Nellore Steers Research Articles

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 < 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.

PSXII-18 Nitrogen balance and ruminal bacterial diversity indexes of Nellore cattle fed with amylolytic and fibrolytic enzymes in feedlot

Abstract This study was carried out to evaluate the use of dietary exogenous enzyme (ENZ) products with amylolytic and fibrolytic activity on nitrogen balance and ruminal alpha and beta diversity of Nellore cattle in feedlot. Rumen cannulated Nellore steers [n = 10; body weigh (BW) = 543 kg ± 28.6 kg] were distributed in a replicate 5 × 5 Latin-square design using individual pens. The treatments consisted of a negative control (CON; without ENZ); Amylase [AML, Amaize, Alltech; 0.5 g/kg of diet dry matter (DM); Xylanase (FBL, Fibrozyme, Alltech; 0.9 g/kg of diet DM]; Half dose (HD; AML 0.25 g/kg of diet DM and FBL 0.45 g/kg of diet DM); and Full dose (FD; AML 0.5 g/kg of diet DM and FBL 0.90 g/kg of diet DM; Table 1). The experimental period lasted 19 d (14 d of adaptation and 5 d of collection). Between d 15 and 18, total urine collection was performed to calculate the nitrogen balance. On d 19 a mixed ruminal sample (6 mL of solid and liquid content) was taken 4 h after feeding and stored at -80 ºC until DNA extraction. Total genomic DNA was extracted using the ZymoBIOMICS DNA Miniprep Kit. The library was prepared using primers for the region V3V4 of the16S rRNA gene; 341F (5’-CCTAYGGGRBGCASCAG-3’) x 806R (5’- GGACTACNNGGGTATCTAAT-3’). The amplicons (~ 470 bp) were sequenced with the Illumina NovaSeq 6000 PE 250 platform. The sequences were analyzed using qiime2 with the SILVA database for the taxonomic assignment. Alpha and beta diversities were calculated in Rstudio using phyloseq. All data were analyzed as orthogonal contrasts assuming treatment as a fixed effect: 1) CON vs. ENZ, 2) AML vs. FBL, 3) HD vs. FD, and 4) AML + FBL vs. HD + FD. Animals that received ENZ had reduced fecal nitrogen excretion (FNE, P = 0.014) and greater efficiency of nitrogen utilization (ENU, P = 0.031) than animals in the CON group. The FBL treatment resulted in greater CP/DOM ratio (P = 0.049), nitrogen balance (P = 0.089), and ENU (P = 0.015) compared with AML treatment. No differences were observed between HD and FD for any nitrogen balance variable (P > 0.10). Animals supplemented with both enzymes (HD + FD) had greater values of N intake (P = 0.018), greater CP/DOM ratio (P = 0.006), and greater FNE (P = 0.002) than animals fed either enzyme alone (AML + FBL). The ENZ supplementation did not impact alpha diversity index or beta diversity (P > 0.10). In conclusion, the addition of exogenous enzymes affected nitrogen balance but not ruminal alpha and beta diversity of Nellore cattle in feedlot.

PSXIII-22 Intake, digestibility, and ruminal parameters of Nellore cattle fed with amylolytic and fibrolytic enzymes in feedlot

