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Simple Summary: The fall gap represents a transitional phase between summer and winter that is characterized by feed scarcity due to the dormancy of warm-season forages while cool-season forages are not yet available. To address this challenge, various feed alternatives, such as hay, supplementation, stockpiling, and silage, are considered feasible options. Limpograss (Hemarthria altissima) is a unique warm-season forage because of its active growth in late fall and its slower decline in digestibility with increasing maturity compared to other grasses. Thus, limpograss silage can be an alternative to feed growing heifers in North Florida during the fall forage gap. A field trial was undertaken to assess the performance and nutritional responses of heifers fed 'Gibtuck' limpograss silage supplemented with protein. Twenty-four crossbred Angus × Brahman heifers were housed in a pen for the trial. Limpograss silage was provided without restriction to the heifers, while the supplement was offered at varying levels. The inclusion of protein supplementation alongside limpograss silage had a significant impact on animal dry matter intake, particularly affecting silage intake through a combination of substitutive and additive effects. Gibtuck limpograss silage associated with protein supplementation is an alternative to feed animals during forage-scarce periods in the southeastern United States. Limpograss (Hemarthria altissima) is a warm-season perennial grass that has the potential to feed livestock during scarcity periods. This study evaluated the intake, nutrient digestibility, and animal performance of beef heifers fed 'Gibtuck' limpograss silage combined with different levels of a range cube supplementation. Twenty-four heifers (330 ± 16 kg live weight) were submitted to four different treatments with 6 replicates: (1) control, no supplementation + limpograss silage ad libitum; (2) 1.4 kg of supplement + limpograss silage ad libitum; (3) 2.8 kg of supplement + limpograss silage ad libitum; and (4) 4.2 kg of supplement + limpograss silage ad libitum. The apparent total tract digestibility of dry matter, organic matter, and crude protein showed a positive quadratic effect with increasing supplementation levels (p = 0.001, p = 0.002, and p < 0.0001, respectively). Overall, the supplement improved diet digestibility and total DM intake but reduced silage intake, indicating a combined effect (substitutive and additive effect) of the protein supplement. The increasing level of protein supplement increased the average daily gain with a quadratic effect (p ≤ 0.0001). Limpograss silage associated with supplementation can improve diet digestibility and increase the animal performance of growing heifers, providing an alternative for livestock in North Florida. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the sulfur hexafluoride (SF6) tracer technique for estimating methane (CH4) emissions in dual-flow continuous culture systems (DFCCS). In experiment 1 (Exp1), fermenters were filled with water, and known CH4 concentrations (0, 1.35, 2.93, or 4.43 g/d) were injected using permeation tubes with SF6 release rates (3.30 or 9.65 mg/d). Headspace gas was collected using canisters, and the SF6 technique estimated CH4 recovery. Experiment 2 (Exp2) involved a DFCCS fermentation trial with ruminal fluid from three Holstein cows, testing diets with soybean meal or its partial replacement (50%) by Chlorella or Spirulina. Headspace gas was collected at intervals post-feeding. Standard curves for SF6 and CH4 quantification were inadequate for DFCCS samples, with the CH4:SF6 ratio differing from standards, indicating the data needs further SF6 release rate evaluation. In Exp1, a high correlation (r = 0.97) was found between infused and calculated CH4, indicating good repeatability. Low and high SF6 rates performed similarly at low CH4 infusion, but high SF6 overestimated CH4 at high infusion. Exp2 showed CH4 emissions irrespective of SF6 rate and indicated reduced CH4 emissions and increased NDF degradation with algae-containing diets. Further evaluation of the SF6 tracer technique is warranted for DFCCS. [ABSTRACT FROM AUTHOR]

