Performance Of Beef Cattle Research Articles

Growth performance and ruminal fermentation characteristics of Thai-native beef cattle fed cassava pulp fermented with Lactobacillus casei TH14 and additives.

Raw cassava pulp is a low-nutritional agro-industry residue with a high moist content that is susceptible to rot. Biodegradation of cassava pulp by adding Lactobacillus spp. plus stimulants could boost bio-acidity to preserve cassava pulp as ruminant feed. This investigation assessed the effect of ensiled cassava pulp without or with Lactobacillus casei TH14 (LTH14), urea, and molasses on the intake, digestibility, rumen fermentation, and growth performance of native Thai beef cattle. Eight Thai-native beef bulls (170.3 ± 20.2kg of initial body weight) were randomly assigned to two treatment groups in a completely randomized design: cassava pulp ensiled without additives (CPFNO; n = 4) and cassava pulp ensiled with the combination of LTH14 (2.5g per ton of fresh material), urea (4% DM), and molasses (4% DM) (CPFWA; n = 4). The intake of the concentrate diet and ensiled cassava pulp did not differ (p > 0.05) between the CPFNO and CPFWA groups, including final body weight, average daily gain (ADG), and feed conversion ratio (p > 0.05). However, CPFWA affected higher rice straw intake compared to the CPFNO group (p < 0.05). The intake and digestibility of crude protein (CP) were greater for the CPFWA group at 43.86% and 30.87%, respectively, compared to the CPFNO group (p < 0.05). Ruminal ammonia-nitrogen (NH3-N)and blood urea-nitrogen (BUN) were increased when animals were fed with CPFWA (p < 0.05). The average total volatile fatty acids (VFA) concentration of CPFWA was greater than that of CPFNO by 27.49% (p < 0.05). In conclusion, CPFWA supplementation can enhance rice straw intake, CP intake and digestion, total ruminal VFA concentration, and BUN levels, without adversely affecting growth performance.

Productivity and economic performance of Nellore young bulls fed diets with increasing fiber content.

Adequate neutral detergent insoluble fiber (NDF) content in the total diet can improve intake efficiency, prevent rumen disorders, and enhance the health and performance of feedlot-finished beef cattle. We hypothesized that an increase in dietary fiber levels would decrease the productive performance but increase the economic performance of young bulls in confinement. Thus, it was aimed to evaluate the effect of increasing fiber levels on feed intake, wastage, and productive and economic performance of Nellore young bulls finished in confinement. We used 20 Nellore cattle, non-castrated males, 30 months old, and average body weight (BW) of 416.35 ± 2.2kg distributed in a completely randomized design, kept in individual stalls. Animals were divided into four treatments consisting of four levels of neutral detergent insoluble fiber (NDF) (25%, 30%, 35%, and 40% NDF) in total DM. Nutrient intake, feed conversion, feed waste, body weight (BW) at slaughter, total weight gain (TWG), average daily gain (ADG), hot carcass weight (HCW), and carcass yield (CR) were evaluated. In addition, economic parameters (revenue, food expenses, and gross margin) were calculated and compared. The dry matter (DMI), organic matter (OMI), crude protein (CPI), and ether extract (EEI) intakes showed quadratic behavior. The DMI maximum estimated was 28.5% NDF in the diet. The NDF and ADF intakes showed a positive linear effect and the starch intake had a negative linear effect. There was a significant positive linear effect (P < 0.05) for the variables total mixed ration (TMR) offered and daily and total RTM intake. Minimum RTM wastage was estimated with a diet containing 30% NDF. The maximum points for BW at slaughter, HCW, and ADG were 29.9%; 29.6%, and 25% NDF, respectively. The costs of concentrate and silage showed a positive linear behavior, as did the ADG costs and the carcass equivalent cost (P < 0.05). The maximum point of the revenue estimate (US$/animal) was 29.9% of NDF, 26.1% of NDF for the total expenditure on food (US$/animal), and 32.5% of NDF for the gross margin (U$/animal). In conclusion, the animals fed a 30% NDF diet showed the best performance and economics, in addition to less food waste. We recommend 25 to 32.5% of NDF in the diet to obtain maximum productive and economic performance when finishing Nellore young bulls in confinement.

Addition of Tannin-Containing Legumes to Native Grasslands: Effects on Enteric Methane Emissions, Nitrogen Losses and Animal Performance of Beef Cattle

Extensive cattle production on native grasslands is vital to the sustainability of the South American Pampas, and the inclusion of tannin-containing legumes can increase farm profitability, improve nitrogen (N) use and reduce greenhouse gas (GHG) emissions. This study quantified the effects of adding tannin-containing legumes to native grasslands on enteric methane (CH4) emissions, animal performance and N balance in cattle. A crossover design trial was conducted with 22 beef heifers under two treatments: native grassland (NG) and native grassland with the addition of Lotus uliginosus and L. angustissimus (NG+L). The results showed that forage mass disappearance was similar between treatments; however, 54% of the forage disappearance in the NG+L corresponded with legumes, indicating that the heifers in this treatment consumed a better-quality diet. While individual CH4 emissions were similar between treatments, heifers grazing the NG+L showed a higher average daily gain (ADG) and lower emissions intensity than heifers grazing NGs (0.25 vs. 0.58 g CH4/g ADG, p &lt; 0.05). Additionally, they also ingested 20% more N and were more efficient in its utilization. Incorporating tannin-containing legumes into native grasslands can improve animal productivity and N use efficiency while reducing the intensity of enteric CH4 emissions.

