; < 0.01, and = 0.69; < 0.01, respectively) to FP&#95;ADG. To assess the potential of shortening the intake test, DMI was analyzed in 7 d increments for grain-fed steers during the growing and finishing periods. Regardless of test length, from 7 to 70 d, DMI was strongly correlated ( ≥ 0.87; < 0.01) to total DMI during the growing period. Heifer forage DMI was correlated ( = 0.58; < 0.01) to grain DMI; subsequently, forage and grain RFI were moderately correlated ( = 0.40; < 0.01). This study suggests that DMI is repeatable across varying stages of maturity in cattle, and accurate feed efficiency measures can be obtained in either the growing or finishing period. The relationship of forage and grain DMI and efficiency in heifers suggests that measures of DMI and feed efficiency in heifers are relevant, regardless of diet fed. Intake evaluation periods can be shortened with minimal effects on the accuracy of predicting individual animal DMI.

Spring-calving cows ( = 49) were used to investigate the effects of excessive prepartum dietary protein intake on late gestation cow performance as well as subsequent progeny growth, carcass characteristics, and plasma glucose and insulin concentrations. Treatments were formulated to be isocaloric and provide 100% (REQ) or 129% (HP) of CP requirement. Treatments were limit-fed 78 ± 12 d prepartum to calving. All cows were fed a common diet postpartum. Cow BW and BCS were recorded at initiation of treatments and within 48 h post-calving. Milk production was estimated via the weigh-suckle-weigh technique 69 ± 11 d postpartum. Calf BW was measured at birth and at weaning (121 ± 11 d of age). Progeny ( = 42) were weaned as a group and placed into a feedlot and fed a common finishing diet. Glucose and insulin concentrations were analyzed on a subset of progeny (12 per treatment) 90, 120, 150, 180, 210, and 240 min post-feeding, 2 d before slaughter (342 ± 11 d of age). Treatment had no effect ( ≥ 0.22) on cow BW, BCS, milk production, and subsequent reproduction or progeny preweaning growth. Progeny finishing growth and marbling scores were not affected ( ≥ 0.24) by treatment, yet 12th rib fat thickness ( < 0.01), KPH ( = 0.04), and YG ( = 0.01) were greater for progeny born to HP dams. Progeny born to HP dams had decreased ( ≤ 0.01) glucose and insulin concentrations, and insulin to glucose ratios, indicating greater insulin sensitivity. Although feeding cows 129% of CP requirement during late gestation did not affect cow performance or progeny preweaning or finishing period growth; carcass adiposity was increased by maternal treatment.

Objectives were to determine the effects of chromium propionate supplementation on growth performance, insulin and glucose metabolism, and carcass characteristics of beef cattle. Steers ( = 34) were stratified by BW and assigned to 1 of 2 treatments: 1) no supplemental Cr (Cont) or 2) 3 mg supplemental Cr·steer·d (CrP). Both supplements, Cont and CrP, were delivered via 0.454 kg ground corn top-dressed on the basal diet. There was no effect ( ≥ 0.45) of CrP on ADG, DMI, G:F, or final BW. However, steers fed CrP needed more ( = 0.10) days on feed (DOF) to achieve the same carcass back fat (BF) as steers fed Cont. There were no effects ( ≥ 0.41) of CrP on HCW, BF, or KPH. Steers fed CrP had increased ( = 0.01) dressing percentage (DP) and tended to have a 4.21 cm greater LM area ( = 0.15), decreased marbling scores ( = 0.11), and decreased intramuscular fat ( = 0.11) compared to steers fed Cont. There were no differences ( ≥ 0.25) in quality or yield grade distributions. A glucose tolerance test was conducted early (21 DOF) and late (98 DOF) in the finishing phase. There was a feedlot treatment (FT) × time × DOF interaction ( = 0.08) for glucose concentrations, but no other interactions ( ≥ 0.21) for glucose or insulin concentrations. There were no FT × DOF interactions ( ≥ 0.21) for insulin area under the curve (iAUC), insulin:glucose ratio, insulin or glucose baseline, or peak insulin or glucose concentrations. At 21 DOF, steers fed CrP had decreased glucose area under the curve (gAUC; = 0.01), decreased glucose clearance rate (; = 0.02), and increased glucose half-life (T; = 0.07) compared to steers fed Cont; however, by 98 DOF, no differences were observed between treatments. At 98 DOF, all steers, regardless of treatment, had increased ( < 0.01) peak glucose and insulin, , iAUC, insulin:glucose ratio, and baseline insulin when compared to values at 21 DOF, but gAUC and T decreased ( < 0.01). Although steers fed CrP tended ( = 0.11) to have increased baseline glucose concentrations compared to steers fed Cont, CrP supplementation did not affect ( ≥ 0.17) other measures of glucose or insulin. Results of this study indicate that CrP increased DP and tended to increase LM area but tended to decrease intramuscular fat, with no effect on growth performance. With increased DOF, all steers became more insulin resistant, using more insulin to clear less glucose, and these effects were not mitigated by CrP supplementation.