Abstract This study was carried out to evaluate the use of dietary exogenous enzyme (ENZ) products with amylolytic and fibrolytic activity on nutrient intake, digestibility, and ruminal volatile fatty acids production (VFA) of Nellore cattle in feedlot. Rumen-cannulated Nellore steers [n = 10; body weight (BW) = 543 kg ± 28.6 BW] were distributed in a replicated Latin-square design (5 × 5) in individual pens. The treatments consisted of a negative control (CON; without ENZ); Amylase (AML; Amaize, Alltech, 0.5 g/kg of DM); Xylanase (FBL, Fibrozyme, Alltech, 0.9 g/kg of DM); Half dose (HD; AML 0.25 g/kg of diet DM and FBL 0.45 g/kg of diet DM); and Full dose (FD; AML 0.5 g/kg of diet DM and FBL 0.90 g/kg of diet DM; Table 1). The experimental period lasted 19 d (14 d of adaptation and 5 d of collection). Between d 15 and 18, total fecal collection was performed and on d 19 rumen fluid was collected at 0, 4, 8, 12, and 16 h post-feeding for ammonia, VFA, and pH determination. The data were analyzed as orthogonal contrasts using SAS: (C1) CON vs. ENZ, (C2) AML vs. FBL, (C3) HD vs. FD, and (C4) AML + FBL vs. HD + FD. There were no C1 differences for nutrient digestibility, total VFA, or ruminal pH (P > 0.10). However, a tendency effect in neutral detergent fiber (NDF) intake (P = 0.065) was observed, where animals fed ENZ had reduced values compared with animals kept in CON group. In the same way, ENZ reduced ther extract (EE) intake (P = 0.023), ruminal ammonia (P < 0.001), and isovalerate proportion (P = 0.080) as well as increased proportion of acetate (P < 0.001), valerate (P < 0.001) and acetate:propionate ratio (P = 0.030). No differences were observed in nutrient intake between AML and FBL (P > 0.10), but AML had greater organic matter (OM) digestibility (P = 0.097) and ruminal valerate (P = 0.039) and decreased butyrate proportion (P = 0.068). Animals that received FD had greater values of dry matter (DM; P = 0.009) and OM (P < 0.001) digestibility than HD. The enzyme combination resulted in greater DM (P = 0.026), OM (P = 0.062), crude protein (P = 0.018), EE (P = 0.063) and NDF (P = 0.040) intake and reduced OM digestibility (P = 0.008) compared with AML and FBL alone. The addition of exogenous enzymes in feedlot diets affected nutrient utilization and ruminal fermentation of Nellore cattle fed a feedlot finishing diet.

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 < 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.

Changes in ruminal fermentation and rumen bacteria population in feedlot cattle during a high lipid diet adaptation

Abstract This study aimed to investigate changes in feed intake and ruminal environmental parameters during a high-lipid diet transition in cattle. Eight Nellore steers were fed a control diet composed of 30% hay and 70% concentrate for 21 days, followed by the inclusion of 60 g/kg dry matter of soybean oil for 21 days. The DM intake expressed as a percentage of BW 21 days after lipid inclusion was lower (1.75% BW) than that observed during the control diet feeding (1.81% BW) (P<0.01). Steers fed the control diet had a lower pH than the ruminal pH recorded on days 7, 14, and 21 after lipid inclusion (P=0.034). Lower total short-chain fatty acid production in the rumen and lower microbial nitrogen synthesis were observed on day 7 after lipid inclusion compared to values found when steers were fed the control diet and on days 14 and 21 after lipid inclusion (P=0.041). Lipid inclusion in the diet decreased the population of protozoa on days 7, 14, and 21 (P<0.001). The abundances of R. albus and F. succinogenes were higher when steers were fed the control diet than the abundance observed on days 7, 14, and 21 after lipid inclusion in the diet (P<0.05). The first seven days of lipid diet inclusion are considered the most critical for ruminal adaptation, involving reductions in fibrolytic bacteria and changes in fermentation parameters. After 14 days the rumen showed signs of recovery and adaptation.

Intensively Reared Nelore Steers with Levels of Concentrate and Protein Sources during the Dry Season.

The objective of this study was to evaluate the effect of different nutritional strategies on the intensification of beef cattle farming on pastures during the dry period of the year. Eighty male cattle (testers) were randomly allocated to 16 paddocks formed with Mombaça grass (Megathyrsus maximus), totaling five animals (testers) per paddock. The strategies consisted of two LCs [10 and 16.7 g·kg-1 body weight (BW)] and two PSs with DDGS and SBM in a completely randomized design with a 2 × 2 factorial arrangement. The chemical, structural, and productive characteristics of the forage were evaluated, as well as the performance, productivity, and serum parameters of the supplemented animals. The forage presented a greater L:C (p = 0.033) and CP content (p = 0.007) when the lowest LC was used. Animals that received the highest LC had the highest supplement intake (p < 0.001) and the lowest pasture intake (p < 0.001). The nutritional strategy with an LC of 16.7 g·kg-1 of body weight (BW) resulted in a greater increase in total BW, i.e., 200 kg·BW ha-1 more. Therefore, higher levels of concentrate ensure greater productivity for beef cattle grazing, and DDGS can replace SBM in supplements used in the intensive raising of beef cattle on pasture without compromising the performance and productivity of the animals.