Risk factors underlining reproductive performance in smallholder beef cattle herds of South Africa

Improving the historically low reproductive performance of beef cattle in smallholder systems is essential for its productivity and profitability. Therefore, identifying and addressing risk factors associated with low performance in this system present an opportunity for improvement. The study aimed to evaluate the effect of animal and management risk factors on pregnancy rate (PR), fetal and calf loss (FC), calving interval (CI) and days open (DO) in smallholder beef cattle farms. A multi-stage selection approach was conducted in five provinces of South Africa. Cow records (3694) collected from 40 smallholder herds over two years (2018–2019) were analysed. Data on animal and herd management factors including body condition score (BCS), cow age class, breed type, lactation status, culling old/non-productive cows, record-keeping, and breeding and calving seasons were recorded. The GLIMMIX procedure was computed to determine risk factors associated with performance indicators (PR, FC, CI and DO). Risk factors highly associated with performance were breed type, BCS, cow-age class and breeding/calving season (P ≤ 0.05). Indicators FC, DO and CI increased with decreased BCS, autumn calving seasons, and in first calvers and aged cows. Whereas, PR increased with increasing odds of BCS and breeding seasons between December-March, November-February and January-March. Optimizing reproductive performance in smallholder beef cattle herds may involve managing cow body condition, breeding with adapted genotypes and synchronizing breeding with favourable seasons. Therefore, record keeping and regular monitoring of herd nutrition, climate and breed performance may be significant in improving reproductive performance in smallholder herds.

Effect of replacing concentrates with cassava root-top silage on feed utilization, rumen fermentation, blood parameters and growth performance in beef cattle.

This experiment aimed to evaluate the effects of replacing concentrates with cassava root-top silage (CARTOS) on feed intake, digestibility, rumen fermentation, blood parameters, and growth performance of beef cattle. Twenty crossbred bulls with a body weight (BW) of 226±56 kg were randomly assigned to one of five treatments for 90 d in a randomized complete block design having four blocks based on BW. The concentrates were replaced by CARTOS at levels of 0%, 25%, 50%, 75%, and 100% dry matter (DM). Animals were fed dietary treatments at 1.8% BW, with rice straw offered ad libitum. The DM and crude protein (CP) intake were decreased (p<0.01, p = 0.04) when the diet's CARTOS level was increased. The digestibility of DM, OM, and CP were not different among treatments, while fiber digestibility was increased with the inclusion of CARTOS (p = 0.03). The addition of CARTOS to replace concentrates did not change ruminal pH or volatile fatty acid proportions except for acetic acid, which increased with the addition of CARTOS (p = 0.03). The ruminal ammonia-nitrogen (NH3-N) was decreased (p<0.01) with increasing levels of CARTOS. The blood glucose and blood urea nitrogen decreased (p = 0.01) with the addition of CARTOS at 100%, whereas total protein and hematological parameters did not change with increasing levels of CARTOS. The use of CARTOS to substitute concentrates at 75% and 100% decreased average daily gain (ADG) and gain to feed ratio (G:F) (p<0.01); therefore, the addition of CARTOS up to 50% maintained ADG and G:F in beef cattle. CARTOS can replace concentrates up to 50% in beef cattle diets without adversely affecting feed intake, nutrient digestibility, rumen fermentation characteristics, blood parameters, or growth performance of beef cattle.

PSXII-24 Use of a commercial blend of tannins as feed additive for feed lot cattle on large pen trial improves carcass weight and carcass feed conversion

Abstract The utilization of commercial tannin extracts as feed additives holds promise for enhancing animal performance and health within commercial feedlot settings. This study aimed to assess the impact of a commercial tannin blend, SilvaFeed BX (Indunor, Buenos Aires, Argentina), sourced from quebracho and chestnut extracts along with saponins, on the performance of beef cattle. Nelore bullocks (n = 1,198) were allocated to 12 pens in a completely randomized block design, stratified by initial date, at a commercial feedlot facility in Goias State, Brazil. Each pen served as an experimental unit, with 10 pens housing 100 animals each and 2 pens containing 99 animals each. The experimental treatments included a Control diet with monensin alone [25 ppm/kg dry matter (DM)] or treated with BX (0.7 g/kg DM) on top of the control diet. Individual body weights (BW) were recorded at processing (initial BW; IBW) and shipment (final BW; FBW), while DM intake (DMI) was averaged per pen throughout the study duration. Carcass weight (CW) was individually measured at the packing plant, and carcass gain was calculated as the discrepancy between carcass weight and the estimated initial carcass weight, set at 50% of the IBW, aligning with customary practices for negotiating feeder cattle in Brazil. Statistical analyses were conducted using Proc Glimmix in SAS, treating pens and treatments as fixed effects and blocks as random effects, with IBW considered as a covariate. Residuals were assessed for normality, identifying three outliers. Mean comparisons were facilitated using LSMEANS. The results indicated that BX-treated cattle exhibited increased FBW (502.17 vs. 493.64 kg, P = 0.0992), carcass weight (275.76 vs. 268.78 kg, P = 0.0343), total carcass gain (107.52 vs. 100.54 kg, P = 0.0343), and improved carcass feed conversion (10.46 vs. 11.45 kg DM/kg; Table). Despite numerical differences, the limited number of replications were not enough to detect significant differences between treatments in average daily gain (P = 0.2419), DMI (P = 0.5508), feed conversion (P = 0.2641), or dressing (P = 0.3757). In conclusion, BX, a blend of tannins, exhibits potential for enhancing carcass weight and feed conversion efficiency in Nelore bullocks. Further investigations employing larger sample sizes are warranted to comprehensively elucidate its effects on other performance parameters.