The main objective was to evaluate if different planes of maternal nutrition during late gestation and weaning age alter microRNA (miRNA) and target gene expression in offspring longissimus muscle (LM). Early (EW) and normal weaned (NW) Angus × Simmental calves (n = 30) born to cows that were grazing endophyte-infected tall fescue and red clover pastures with no supplement [low plane of nutrition (LPN)], or supplemented with 2.3 and 9.1 kg of dried distiller's grains with solubles and soy hulls [medium and high plane of nutrition (MPN, HPN), respectively] during the last 105 ± 11 days of gestation were used. Biopsies of LM were harvested at 78 (early weaning), 187 (normal weaning) and 354 days of age. Results indicate a role of pro-adipogenic miRNA in the control of adipogenesis in LM of NW-MPN steers between 78 and 187 days of age through upregulation of (1) miR-103 which inhibits CAV1, a protein that destabilizes INSR and leads to insulin resistance; (2) miR-143 which inhibits DLK1, a protein that inhibits adipocyte differentiation; and (3) miR-21 which impairs TGFBR2-induced inhibition of adipocyte differentiation. Among the studied anti-adipogenic miRNA, cow plane of nutrition resulted in downregulation of miR-34a expression in MPN steers compared with HPN and LPN at 78 days of age. Data for miR-34a provided a potential sign of epigenetic regulation of LM in beef offspring due to the cow plane of nutrition during late gestation.

Spring-calving, mature cows ( = 191 total) and their progeny were used to evaluate the effects of late gestation drylot rations differing in RUP and fat content on cow performance as well as performance and carcass characteristics of subsequent progeny. Cows were blocked by BW and anticipated calving date and assigned to 16 pens. Pens were randomly allotted to 1 of 2 treatments: limit-fed corn coproducts and ground cornstalks (COP; TDN = 64.4%, CP = 11.1%, RDP = 60.2% of CP, and fat = 5.1%) or limit-fed ground mixed, cool-season grass hay (HY; TDN = 55.7%, CP = 9.5%, RDP = 86.0% of CP, and fat = 2.3%). Treatments were limit fed as isocaloric, isonitrogenous rations from 88 ± 11 d prepartum to calving. All cows were fed a common diet postpartum. Cow BW and BCS were collected at the beginning of the feeding period, within 48 h after calving, and at breeding. Calf BW was collected at birth and at 64 ± 11 and 124 ± 11 d of age. Milk production was determined using the weigh-suckle-weigh technique at 64 ± 11 and 124 ± 11 d postpartum. At 124 ± 11 d of age, steers ( = 68) and nonreplacement heifer calves ( = 25) were weaned and placed on a common feedlot diet with individual feed intake monitored using GrowSafe. Feedlot calves were slaughtered at a commercial facility 35 ± 10 d after a minimum ultrasound 12-rib fat thickness estimation of 0.9 cm. After calving, cow BW was greater ( < 0.01) and BCS was greater ( < 0.01) for cows fed COP than for cows fed HY. Calf birth BW was greater ( = 0.04) for those born to cows fed COP with no difference ( = 0.43) in percentage of unassisted births across treatment. Cows fed HY were lighter ( < 0.01) at breeding with lower BCS ( = 0.03); nevertheless, overall pregnancy rate was not different ( = 0.80). No differences ( ≥ 0.22) in milk production were detected. For feedlot progeny, initial feedlot BW, final BW, and days on feed were not different ( ≥ 0.23), and as a result, no difference ( = 0.21) in feedlot ADG was detected. Feedlot DMI and G:F were not different ( ≥ 0.19) across treatments. Feedlot calf health was monitored with no differences ( ≥ 0.68) in morbidity and mortality observed. No differences ( ≥ 0.27) were detected for HCW, LM area, backfat, marbling score, yield grade, or KPH. Increased dietary RUP and fat content during late gestation increased cow BW and BCS but did not alter milk production, subsequent reproduction, or subsequent calf performance or carcass characteristics.

