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This experiment compared performance, health, and physiological responses of high-risk stocker cattle receiving a Bacillus subtilis derivative during a 90-d grazing period. Crossbred steers (n = 120) were obtained from an auction yard and transported to the experimental facility. Steer shrunk body weight (BW) was recorded at arrival (d -1). This value was averaged with BW recorded on d 0 to represent initial BW (236 ± 2 kg). On d 0, steers were ranked by BW and allocated to 1 of 12 pastures (4-ha pastures; 10 steers/pasture). Pastures were randomly assigned to receive daily supplementation with dried distillers' grains at 1% of BW containing either: 1) Bacillus licheniformis and B. subtilis ingredient (BOV; 2 g/steer daily of Bovacillus, Chr Hansen A/S, Horsholm, Denmark) or 2) no additive (CON). Cattle received treatments from d 0 to 90 while housed in pastures containing stockpiled grass forage, as well as free-choice access to water and a commercial mineral + vitamin mix without ionophores. Steers were assessed for bovine respiratory disease (BRD) signs daily, and shrunk BW recorded on d 91. Blood samples were collected, and BW recorded on d 0, 14, 28, 56, and 90. No treatment differences were detected (P ≥ 0.19) for glucose, non-esterified fatty acids, P-hydroxybutyrate, haptoglobin, or insulin-like growth factor 1, whereas a treatment x day interaction indicated increased cortisol in BOV cattle on d 56 (P < 0.01). A treatment x day interaction was detected for serum concentrations of parainfluenza type 3 antibodies, which was greater in BOV steers on d 90 (P < 0.01). No treatment differences were detected (P ≥ 0.23) for serum concentrations of antibodies against other BRD pathogen. Average daily gain (ADG) tended to be increased (P = 0.09) in BOV compared with CON steers from d 56 to d 90 (0.858 and 0.760 kg/d, respectively, although did not impact overall ADG (P = 0.48). No treatment differences were detected for steer final BW (P = 0.43). Total BW change per pasture was greater in BOV compared with CON (790 vs. 550 kg BW change; P = 0.02). No treatment differences were detected (P = 1.00) for BRD incidence, although steers removed from the experiment for health reasons tended to be increased in CON compared with BOV (P = 0.08). Despite lacking differences in health or physiological responses, B. licheniformis and B. subtilis supplementation increased overall production of BW in high-risk stocker steers during a 90-d grazing period. [ABSTRACT FROM AUTHOR]

This experiment evaluated growth and reproductive development of beef heifers reared at a high stocking density and provided with access to an exercise area. The experiment was replicated over 2 yr, with a total of 180 Angus x Brahman heifers. Each year, 90 heifers were ranked by age (264 ± 1 d) and body weight (BW; 200 ± 2 kg) on d 0, and assigned to a) 1 of 6 drylot pens (10 x 14 m pens; 10 heifers/pen) resulting in a stocking density of 14 m²/heifer (DENS), or b) 1 of 3 paddocks (2-ha paddocks; 10 heifers/paddock) resulting in a stocking density of 2,000 m²/heifer (CON). On d 15, 3 DENS pens were randomly selected and given access to an exercise area (DENS-EX) for 1 h three times weekly. Negligible forage was available for CON heifers, whereas all heifers received the same limit fed diet which averaged 13 kg/heifer daily of a corn-based diet. Heifer shrunk BW was recorded after 16 h of feed and water withdrawal on d -3 and 225 for BW gain calculation. Heifer temperament (chute score, exit velocity, and temperament score) were evaluated on d 0 and 225. Heifers were also fitted on d 0 with a pedometer behind their shoulder and an ear tag (CowManager, Select Sires, Plain City, OH) to record behavioral responses. Each week, pedometer results were recorded, and blood samples were collected for puberty evaluation via plasma progesterone. Heifers from CON had more (P < 0.05) steps per week compared with DENS and DENS-EX (23,973, 6,706, and 12,354 steps/week, respectively; SEM = 1,247), and DENS-EX heifers had more (P < 0.05) steps per week compared with DENS. Heifers from CON spent more (P < 0.05) time ruminating and eating compared with DENS and DENS-EX. No treatment effects (P > 0.91) were detected for heifer BW gain (0.820, 0.815, and 0.824 kg/d for CON, DENS, and DENS-EX, respectively; SEM = 0.016). Heifers from DENS had greater (P ≤ 0.05) exit velocity and temperament score on d 225 compared with DENS-EX and CON. Heifers from DENS experienced delayed puberty attainment (treatment x day; P < 0.01) compared with DENS-EX and CON. A greater (P ≤ 0.05) proportion of CON heifers were pubertal by day 105 compared with DENS and DENS-EX (30.0, 11.6, and 15.0%, respectively; SEM = 6.5), whereas a greater (P < 0.05) proportion of CON and DENS-EX heifers were pubertal by d 154 compared with DENS (61.7, 66.7, and 43.3%, respectively; SEM = 6.5). Results from this experiment demonstrate that providing heifers with an exercise area alleviated the negative effects associated with high stocking density on their reproductive development. This work is supported by the USDA-NIFA AFRI program (#2021-67015-34083). [ABSTRACT FROM AUTHOR]