PSIII-14 Cotton gin byproduct in growing diets for beef steers

Abstract The purpose of this study was to evaluate the performance of beef cattle during the stocker phase when fed different concentrations of cotton gin byproduct (CGB). Angus steers [n = 50; initial body weight (BW) = 349 ± 66 kg) were stratified by BW and grouped in slatted floor pens (10 steers/pen). Steers were assigned randomly within pen (2 per pen) to one of five diets containing 0, 10, 20, 30, and 40% CGB (dry matter basis). Diets were balanced for protein and energy, and the steers were fed for 84 d. Steers were weighed on d -1, 0, 28, 56, 83, and 84 for the stocker phase with d -1 and 0, 83 and 84 averaged to give start and end BW. Following the growing period, steers were switched to the same finishing diet and fed for an additional 55 d prior to being transported to PA for harvest and carcass data collection. Data were analyzed using procMIXED of SASv9.4 to determine the significance of linear, quadratic, cubic, and quartic trends. During the growing phase, dry matter intake increased linearly (P = 0.0017) with 10.16, 11.23, 11.59, 11.86, and 11.96 kg/d for 0, 10, 20, 30, and 40% CGB, respectively. Average daily gain tended to increase (P = 0.0631) with a cubic trend, increasing with the first addition of CGB, declining at the intermediate levels, and then increasing again at the 40% level (1.34, 1.54, 1.36, 1.39, and 1.52 kg/d for 0, 10, 20, 30, and 40% CGB, respectively). Feed efficiency showed a similar cubic trend (P = 0.10) with 0.133, 0.138, 0.119, 0.117, and 0.128 for 0, 10, 20, 30, and 40% CGB, respectively. Within the finishing phase, average daily gain was significant (P = 0.026) as a quadratic trend with 1.54, 1.25, 1.18, 1.20, and 1.33 kg/d for 0, 10, 20, 30, and 40% CGB, respectively. Diets did not differ (P &amp;gt; 0.10) for dry matter intake (10.08 kg/d), feed conversion (8.31), or feed efficiency (0.130). Treatment did not influence (P &amp;gt; 0.10) marbling or other carcass measurements. Data suggest CGB supported good animal gains with only minor impact on feed intake and feed efficiency for stocker steers up to an inclusion rate of 40%.

PSLBI-27 Rumen microbiome dynamics in feedlot steers receiving free-choice garlic-infused mineral supplements

Abstract Garlic (Allium sativum) in its dehydrated or distillate (garlic oil) form has been used as a feed additive owing to its insecticidal, antimicrobial, and organoleptic properties. Commercial mineral mixtures have been formulated to contain a low proportion of dehydrated garlic powder as a strategy to deter pest flies and increase mineral intake in cattle. As an antimicrobial, garlic powder has the potential to alter the rumen microbiome, with possible implications for feed digestibility and the growth performance of beef cattle. This study evaluated the effect of short-term feeding of a garlic-mineral mixture in feedlot steers receiving high-grain diets. Four groups of twenty steers [total = 80, ~14 mo old, body weight (BW) = 599 ± 32 kg] were randomly assigned to either a 5% garlic-mineral (5DGP) or plain mineral supplement (MS). The individual feed and mineral intakes of the steers were measured with an automatic feeding system. Feed and mineral supplements were tracked in different bunks for each group. Baseline rumen fluid samples were collected from all steers at the end of an acclimatization period before administering the trial supplements. Rumen samples were later collected from 10 steers in each group with the greatest mineral supplement intake over the trial period. Total DNA and RNA were extracted from all rumen samples and subjected to metagenomic and metatranscriptomic sequencing, respectively. None of the bacterial species with an overall relative abundance of greater than 0.1% were differentially abundant between the two supplement treatments, nor did the rumen microbial community structures differ between the two groups (PERMANOVA: R2 = 0.02, P = 0.43). Regardless of the dietary supplement, the rumen microbiome of the steers was dominated by uncultured Prevotella spp. (in addition to Prevotella lacticifex) as well as the uncharacterized UBA2810 sp900317945 and UBA2810 sp002351705. Overall, these results show that a 5DGP can be effectively administered to cattle without significantly disrupting the rumen microbiome.