Fall-calving, mature Angus and Simmental × Angus cows ( = 251 total) and their progeny were used to evaluate the effects of late gestation dried distillers grains plus solubles (DDGS) supplementation on cow performance and progeny growth and carcass characteristics. Cows were blocked by breed and allotted to 12 tall fescue pastures (6.8 ha average). Pastures were randomly assigned to 1 of 2 treatments: cows were offered 2.1 kg DM DDGS·cow·d (SUP; CP = 23%, fat = 7%; = 6 pastures) or were not offered a supplement (CON; = 6 pastures) 69 ± 9 d before expected calving date. Cows remained on treatments until calving. Once weekly, cows that had calved were removed from treatment pastures and were moved to new tall fescue pastures (21.6 ha average) where cows from both treatments were comingled without further supplementation. Cows ( = 74) were removed from study for calving more than 30 d after expected calving date, calf loss and injury, or euthanasia. Cow BW and BCS were recorded at the beginning of the supplementation period, after calving, and at breeding. Calf BW was taken at birth and early weaning (82 ± 14 d of age). After weaning, 71 steer progeny (representative of dam breed and treatment pastures) were transitioned to a common feedlot diet with individual feed intake monitored using the GrowSafe feeding system. Steers were slaughtered at 47 ± 4 d after a minimum 12th rib fat thickness (back fat) estimation of 0.6 cm, with cattle being shipped in 3 groups. Forage availability was not different between treatments ( = 0.69). Cows offered SUP gained more BW and BCS ( ≤ 0.02) during the supplementation period. There were no differences ( ≥ 0.12) in calving date, calf birth or weaning BW, or preweaning ADG. Cow BW at breeding was not different ( = 0.19); however, BCS at breeding was greater ( < 0.01) for cows offered supplement. No differences ( ≥ 0.11) in milk production, AI conception, or overall pregnancy rate were detected. For steer progeny, initial feedlot BW, final BW, and days on feed were not different ( ≥ 0.35); no difference ( = 0.77) in feedlot ADG was detected. Feedlot DMI and G:F were not different ( ≥ 0.52) across treatments. No differences ( = 0.62) in morbidity were observed in the feedlot. No differences ( ≥ 0.19) were detected for HCW, LM area, marbling score, or yield grade. Prepartum DDGS supplementation improved cow BW and BCS but did not alter milk production, subsequent reproduction, or subsequent calf performance or carcass characteristics.

Objectives were to determine the interaction of prepartum dam supplement level and age at weaning on growth performance, glucose and insulin concentrations, and carcass characteristics of steers (134 steers in yr 1; 147 steers in yr 2). Mature, multiparous Angus × Simmental cows were used in a split-plot design that included 3 supplement levels (no supplement [NS], 2.16 kg·cow·d [LS], and 8.61 kg·cow·d [HS]) and 2 ages at weaning (78 ± 11 d of age [early weaned; EW] or 186 ± 11 d of age [normal weaned; NW]). Cows grazed endophyte-infected tall fescue/red clover pastures and were bunk fed supplement (70% dried distiller's grains plus solubles and 30% soybean hulls) 103 ± 11 d prepartum to 2 ± 11 d postpartum. Dam prepartum supplement level did not affect ( ≥ 0.29) finishing phase growth performance or morbidity. The percentage of steers grading Average Choice or greater was increased ( = 0.04) for steers from cows fed HS compared to the percentage of steers from cows fed NS. Early weaning increased ( < 0.01) finishing phase initial BW and final BW and reduced ( < 0.01) G:F compared to normal weaning. A year × wean interaction ( = 0.04) occurred for ADG; EW resulted in reduced ( < 0.01) ADG compared to NW in yr 2. At slaughter, EW steers had greater ( < 0.01) HCW, yield grade, and back fat than NW steers. A year × wean interaction ( ≤ 0.05) occurred for quality grade distribution; in yr 2, EW steers had a greater ( < 0.01) proportion of carcasses that graded Low Choice or greater and Average Choice or greater than carcasses from NW steers. The EW steers had greater ( ≤ 0.05) occurrence of single antibiotic treatments in yr 2 and mortality due to respiratory disease than NW steers. A trend for a year × wean interaction ( ≤ 0.07) occurred for plasma insulin concentration and insulin:glucose; EW steers had numerically greater plasma insulin concentrations and insulin:glucose than NW steers in yr 1. In conclusion, these data suggest that there is no interaction between maternal level of supplement during late gestation and age at weaning on steer finishing phase performance, glucose and insulin concentrations, and carcass yield and quality characteristics. Overfeeding supplement to the dam did not affect finishing phase growth performance but did improve quality grades of steers. Early weaning increased HCW and improved carcass quality. Both dam supplement level and age at weaning are effective strategies in increasing beef quality and are independent of each other.