Carcass and meat characteristics of Nellore young bulls fed diet using cottonseed cake as a replacer of the forage fiber source

The aim of this study was to assess the effects of substituting traditional forage fiber sources with cottonseed cake in the diet on both the quantitative and qualitative characteristics of carcass and meat in Nelore young bulls. Twenty-four Nelore steers starting with an average weight of 377.8 ± 43.5 kg, were individually housed in stalls and provided with individualized feeding over a 112-day confinement period. The study followed a completely randomized design with two treatments and 12 replications. The diets incorporated either whole plant corn silage (WPCS) and, cottonseed cake (CSC) as fiber sources, at a rate of 300 g/kg of dry matter. The CSC diet promoted higher carcass weight. Aging animal meat for seven days significantly decreased the shear force from 83.4 to 71.6 N. Although diets did not influence meat composition, WPCS diet provided higher concentrations of C16:1, C18:1n9c, C18:3n3, and C22:2 acid, and CSC diet higher concentrations of C15:0, C18:1n9t, C18:2n6c, and 20:3n3. The WPCS diet provided higher concentrations of monounsaturated fatty acids and ω9, and the CSC diet had higher concentrations of ω6 and ω6:ω3 ratio in meat. Cottonseed cake used as a fiber source increases the concentration of polyunsaturated fatty acids and ω6 fatty acids in the meat of young bulls finished in feedlot.

Genetic group and heterosis in the behavioural evolution of steers during finishing in confinement

Crossbreeding is one way of achieving complementarity between breeds in relation to economically important characteristics; in addition, it allows the effect of heterosis to be exploited. The aim of this study was to measure the behavioural evolution of different genetic groups and mating systems in continuous alternating crosses of Charolais and Nellore cattle. Seventy-nine purebred Charolais (C) and Nellore (N) steers were evaluated during finishing in confinement, together with their second (3/4C 1/4 N and 3/4 N 1/4C), third (5/8C 3/8 N and 5/8 N 3/8C) and fourth generation (11/16C 5/16 N and 11/16 N 5/16C) crosses. The confinement period was 97 days, including 13 days for adaptation to the environment and feeding regime. Behavioural assessments were carried out when weighing, evaluating the composite scale score, time taken to exit the scales, measurement of flight distance, location of the facial hair whorl, and plasma cortisol level at slaughter. The Charolais animals showed a better composite scale score, longer exit time and shorter flight distance than the Nellore animals. For generation 3 (5/8 animals), the inclusion of Charolais genes afforded a higher composite scale score in each of the assessments, longer flight time in the assessments at 14 and 77 days, shorter flight distance in each of the assessments, with the facial hair whorl positioned further below the eye line, determining animals of a calmer behaviour. Purebred Nellore and predominantly Nellore animals from the third generation of crosses were higher in cortisol at slaughter than the purebred Charolais or predominantly Charolais animals, showing significant heterosis only in the second generation. Bos taurus animals are calmer and have a more suitable temperament than Bos indicus, however, the behaviour of zebu cattle can improve as the period of confinement increases, with the type of handling affecting behaviour and reactivity throughout the assessments.

Carcass traits and meat quality of steers fed palm kernel cake as a replacement for grain sorghum

The objective of this study was to evaluate the effect of replacing grain sorghum (GS) with palm kernel cake (PKC) on the performance, carcass traits and meat quality of feedlot steers fed highgrain diets. Forty male ½ Holstein × ½ Nellore steers with an initial weight of 331.1 ± 36.2 kg, at 24 ± 2 months of age, were housed in group stalls (10 cattle/stall) where they received diets containing 0, 80, 160, or 240 g/kg PKC on a dietary dry matter basis. After 126 days, the animals were slaughtered and their carcass and meat evaluated. The replacement of GS with PKC did not influence empty body weight, carcass weight, carcass length, or carcass yield. However, the thickness of subcutaneous fat in the carcass decreased with the replacement of GS with PKC. The meat pH increased linearly, whereas there were no changes in cooking loss, shear force, lightness (L*), and fat or cholesterol contents in the meat of the steers. Partial replacement (41,57%) of GS with PKC is recommended, with an inclusion of up to 240 g/kg PKC in high-grain diets for steers.

Effect of forage quality and narasin inclusion on ruminal fermentation, nutrient intake, and total tract digestibility of Nellore steers.