130 Meta-analysis of the impact of Quebracho and Chestnut tannin extract supplementation on the growth performance in growing and finishing beef cattle

Abstract Integrating tannin extracts (TE) into the diet of growing and finishing beef cattle has shown promise in optimizing protein utilization while potentially mitigating methane emissions. Despite these potential benefits, there is a notable gap in a comprehensive analysis of the influence of TE on growth rate. This study addressed this gap by collecting data on the supplementation of a blend of condensed (from Schinopsis spp.) and hydrolyzable (from Castanea spp.) tannins, which has about 70% total tannins, and its impact on critical metrics, such as average daily gain (ADG, kg/d), dry matter intake (DMI, kg/d), and feed efficiency ratio (FER, g/kg). Our objective was to conduct meta-regression analyses to understand better the nuanced effects of condensed tannin supplementation on the overall performance of beef cattle during the critical stages of growth and finishing. The dataset was constructed by collecting published studies that reported in vivo experimental data on growing and finishing beef cattle supplemented with different levels of TE. It contained 132 observations from 35 publications. The meta-analysis was conducted by linear regression with a mixed-effects model fitted by the restricted maximum likelihood method using the nlme package of R software (ver. 4.3.1). Studies were assumed as random variables, and their interaction with the intercept and slope were included in the regression. The number of animals per treatment was used as a study-specific weight. Studies accounted for 32%, 35%, or 27% of the total variance when regressing ADG, DMI, or FER, respectively, on TE (% DM). After adjusting for random effects, the ADG increased (P &amp;lt; 0.001) with increasing levels of dietary TE (P &amp;lt; 0.001): 1.344 (± 0.0071) + 0.240 (±0.0298) × TE (n = 99, r2 = 0.40). It was observed that as the dietary TE level increased, its impact on the ADG tended to decrease from 0.33 kgּ d-1ּ % TE-1 when fed up to 0.5% TE to 0.24 kgּ d-1ּ % TE-1 when fed up to 1.5% TE, suggesting a possible nonlinear relationship between these two variables. Similarly, DMI decreased slightly (P &amp;lt; 0.001) at 0.61 kg/d/% TE, but with a lower precision (n = 115, r2 = 0.14). Consequently, FER increased (P &amp;lt; 0.001) at 17 kgּ d-1ּ % TE-1 (n = 93, r2 = 0.34). Initial findings suggest that incorporating TE into the diet of growing and finishing cattle, up to a concentration of 0.5% DM, positively influences the growth rate and enhances FER while minimally affecting DMI. Subsequent research endeavors should delve into a more intricate examination of optimal TE inclusion levels and explore additional performance indicators for a comprehensive understanding of its impact.

360 Effect of the administration of a protected source of calcium gluconate on growth, feed efficiency, nutrient digestibility, and health in beef cattle

Abstract The gastrointestinal tract has a central role in production efficiency due to its involvement in the digestive function as well as in immunological, nervous, and metabolic functions. In ruminants, a great deal of attention is placed on ruminal functionality and safety. However, it is now recognized that the hindgut is involved in the onset of some metabolic issues, normally associated with ruminal imbalances, as well as in the digestion efficiency. Thus, the application of nutritional strategies that target the hindgut are gaining interest in cattle nutrition. The study evaluated the effects of a protected source of calcium gluconate on performance, digestibility, and health in beef cattle. Charolaise bulls (n = 241) were randomly divided into two groups: i) Control (n = 120) basal diets + 10g/head/day of a placebo of wheat bran; ii) Treatment (n = 121) basal diets + 10 g·bull⁻¹·d⁻¹of a protected source of calcium gluconate (Lactibute, Selko Trouw Nutrition). The population was further divided into two subgroups: i) “Overall population” (n = 201) housed in pens of 7to 8 animals each; ii) “Beefmonitor population” (n = 40). The latter was housed in two pens (Control and Treatment) with 20 animals each equipped with two automatic scales for BW located at the drinkers, to evaluate the daily growth trends. Growth performance, feed intake (FI), feed conversion ratio (FCR), were evaluated with specific approaches in the two populations. The incidence of diseases was evaluated equally in the two populations. The apparent total tract digestibility (aTTD) was evaluated on 10 representative pens per group using a portable near-infrared system that compares the composition of the diets and the correlated feces. All the data were analyzed statistically using the SAS software and applying specific models. The average daily gain (ADG) was improved by the Treatment (+40 and +43 g·bull⁻¹·d⁻¹compared with the Control group, in the “Overall” and “Beefmonitor” populations; Table 1 and Figure 1; P = 0.0084 and &amp;lt; 0.0001, respectively), and the final BW were also heavier (706.82 and 705.83 vs 699.75 and 697.33 kg in the “Overall” and “Beefmonitor” populations; P = 0.0084 and 0.037, respectively). The treatment improved both, FCR (6.90 and 7.03 vs 7.51 and 7.28 in the “Overall” and “Beefmonitor” populations; P = 0.0008 and &amp;lt; 0.0001 respectively; Table 1 and Figure 1) and the aTTDs of starch (97.05 vs 95.71%; P &amp;lt; 0.0001), cellulose (57.91 vs 52.95%; P &amp;lt; 0.0001) and NDF (52.02 vs 50.02%; P = 0.020). The incidence of lameness was reduced in the Treatment group (0.99 vs 7%; P = 0.0282). Including protected sources of calcium gluconate can be functional to improve production efficiency and animal health, as a consequence of its proactive role on intestinal health, functionality and epithelial integrity.