Objectives were to determine the interaction of prepartum supplement level and age at weaning on cow BW, BCS, milk production, reproduction, and calf performance up to weaning in a fall-calving system over 2 yr. Mature, multiparous, Angus × Simmental cows (yr 1: 326 cows, 9 pastures, BW = 632 ± 67 kg, and BCS = 5.7 ± 0.58; yr 2: 383 cows, 9 pastures, BW = 606 ± 70 kg, and BCS = 5.8 ± 0.74) were used in a split-plot design that included 3 supplement levels-no supplement (NS), low supplement (LS; 2.16 kg∙cow∙d), or high supplement (HS; 8.61 kg∙cow∙d)-and 2 ages at weaning-78 ± 11 d of age (early weaned; EW) or 186 ± 11 d of age (normal weaned; NW). Cows grazed endophyte-infected tall fescue/red clover pastures and were bunk fed supplement (70% dried distillers' grains with solubles and 30% soybean hulls) 103 ± 11 d prepartum to 2 ± 11 d postpartum. Cow BW was greater ( < 0.01) for cows fed HS at precalving (49 ± 11 d prepartum), postcalving (26 ± 11 d postpartum), and postbreeding (81 d after AI) compared with cows fed NS and LS. Prepartum supplementation did not affect ( ≥ 0.62) calf birth BW, percent of calves dead at birth, or percent of cows calving unassisted. Prepartum supplementation tended ( = 0.10) to improve AI conception. Early weaning increased ( ≤ 0.05) AI conception and postbreeding cow BW and BCS compared with cows with NW calves. Neither prepartum supplementation nor age at weaning affected ( ≥ 0.28) overall pregnancy rate. At time of early weaning, BW was increased ( = 0.05) for steers from cows fed LS compared with steers from cows fed NS. Steer BW at time of normal weaning and ADG between early and normal weaning was greater ( < 0.01) for EW steers compared with NW steers. A year × age at weaning interaction occurred ( < 0.01) for ultrasound marbling score at time of normal weaning. In yr 1, marbling was decreased ( = 0.04) for EW steers compared with NW steers; however, in yr 2, marbling was increased ( < 0.01) for EW steers compared with NW steers. In conclusion, there was no interaction between level of supplement during late gestation and age at weaning on cow BW, BCS, milk production, AI conception, and overall pregnancy rate in mature beef cows nor in their steer progeny's BW or ultrasound marbling. Both prepartum supplementation and early weaning improved cow BW, BCS, and reproduction. Minimal effects of dam prepartum supplement level on calf performance up to weaning were observed. Early weaning improved calf growth but had inconsistent effects on ultrasound marbling across years.