This study evaluated the effects of maternal supplementation of Bacillus-based direct-fed microbials (DFM) on physiology and growth performance of Bos indicus-influenced cow-calf pairs. On d 0 (~139 d before expected calving date), 72 fall-calving, Brangus crossbred beef heifers (25 to 37.5% Bos indicus; 20 to 22 mo of age) pregnant with their first offspring were stratified by their initial body weight (BW; 431 ± 31 kg) and body condition score (BCS; 6.0 ± 0.36; scale 1 to 9), and randomly allocated into 1 of 12 bahiagrass pastures (1 ha and 6 heifers per pasture). Treatments were randomly assigned to pastures (6 pastures per treatment) and consisted of heifers supplemented with 1 kg/d of soybean hulls dry matter (DM) added (BAC) or not (CON) with a Bacillus-based DFM mixture (BovacillusTM; Chr. Hansen A/S, Horsholm, Denmark) from d 0 to 242 (139 ± 4 d prepartum to 104 ± 4 d postpartum). Calves were weaned on d 242 (96 ± 30 d of age) and then allocated into 1 of 16 drylot pens and limit-fed the same concentrate at 3.25% of BW until d 319. Maternal treatment effects were not detected (P ≥ 0.29) for herbage allowance, forage nutritive value, and heifer activity on pasture. Heifer BCS on d 39 and 63 tended (P ≤ 0.09) to be greater, whereas heifer BCS on d 91 was greater (P = 0.01) for BAC vs. CON heifers and did not differ (P ≥ 0.20) between treatments on d 179 and 242. Plasma concentrations of glucose did not differ from d 0 to 63 (P ≥ 0.14) but were greater (P = 0.005) on d 179 and tended (P = 0.09) to be greater on d 242 for BAC vs. CON heifers. First offspring BW at birth, ADG from birth to early weaning, and BW weaning did not differ (P ≥ 0.19), but BW at drylot exit (d 319) was greater (P = 0.05) for BAC vs. CON calves. Maternal treatment effects were not detected (P ≥ 0.42) for calf serum concentrations of IgG at birth, and post-vaccination plasma concentrations of glucose, cortisol and haptoglobin. However, serum titers against bovine respiratory syncytial virus (BRSV) were greater (P = 0.04) for BAC vs. CON calves on d 287, whereas seroconversion against parainfluenza 3 virus (PI-3) was greater (P < 0.01) for BAC vs. CON calves on d 271. Thus, maternal supplementation of Bacillus-based DFM increased prepartum BCS gain and postpartum plasma concentrations of glucose of heifers and led to positive carryover effects on post-weaning BW gain and some indicators of humoral immune response to vaccination in their first offspring. [ABSTRACT FROM AUTHOR]

This study compared the relative abundance of bacteria in the upper respiratory tract (RT) of newly received feedlot heifers according to incidence of bovine respiratory disease (BRD). Angus-influenced heifers (n = 76) were transported for 1,100 km (11 h) to the feedlot (d -1). At feedlot arrival (d 0), heifers were weighed [initial shrunk body weight (BW) = 234 ± 15 kg] and a nasal swab collected for analysis of the upper RT microbiome. Heifers were ranked by arrival BW and allocated into 6 pens on d 1 where they remained until d 55. Heifers were evaluated daily for BRD signs (d 0 to 55), and a final shrunk BW was recorded on d 56 (16-h feed and water deprivation). Heifers were classified according to number of antimicrobial treatments for BRD received (0, 1, or ≥ 2), or according to time of first incidence of BRD signs [no incidence (NOBRD), early incidence (EARLY; 4.1 ± 0.1 d), or late incidence (LATE; 18.5 ± 9.6 d). All data were analyzed using heifer as the experimental unit, the PROC MIXED procedure of SAS and Satterthwaite approximation to determine the denominator degrees of freedom for tests of fixed effects. The first model statement included the number of BRD treatments received, the second model statement included the time of first incidence of BRD signs. Average daily gain decreased linearly (P = 0.04) according to number of BRD treatments and was less (P = 0.04) in LATE and tended (P = 0.08) to be less in EARLY compared with NOBRD heifers. The abundance of the phyla Tenericutes increased linearly (P < 0.01), while the