Our previous studies showed that processing sorghum silage at harvest and storing for approximately 150d, improved average daily gain (ADG), feed efficiency (FE) and apparent total tract digestibility (ATTD) of starch when included as the basal ingredient in diets fed to growing Angus heifers. However, differences in animal performance and nutrient digestibility disappeared when the same sorghum silage was fed again after 1yr of storage. An experiment was performed to evaluate the effects of kernel processing and storage time on ruminal in situ degradability of sorghum silage (SS). A grain sorghum (ADV2450IG, Advanta seeds, Irving, TX) was harvested (Claas Jaguar 930, Harsewinkel, Germany) at the late-dough stage of grain maturity. Treatments were applied at harvest and consisted of sorghum berry processing (PRO) with a specific SS kernel processor (196 mm rolls of 125 teeth each, 40% speed differential, 1.1 mm roll gap), or not processed at all (NPR). Silage was chopped at 15 mm theoretical length of cut and ensiled in polyethylene ag bags (60 m long and 2.74m diameter), for 455 d. Samples were taken from each treatment on d 0, 66, 112, 157, 202, 246, 291, 336, 381, 426, and 455 and were kept frozen until analyzed. Samples were dried but not ground, to avoid affecting treatments. Ruminal in situ degradability of dry matter (DM) and starch was determined by incubating nylon bags for 24 h in duplicate, in the rumen of four ruminally cannulated steers consuming a corn silage-based diet. Data were analyzed as a randomized block design with repeated measures. The fixed effect of treatment, day and their interaction were included in the model and the repeated subject was considered the animal within treatment. A storage day × treatment interaction was detected for in situ DM degradability (P < 0.001). The PRO treatment increased (P < 0.05) in situ DM degradability at 66 and 202 d of storage and tended to increase it (P = 0.07) at 157 and 291 d of storage. An effect of storage day (P < 0.05) was observed for in situ starch degradability and because there was no interaction with treatment (P = 0.43), treatments means were compared across storage days. No differences were detected in ruminal in situ digestibility of DM or starch when silage was stored for 202 d, when compared with d 0 (P = 0.43), while starch degradability increased when silage was stored for 202 and 291 d (P < 0.03). At 381 d of storage, no differences were detected for starch degradability when compared with d 0. In conclusion, berry processing of sorghum when harvested for silage, increased ruminal in situ DM degradability. However, those differences disappear after more than 200 d of storage, in agreement with animal performance data previously reported by our group. [ABSTRACT FROM AUTHOR]

At 11 ± 4 d of lactation, 30 multiparous Angus cows [body weight (BW) = 476 ± 17 kg, body condition score (BCS) = 4.5 ± 0.3) were stratified by BW and allotted in 6 pens (5 cows/pen). During 75 d of experiment, all pens received ad libitum low quality hay (Panicum italicum; 54.7% TDN, 6.1% CP DM basis) and were randomly assigned to one of two treatments: 1) PS; cows received ad libitum 30% CP supplement including an intake limiter component (Controlmix, Nutralmix SRL, Argentina), or 2) NS; cows were not supplemented. After the experimental period, dams and their calves (PS: 7 males and 8 females; NS: 8 males and 7 females) were managed on improved pastures as a single group until weaning at 213 d of age. After weaning, heifer and steer calves were reared on improved pastures until 448 d of age, then placed into a feedlot with a finishing diet during 73 d until slaughter. Pens were considered the experimental unit and data were analyzed using the PROC MIXED of SAS, considering treatment and sex as a fixed effects and pen as a random effect. Overage dry matter intake (DMI) of hay was not affected by treatments (P > 0.10), and DMI of supplement in PS cows was 4.4 kgּ·cow-1ּ·d-1. Milk production was greater in PS than NS cows (PS: 5.3, NS: 3.6 kgּ·cow-1ּ·d-1ּ; P < 0.01). Progeny from PS cows increased BW at weaning (PS: 180, NS: 141 kg; P < 0.01), BW at initial feedlot phase (PS: 300, NS: 252 kg; P = 0.01) and final BW (PS: 415, NS: 354 kg; P = 0.01). After slaughter, progeny from PS cows tended to have in- creased dressing percentage (PS: 59.0, NS: 58.1%; P = 0.09), had an increased hot carcass weight (PS: 227, NS: 191 kg; P < 0.01), and increased Longissimus muscle (LM) area (PS: 68.5, NS: 60.1 cm2; P = 0.02), while rib fat thickness was not affected by treatments (PS: 7.8, NS: 7.6 mm; P = 0.68). There was no effect of protein supplementation on color (L*, a*, b*) and pH of LM at 24 h postmortem (P > 0.10). In addition, moisture, ether extract and shear force of LM after 4 d of aging were similar between treatments (P > 0.10). There was no treatment × sex interaction for any variables (P > 0.10). This study showed that protein supplementation during early lactation im- proved growth performance and carcass quality, but did not result in enhanced meat quality of progeny. [ABSTRACT FROM AUTHOR]