260 Industrial hemp (Cannabis sativa) supplementation improved plasma antioxidant enzymes and stress hormones in beef cattle

Abstract Industrial hemp is a rich source of antioxidants due to its high CBD but there is little information known about its impact on plasma antioxidant enzyme activity and stress hormone in beef cattle. The objective of this study was to determine the effect of industrial hemp supplementation on plasma antioxidant enzymes and stress hormone of Angus cattle. Black Angus heifers (n = 20) were completely randomized into either control (CON: n = 10, receiving 0 g of hemp) or hemp (HEMP: n = 10, receiving 30 g of hemp in 200 g of commercial concentrate) in a trial that lasted for 6 wk. Each group was replicated twice. Hay and water were offered ad libitum, experimental diets were offered o700 h daily. Blood samples were collected on d 0, 7, 14, 21, 28, 35 of the experiment for enzyme-linked immunosorbent assay to determine enzyme activity using standard kits. Data were analyzed using GLIMMIX procedure for repeated measure in SAS 9.4 with Compound symmetry as covariance structure while means were separated with Tukey at 5% alpha. There was significant (P &amp;lt; 0.05) difference in cortisol with HEMP group having 97.54 ng/mL and 122.23 ng/mL for CON. There was treatment x time interaction in total antioxidant capacity (TAOC) and malondialdehyde, TAOC range was 7.26 to 13.95 U/mL in HEMP group and 7.56 to 11.80 U/mL in CON. In conclusion, industrial hemp improved plasma antioxidant status, reduced lipid peroxidation and decreased stress level thereby improving the performance and welfare of beef cattle

Effects of monensin and a blend of magnesium oxide on performance, feeding behavior, and rumen morphometrics of Zebu beef cattle fed high-starch diets

Abstract This study aimed to evaluate the effects of a blend of different sources of magnesium oxide associated or not with monensin, on productive, ruminal, and nutritional parameters of steers. Eighty-four Nellore steers with an initial body weight (BW) of 367.3 ± 37.9 kg were allocated to one of 28 pens, with three steers per pen. Each pen was considered an experimental unit, and using a completely randomized design with a 2 × 2 factorial arrangement, the following treatments were assigned to each pen: (1) Control (CON) – a basal diet without additive inclusion; (2) Magnesium oxide blend (MG) – basal diet plus a magnesium-based product (pHix-up®, Timab Magnesium, Dinard, France) provided at 0.50% of dry matter (DM); (3) Monensin (MON) – basal diet plus 25 mg/ kg of DM of sodium monensin (Rumensin, Elanco Animal Health, Greenfield, IN); and (4) MG association with MON – basal diet plus MG + MON, at the same doses of the individual treatments. The experimental period lasted 100 days. Blood samples were collected on days 0, 13, and 70 to determine D-lactate levels. Daily feed intake was recorded, and animal ingestive behavior was visually observed on days 66 and 67. On day 70, skeletal muscle tissue samples were obtained through biopsy for gene expression analysis. At the end of the experimental period, carcass ultrasonography was conducted. Subsequently, the steers were slaughtered, and rumen epithelium samples were collected for morphometric analysis. The use of monensin, of magnesium oxide blend, and their interactions, were treated as fixed effects, while the pens were considered as a random effect. Statistical differences were considered when P &amp;lt; 0.05. Steers fed MG-containing diets consumed approximately 0.6 kg more dry matter per day than those fed diets without this additive (P = 0.01; 11.3 vs. 11.9 kg/day). The inclusion of MG in the diet increased (P = 0.02) the average daily gain (ADG). There was a greater Longissimus muscle area (LMA) and LMA per 100 kg of body weight (BW) (P ≤ 0.03) for steers-fed diets with MG. Steers fed MON exhibited reduced mRNA expression of the Atrogin-1 and mTOR compared to steers fed MG + MON diets (MON × MG: P ≤ 0.04). Steers fed MON had 6.9% greater feed efficiency (P = 0.02). Papillae width was lesser for CON than other treatments (MON × MG: P = 0.02). In conclusion, the magnesium oxide blend improved performance and carcass traits in high-energy feedlot diets, while monensin enhanced feed efficiency, suggesting potential for their use as alternatives or complements in beef cattle nutrition.