abundance of Firmicutes, Bacteroidetes, Actinobacteria, Verrucomicrobia, Spirochaetes, Euryarchaeota, Chlorobi, and Chloroflexi decreased linearly (P ≤ 0.05) according to number of BRD treatments. Heifers classified as EARLY had greater (P = 0.01) abundance of Tenericutes and less (P = 0.03) abundance of Firmicutes compared with NOBRD, as well as less (P ≤ 0.03) abundance of Euryarchaeota and Chloroflexi compared with both NOBRD and LATE heifers. The abundance of the genera Mycoplasma increased linearly (P < 0.01) while the abundance of Corynebacterium, Blautia, Jeotgalicoccus, Clostridium, and Dietzia decreased linearly (P ≤ 0.03) according to number of BRD treatments. Heifers classified as NOBRD had less (P = 0.01) abundance of Mycoplasma compared with EARLY, and greater (P ≤ 0.05) abundance of Corynebacterium, Jeotgalicoccus, Dietzia, and Planomicrobium compared with EARLY and LATE heifers. Collectively, heifers that developed BRD had altered upper RT microbiome at the time of feedlot arrival compared with heifers that remained healthy, particularly increased prevalence of Tenericutes phylum and Mycoplasma genera. Such differences in upper RT microbiome were heightened in heifers that developed BRD shortly after arrival, or that required multiple antimicrobial treatments. [ABSTRACT FROM AUTHOR]

This experiment compared performance, health, and physiological responses of weaned cattle receiving Bacillus subtilis derivative in a 90-d grazing period. Recently weaned Angus-influenced steers (n = 120) were obtained from an auction yard on d -1 and transported 150 km to research facility. Immediately after arrival on d -1, shrunk body weight (BW) was recorded and steers were grouped with access to native forage and water. On d 0, an additional body weight was recorded and combined with d -1 values to represent initial body weight (BW; 236 ± 2 kg). Steers were ranked according to initial BW and allocated to 1 of 12 pastures (4-ha pastures; 10 steers/pasture). Pastures were randomly assigned to receive daily supplementation with dried distillers grains at 1% of BW with either: 1) Bacillus subtilis ingredient (BOV; 2 g/steer daily of Bovacillus; Chr Hansen A/S, Horsholm, Denmark), or 2) no additive (CON). Cattle received treatments for the duration of the experiment (d 0 to d 90) while housed in pastures containing stockpiled native forage, primarily Cynodon dactylon and Paspalum dilatatum, as well as free-choice access to water and a commercial mineral + vitamin mix not including ionophores. Bovine respiratory disease (BRD) signs were assessed daily throughout the experimental period. Steer unshrunk BW was recorded on d 14, 28, 56, and 90 and shrunk BW recorded on d 91 added 8% shrink as final BW. Blood samples and fecal swabs were collected from all steers on d 0, 14, 28, 56, and 90. Average daily gain (ADG) was increased in BOV groups compared with CON (0.858 and 0.760 kg/d, respectively) from d 56 to d 90 (P = 0.09) although this BW gain was not sufficient to impact final BW. Steer BW did not differ between treatments for all days (P = 0.43). Incidence of BRD was within the expected range for high-risk stocker cattle, although the number of sick animals was not reduced due to BOV supplementation (P = 1.00). Steers not completing the trial due to health-related complications tended to be increased in CON vs. BOV (P = 0.08). Differences in percentage of steers not completing the experiment, in conjunction with treatment effects for ADG in the final third of the experiment, increased the production total BW per BOV pasture by 43% (790 vs. 550 kg BW change; P = 0.02). Bacillus subtilis supplementation was effective in increasing production BWt during a 90-d grazing period despite no observed difference in BRD incidence. [ABSTRACT FROM AUTHOR]

Components of the immune system, such as cytokines and chemokines, can influence female reproductive efficiency. Recently, studies have begun to characterize the influence of nutrition on cytokines and reproductive function. Characterizing the influence of nutritional components on shifting circulating cytokine concentrations will allow for a better understanding of reproductive efficiency in cattle. The objective of this study was to determine the effect of diet composition on cytokine concentrations in blood plasma in beef heifers. Using a 3 x 3 Latin square design, fifteen rumen-cannulated, pubertal Bos taurus-influenced heifers were fed a diet based on ranging concentrate percentages. Their treatment period consisted of 28-day feeding periods with a washout interval of 21 days. The treatment groups were fed 100% grass