The study aimed to evaluate the effects of forage quality and narasin inclusion on intake, digestibility, and ruminal fermentation of Nellore steers. Twenty-eight rumen-cannulated Nellore steers (initial body weight [BW] = 350 ± 32.4kg) were allocated to individual pens in a randomized complete block design, with 7 blocks, defined according to the fasting BW at the beginning of the experiment. The steers were randomly assigned within blocks to 1 of 4 experimental diets in 2 × 2 factorial arrangements, being the first-factor forage quality (MEDIUM = 81g of CP/kg of dry matter [DM], and HIGH = 153g of CP/kg of DM), and the second factor was the inclusion (N13 = diet plus 13mg/kg of DM of narasin) or not (N0) of narasin (Zimprova; Elanco Animal Health, São Paulo, Brazil). The experiment consisted of a 28-d period with 22 d for adaptation and the last 6d for data collection. No haylage quality × narasin interaction (P ≥ 0.68) was observed on DM and nutrient intake. Haylage quality affected (P ≤ 0.01) DM intake, with greater values observed for steers fed HIGH compared with MEDIUM haylage. There was an increase (P < 0.001) in OM, NDF, hemicellulose, and CP intake for steers consuming HIGH vs. MEDIUM haylage. Including N13 did not affect (P > 0.39) DM and nutrient intake of steers. No haylage quality × narasin interactions were detected (P ≥ 0.60) for total tract nutrient digestibility. However, steers fed with HIGH haylage showed an increase (P > 0.001) in DM and digestibility of all nutrients compared with MEDIUM. Steers fed a MEDIUM haylage had a greater (P < 0.01) proportion of acetate compared with steers fed HIGH during all evaluated hours. Steers fed HIGH haylage had a greater (P < 0.01) proportion of propionate at 0h compared with steers consuming MEDIUM, whereas at 12h, steers consuming MEDIUM hay had a greater (P < 0.01) proportion of propionate vs. HIGH haylage. A haylage quality × narasin and haylage quality × time of collection interactions were detected (P ≤ 0.03) for rumen ammonia concentration, which was reduced (P < 0.03) in N13 vs. N0 steers consuming HIGH haylage. Collectively, high-quality haylage allows increased consumption and digestibility, with more energy-efficient ruminal fermentation. In addition, narasin might be an important nutritional tool in forage-based diets to enhance the ruminal fermentation parameters of Bos indicus Nellore steers.

Lecitina integral de soja na produtividade e qualidade de carcaças de bovinos confinados

Abstract The present study aimed to evaluate the effect of different levels of whole soy lecithin on the apparent digestibility of the diet, ingestive behavior, productive performance, and carcass characteristics of feedlot-finished beef cattle. This was a completely randomized experimental design involving three treatments: Control diet; Diet with whole soy lecithin (10 g animal-1 day-1); and Diet with whole soy lecithin (20 g animal-1 day-1), with five replications. The diets were formulated and constituted of 33% corn silage and 67% concentrate, on a dry matter basis. Thirty non-castrated ½ Angus × ½ Nellore steers, with an average age of 14 months and average initial body weight of 432 kg, were used in the experiment. The dietary inclusion of whole soy lecithin improved the digestibility of ether extract and neutral detergent fiber but did not influence ingestive behavior. Supplementation with 10 g animal-1 day-1 of whole soy lecithin resulted in higher average weight gain (1.707 kg day-1) followed by non-supplemented animals (1.645 kg day-1) and those supplemented with whole soy lecithin at 20 g animal-1 day-1 (1.587 kg day-1). Carcass fatness was not altered with the supplementation of whole soy lecithin. The supply of whole soy lecithin improved the use of the ether extract and fiber fraction of the diet and resulted in the highest average weight gain. The level of 10 g animal-1 day-1 provided the best responses.

Prediction models of carcass characteristics from non‑castrated Nellore cattle finished in the feedlot system under tropical conditions.

