Nellore Bulls Research Articles

Canopy Characteristics of Gamba Grass Cultivars and Their Effects on the Weight Gain of Beef Cattle under Grazing

Gamba grass (Andropogon gayanus Kunth) is a tussock-forming forage species adapted to acid soils of Brazilian savannas and cultivated for grazing pastures. Four decades since its release, Planaltina prevails as the most commercialized cultivar of the species, even though the new cultivar BRS Sarandi could be a better alternative for Gamba-grass-based farms by presenting a greater leaf:stem ratio. The objective of this study was to evaluate the average daily live weight gain (ADG) of Nellore bulls (Bos indicus) for two Gamba grass cultivars—Planaltina and Sarandi. The experiment was conducted in Planaltina, Federal District, Brazil, for 3 years, namely 2018, 2018–2019, and 2020. The experimental design was a completely randomized block design with two treatments and three replicates, each one continuously stocked at three stocking rates (SR)—1.3, 2.6, and 4 young bulls/ha. Canopy height (CH), forage mass (FM), plant-part proportion (green leaf, stem, and dead material), and nutritive value were evaluated. In 2018, mean ADG for Sarandi pastures was greater (0.690 kg/bull/d) than that of Planaltina (0.490 kg/bull/d) (p < 0.10). In the subsequent year (2018–2019), there was no effect of cultivar (p > 0.10), while in 2020 the ADG was again affected by cultivar (p < 0.10), confirming the advantage of Sarandi (0.790 kg/bull/d) over Planaltina (0.650 kg/bull/d). In 2018 and 2020, the percentage of stems for Sarandi was about 3–6 pp less than for Planaltina (p < 0.10). As well as for stems, Sarandi pastures presented a shorter CH in 2028 and 2020 (6–7%) (p < 0.10). The positive high correlation of leaf:stem ratio with ADG (r = 0.70) probably predisposed the superiority of Sarandi over Planaltina. The distinguishing plant-part composition of Sarandi canopy promotes increasing weight gain of beef cattle when compared to cv. Planaltina.

Impact of sperm sex sorting on sperm quality and in vitro embryo production in bovine

Increasing evidence suggests that environmental exposures can modify epigenetic marks in the germline, leading to the transmission of abnormal post-fertilization sperm epigenetic indicators and affecting embryonic development. Given the pivotal role of sperm cells in determining embryo quality, there is growing interest in understanding the potential effects of sperm sex sorting on embryo quality. This study aimed to investigate the impact of bovine sperm sexing on in vitro embryo production (IVP) and to associate molecular aspects of embryos analysis. Frozen semen samples from five Nellore bulls were used, with each bull contributing unsexed sperm (conventional semen – CV treatment) and female and male sexed sperm pooled after thawing (SX treatment). First, semen quality was assessed, including motility, morphology, acrosome integrity, and chromatin integrity to denaturation. Then, IVP was carried out, focusing on embryonic production and developmental kinetics. In the third experiment, embryo quality was evaluated by examining the gene expression of key markers (OCT4, NANOG, DNMT3A, TET1, and Fematrin-1) and the methylation pattern of the Satellite-1 and α-Satellite genes in blastocysts. Differences between CV and SX semen were only observed in motility, which was lower in SX compared with CV (P < 0.05). Although cleavage was similar, the SX groups showed lower blastocyst production than CV (P < 0.05). Of the genes evaluated, only NANOG showed high expression in the CV blastocysts compared with the SX blastocysts, but the methylation pattern revealed no differences. In conclusion, sex sorting markedly affects sperm motility and in vitro embryo production but showed no significant impact on embryo quality.

PSLBI-9 The growth performance and total tract starch digestibility of finishing Nelore bulls fed flint corn-based diets are improved by the corn processing method and urea source