hay (high forage; HF), 60% grass hay with 40% corn-based concentrate (intermediate; INT), and 25% grass hay with 75% corn-based concentrate (high grain; HG) within their respective treatment group. Heifers were offered 2% of their body weight daily. Blood was collected on days 0 and 28 of the treatment period for cytokine analysis. Plasma cytokine concentrations were quantified using RayBiotech Quantibody Bovine Cytokine Array Q1 kit according to manufacturer instructions. Data analysis was conducted using orthogonal contrasts (linear and quadratic) with day 0 as independent covariates and heifers as the experimental unit. There were no significant quadratic contrasts. Concentrations of interferon gamma-induced protein 10 (IP-10) linearly decreased with an increased concentrate diet (P = 0.04). Concentrations of IP10 significantly differed for heifers consuming the HF diet versus the HG diet (3,069.5 ± 672.2 vs. 1,001.8 ± 669.3 pg/mL, respectively) and heifers consuming the INT diet versus the HG diet (2,886.8 ± 665.6 vs. 1,001.8 ± 669.3 pg/mL, respectively); however, there were no significant differences in IP10 concentrations between the HF and INT heifers. Interferon-gamma (IFNg) concentrations significantly differed between feeding periods with period 2 having the least circulating concentrations when compared with periods 1 and 3 (5.2 ± 66.2 vs. 183.4 ± 68.4 and 221.3 ± 67.8 pg/mL, respectively; P < 0.05). Additionally, monokine induced by gamma interferon (MIG) significantly differed by period with period 2 having the least circulating concentrations compared with periods 1 and 3 (862.2 ± 285.4 vs. 1675.8 ± 283.4 and 1,170.8 ± 286.9 pg/mL, respectively; P < 0.05). Interestingly, both IP10 and MIG are chemokines, or small cytokines with chemotactic functions, that are secreted by immune cells in response to IFNg. Results suggest that heifers consuming a high concentrate diet have decreased concentrations of circulating cytokines, specifically IP10. Additionally, in the current study, cytokines that were influenced were associated with IFNg. Further research is necessary to better comprehend the dietary influence on the immune system in developing heifers and how this is associated with reproductive efficiency. [ABSTRACT FROM AUTHOR]

This experiment evaluated reproductive and productive responses of beef cows receiving self-fed low-moisture blocks (LMB) enriched or not with Ca salts of soybean oil (CSSO) throughout the breeding season. Non-pregnant, suckling multiparous Angusinfluenced cows (n = 554) were assigned to a fixedtime artificial insemination (AI) protocol (day -10 to 0) followed by natural service (day 15 to 70). Cows were managed in 12 groups (46 ± 4 cows/group) maintained in individual pastures, and groups received LMB enriched with 25% (as-fed basis) of CSSO or ground corn (CON) from day -10 to 100. Both treatments were designed to yield a daily LMB intake of 0.454 kg/cow (as-fed basis). Groups were enrolled in an estrus-synchronization + fixed-time AI protocol from day -10 to 0 (AI occurred on day 0) of the experiment and beginning 15 days after AI cows were exposed to mature Angus bulls for 55 d. Pregnancy status was verified on day 55 and 100 of the experiment, and cows that gave birth during the initial two weeks were considered pregnant to fixed-time AI. Calf birthdate and weight was recorded during the subsequent breeding season. All calves were weaned at the same time, and a calf BW and age were recorded. Blood samples were also collected from a subsample of cows on days -10, 0 (fixed-time AI), and 55 (pregnancy diagnosis). All data were analyzed using group as the experimental unit and Satterthwaite approximation to determine the denominator df for the tests of fixed effects. Quantitative data were analyzed with the MIXED procedure of SAS, and binary data analyzed with the GLIMMIX procedure of SAS with a binomial distribution and logit link function. Data were analyzed with group (treatment x location), cow(group), and location as random variables. Significance was set at P ≤ 0.05 and tendencies were determined if P > 0.05 and ≤ 0.10. Cows receiving CSSO had greater (P < 0.01) mean concentrations of ω-6 fatty acids in plasma samples collected on days 0 and 55. Cows receiving CSSO had greater (P = 0.05) pregnancy rate to fixed-time AI (67.2 vs. 59.3%), whereas final pregnancy rate did not differ (P = 0.92) between treatments. Pregnancy loss was less (P = 0.03) in CSSO cows (4.50 vs. 9.04%), which also calved earlier during the calving season (treatment x week; P = 0.04). Weaning rate tended to be greater (P = 0.09) in CSSO (84.8 vs. 79.4%), although calf weaning age and weight did not differ (P ≥ 0.72) between treatments. Kilos of calf weaned/cow exposed was greater (P = 0.04) in CSSO cows (234 vs. 215 kg). Therefore, supplementing CSSO to beef cows via LMB during the breeding season improved their reproductive and overall productivity during a cow-calf cycle. [ABSTRACT FROM AUTHOR]