The objectives of this study were to determine the effect of fat concentration from corn distillers' solubles (CDS), fed during the growing phase, on DMI, gain, carcass traits, digestibility, ruminal metabolism, and methane emissions of steers. In Exp. 1, 40 steers (age = 136 ± 20 d; BW = 185 ± 11 kg) were randomly allotted to 1 of 5 dietary treatments: 1) a cosrn-based gro\wing diet (CNT), 2) 0% CDS, 3) 10% CDS, 4) 19% CDS, or 5) 27% CDS. Diets 2 through 5 included coproducts (corn gluten feed and soybean hulls) and were formulated to achieve fat concentrations of 3, 5, 7, and 9%, respectively. Diets were fed once daily for 106 d (growing phase). All steers were fed a corn-based diet from d 107 to 196. Contrasts were used to examine 1) the difference between CNT and 10% CDS and 2) linear and quadratic effects of CDS inclusion. During the growing phase, steers fed CNT had increased ( < 0.01) ADG and G:F compared with steers fed 10% CDS. Increasing CDS inclusion increased (linear, ≤ 0.02) ADG and G:F. Overall, steers fed CNT had increased ( < 0.01) ADG compared with steers fed 10% CDS, but increasing CDS inclusion had no effect ( = 0.19) on overall ADG. Overall DMI and G:F were not different ( ≥ 0.16) in any contrast. There was a trend (Linear; = 0.08) for ultrasound marbling at d 196 to increase as CDS inclusion increased; however, there were no effects ( ≥ 0.20) of treatment on carcass marbling or quality grade. In Exp. 2, 5 steers (BW = 335 ± 56 kg) were fed Exp. 1 diets for ad libitum intakes in a 5 × 5 Latin square design. Apparent DM digestibility increased (linear, = 0.02) with increasing dietary CDS inclusion. Steers fed CNT had greater ( = 0.01) DM digestibility than those fed 10% CDS. Fat digestibility increased (linear, < 0.01) in steers with increasing CDS, but NDF and ADF digestibility were not affected ( ≥ 0.17) by treatment. Similarly, ruminal pH and VFA concentrations were not affected ( ≥ 0.13). Also, there was no difference ( ≥ 0.37) in ruminal methane emissions (g/h). In conclusion, feeding corn during the growing phase increased overall ADG compared with 10% CDS coproduct-based diet but did not affect carcass traits or methane production. Increasing dietary fat inclusion from CDS in coproduct-based diets linearly increased DM and fat digestibility and predicted marbling scores via ultrasound but did not affect marbling at slaughter, NDF digestibility, propionate, or methane production.

In model organisms both the nutrition of the mother and the young offspring could induce long-lasting transcriptional changes in tissues. In livestock, such changes could have important roles in determining nutrient use and meat quality. The main objective was to evaluate if plane of maternal nutrition during late-gestation and weaning age alter the offspring's Longissimus muscle (LM) transcriptome, animal performance, and metabolic hormones. Whole-transcriptome microarray analysis was performed on LM samples of early (EW) and normal weaned (NW) Angus × Simmental calves born to grazing cows receiving no supplement [low plane of nutrition (LPN)] or 2.3 kg high-grain mix/day [medium plane of nutrition (MPN)] during the last 105 days of gestation. Biopsies of LM were harvested at 78 (EW), 187 (NW) and 354 (before slaughter) days of age. Despite greater feed intake in MPN offspring, blood insulin was greater in LPN offspring. Carcass intramuscular fat content was greater in EW offspring. Bioinformatics analysis of the transcriptome highlighted a modest overall response to maternal plane of nutrition, resulting in only 35 differentially expressed genes (DEG). However, weaning age and a high-grain diet (EW) strongly impacted the transcriptome (DEG = 167), especially causing a lipogenic program activation. In addition, between 78 and 187 days of age, EW steers had an activation of the innate immune system due presumably to macrophage infiltration of intramuscular fat. Between 187 and 354 days of age (the "finishing" phase), NW steers had an activation of the lipogenic transcriptome machinery, while EW steers had a clear inhibition through the epigenetic control of histone acetylases. Results underscored the need to conduct further studies to understand better the functional outcome of transcriptome changes induced in the offspring by pre- and post-natal nutrition. Additional knowledge on molecular and functional outcomes would help produce more efficient beef cattle.

The number of animals required to represent the collective characteristics of a group remains a concern in animal movement monitoring with GPS. Monitoring a subset of animals from a group instead of all animals can reduce costs and labor; however, incomplete data may cause information losses and inaccuracy in subsequent data analyses. In cattle studies, little work has been conducted to determine the number of cattle within a group needed to be instrumented considering subsequent analyses. Two different groups of cattle (a mixed group of 24 beef cows and heifers, and another group of 8 beef cows) were monitored with GPS collars at 4 min intervals on intensively managed pastures and corn residue fields in 2011. The effects of subset group size on cattle movement characterization and spatial occupancy analysis were evaluated by comparing the results between subset groups and the entire group for a variety of summarization parameters. As expected, more animals yield better results for all parameters. Results show the average group travel speed and daily travel distances are overestimated as subset group size decreases, while the average group radius is underestimated. Accuracy of group centroid locations and group radii are improved linearly as subset group size increases. A kernel density estimation was performed to quantify the spatial occupancy by cattle via GPS location data. Results show animals among the group had high similarity of spatial occupancy. Decisions regarding choosing an appropriate subset group size for monitoring depend on the specific use of data for subsequent analysis: a small subset group may be adequate for identifying areas visited by cattle; larger subset group size (e.g. subset group containing more than 75% of animals) is recommended to achieve better accuracy of group movement characteristics and spatial occupancy for the use of correlating cattle locations with other environmental factors.