Abstract The aim of this study was to evaluate the flint corn processing method (CPM) and urea source for finishing Nellore bulls fed corn-based diets. In this study, 80 Nellore bulls [initial body weight (BW) = 388 ± 45.7 kg] were allocated into 28 pens (7 pens/treatment; 6 pens with 3 bulls + 1 pen with 2 bulls). A completely randomized design with a 2 × 2 factorial arrangement of treatments was used to test two CPMs: dry ground corn (DGC) and reconstituted and ensiled corn (REC), and two US: feed-grade urea (FGU) and post-ruminal release urea (PRU). Dietary inclusion (% DM) of flint corn (vitreousness = 86.0%) was 61.3% (DGC or REC), and urea source addition was 0.5% as non-protein nitrogen (NPN; as FGU or PRU). The PRU source (Trouw Nutrition, Netherlands) contained 82% urea on a DM basis. In an in vitro assay, 27% of this urea was released into the rumen. Experimental period lasted 100 d (with 14 d of adaptation). Fecal samples from each bull were collected in two periods of three consecutive days (d 44 to 46 and 94 to 96) at different time (0600, 1200, and 1800 h). Samples were composited by pen and analyzed for fecal starch (FS) and indigestible NDF as markers for fecal excretion. At the end of the experiment, bulls were slaughtered and the jejunum and pancreas were sampled from one bull per pen. Interaction effects were not found (P ≥ 0.31) for any feedlot growth performance variables (Table 1). Final BW, average daily gain, and feed efficiency (gain to feed; G:F) were greater for bulls fed REC and PRU than for those fed DGC and FGU (P &amp;lt; 0.02), respectively. As a result, observed dietary net energy (NE) for maintenance and BW gain were about 7.0% and 9.0% greater for bulls fed REC diets, and 4.3% and 5.6% greater for bulls fed PRU diets, respectively. Bulls fed DGC had 2.2 times greater FS compared with bulls fed REC, resulting in lower fecal pH and total tract starch digestibility (TSD) for bulls fed DGC compared with those fed REC (P &amp;lt; 0.01). Interestingly, a similar trend was observed in bulls fed PRU compared with those fed diets with FGU (P &amp;lt; 0.06). Jejunal gene expression of SLC5A1 was not affected by treatments (P &amp;gt; 0.14). Nevertheless, bulls fed diets with PRU presented greater jejunal α-amylase activity (P = 0.02). Pancreatic α-amylase activity was less when bulls were fed DGC + PRU diet. In conclusion, REC markedly improved TSD and growth performance compared with DGC. Additionally, independent of CPM, PRU inclusion as NPN source increased G:F and dietary NE concentration due to the positive effects on jejunal amylase activity and TSD.

PSX-3 Transcriptional response to an alternative diet on liver, muscle, and rumen of beef cattle

Abstract Feed cost represents a major economic determinant within cattle production, amounting to an estimated 75% of the total variable costs. Consequently, comprehensive approaches such as optimizing feed utilization through alternative feed sources, alongside the selection of feed-efficient animals, are of great significance. Here, we investigate the effect of two diets, traditional corn-grain fed and alternative by-product based, on 14 phenotypes related to feed, methane emission and production efficiency and on multi-tissue transcriptomics data from liver, muscle, and rumen wall, derived from Nellore bulls (n = 52), 26 on each diet. To this end, diets were contrasted at the level of phenotype, gene expression, and gene-phenotype network connectivity. As regards the phenotypic level, at a P-value &amp;lt; 0.05, significant differences were found in favor of the alternative diet for average daily weight gain at finishing, dry matter intake at finishing, methane emission, carcass yield and subcutaneous fat thickness at the rib-eye muscle area. In terms of the transcriptional level of the 14,776 genes expressed across the examined tissues, we found 487, 484, and 499 genes differentially expressed due to diet in liver, muscle, and rumen, respectively (P-value &amp;lt; 0.01). To explore differentially connected phenotypes across both diet-based networks, we focused on the phenotypes with the largest change in average number of connections within diets and tissues, namely methane emission and carcass yield, highlighting, in particular, gene expression changes involving SREBF2, and revealing the largest differential connectivity in rumen and muscle, respectively. Similarly, from examination of differentially connected genes across diets, the top-ranked most differentially connected regulators within each tissue were MEOX1, PTTG1, and BASP1 in liver, muscle, and rumen, respectively. Changes in gene co-expression patterns suggest activation or suppression of specific biological processes and pathways in response to dietary interventions, consequently impacting the phenotype. The identification of genes that respond differently to diets and their associated phenotypic effects serves as a crucial steppingstone for further investigations, aiming to build upon our discoveries. Ultimately, such advancements hold the promise of improving animal welfare, productivity, and sustainability in livestock farming.