This experiment evaluated the physiological and reproductive responses of beef heifers reared at a high stocking density and provided with access to an exercise area. Ninety Angus × Brahman heifers were ranked by age (257 ± 2 days), body weight (BW; 216 ± 2 kg), and temperament score on day 0 and assigned to a) 1 of 6 drylot pens (10x14 m pens; 10 heifers/pen) resulting in a stocking density of 14 m2/heifer (DENS), or b) 1 of 3 paddocks (2-ha paddocks; 10 heifers/paddock) resulting in a stocking density of 2,000 m2/heifer (CON). On day 15, 3 DENS pens were randomly selected and given access to an exercise area (DENS-EX) for 1 hour three times weekly. Negligible forage was available for CON heifers, whereas all heifers received the same limit fed diet which averaged 13 kg/heifer daily of a corn-based diet. Heifer shrunk BW was recorded after 16 h of feed and water withdrawal on days -3 and 225 for average daily gain calculation. On day 0, heifers were fitted with a pedometer behind their shoulder and an ear tag (CowManager, Select Sires, Plain City, OH) to record behavioral responses. Each week, pedometer results were recorded, and blood samples were collected for puberty evaluation via plasma progesterone. Heifers from CON had more (P < 0.05) steps per week compared with DENS and DENS-EX, and DENS-EX heifers had more (P < 0.05) steps per week compared with DENS. Heifers from CON spent more (P < 0.05) time ruminating and eating compared with DENS and DENS-EX. No treatment effects (P = 0.12) were detected for heifer BW gain or temperament variables. Heifers from DENS experienced delayed puberty attainment given a greater (P < 0.05) proportion of CON heifers were pubertal by day 98 compared with DENS and DENS-EX, whereas a greater (P < 0.05) proportion of DENS-EX heifers were pubertal by day 154 compared with DENS heifers (treatment × day interaction, P < 0.01). Collectively, results from this experiment demonstrate that providing heifers reared at a high stocking density access to an exercise area does not result in similar reproductive responses as those reared on pasture at a low stocking density. This work is supported by the USDA National Institute of Food and Agriculture (#2021-67015-34083). [ABSTRACT FROM AUTHOR]

This study evaluated the growth and immune function of Bos indicus-influenced offspring born to cows offered prepartum supplementation of bakery waste containing 2 concentrations of crude fat. On day 0 (~90 d before calving), 108 Brangus crossbred cows were stratified by body weight (BW; 551 ± 65 kg) and body condition score (BCS, 5.5 ± 0.9) and were randomly allocated into 1 of 18 bahiagrass pastures (6 cows and 4.3 ha/pasture). Treatments were randomly assigned to pastures (6 pastures/treatment) and consisted of no prepartum supplementation (NOSUP) and 1 kg/d of low-fat (LFAT; 6.4% crude fat) or high-fat (HFAT; 10.7% crude fat) bakery waste-based supplement from day 0 to 70. Calves were weaned on day 292. Then, 15 heifers/treatment were randomly selected, acclimated for 7 d, and assigned to drylot pens from day 300 to 345. Heifers were vaccinated against respiratory pathogens on days 300 and 315. Cow BCS on day 70 was the least (P ≤ 0.05) for NOSUP cows and did not differ (P ≥ 0.12) between LFAT and HFAT cows. Cow BCS on day 140 (start of breeding season) was greater (P = 0.05) for HFAT vs. NOSUP cows and intermediate (P ≥ 0.35) for LFAT cows. Plasma concentrations of total polyunsaturated fatty acids (PUFA) in HFAT cows did not differ (P ≥ 0.76) compared with LFAT cows on day 70, were greater (P ≤ 0.05) compared with NOSUP cows on day 70 and were the greatest on day 140 (P ≤ 0.05). Percentage of cows pregnant on day 292 did not differ (P ≥ 0.26) among treatments but more HFAT cows calved (P ≤ 0.05) their second offspring from day 429 to 450 compared with NOSUP and LFAT cows. First offspring BW on day 292 were greatest (P ≤ 0.05) for LFAT calves and least for NOSUP calves. Maternal treatments did not impact (P ≥ 0.11) post-weaning average daily gain (ADG) and total DM intake. Average plasma cortisol concentrations were greater (P = 0.03) for NOSUP vs. HFAT heifers and intermediate for LFAT heifers (P ≥ 0.26). Final serum titers against infectious bovine rhinotracheitis (IBR) and bovine respiratory syncytial virus (BRSV) were greater (P ≤ 0.08) for LFAT vs. HFAT heifers and intermediate (P ≥ 0.27) for NOSUP heifers. Therefore, crude fat concentration in bakery waste offered to late-gestating beef cows had variable effects on offspring performance. Lowfat bakery waste led to greatest offspring preweaning growth whereas high-fat bakery waste enhanced maternal reproductive success and offspring post-weaning humoral immune response. [ABSTRACT FROM AUTHOR]