143 Short- and long-term effects of heat stress in cow-calf pairs adapted to tropical and subtropical regions

Abstract Chronic exposure to high temperatures and humidity can limit beef cattle performance in tropical/subtropical environments, regardless of breed. Despite better heat adaptability compared with Bos taurus cattle, heat-stressed Bos indicus cattle also experience an increase in body temperature above the physiological limit. As body temperature increases, cascades of behavioral and physiological events are triggered to lessen heat load but often at the expense of productive outcomes. Contrary to other species and feedlot beef cattle, the effects of heat stress on physiology and performance of grazing cow-calf pairs have not been evaluated in detail, particularly for Bos indicus cattle. Preliminary data showed opposite outcomes to heat stress in Bos indicus vs. Bos taurus cattle, limiting the implications of the existing data generated from studies using beef and dairy Bos taurus cattle. This presentation will share some nutritional and management practices to mitigate heat stress in grazing beef cattle. Practices mentioned herein include altering the timing of body weight (BW) growth pattern (stair-step, SST) and immunomodulatory feed ingredient (IFI) supplementation for replacement beef heifers, and maternal access to shade to reduce heat load. For 100 d before the breeding season, Bos indicus-influenced beef heifers grazing warm-season grasses received a constant supplementation amount or SST strategy (50 d of low then 50 d of high supplementation), with or without IFI. Under severe heat stress conditions, IFI supplementation reduced heifer vaginal temperature but did not increase their growth and reproduction, whereas the SST strategy lowered internal body temperature, enhanced growth performance and pregnancy success compared with a conventional constant supplementation practice. Our group is also focused on the critical need to determine the specific effects of heat stress mitigation during pre- and postnatal phases on physiology and performance of Bos indicus-influenced cow-calf pairs. Study 1 evaluated the impacts of maternal access to artificial shade from 83 d prepartum until 50 d postpartum on body thermoregulation, performance, and physiology of beef heifers and their first offspring. Removing maternal access to shade led to greater maternal respiration rate, vaginal and body surface temperatures and reduced maternal body condition score and calf BW at birth. Nonetheless, offspring born from cows with no access to shade were remarkably heavier during a 60-d post-weaning period and had decreased plasma indicators of inflammation and positive effects to humoral immune response. Study 2 is a multi-year, USDA/NIFA-funded study designed to capitalize on the ability of cattle to reprogram physiological/immunological systems following exposure to stress during gestation. Study 2 combined gestational and postnatal heat abatement to enhance the overall growth/immune/reproductive performance of grazing Bos indicus-influenced cow-calf pairs. Partial data on long-term growth and reproductive performance, physiology, metabolome, and microbiome of both cows and their female offspring will be shared in this presentation.

Effect of exogenous cellulase pretreatment of straw-type fermented total mixed ration on digestibility and ruminal fermentation in growing beef cattle.

This study aimed to assess the impact of corn straw-based unfermented and fermented total mixed rations (TMR) supplemented with exogenous cellulase on the in vitro fermentation characteristics, growth performance, feeding behavior, apparent digestibility, rumen fermentation and digestive enzyme activities of Chinese Simmental bulls. Unfermented (direct spraying of exogenous cellulase onto TMR, TMR) and fermented (exogenous cellulase fermentation for more than 7 d, fermented total mixed rations [FTMR]) TMR were collected, dried, powdered and used as fermentation substrates. The fermentation liquid was ruminal fluid collected from Chinese Simmental bulls. The artificial rumen culture fluid were continuously cultured in vitro for 48 h. Based on the diets they were fed, 24 healthy Chinese Simmental bulls (average weight of 495.93 ±10.89 kg) were randomly divided into two groups, with 12 bulls in each group, which were fed TMR or FTMR. The study lasted 56 d. In in vitro experiments, the neutral detergent fiber degradability and total volatile fatty acid, propionate, iso-butyrate, iso-valerate and valerate concentrations were greater in the FTMR group (p<0.05) than in the TMR group. However, the methane production, pH and A/P of the FTMR group tended to be lower (p<0.05) than those of the TMR group. In the in vivo experiments, the average daily gain, eating rate, and feed efficiency of the FTMR groups were greater (p<0.05) than those of the TMR group. Similarly, the NDF degradability of the FTMR group was greater (p<0.05) than that of the TMR group. Compared to those in the TMR group, the concentrations of total volatile fatty acids, iso-butyrate, propionate and butyrate were greater in the FTMR group (p<0.05), and the A/P ratio was lower (p<0.05). Similarly, cellulase, xylanase, and β-glucosidase activities were greater (p<0.05) in the FTMR group than in the TMR group. Corn straw-based fermented total mixed rations supplemented with exogenous cellulase play a vital role in decreasing the structural carbohydrate content of TMR and ruminal methane production in vitro, improving nutrient digestion and absorption, optimizing rumen fermentation, and improving the growth performance of beef cattle.

Licorice Extract Supplementation Benefits Growth Performance, Blood Biochemistry and Hormones, Immune Antioxidant Status, Hindgut Fecal Microbial Community, and Metabolism in Beef Cattle.