PSVII-14 Influence of dam parity and weaning strategy in previous lactation on feedlot performance of Nellore steers

Abstract In tropical beef cattle production systems, the impact of seasonality may be particularly challenging for young cows (primiparous or secondiparous) due to their increased nutritional requirements, encompassing maintenance, growth, gestation, and, in the case of secondiparous cows, lactation. Literature indicates that extending the duration of lactation during gestation is associated with decreased performance of progeny in their postnatal life. Therefore, implementing an early weaning approach can be an effective strategy to alleviate the nutritional demands of lactation in dams, thereby allocating more nutrients for fetal growth. This study aimed to evaluate the effect of early weaning on the feedlot performance of progeny that were in utero at the time of weaning intervention. To create experimental units, secondiparous and multiparous Nellore cows were assigned to one of two weaning strategies, where suckling calves were either; 1) early weaned 150 d (EW); or 2) conventional weaned at 240 d (CW). All calves were weaned at 150 d of lactation in 2022. Three bulls were used: Bull 1: had 13 calves with multiparous cows, had 7 calves with secondiparous cows, comprising 11 EW and 9 CW; Bull 2: had 10 calves with multiparous cows, had 6 calves with secondiparous cows, comprising 6 EW and 10 CW; and Bull 3: had 7 calves with multiparous cows, had 15 calves with secondiparous cows, comprising 11 EW and 11 CW. All cows were managed similarly after weaning, and through parturition, and weaning of subsequent calf, with resulting calves used for the current experiment. Nellore bulls (n = 57) with an initial body weight (BW) of 417.23 ± 9.12 kg and 18 mo of age were allocated to feedlot pens (equipped with Intergado equipment) and fed a common total mixed ration (80:20; concentrate:corn silage) for 97 ± 1.60 d. Bulls were distributed in a randomized complete block in a 2 × 2 factorial arrangement, considering dam weaning strategy in the previous lactation (EW and CW) and dam parity at subsequent calving (multiparous or secondiparous cows, MC and SC, respectively). Data were analyzed using PROC MIXED of SAS 9.4, with a model including the effects of dam weaning strategy, dam parity, and their interaction. Data were considered significant when P values were less than 0.05 and indicated a trend when 0.05 &amp;lt; P ≤ 0.10. There was an interaction between weaning strategy and cow parity, with calves born to SC-CW having reduced initial (P = 0.04) and final BW (P = 0.01) compared with all other groups (Figure 1 and 2). Steers from MC had greater dry matter intake (P = 0.003), and greater biological efficiency (P = 0.03; Table 1). Early weaning improved the final BW of steers born to secondiparous cows, suggesting it could be a strategy to enhance the performance of offspring and the reproductive performance of both secondiparous and multiparous cows.

PSXI-19 Effects of different forage levels on performance and feeding behavior of feedlot cattle

Abstract Body weight (BW) gain is highly correlated with profitability and positively associated with feed efficiency and reduced environmental impact of beef production. Fiber stimulates rumination which is essential for digestion, nutrient absorption, and maintenance of animal health. The quantity and quality of fiber in the diet affect BW gain and feeding and rumination patterns. Forage neutral detergent fiber (fNDF) has a key role in regulating intake and health. This study tested two levels of forage inclusion NDF on performance and feeding behavior of Nellore bulls. Corn silage was the source of forage fiber, diets had 12% or 7% fNDF [23.3% or 13.6% in the total dry matter (DM). Diets had 64% and 73.5% ground corn, and 0.2 and 0.5% potassium chloride respectively for 12% and 7% fNDF. Both treatments included soybean meal (1.5%); cottonseed (7%), urea (1.2%), mineral mixture (2.7%) and monensin (25 ppm). Diets were formulated to meet protein and mineral requirements with RLM model (rlm.app.br). Nellore bulls (n = 40; BW = 460 ± 38 kg and an average age of 20 mo) were fed for 50 d after 21 d adaptation. Each animal was considered as experimental unit in a completely randomized design. On d 21 and 42 behavior was evaluated every 10 min for 24 h. Feed intake was measured using Growsafe feeders. Average daily gain (ADG) was estimated by linear regression based on BW (without fast) obtained in real time scales at the water trough. Data were evaluated by SAS PROC GLM. Daily gain (1.71 vs. 1.43 kg/d, P = 0.0002), DM intake (10.97 vs. 10.00 kg/d, P &amp;lt; 0.001) and feed efficiency (0.154 vs. 0.139, P = 0.04) were greater for the 12% fNDF treatment. Likewise, rumination time was greater for the 12% fNDF compared with the 7% fNDF treatment; 356 and 275 min/d respectively (P = 0.0005). Animals fed 12% fNDF had longer rumination times and improved performance compared with those fed 7%. There were no differences in the number of visits to the troughs or in total feeding time (P &amp;gt; 0.05), with mean visits of 15.17 and 15.43, and feeding times of 145.6 and 146.8 minutes for the 12% and 7% fNDF diets, respectively. Linear correlation between ADG and rumination time was positive r = 0.49 (P &amp;lt; 0.03) and r = 0.28 (P &amp;lt; 0.23), indicating that rumination is associated with an increase in ADG. Coefficient of variation for ADG was 13.4 and 27.2% for 12 and 7% fNDF diets, with greater variability for the low fiber diets. The results highlight the importance of providing adequate forage to feedlot cattle. Results are consistent with previous work from our group demonstrating that the maximum performance is achieved at around 11 to 13% fNDF. Bulls fed 12% fNDF diets had greater BW gain, higher rumination and reduced ADG variation compared with those fed 7% fNDF diets.