This experiment examined the effects of a synbiotic supplement (yeast-derived prebiotic + Bacillus subtilis probiotic), which replaced or was fed with feed-grade antimicrobials (monensin and tylosin), on performance and health responses of feedlot cattle. Angus-influenced steers (n = 192) from 4 different sources were weaned and transported 800 km to an experimental feedlot. Steers arrived on d 0 and a shrunk body weight (BW) was recorded. Steers were then ranked by source and shrunk BW and allocated to 1 of 24 drylot pens (8 steers/pen). Steers a received free-choice diet of 3 treatments: 1) monensin and tylosin (RT; 360 mg/steer/day from Rumensin and 90 mg/steer/day from Tylan; Elanco Animal Health, Greenfield, IN), 2) yeast-derived ingredient and B. subtilis probiotic (CC;8 g·steer-1·day-1 of Celmanax and 28 g·steer-1·day-1 of Certillus; Church and Dwight Co., Inc., Princeton, NJ), or 3) a combination of RT and CC (RTCC). Animals were adapted to diets in a stepwise manner which consisted of a receiving diet (d 0 to 56), two step-up diets (step-up: d 57 to 63; step-up 2: d 64 to 70), and a final diet (d 71 to slaughter). The cattle were slaughtered in four groups according to BW and balanced by treatments. More specifically, 33 steers were slaughtered on d 200, 33 steers on d 230, 63 steers on d 257, and 63 steers on d 285. Upon slaughter, hot carcass weight, backfat thickness, Longissimus muscle area, USDA marbling score, USDA yield/quality grades, and liver abscess score were recorded. Overall, feed intake during the duration of the experimental period (d 0 to slaughter) was greater (P < 0.01) in CC compared with RT and RTCC. However, no differences were observed for ADG (P = 0.61), final BW (P = 0.67), or morbidity (P = 0.15). With increases in intake but no differences in ADG the CC group had lower feed efficiency (P = 0.02) when compared with RT and RTCC. Upon slaughter, CC had higher marbling scores compared with RT (P = 0.04). Both the CC and RTCC cattle had larger Longissimus muscle area (P = 0.07) and more carcasses grading choice or better (P < 0.01) when compared with RT. Whereas, hot carcass weight, backfat thickness, and yield grade did not differ among treatments (P = 0.20). There was tendency observed for liver abscesses (P = 0.09) to be greater in CC compared with RT and RTCC. Overall, supplementing feedlot steers with RT and CC improved feed intake and some carcass measures despite the decreased feed efficiency experienced by these cattle but combining CC and RT did not yield any additional performance or health benefits. [ABSTRACT FROM AUTHOR]

This experiment compared performance and physiological responses of feedlot cattle receiving a saponin containing feed ingredient manufactured from purified extract of Yucca schidigera [Micro-Aid (MA); DPI Global, Porterville, CA] which replaced or was fed in conjunction with feed-grade antimicrobials. Yearling, Angus-influenced steers (n = 20) arrived at the experimental feedlot on d -19 and a shrunk body weight (BW; 309 ± 4 kg) was immediately recorded. Steers were ranked by BW and allocated to 4 groups of 30 steers each. Groups were housed in of 4 drylot pens equipped with GrowSafe automated feeding systems (4 bunks/pen) during the experiment (d -15 to 69). On d 0 groups were randomly assigned to receive a total mixed ration containing: monensin and tylosin (RT; 360 mg/steer daily from Rumensin and 90 mg/steer daily from Tylan; Elanco Animal Health, Greenfield, IN) and/or 4 g/steer daily of MA in a 2 × 2 factorial arrangement of treatments. During the experimental period non-supplemented (CON) steers received a total mixed ration containing no additives. Individual feed intake was recorded daily, and steer BW was recorded every 28 d and before slaughter. Steers were slaughtered according to BW and slaughter groups were balanced by treatments (36 steers on d 120, 36 steers on d 146, and 48 steers on d 174). Carcass traits were recorded upon slaughter. On d 55 eight rumen-cannulated heifers were housed with yearling steers (1 pair/pen). Pairs rotated among groups every 21 d, resulting in a 4 × 4 Latin Square design (n = 8 per