The inclusion of Aspergillus oryzae prebiotic (AOP; Amaferm, Biozyme Inc., St Joseph, MO) in ruminant diets has been proven to stimulate cellulolytic ruminal microorganisms, although, its positive effect on nutrient digestibility seems to be diet dependent. Our objective was to evaluate how AOP influences the apparent total tract digestibility of dry matter (DM) and neutral detergent fiber (NDF) at varying levels of intake, for diets with different forage sources and inclusion levels. Data were compiled from 3 experiments containing 4 diets for backgrounding cattle, assessing the use of AOP as a feed additive. The studies were Exp. 1): corn silage-based diet (CS; n = 24 steers), Exp. 2-A): sorghum silage-based diet (SS; n = 20 heifers), Exp. 2-B): citrus pulp and cotton gin byproducts-based diet (BP; n = 20 heifers), and Exp. 3): bermudagrass hay-based diet (BH; n = 24 steers). Separate ANCOVA analyses by diet were conducted using SAS, including in the model the effect of treatment (TRT; AOP vs. No AOP) and the interaction between TRT and level of intake (dry matter intake; DMI). Level of intake was calculated as percentage of body weight (DMI/BW). Least square mean differences between treatments were conducted at different levels of intake at which both treatments were represented. For apparent total tract digestibility of DM and NDF (NDFD), the TRT × DMI/BW interaction was significant (P ≤ 0.05) in the case of the CS and SS diets, but not in the BP and BH diets (P ≥ 0.10). For both silage diets, NDF and DM digestibility decreased as the level of intake increased. Consequently, the positive effect of AOP on NDFD was greater at increased levels of intake (3.3 and 3.5% of the BW for CS and SS, respectively), resulting in 9.8% improvement on NDFD for the CS diet (P = 0.04, 37.9 vs. 41.6% for No AOP vs. AOP, respectively) and 25% improvement in the SS diet (P = 0.01, 42.5 vs. 53.2% for No AOP vs. AOP, respectively). At a moderate intake (2.5% of the BW), AOP improved NDFD by 6.0 and 14.1% for the CS and SS diets, respectively (P ≤ 0.05). While at reduced intake (1.8 and 1.7% of BW, for CS and SS), NDFD did not differ (P ≥ 0.10) between treatments for either CS (47.9%) or SS (56.5%) diets. In conclusion, the inclusion of AOP in silagebased diets attenuates the decline on apparent total tract digestibility of NDF associated with increased feed intake, helping to maintain digestibility closer to its maximum potential. Whereas, at reduced levels of intake, it is more unlikely to observe a positive effect of AOP on fiber digestibility. [ABSTRACT FROM AUTHOR]

Feedlots have a crucial role in meeting the increasing global demand for meat. Despite ongoing efforts to improve feed efficiency in finishing diets, cattle in feedlots may experience methane (CH4) losses ranging from 2 to 12% of dietary gross energy (GE). Identifying strategies to mitigate energy losses in finishing diets is imperative for ensuring the sustainability of beef production. Anacardic acid, contained in the cashew nutshell extract (CNSE) has shown promising results in reducing CH4 emissions in forage-based diets; however, its impact on high-grain diets remains to be analyzed. Therefore, this study aimed to evaluate CNSE addition (5 g steer-1 d-1) in a finishing diet (85:15% grain: forage) on in vivo enteric CH4 emissions, apparent total tract digestibility, and feeding behavior. It was hypothesized that CNSE addition to a finishing diet would reduce enteric CH4 emissions without reducing feed intake or nutrient digestibility. To this aim, Angus crossbred steers (n = 16; 599 ± 40 kg) were used in a crossover design with two periods of 56 d each. Steers were adapted (14 d) to the finishing diet and assigned to receive CNSE or no additive (CON). The diet was offered twice daily as a total mixed ration (TMR) in the feed bunk, while CNSE was independently delivered through the Super Smart Feed system (C-Lock, Inc, Rapid City, SD) using ground corn gluten feed as a carrier. In vivo CH4 emissions, apparent total tract digestibility of nutrients, and feeding behavior were analyzed. Data were recorded during 35 d after the adaptation, followed by 7 d of washout, and analyzed as a crossover design using the MIXED procedure of SAS. Compared with CON, the addition of CNSE increased meal duration (P = 0.03), bunk visit duration (P < 0.01), and dry matter intake (DMI) of TMR (P = 0.03) by 25, 23, and 7%, respectively. Dry matter digestibility was increased (P = 0.02) by CNSE addition. Steers receiving CNSE, had a reduction in enteric CH4 emission rate (g/d; P < 0.001), yield (g/kg of DMI; P < 0.001), and intensity (g/kg of average daily gain; P < 0.01) in 29, 32, and 39% respectively. The loss of dietary GE as CH4 was reduced in CNSE (3.2 vs. 4.7%) compared with CON (P < 0.01). This study showed that CNSE at the evaluated inclusion rate, reduced CH4 yield and emission intensity by more than 31% in beef steers receiving a finishing diet. Moreover, given that CNSE addition promoted a longer feed bunk occupancy and a greater TMR intake, it could be suggested that the observed CH4 mitigation may be linked to shifts in ruminal fermentation rather than changes in DMI. [ABSTRACT FROM AUTHOR]