PSXII-21 How does the inclusion of dried distillers grains plus soluble affect short-chain fatty acid and methane production in feedlot diets?

Abstract The inclusion of the coproduct dry distillers grains plus soluble (DDGS) in the diet of finishing cattle can lead to changes in the nutritional profile of the diets, causing an increase in protein content and a reduction in starch. It is necessary to understand how changes in rumen substrates affect rumen metabolic activity, acids, and enteric methane (CH4) production. Five treatments were used, considering levels of DDGS inclusion in the dry matter (DM) of 1) 0 g/kg of DDGS, 2) 150 g/kg of DDGS, 3) 300 g/kg of DDGS, 4) 450 g/kg DDGS, or 5) 600 g/kg DDGS in finishing diets. The metabolism experiment was conducted with rumen-cannulated Nellore bulls (n = 20) with initial body weight (BW) of 401.8 ± 27.0 kg. The production of short-chain fatty acids (SCFA) and CH4 were determined using the ex-situ ruminal fermentation technique. Rumen content was manually collected from 0, 4, 8 and 12 h post-feeding. The liquid and solid fractions of rumen content were used in four 50 mL penicillin-type flasks per animal. Of the four flasks prepared, two are called “blank” and inactivated in boiling water to stop fermentation, and the other two (microrumen) are incubated in a thermostatic bath, simulating the conditions existing in the rumen of animals (presence of microorganisms, anaerobes, temperature of 39ºC, natural animal saliva, physiological pH) for 30 min. After 30 min, incubated flasks were also inactivated in boiling water to stop fermentation. Subsequently, measurements of the final products of rumen fermentation (SCFA and CH4) were carried out in each bottle. Total rumen emptying was performed to determine the rumen pool of DM. The data will be analyzed in the SAS software, the mean of the treatments will be compared using test of mean and orthogonal contrasts. The declared significance is P ≤ 0.05. The inclusion or levels of DDGS did not affect CH4 production of gּ kg DM-1ּ d-1 and gּ kg DM-1ּ d-1 (P &amp;gt; 0.05). There was an effect of the treatments on the production of propionate (gּ kg DM-1ּ d-1; P = 0.0448), with a decreasing linear effect (P = 0.0087) with the increase in the inclusion of DDGS in diet (0; 150; 300; 450; 600 g/kg of DDGS; means 137.20; 160.32; 117.60; 87.09; 91.52 gּ kg DM-1ּ d-1 propionate, respectively). There was no effect of DDGS levels on the production of Acetate, Butyrate, or total SCFAs (gּ kg DM-1ּ d-1). In summary, DDGS inclusion affects rumen metabolic activity, decreasing propionate production, but does not affect the production of other SCFAs nor CH4 production.

PSXIII-24 Inclusion of dried distillers grains with solubles in feedlot diets containing flint corn and citrus pulp: Metabolism and performance of finishing Nellore bulls

PSXIII-24 Inclusion of dried distillers grains with solubles in feedlot diets containing flint corn and citrus pulp: Metabolism and performance of finishing Nellore bulls

PSXIII-29 How does the combination of 3-nitrooxypropanol with feed additives affect the performance, carcass characteristics, and meat quality of feedlot young Nellore bulls?

PSXIII-29 How does the combination of 3-nitrooxypropanol with feed additives affect the performance, carcass characteristics, and meat quality of feedlot young Nellore bulls?

PSXII-25 Impacts of crude protein level and urea source on finishing performance of Nellore bulls

PSXII-25 Impacts of crude protein level and urea source on finishing performance of Nellore bulls

PSXI-15 Effect of different levels of dry distillers bran plus solubles on performance of Nellore bulls finished on pasture receiving high supplementation

PSXI-15 Effect of different levels of dry distillers bran plus solubles on performance of Nellore bulls finished on pasture receiving high supplementation

Effect of access to natural shade on scrotal thermoregulatory capacity, integrity of the testicular parenchyma and sperm morphology of Nelore (Bos indicus) and Canchim (Bos taurus x Bos indicus) bulls.