Angus×Simmental crossbred heifers (n=150) and steers (n=100) were used to evaluate 1 of 5 growing diets: 1) a corn-based growing diet (CRN); 2) a high-fat, high-protein coproduct blend; 3) a high-fat, low-protein coproduct blend; 4) a low-fat, high-protein coproduct blend; and 5) a low-fat, low-protein coproduct blend in a 2×2+1 factorial arrangement. Low-protein and low-fat diets were formulated to be isonitrogenous and isofat to CRN (16.0% CP and 3.0% fat), and high-protein and high-fat diets were formulated to have 20.0% CP and 5.0% fat, respectively. Calves were weaned at 85±1.2 d, blocked by weight, and allotted to pens (10 calves/pen) within sex (10 pens of steers and 15 pens of heifers). The objective of this experiment was to determine if the concentration of protein or fat or their interaction in coproducts used in growing diets fed to early-weaned calves affects feedlot performance or carcass composition. Starting on d 0, calves (141±1.2 d of age) were fed experimental diets for 112 d and then fed a common feedlot diet for an additional 112 d. Body weight, hip height, and ultrasound data were collected at the end of each 112-d feeding phase. Carcass data included HCW, LM area (LMA), 12th-rib back fat (BF), marbling score (MS), KPH, and USDA quality grade. There was no fat×protein interaction (P≥0.27); therefore, only main effects are discussed. No effects (P≥0.47) of CRN, protein, or fat were detected for BW at d 112 or 224. Increased dietary protein resulted in greater (P=0.04) ADG at d 112 compared to calves fed low protein. Feeding cattle CRN decreased (P=0.04) DMI and increased (P<0.01) G:F during the growing phase compared to coproducts. High-fat diets increased (P=0.05) BF in calves at d 112 compared to low-fat diets. High-protein diets decreased (P=0.02) ultrasound MS at d 112 compared to low-protein diets. Carcasses from cattle fed high-fat diets had greater (P=0.03) MS compared to those from cattle fed low-fat diets. No differences (P≥0.14) were observed for HCW, LMA, BF, KPH, or yield grade. These data indicate that final BW was unaffected by protein and fat content of growing calf diets but that increased dietary fat and low dietary protein increased MS.

Background: The identification of genetic markers associated with complex traits that are expensive to record such as feed intake or feed efficiency would allow these traits to be included in selection programs. To identify large-effect QTL, we performed a series of genome-wide association studies and functional analyses using 50 K and 770 K SNP genotypes scored in 5,133 animals from 4 independent beef cattle populations (Cycle VII, Angus, Hereford and Simmental×Angus) with phenotypes for average daily gain, dry matter intake, metabolic mid-test body weight and residual feed intake., Results: A total of 5, 6, 11 and 10 significant QTL (defined as 1-Mb genome windows with Bonferroni-corrected P-value<0.05) were identified for average daily gain, dry matter intake, metabolic mid-test body weight and residual feed intake, respectively. The identified QTL were population-specific and had little overlap across the 4 populations. The pleiotropic or closely linked QTL on BTA 7 at 23 Mb identified in the Angus population harbours a promising candidate gene ACSL6 (acyl-CoA synthetase long-chain family member 6), and was the largest effect QTL associated with dry matter intake and mid-test body weight explaining 10.39% and 14.25% of the additive genetic variance, respectively. Pleiotropic or closely linked QTL associated with average daily gain and mid-test body weight were detected on BTA 6 at 38 Mb and BTA 7 at 93 Mb confirming previous reports. No QTL for residual feed intake explained more than 2.5% of the additive genetic variance in any population. Marker-based estimates of heritability ranged from 0.21 to 0.49 for residual feed intake across the 4 populations., Conclusions: This GWAS study, which is the largest performed for feed efficiency and its component traits in beef cattle to date, identified several large-effect QTL that cumulatively explained a significant percentage of additive genetic variance within each population. Differences in the QTL identified among the different populations may be due to differences in power to detect QTL, environmental variation, or differences in the genetic architecture of trait variation among breeds. These results enhance our understanding of the biology of growth, feed intake and utilisation in beef cattle.