treatment) with a 5-day washout between rotations. Rumen fluid was collected from pairs on d 55, 75, 90,110, 125, 145, 160, and 180 (beginning and end of each 21-day rotation) and pH was recorded immediately after collection. No RT × MA treatment interactions were detected (P > 0.10). Feed intake was decreased (P < 0.01) in steers receiving RT, whereas feed efficiency was greater (P = 0.02) in steers receiving RT. Carcass variables including hot carcass weight, backfat thickness, Longissimus muscle area, marbling, yield grade, and percent of carcasses grading choice or better did not differ among treatments (P = 0.17). Rumen fluid pH was greater (P = 0.04) in steers receiving RT. Steers receiving MA had greater (P = 0.03) rumen fluid pH and decreased (P = 0.04) rumen fluid viscosity. Collectively, supplementing feedlot cattle with Yucca schidigera extract improved rumen pH and viscosity, but failed to impact performance or carcass measures in feedlot cattle. [ABSTRACT FROM AUTHOR]

This experiment compared productive and physiological responses in feedlot cattle receiving a finishing diet that included Ca salts of palm oil (CSPALM), or a blend of Ca salts of palm, cottonseed, and soybean oils (CSMIX). Ninety yearling steers were housed in 15 pens equipped with Calan-gate feeders (6 steers/pen). Steers within each pen were ranked by shrunk body weight (BW; 410 ± 3.3 kg) on d 0 and assigned to receive a total-mixed ration (TMR) containing (as-fed basis) 2% of CSMIX (n = 30), 2% of CSPALM (n = 30), or no supplemental fat (CON; n = 30). Individual TMR intake was evaluated weekly. Blood samples were collected on d 0, 28, 56, 119, and 147. Samples of the Longissimus muscle (LM) were collected on d 84 via needle biopsy. Upon slaughter on d 148, hot carcass weight (HCW) was recorded and used to determine final BW (63% dressing), whereas one LM steak sample (2.54 cm) was removed from the right side of each carcass. Steer ADG was greater (P = 0.02) for CSMIX compared with CSPALM and tended to be greater (P = 0.09) for CSMIX compared with CON. Feed efficiency was greater (P = 0.05) for CSMIX compared with CSPALM and CON, and carcass LM area was less (P = 0.01) for CSPALM compared with CSMIX and CON. No treatment effects were detected (P = 0.21) for TMR intake, final BW, and other carcass merit traits including marbling. Mean plasma cholesterol concentrations were greater (P < 0.01) in CSMIX and CSPALM compared with CON, and expression of adipocyte fatty acid binding protein in the LM was greater (P = 0.04) in CSPALM compared with CSMIX and CON. No treatment effects were detected (P = 0.15) for plasma concentrations of glucose, insulin, insulin-like growth factor I, and leptin, nor for other LM genes associated with marbling and muscle growth. Concentrations of total fatty acids (FA) in plasma and in LM steaks were greater (P < 0.01) in CSMIX compared with CSPALM and CON, and greater (P < 0.01) in the LM steaks of CSPALM steers compared with CON. Moreover, steers receiving CSMIX had greater (P < 0.01) concentrations of polyunsaturated and ω-6 FA in plasma samples and LM steaks compared with CSPALM and CON. Collectively, supplementing CSMIX improved performance traits and FA profile in the LM of feedlot steers, but the same responses were not observed when CSPALM was offered. The advantages noted from CSMIX supplementation appear to be resultant from the nutraceutical benefits of increased polyunsaturated ω-6 FA supply to the finishing diet. [ABSTRACT FROM AUTHOR]

This experiment examined the effects of diet composition on rumen, vaginal, and uterine environments in beef heifers. Fifteen rumen-cannulated, pubertal Angus-influenced heifers were used in a replicated 3 x 3 Latin square design (28-d periods and 21-d washout intervals). Dietary treatments included (as-fed) diets based on 100% grass hay (HF), 61% grass hay + 39% corn-based concentrate (INT), or 25% grass hay + 75% corn-based concentrate (HG). Treatments were offered individually to heifers once daily at 2% of their body weight. Heifers also received 280 g/d of a mineral mix containing melengestrol acetate. Rumen, vaginal, and uterine fluid samples were collected on d 0 and 28 of each period for pH measurement. Data were analyzed using the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC) using results from d 0 as independent covariates, and heifer as the experimental unit. Rumen pH on d 0 did not differ (P = 0.97) among treatments (7.197, 7.194, and 7.188 for HF, INT, and HG, respectively; SEM = 0.038). Ruminal pH on d 28 was greater (P = 0.01) in HF compared with INT and HG (6.805, 6.628, and 6.380, respectively; SEM = 0.049), and greater (P < 0.01) in INT compared with HG. Vaginal and uterine pH on d 0 did not differ (P = 0.24) among HF, INT, and HG (6.914, 6.965, 6.780 of vaginal pH, respectively, SEM = 0.082; 6.644, 6.760, 6,592 of uterine pH, respectively, SEM = 0.079). Uterine and vaginal pH on d 28 also did not differ (P = 0.64) among HF, INT, and HG heifers (6.926, 6.937, 6.918 of vaginal pH, respectively, SEM = 0.051; 6.567, 6.507, and 6.457 of uterine pH, respectively, SEM = 0.084). Therefore, dietary composition impacted rumen pH of beef heifers as expected, but without consequences to their vaginal and uterine pH. [ABSTRACT FROM AUTHOR]