The objective of this work was to evaluate the effect of using naturally shaded pastures on scrotal thermoregulatory capacity, testicular echotexture, and sperm morphology of Nelore (Bos indicus) and Canchim (5/8 Bos taurus x 3/8 Bos indicus) bulls in a tropical climate region. Sixty-four adult Nelore and Canchim bulls were used, equally allocated in Full Sun (FS, n = 32) or Crop-Livestock-Forestry (CLF, n = 32) pasture systems. During five consecutive climate seasons, the bulls underwent monthly breeding soundness evaluations and the biometeorological variables in the systems were continuously monitored. Microclimate was significantly different between systems. CLF system had lower BGHI than FS throughout the experimental period. No triple interaction (Season x Breed x Treatment, P > 0.05) was observed for any of the variables. Animals in CLF showed lower body temperature in Summer (FS:39.41 ± 0.05 vs. CLF:39.30 ± 0.05°C; P = 0.005) and in Autumn (FS:39.54 ± 0.05 vs. CLF:39.35 ± 0.05°C; P = 0.005). Access to shading did not determine differences in the evolution of scrotal biometry, temperatures, and scrotal thermal gradients (P > 0.05). Regardless of breed, animals in CLF showed greater right testicular volume (FS:247.5 ± 5.7 vs. CLF:259.0 ± 5.7cm³; P < 0.05), more suitable parenchyma echotexture, and fewer microlithiasis spots in the Spring and Summer. Testosterone concentration was higher in FS (FS:2.6 ± 0.2 vs. CLF:2.1 ± 0.2 ng/mL; P = 0.035). Canchim bulls presented higher total sperm defects during the Autumn and Winter (P = 0.010), but the total defects levels for Canchim and Nelore bulls were in normal range for adult bulls. Thus, the natural shade in CLF system was effective in improving the microclimate of pastures and minimizing adverse environmental effects on some reproductive features of interest in beef cattle.

Effects of rumen-protected fat on performance, carcass and meat characteristics, and feeding behaviour of Nellore bulls finished in intensive grazing systems

Context Beef cattle production in the tropics is based on the grazing system. Concentrate supplementation has a significant influence on carcass gain and meat quality. Additionally, the inclusion of some lipid feedstuffs, such as rumen-protected fat (RPF), can increase the net energy for weight gain, and be an alternative to increase the productive performance and carcass traits of grazing beef cattle. Aims This study evaluated the effects of RPF on performance, carcass traits and feeding behaviour of Nellore bulls in an intensive grazing system during the rainy season. Methods Twenty-four Nellore bulls (initial bodyweight of 454.0 ± 46.1 kg) were used in a randomised completed block design, based on initial bodyweight. The animals were distributed in 12 paddocks (two bulls per paddock) in a continuous grazing system and randomly assigned to one of two treatments: control (n = 6), a concentrate without added protected fat provided ad libitum, and RPF (n = 6), a concentrate with the addition of 3% protected fat (Nutricorp, Araras, São Paulo, Brazil) provided ad libitum. Statistical analysis was performed using the MIXED procedure of SAS 9.4 with paddock as the experimental unit (12 paddocks). The principal model included fixed effect of treatment and block as a random effect. For forage characteristics, the experimental period was a considered fixed effect. The study lasted 105 days, and was divided into four periods. At the end of each period, forage collections were performed, bulls were weighed and feeding behaviour was recorded. After 105 days, the bulls were slaughtered in a commercial slaughterhouse, and three 2.54-cm Longissimus dorsi steaks of each animal were collected to evaluate the colour, the chemical and physical composition, and the sensory analysis of the meat. Keys results The inclusion of RPF in the concentrate did not affect (P &gt; 0.05) the final bodyweight, average daily gain, concentrate intake and feed efficiency, but there was a tendency (P &lt; 0.07) for higher carcass weight for the bulls that received RPF. Bulls supplemented with RPF had a greater (P &lt; 0.05) average carcass gain. For meat quality, an effect (P &lt; 0.01) was observed for hue (25.32 and 27.91 for control and RPF, respectively). Conclusions The addition of 3% RPF in the concentrate ration has the potential to improve carcass traits and meat quality of beef cattle in an intensive pasture finishing system. Implications The inclusion of RPF will increase dietary energy density of grazing beef cattle with a tendency to increase carcass gain. This can be an opportunity to increase the production per animal and income of farmers.