Our objective was to use measures of intake and productive performance to adjust prediction models for the carcass traits of non-castrated Nellore cattle finished in a feedlot. Individual data from 168 non-castrated male Nellore steers finished in feedlot between the years 2016-2021 were used. Descriptive statistical analyzes and Pearson correlation coefficients were performed. The outliers were tested by evaluating the studentized residuals in relation to the values predicted by the equations. Residues that were outside the range of -2.5 to 2.5 were removed. The goodness of fit of the developed equations was evaluated by the coefficients of determination (R2) and root mean square error (RMSE). Models for carcass yield, subcutaneous fat thickness, ribeye area, and shear force were adjusted. Means of 53.5% carcass yield, 4.8mm subcutaneous fat thickness, 73 cm2 loin eye area, and 8.1kg shear force were observed. The observed average intakes were 9.9kg/day of dry matter, 3.3kg/day of neutral detergent fiber content, 1.5kg/day of crude protein, and 7.1kg/day of total digestible nutrients. The average confinement time was 113days, the average total weight gain was 152.2kg and the average daily gain was 1.35kg/day. Intake measures significantly correlated with shear force and subcutaneous fat thickness and ribeye area. Carcass yield was significantly correlated with total weight gain, feedlot time, and hot carcass weight. Measures of nutrient intake, performance, and confinement time can be used as predictors of carcass yield, ribeye area, fat thickness, and shear force of non-castrated Nellore cattle finished in a feedlot. The prediction equations for ribeye area, carcass yield, subcutaneous fat thickness, and shear force showed sufficient precision and accuracy for non-castrated Nellore cattle finished in confinement systems under tropical conditions. All equations can be used with caution to estimate carcass traits of cattle finished in a feedlot using measures of intake and productive performance.

Effects of feeding mycotoxin-contaminated diets and the use of an adsorbent on the intake, digestibility, rumen fermentation, nitrogen balance and physiological parameters in the blood of Nellore steers

The study objective was to investigate the effects of mycotoxin contaminated diets and the use of an adsorbent (yeast cell wall extract; YCWE) on the intake, digestibility, rumen fermentation, nitrogen balance and physiological parameters in the blood of Nellore steers. Eight rumen-cannulated Nellore steers (initial BW = 417 ± 42 kg) were used in a 4 × 4 replicated Latin square design. A 2 × 2 factorial treatment structure was used to investigate the effects of mycotoxin contamination of the diet, the use of a mycotoxin adsorbent and their interactions. The dietary contamination consisted of: (1) diet without mycotoxins (CTRL), and (2) control diet added mycotoxins (MYCOT). The second factor was: (1) absence (YCWE–) or (2) presence (YCWE+) of YCWE. Mycotoxin contamination negatively affected dry matter intake during the first week of treatment application (P = 0.05) and tended to lower intake during the sampling period (P = 0.08). MYCOT resulted in lower (P = 0.03) digestibility of neutral detergent fiber and tended to lower (P = 0.08) ruminal pH compared with CTRL. There was MYCOT × YCWE interaction on the proportion of isovalerate (P < 0.01) and trend on the proportion of valerate (P = 0.08) in the rumen. There was also an effect of MYCOT (P = 0.04) and a trend of YCWE (P = 0.10) on the proportion of isobutyrate. Animals received MYCOT treatments had higher N excretion in the urine (P = 0.01), and consequently lower N retention (P = 0.05). There was MYCOT × YCWE interaction effect (P = 0.04) on the serum glucose concentration, where the MYCOT YCWE– treatment had a higher glucose concentration than the CTRL YCWE–, and the use of YCWE in MYCOT diet resulted in a concentration similar to CTRL treatments. The use of YCWE resulted in higher (P = 0.03) serum concentration of total proteins and lower (P < 0.01) proportion of ceruloplasmin. Animals fed mycotoxins had a lower (P < 0.01) proportion of IgA. MYCOT × YCWE effects (P < 0.01) on hemoglobin concentration and hematocrit were observed, where MYCOT had lower concentrations than the control and the use of YCWE in the contaminated diet resulted in values similar to CTRL. Animals fed mycotoxins tended to have lower (P = 0.08) number of lymphocytes and had lower (P = 0.02) lymphocytes: neutrophils ratios. This study suggests that mycotoxins may have negative impacts on certain physiological parameters that can influence health and performance of beef cattle, and the use of YCWE can mitigate some of these negative changes.