The objectives of this study were to determine the effects of feeding dried corn distillers grains (DDGS) or modified wet corn distillers grains (MDGS) with or without CaO treatment to feedlot steers on 1) growth performance and carcass characteristics and 2) diet digestibility, pattern of intake, and meal distribution. In Exp. 1, steers (n = 139; average initial BW = 336 ± 75 kg) were used in a randomized complete block design. Treatments were arranged in a 2 × 2 factorial design, and pens were randomly allotted to 1 of the 4 dietary treatments (DM basis): 1) 50% DDGS untreated, 2) 48.8% DDGS treated with 1.2% CaO, 3) 50% MDGS untreated, or 4) 48.8% MDGS treated with 1.2% CaO. The remainder of the diet was corn husklage, dry rolled corn, and vitamin and mineral supplement. In Exp. 2, fistulated steers (n = 8; average initial BW = 540 ± 250 kg) were used in a replicated 4 × 4 Latin square design with the same dietary treatments as in Exp. 1. There was no interaction (P ≥ 0.14) between distillers grains plus solubles (DGS) and CaO inclusion for DMI, ADG, final BW, or USDA yield and quality grades. However, steers fed CaO-treated DGS had decreased (P < 0.01) DMI, regardless of DGS type. Because CaO treatment decreased DMI without affecting (P = 0.66) ADG, steers fed CaO-treated DGS had increased (P < 0.01) G:F compared to steers not fed CaO. The variation in DMI found in this experiment could be explained by differences in meal size and distribution. Steers fed CaO-treated DGS ate a similar (P = 0.36) number of meals but ate smaller (P < 0.01) meals. No effects (P ≥ 0.55) of CaO treatment or its interaction with DGS type were found for apparent total tract DM or NDF digestibility. However, steers fed MDGS had increased (P < 0.01) NDF digestibility compared to steers fed DDGS. In conclusion, CaO treatment of DGS improved feed efficiency when DGS-based diets were fed but did not improve digestibility.

Adipogenic/lipogenic transcriptional networks regulating intramuscular fat deposition (IMF) in response to weaning age and dietary starch level were studied. The longissimus muscle (LM) of beef steers on an early weaning (141 days age) plus high-starch diet (EWS) or a normal weaning (NW, 222 days age) plus starch creep-feed diet (CFS) was biopsied at 0 (EW), 25, 50, 96 (NW), 167, and 222 (pre-slaughter) days. Expression patterns of 35 target genes were studied. From NW through slaughter, all steers received the same high-starch diet. In EWS steers the expression of PPARG, other adipogenic (CEBPA, ZFP423) and lipogenic (THRSP, SREBF1, INSIG1) activators, and several enzymes (FASN, SCD, ELOVL6, PCK1, DGAT2) that participate in the process of IMF increased gradually to a peak between 96 and 167 days on treatment. Steers in NW did not achieve similar expression levels even by 222 days on treatment, suggesting a blunted response even when fed a high-starch diet after weaning. High-starch feeding at an early age (EWS) triggers precocious and sustained adipogenesis, resulting in greater marbling.