Effects of natural additives as an alternative to ionophores on performance and carcass traits of Nellore cattle in feedlot submitted to transport stress

The present study aimed to evaluate the use of natural additives, based on essential oils and yeast cell wall products, as alternatives for monensin as a growth promoter for beef cattle. A total of 160 Nellore bulls with an average initial body weight of 352 kg were randomly distributed (40 animals/treatment) in four collective pens equipped with 24 automatic feeders (6 devices per pen). The feedlot period lasted 116 days, with a 14-day period of animal adaptation to the facilities. After the adaptation period, a transport stress (8 hours/400 km) was induced in all animals to simulate a commercial feedlot situation. The treatments were: 1) CON - Negative control (no additive); 2) MON - Monensin (27 mg/kg of dry matter (DM)); 3) EO - Essential oil-based additive (Valkalor Plus: 1.3 g/ kg DM); 4) EOYW - Essential oil and yeast cell wall-based additive (Viandi Plus: 1.8 g/ kg DM). The EO additive Valkalor Plus (IDENA®, Sautron, France) consists of a blend of essential oils (eugenol and geranyl acetate), while the EOYW additive Viandi Plus (IDENA®, Sautron, France) contains a combination of essential oils (linalol and geranyl acetate) with yeast cell wall. All statistical analyses were performed in SAS version 9.4 (SAS Institute Inc.), using GLIMMIX procedure and comparing the least square means by Tukey’s test at P < 0.05 and tendency between 0.05 <P < 0.10. A tendency (P = 0.091) and a significant effect (P = 0.032) were observed for final body weight (FBW) and average daily gain (ADG), respectively. Treatment MON presented greater FBW and ADG compared to CON (546 kg; 1.656 kg/d vs. 529 kg; 1.486 kg/d) but did not differ from treatment EO and EOYW. Dietary treatment EOYW presented greater dry matter intake (DMI), compared to MON (7 %; P = 0.006), but did not differ from CON and EO (P > 0.10). On the other hand, dietary treatment MON presented greater gain: feed ratio than all other treatments (P = 0.003). The treatments CON and EO presented greater presence of liver abscesses compared to MON and EOYW (P = 0.030). On average, the presence of liver abscess was 4.62 % for MON and EOYW vs. 23 % for CON and EO. Animals fed EO and EOYW diets, particularly during the initial adaptation period (0–12 days), had greater fluctuations in DMI compared to bulls fed CON and MON diets (P < 0.0001). Bulls treated with MON spent more time eating and had a greater DMI rate (min/kg; P < 0.0001) per kg compared to EOYW bulls during both the adaptation phase and the entire study period. In terms of daily feeding behavior, MON and EO-treated bulls exhibited more visits than EOYW bulls throughout the adaptation, final, and overall study periods (P < 0.0001). The serum haptoglobin concentration was greater for animals fed EO and EOYW compared to other treatments on average and at d 116 after enrollment (P < 0.0001). Altogether, these outcomes indicate that EOYW may be a viable alternative to MON in feedlot diets for finishing animals.

Adaptive integumentary features of beef cattle raised on afforested or non-shaded tropical pastures

We aimed to analyze the seasonal acclimatization process of Nelore and Canchim cattle raised on two production systems (non-shaded, NS, and integrated crop-livestock-forest, ICLF), based on the dynamics of the morphological and functional attributes of the hair coat and skin during winter and summer. The study was conducted in Brazil, in a low-altitude tropical climate region. A completely randomized 2 × 2 factorial design was adopted as follows: two production systems (NS and ICLF), two breeds (Nelore and Canchim) in a longitudinal structure, with measurements repeated over time through two stations (winter and summer). The experimental animals consisted of 32 Nelore (Bos indicus) and 32 Canchim (5/8 Bos taurus × 3/8 Bos indicus) bulls. The animals were equally distributed between two intensive rotational grazing systems. In both breeds, the hair coat was significantly thicker in winter but longer in summer, which increased epidermal protection. The Nelore bulls had shorter, wider, and thicker hairs, which are attributes that promote heat loss via conduction. The Canchim bulls showed significantly lower hair density and higher epithelium distance to sweat glands, which resulted in higher core temperature and respiratory rate. In turn, Nelore bulls had higher serum concentrations of triiodothyronine and lower serum concentrations of cortisol. However, Canchim bulls more frequently and intensely activated their thermoregulatory system and markedly adjusted their hair coat and hair features to reduce heat gain, especially in summer. Therefore, the anatomical plasticity and functional integumentary characteristics of Nelore and Canchim bulls reflect their acclimatization to tropical conditions.

Soybean molasses can be used as a substitute for corn in grazing beef cattle supplements during the rainy season.