This study aimed to evaluate the effects of licorice extract (LE) on growth performance, nutrient apparent digestibility, serum index (biochemistry, hormones, humoral immunity, and antioxidant function), hindgut fecal microbiota, and metabolism in beef cattle. In total, 12 male yellow cattle aged 12 months were divided into two groups (6 cattle per group): the basal diet (CK group) and the basal diet supplemented with 2 g/kg LE (CHM group). The entire experimental phase lasted for 120 days, including a 30-day pre-feeding period. Compared to the CK group, the average daily gain, crude fiber, calcium, and crude protein nutrient digestibility were greater on d 30 than d 60 (p < 0.05) and the feed meat ratio was lower for LE addition (p < 0.01). In terms of serum indexes, the insulin and nitric oxide contents were enhanced on d 30, the alkaline phosphatase level was improved on d 60, and the levels of albumin, immunoglobulin A, and catalase were increased on d 90 (p < 0.05). In contrast, the cholesterol content was lower on d 60 for LE addition compared with the CK group (p < 0.05). The higher enrichment of [Eubacterium]-oxidoreducens-group, p-2534-18b5-gut-group, and Ileibacterium were observed in the CHM group (p < 0.05), while the relative abundances of Gallibacterium and Breznakia in the CHM group were lower compared with the CK group (p < 0.05). In addition, the differential metabolites related to healthy growth in the CHM group were increased compared with the CK group. And there was a close correlation between hindgut microbiota and metabolic differentials. In general, LE has a promoting effect on the growth performance and health status of beef cattle over a period (30 to 60 days).

Economic impact of the use of anthelmintics in beef cattle in the rearing phase

The objective of the present study was to evaluate the effectiveness of anthelmintics and their influence on the performance of beef cattle supplemented during the rearing period, carrying out a cost analysis of the different treatments. 120 Nelore animals were used, with an average of 9 months of age, 60 males and 60 females. The animals were distributed into 6 groups of males and 6 of females, five treated with anthelmintics and a control group, G1: Moxidectin 1%, G2: Levamisole Phosphate 18.8%, G3: Ivermectin 0.8% + Albendazole Sulfoxide 10%, G4: Albendazole 10%, G5: Fenbendazole 10%, G6: Control (saline solution). Individual weighing was carried out using an electronic scale, at the beginning of the experiment (D0), fourteen days later (D14) and at the end of the experiment (D90), with performance assessed through weight gain (GP). Fecal collections were carried out on the same days as weighing, with individual egg counts per grams of feces (OPG) and stool culture to identify helminth genders. Economic viability was calculated based on the price of the calf and total production cost. The data obtained was subjected to the 5% Tukey test and the effectiveness of the anthelmintics was evaluated using the RESO program. It is concluded that the anthelmintics evaluated were effective, with the exception of Ivermectin 0.8% + Albendazole Sulfoxide 10%, which showed anthelmintic resistance. The anthelmintic treatment provided the animals with better performance, with the greatest weight gain observed in animals treated with Moxidectin 1%, demonstrating better economic indices.

Urea fertilization for potentializing beef cattle performance in agroforestry systems in the humid tropics

AbstractThis study hypothesized that urea fertilization could optimize animal performance in an agroforestry system. This study evaluated how increasing rates of N fertilization (0, 100, 200, and 400 kg N ha−1 year−1) using urea (CH4N2O) affected forage mass, nutritive value, and beef cattle (Bos indicus) performance in an agroforestry system with Massai grass (Megathyrsus maximus Jacq. cv. Massai) and legume tree (Mimosa caesalpiniifolia Benth.), in the humid tropic region of Brazil, over 2‐year period. The experiment was carried out in a randomized complete block design with four treatments (N fertilizer rates) and three replications. Forage mass was positive and linearly affected by N fertilization (p = .0236, R2 = 0.92), ranging from 1297 to 1583 kg DM ha−1 under 0 and 400 kg N ha−1 year−1, respectively. There was greater average forage mass during the rainy period (1826 kg ha−1) (p &lt; .05). Crude protein in green forage mass increased linearly (p = .0041, R2 = 0.91) in function of the N applied. Cattle average daily gain showed a positive quadratic response to the rates of N applied (p = .0298, R2 = 0.97), ranging from 0.46 kg to 0.68 kg animal day−1; and the gain per area increased linearly from 1.84 to 2.68 kg LW ha−1 day−1 (p = .0640, R2 = 0.96). The findings indicate that applying 200 kg N ha−1 year−1, split‐applied during the rainy season, would yield acceptable outcomes in terms of forage mass, nutritive value, and animal performance for this type of agroforestry system.