A 4-yr study was conducted using 736 steers of known Angus, Simmental, or Simmental × Angus genetics to determine performance, carcass, and feed efficiency factors that explained variation in economic performance. Steers were pen fed and individual DMI was recorded using a GrowSafe automated feeding system (GrowSafe Systems Ltd., Airdrie, Alberta, Canada). Steers consumed a similar diet and received similar management each year. The objectives of this study were to: 1) determine current economic value of feed efficiency and 2) identify performance, carcass, and feed efficiency characteristics that predict: carcass value, profit, cost of gain, and feed costs. Economic data used were from 2011 values. Feed efficiency values investigated were: feed conversion ratio (FCR; feed to gain), residual feed intake (RFI), residual BW gain (RG), and residual intake and BW gain (RIG). Dependent variables were carcass value ($/steer), profit ($/steer), feed costs ($/steer • d(-1)), and cost of gain ($/kg). Independent variables were year, DMI, ADG, HCW, LM area, marbling, yield grade, dam breed, and sire breed. A 10% improvement in RG (P < 0.05) yielded the lowest cost of gain at $0.09/kg and highest carcass value at $17.92/steer. Carcass value increased (P < 0.05) as feed efficiency improved for FCR, RG, and RIG. Profit increased with a 10% improvement in feed efficiency (P < 0.05) with FCR at $34.65/steer, RG at $31.21/steer, RIG at $21.66/steer, and RFI at $11.47/steer. The carcass value prediction model explained 96% of the variation among carcasses and included HCW, marbling score, and yield grade. Average daily gain, marbling score, yield grade, DMI, HCW, and year born constituted 81% of the variation for prediction of profit. Eighty-five percent of the variation in cost of gain was explained by ADG, DMI, HCW, and year. Prediction equations were developed that excluded ADG and DMI, and included feed efficiency values. Using these equations, cost of gain was explained primarily by FCR (R(2) = 0.71). Seventy-three percent of profitability was explained, with 55% being accounted for by RG and marbling. These prediction equations represent the relative importance of factors contributing to economic success in feedlot cattle based on current prices.

This study was conducted to evaluate maternal breed effects, direct breed effects, and individual heterosis on subsequent steer performance, carcass, and feed efficiency traits. This was a consecutive 2-yr trial using 158 steers. The same dam breeds, Angus (AN) and purebred Simmental (SM), were used both years. Also, the same AN and SM sires (n=11) were used both years. Steers were AN, SM, or AN×SM breed composition. Steers were managed similarly before weaning and early weaned at 56±9 d of age. Steers were then randomly allotted to pens and fed a common finishing ration. Contrasts were written to evaluate direct and maternal breed effects and individual heterosis in the PROC MIXED procedure of SAS (SAS Inst. Inc., Cary, NC) using dam breed, sire breed, and year as fixed effects. Simmental direct breed effect resulted in a 26 kg heavier initial BW (P<0.05) and a 46 kg heavier final BW (P<0.05). Simmental maternal breed effect increased initial BW by 43.5 kg (P<0.05). Dry matter intake was not impacted by direct breed effects, maternal breed effects, or individual heterosis. Individual heterosis did improve G:F 3.4% (P<0.05) and residual BW gain 0.048 kg/d (P<0.05). Residual intake and BW gain tended (P=0.07) to improve as a result of individual heterosis. Residual feed intake (RFI) was impacted by direct breed effect with SM cattle having a more desirable RFI (P=0.05). Angus direct breed effect increased backfat (P<0.05) and improved marbling score by 126 units (P<0.05). Simmental direct breed effect increased LM area (P<0.05), had the highest HCW at 410 kg (P<0.05), and had the most desirable yield grade at 2.74 (P<0.05). Individual heterosis improved marbling score (P=0.05). Maternal breed effect increased HCW (P<0.05) as a result of the SM dam. Direct breed effects were present for performance, feed efficiency measures, and carcass traits. Overall, heterosis impacted feedlot performance, carcass characteristics, and feed efficiency, which impacts beef production.

Transcriptome dynamics in the longissimus muscle (LM) of young Angus cattle were evaluated at 0, 60, 120, and 220 days from early-weaning. Bioinformatic analysis was performed using the dynamic impact approach (DIA) by means of Kyoto Encyclopedia of Genes and Genomes (KEGG) and Database for Annotation, Visualization and Integrated Discovery (DAVID) databases. Between 0 to 120 days (growing phase) most of the highly-impacted pathways (eg, ascorbate and aldarate metabolism, drug metabolism, cytochrome P450 and Retinol metabolism) were inhibited. The phase between 120 to 220 days (finishing phase) was characterized by the most striking differences with 3,784 differentially expressed genes (DEGs). Analysis of those DEGs revealed that the most impacted KEGG canonical pathway was glycosylphosphatidylinositol (GPI)-anchor biosynthesis, which was inhibited. Furthermore, inhibition of calpastatin and activation of tyrosine aminotransferase ubiquitination at 220 days promotes proteasomal degradation, while the concurrent activation of ribosomal proteins promotes protein synthesis. Therefore, the balance of these processes likely results in a steady-state of protein turnover during the finishing phase. Results underscore the importance of transcriptome dynamics in LM during growth.