Soybean molasses (SBMO) is a byproduct derived from the production of soy protein concentrate, obtained through solubilization in water and alcohol. The utilization of SBMO as an animal feed ingredient shows promising potential, primarily due to its low cost and as a potential energy concentrate. This study aimed to assess the intake, digestibility, ruminal parameters (pH and ruminal ammonia - NH3), nitrogen retention (NR) and microbial protein synthesis in grazing beef cattle supplemented with SBMO as a substitute for corn during the rainy season. Five Nellore (10-month-old) bulls with an average initial weight of 246 ± 11.2kg were utilized in a 5 × 5 Latin square design. The animals were housed in five paddocks, each consisting of 0.34ha of Marandu grass (Urochloa brizantha). Five isonitrogenous protein-energy supplements (300g crude protein [CP]/kg supplement) were formulated, with SBMO replacing corn at varying levels (0, 0.25, 0.50, 0.75, or 1.00g-1g). The supplements were provided daily at a quantity of 2.0kg-1 animal. The inclusion of SBMO at any level of corn substitution did not significantly affect the intake of pasture dry matter or total dry matter (P > 0.10). Likewise, the intake of CP and, consequently, the ruminal concentration of NH3 did not differ among the SBMO levels. Increasing the inclusion of SBMO did not have a significant impact on NR (P > 0.10), indicating that animals receiving supplements containing 100% SBMO as a substitute for corn may perform similarly to animals receiving supplements with 100% corn (0% SBMO). Soybean molasses represents a viable alternative energy source for grazing beef cattle during the rainy season and can entirely replace corn without adversely affecting animal nutritional performance.

Effects of condensed tannin-enriched alternative energy feedstuff supplementation on performance, nitrogen utilization, and rumen microbial diversity in grazing beef cattle

This study aims to investigate the effects of alternative energy feedstuff supplementation containing condensed tannin (CT) on palisade grass pastures, focusing on intake, nutrient digestibility, animal performance, ruminal and blood parameters, nitrogen use efficiency (NUE), and its impacts on the ruminal bacterial community in backgrounding Nellore young bulls. Two experiments were conducted simultaneously. Animal performance was evaluated in Experiment 1. The experimental design was a completely randomized block; ninety Nellore bulls (Bos taurus indicus) with an average initial body weight (BW) of approximately 240 ± 5 kg were used (64 as testers and 26 as regulators). The feed intake, digestibility of dry matter and nutrients, ruminal parameters, NUE, and the impact on the ruminal bacterial community were evaluated in Experiment 2. The experimental design was a 4 × 4 double Latin square involving eight Nellore bulls with an average initial BW of 290 ± 8 kg, all of which were cannulated in the rumen. The treatments consisted of energy supplementation at 0.3 % of BW with peanut skin (PS), 0.3 % of BW with sorghum grain (SG), 0.3 % of BW with soybean hulls (SHs), and a control treatment with a supply of mineral salt ad libitum. The total digestible nutrient intake was lower in animals that received only mineral supplements (p < 0.005). The dry matter (DM) intake decreased with treatment PS, while the DM and nutrient digestibility increased (p < 0.005). There was a reduction in ruminal ammonia nitrogen and an improvement in NUE in the PS treatment (p < 0.005). However, the bacterial and Archaea populations were unaffected (p = 0.619). Individual animal performance and gain per kg were increased in the treatment with supplements containing or without CT compared to the mineral supplement (p < 0.001). The NUE improved in treatments PS, SG, and SH (p < 0.01). Feedstuff supplementation using no edible foods by products containing CTs is an effective alternative energy source for Nellore bulls grazing on palisade grass during the rainy season. Additionally, it can be used to mitigate the environmental impacts of N excretion.

Genetic variability of the regulatory region of the FSH-β gene and its association with reproductive traits in Nellore bulls

Genetic variability of the regulatory region of the FSH-β gene and its association with reproductive traits in Nellore bulls

Evaluation of increasing levels of condensed tannin extracted from Acacia mearnsii on performance, carcass traits, meat quality, methane emission, and health of finishing Nellore bulls