Fermentation Products, Microbial Protein Synthesis, and Hydrolytic Enzymes Activity of Rumen Fluids Local Beef Cattle Supplemented by Direct-Fed Microbials and Waru Leaf Flour

The aim of this study was to evaluate the effect of Waru Leaf Flour (WLF) and Direct-Fed Microbials (DFM) supplementation on volatile fatty acid (VFA) and ammonia (N-NH3) concentrations, total protozoa, microbial protein synthesis (MPS), and the specific activity of cellulase, amylase, protease in rumen fluids of local beef cattle. The study was conducted as an experimental investigation using a factorial Completely Randomized Design (FCRD). The first factor were three levels of DFM (P) mixed with rice straw (0%, 0.5%, and 1% dry matter of rice straw). The second factor consisted of three levels of WLF supplementation (D) in concentrates (0%, 0.24%, and 0.48% of dry matter concentrate). This resulted nine treatment groups, each it replicated three times.The diet composition consisted of rice straw and concentrate at 40:60 ratio (% dry matter). The interaction between DFM and WLF had a statistically significant impact (p&lt;0.01) on the rumen fluid's total protozoa, N-NH3, and protein content. However, this interaction was not statistically significant (P&gt;0.05) in relation to VFA, MPS, cellulase, amylase, and protease activity. While no significant interaction were observed for total VFA, cellulase, amylase, and protease, DFM supplementation had a statistically significant effect (P&lt;0.01) on reducing enzymes activity, and total VFA (P&lt;0.05). SDS-PAGE and zymography analyzes showed two protease molecules at all treatments with molecular weight of 144 kDa and 133 kDa, cellulase molecules at 62-67 kDa and 19-21 kDa respectively. The addition of DFM showed a new protease band, they had a measurement of 14 and 25 kDa.This study provides valuable insights into enzyme activities in rumen, particularly protease, cellulase, and amylase. The results suggest that the combination of 0.24% WLF and 0.5% DFM supplementation holds promise for optimizing rumen conditions and improving the performance of local beef cattle.

Transgenerational effects of the maternal gestational environment on the post-natal performance of beef cattle: A reaction norm approach.

In tropical beef cattle production systems, animals are commonly raised on pastures, exposing them to potential stressors. The end of gestation typically overlaps with a dry period characterized by limited food availability. Late gestation is pivotal for fetal development, making it an ideal scenario for inter- and transgenerational effects of the maternal gestational environment. Intergenerational effects occur due to exposure during gestation, impacting the development of the embryo and its future germline. Transgenerational effects, however, extend beyond direct exposure to the subsequent generations. The objective of the present study was to verify these effects on the post-natal performance of zebu beef cattle. We extended the use of a reaction norm model to identify genetic variation in the animals' responses to transgenerational effects. The inter- and transgenerational effects were predominantly positive (-0.09% to 19.74%) for growth and reproductive traits, indicating improved animal performance on the phenotypic scale in more favourable maternal gestational environments. Additionally, these effects were more pronounced in the reproductive performance of females. On average, the ratio of direct additive genetic variances of the slope and intercept of the reaction norm ranged from 1.23% to 3.60% for direct and from 10.17% to 11.42% for maternal effects. Despite its relatively modest magnitude, this variation proved sufficient to prompt modifications in parameter estimates. The average percentage variation of direct heritability estimates ranged from 19.3% for scrotal circumference to 33.2% for yearling weight across the environmental descriptors evaluated. Genetic correlations between distant environments for the studied traits were generally high for direct effects and far from unity for maternal effects. Changes in EBV rankings of sires across different gestational environments were also observed. Due to the multifaceted nature of inter- and transgenerational effects of the maternal gestational environment on various traits of beef cattle raised under tropical pasture conditions, they should not be overlooked by producers and breeders. There were differences in the specific response of beef cattle to variations in the quality of the maternal gestational environment, which can be partially explained by transgenerational epigenetic inheritance. Adopting a reaction norm model to capture a portion of the additive variance induced by inter- or transgenerational effects could be an alternative for future research and animal genetic evaluations.

A Meta-Analysis of 3-Nitrooxypropanol Dietary Supplementation on Growth Performance, Ruminal Fermentation, and Enteric Methane Emissions of Beef Cattle

This study aimed to evaluate the effects of dietary supplementation with 3-nitrooxypropanol (3-NOP) on growth performance, ruminal fermentation, and enteric methane emissions of beef cattle using a meta-analytic approach. The final meta-analysis database included results from 15 scientific articles. The response variables were analyzed through random effects models, where the results were reported as weighted mean differences (WMD) between the treatments without 3-NOP and those supplemented with 3-NOP. The dietary inclusion of 3-NOP decreased (p &lt; 0.001) dry matter intake but did not affect (p &gt; 0.05) average daily gain and increased (p &lt; 0.05) feed efficiency. In the rumen, 3-NOP supplementation increased (p &lt; 0.01) the pH and ruminal concentration of propionate, butyrate, valerate, isobutyrate, and isovalerate. In contrast, dietary supplementation with 3-NOP decreased (p &lt; 0.001) the rumen concentration of ammonia nitrogen, total volatile fatty acids, acetate, and the acetate/propionate ratio. Furthermore, daily methane (CH4) emission, CH4 yield, and CH4 emission as a percentage of gross energy ingested decreased (p &lt; 0.001) in response to 3-NOP dietary supplementation. In conclusion, dietary supplementation with 3-nitrooxypropanol can be used as a nutritional strategy to improve feed efficiency and ruminal fermentation in beef cattle and, at the same time, reduce enteric methane emissions.