This experiment compared performance and health responses of feedlot cattle receiving a synbiotic supplement (yeast-derived prebiotic + Bacillus subtilis probiotic), which replaced or were fed in conjunction with feed-grade antimicrobials (monensin and tylosin) during a 56-d receiving period. Angus-influenced steers (n = 192) from 4 different sources were transported for 800 km, and arrived on the experimental feedlot on d 0 when shrunk body weight (BW) was recorded. Steers were ranked by source and shrunk BW, and were allocated to 1 of 24 drylot pens. Pens were assigned to receive a free-choice diet containing: 1) monensin and tylosin (RT; 360 mg/steer daily from Rumensin and 90 mg/steer daily from Tylan; Elanco Animal Health, Greenfield, IN), 2) yeast-derived ingredient and B. subtilis probiotic (CC; 18 g/steer daily of Celmanax and 28 g/steer daily of Certillus; Church and Dwight Co., Inc., Princeton, NJ), or 3) monensin and tylosin combined with yeast-derived and B. subtilis ingredients (RTCC) as in RT and CC. Feed intake was greater (P < 0.01) in CC compared with RT and RTCC cattle (7.34, 6.15, 6.22 kg of dry matter/head daily, respectively; SEM = 0.29). Average daily gain tended (P = 0.10) to be greater in CC compared with RT and RTCC cattle (1.23, 1.16, 1.16 kg/d, respectively; SEM = 0.03). Feed efficiency was less in CC compared with RT and RTCC cattle (0.160, 0.173, 0.171 kg/kg, respectively; SEM = 0.003). Incidence of bovine respiratory disease did not differ (P = 0.37) between treatments (25.9, 20.2, and 15.5% for CC, RT, and RTCC, respectively; SEM = 5.2) during the 56-d receiving period. Collectively, replacing RT with CC improved feed intake and BW gain during a 56-d receiving period, despite reducing feed efficiency. Combining RT and CC ingredients, however, did not yield additional productive and health benefits to receiving cattle. [ABSTRACT FROM AUTHOR]

Components of the immune system (e.g., cytokines and chemokines) can influence reproductive efficiency. Characterizing the influence nutrition has on shifts in circulating cytokine concentrations will allow for a better understanding of reproductive efficiency in beef cattle. This study aimed to determine the effect of diet composition on circulating cytokine concentrations of beef heifers. Using a 3 × 3 Latin square design, pubertal Bos taurus -influenced rumen-cannulated heifers ( n  = 15) were fed a diet based on different concentrate percentages. The treatment period consisted of 28-d feeding periods with a washout interval of 21 d. Treatment groups were fed 100% grass hay (high forage; HF), 60% grass hay with 40% corn-based concentrate (intermediate; INT), and 25% grass hay with 75% corn-based concentrate (high grain; HG). Heifers were offered 2% of their body weight in feed daily. Blood was collected on days 0 and 28 of the treatment period for cytokine analysis. Plasma cytokine concentrations were quantified using RayBiotech Quantibody Bovine Cytokine Array Q1 kit according to manufacturer instructions. Concentrations of interferon gamma-induced protein 10 (IP10) linearly decreased with an increased concentrate diet ( P  = 0.037). Concentrations of IP10 differed for heifers consuming HF diet vs. HG diet (3,069.52 vs. 1,001.84 ± 669.01 pg/mL, respectively) and heifers consuming INT diet vs. HG diet (2,886.77 vs. 1,001.84 ± 669.01 pg/mL, respectively); however, there were no significant differences in IP10 concentrations between HF and INT heifers. There was a tendency for interleukin-1 family member 5 (IL1F5) concentrations to be lower for heifers consuming the HG diet compared to INT diet ( P  = 0.08). Results suggest that heifers consuming a high-concentrate diet have lower concentrations of IP10 and IL1F5. Additional research is necessary to better understand the dietary influence on the immune system in developing heifers., Competing Interests: The authors declare no conflict of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)