The objective of this study was to evaluate the impact of increasing levels of condensed tannin extracted from Acacia mearnsii on the performance, carcass traits, meat quality, methane (CH4) emissions, and health of finishing Nellore bulls in a feedlot system. Eighty 20-month-old Nellore bulls (426.7 ± 24.46 kg of body weight (BW)) were individually housed with ad libitum access to feed and water. The study followed a completely randomized design with five treatments, each consisting of sixteen animals. Treatments included a negative control (no additives), 3 levels of tannin (0.8, 1.6, and 3.2 g of tannin/kg DM; Tanfeed®, Tanac Company), and a positive control (28 mg/kg DM monensin; Elanco®). Animals underwent a 21-day adaptation period with three step-up adaptation diets before entering the 89-day finishing phase. The adaptation dietary program consisted of ad libitum feeding with 3 adaptation diets over 21 days, in which the finishing phase lasted 89 days. The adaptation dietary program consisted of ad libitum feeding of 3 step-up adaptation diets for 3 weeks (21 d). The concentrate level of the diet (DM basis) increased from 40 % to 50 % in week 1, 50–56 % in week 2, and 56–75 % in week 3 (finishing diet). The experimental period (adaptation + finishing phases) lasted 110 d. The diet was formulated to meet the requirements while considering an average daily gain (ADG) of 1.6 kg/d. Enteric CH4 emissions were estimated using the sulfur hexafluoride (SF6) tracer gas technique. Performance and carcass traits, except for shear force and ash in meat, were not affected by increasing levels of dietary tannin or monensin (P>0.10). Regression analysis indicated a quadratic effect on shear force, with the lowest value observed at 1.6 g/kg DM of dietary tannin inclusion (P=0.05). Ash in meat increased quadratically with tannin inclusion, peaking at 1.6 g/kg DM of tannin addition, differing from monensin-treated bulls (P=0.05). However, CH4 emission as g/d decreased quadratically with increasing tannin levels (P<0.01), reaching the lowest emission at 0.8 g/kg DM of tannin inclusion, differing from monensin treatment (P<0.01). Also, CH4 emission intensity (g/kg DMI at CH4 sampling period) tended to decrease quadratically with tannin inclusion (P=0.09), with the lowest intensity observed at 0.8 g/kg DM of tannin inclusion, but not differing from monensin-treated bulls. Liver abscess and rumen scores were not impacted by tannin level in the diet (P = 0.26 and 0.19, respectively); however, the odds of having a liver (0 to A+ scale) and ruminitis score (0-10 scale) of 0 was 0.178 less for monensin-treated bulls compared to control and 0.224 less for monensin than tannin-treated bulls at 3.2 g/kg DM of inclusion, respectively. Overall, condensed tannin effectively reduced meat shear force and CH4 emissionin finishing Nellore bulls in a dose-dependent manner, without detrimental effects on performance.

Selection based on the Breeding Soundness Evaluation is associated with the improvement of the reproductive quality of young Nellore bulls

Breeding soundness evaluation (BSE) is the best methodology to estimate the fertility potential of future bulls and performing indirect selection for their fertility. However, the outcome of the BSE is influenced by several factors, including genetics, environment, and BSE guidelines. Herein, in this retrospective study, our first aim was to characterize the reasons for failure in 46,566 BSE from 2-year-old beef Bos indicus bulls (Nellore) born from 1997 to 2018. Our second aim was to determine whether or not BSE was associated with reproductive potential improvement of the bulls over the years. Due to changes in the BSE criteria, we used the same dataset, but only bulls born from 2002 to 2018 were included resulting in 35,856 BSE. For the second aim, the effect of the year and farm were included in the model of the multivariate logistic regression. We also determined if the main reasons for BSE failure decreased over time. Bulls were classified as approved (satisfactory potential breeders and qualified for natural breeding service) and not approved (deferred and unsatisfactory potential breeders). The reasons for BSE failure in Nellore bulls were poor semen quality (53.1 %) and physical defects (46.9 %), with the main physical defect being testis abnormalities (19.7 %). The overall percentage of bulls approved each year was 87.1 %, with no improvement over the years of study. However, the percentage of approved bulls at the first BSE increased over the years (P < 0.05). This increase was evident by a reduction in the difference between the overall percentage of the bulls approved vs the percentage of bulls approved at the first BSE. Furthermore, there was an increase in the percentage of bulls classified as satisfactory potential breeders in the BSE and an evident decrease in the percentage of bulls qualified only for natural breeding service (P < 0.05). In addition, an increase of the scrotal circumference (SC) of the herd was found (P < 0.05). These results indicate the overall quality of the bulls improved over the years. To associate and identify the main sperm abnormalities, 3461 not approved bulls were clustered. The most frequent defects were strongly coiled tail spermatozoa, proximal droplets, and acrosomal defects. Overall, there was no change in the frequency of bulls not approved by the sperm morphology nor the frequency of the main sperm abnormalities over the years. Nevertheless, the frequency of the defects remained very low, implying they were controlled. Additionally, abnormalities in the testis decreased over the years and was associated with the increase in the SC of the herd and a decrease of culled bulls due to low SC. In conclusion, this study demonstrates that there is an association between implementation and use of BSE with improvements in the reproductive quality of future generation bulls.