PSXII-26 Effect of Different Supplements Plus Phytogenic Additives on Ruminal Bacterial Community of Grazing Beef Cattle

Abstract Changes in ruminal microbial community can affect animal productivity, nutrient utilization efficiency, and environmental impact. This study aimed to evaluate the effect of two levels of supplementation plus a blend of phytogenic additives (essential oils, saponins, and spices) on the ruminal bacterial community in beef cattle grazing tropical pastures. The experiment was conducted at the Beef Cattle Sector of UNESP, Jaboticabal-BR, and lasted 84 days. Nine castrated Nellore steers (body weight of 262 ± 31.2 kg) cannulated in the rumen were assigned to 3 simultaneous 3 × 3 Latin square designs. Animals were kept on pasture of Urochloa brizantha cv. Marandu during the rainy season. The treatments included ad libitum mineral supplementation (MS) as the control group, added mineral supplementation of 0.1% of body weight per day plus Cargill phytogenic blend (AMSP), and energetic-protein supplementation, 0.3% of body weight per day plus Cargill phytogenic blend (EPSP). Ruminal samples were collected on day 26 of each experimental period. A mix of liquid and solid rumen content (6 mL) was taken before supplementation and immediately frozen in liquid nitrogen. Total genomic DNA was extracted using the Quick-DNA Fecal/Soil Microbe kit. The V3-V4 hypervariable regions of the bacterial 16S rRNA gene were amplified using universal primers 341F and 806R. The PCR fragments were submitted to sequencing on an Illumina NovaSeq 6000 PE 250 platform. The sequences were processed using mothur, grouped into operational taxonomic units (OTUs) using a similarity cut-off value of 97%, and the bacterial OTUs were classified using the SILVA database. Bacterial community composition was compared between treatments using a Kruskal–Wallis test and Wilcoxon’s post-hoc test using Rstudio. A total of 27 phyla, 224 families, and 577 genera were assigned by the taxonomic analysis of the ruminal bacterial community (Figure 1). The phyla Bacteroidetes (44.45 ± 9.43) and Firmicutes (42.50 ± 7.18) represent over 86% of the total relative abundance in the rumen of Nellore steers and were not influenced by the supplementation (P ≥ 0.250). The relative abundances of the Spirochaetes phylum, Spirochaetaceae family, and Treponema genus decreased in the rumen of AMSP supplemented animals (P ≤ 0.037) and were similar between MS and EPSP (Figure 2). Additionally, the EPSP supplementation resulted in decreased relative abundances of TM7, TM7 family Incertae sedis, and TM7 genus Incertae sedis relative abundances compared with those in MS (P = 0.031) but not between AMSP and EPSP supplementations. The addition of phytotherapy blend in the supplements led to decreased SR1, SR1 family Incertae sedis, and SR1 genus Incertae sedis abundances in the rumen (P ≤ 0.012). This study indicates that the relative abundance of the dominant phyla was not affected by the supplementation levels, but the addition of the phytogenic blend in the supplement decreased the relative abundances of specific bacterial phyla, families, and genera,

PSXI-30 Ruminal Bacterial Diversity Indexes of Grazing Beef Cattle Receiving Different Supplements Plus Phytogenic Additives

Abstract The addition of phytogenic compounds that have antimicrobial activity in cattle supplements can promote changes in ruminal bacterial diversity. This study aimed to evaluate the effect of two levels of supplementation plus a blend of phytogenic additives (essential oils, saponins, and spices) on the measures of alpha and beta diversity in the rumen of beef cattle grazing tropical pasture. The experiment was carried out in the Beef Cattle Sector of UNESP, Jaboticabal-BR. The trial lasted 84 days and nine castrated Nellore steers (body weight of 262 ± 31.2 kg) cannulated in the rumen were assigned in 3 simultaneous 3 × 3 Latin square designs. Animals were kept on the pasture of Urochloa brizantha cv. Marandu in the rainy season. The treatments were: ad libitum mineral supplementation (MS) as control group; added mineral supplementation, 0.1% of body weight per day plus Cargill phytogenic blend (AMSP); and energetic-protein supplementation, 0.3% of body weight per day plus Cargill phytogenic blend (EPSP). Ruminal samples were collected on day 26 of each experimental period. A mix of liquid and solid rumen content (6 mL) was taken before supplementation, placed in cryogenic tubes, and immediately frozen in liquid nitrogen. All samples were stored at −80 °C until DNA extraction and analysis. Total genomic DNA was extracted using the Quick-DNA Fecal/Soil Microbe Miniprep kit. The V3-V4 hypervariable regions of the bacterial 16S rRNA gene were amplified primers 341F (CCTACGGGNGGCWGCAG) and 806R (GGACTACHVGGGTWTCTAAT). The PCR fragments were submitted to sequencing on an Illumina NovaSeq 6000 PE 250 platform. The sequences were processed using mothur, grouped into operational taxonomic units (OTUs) using a similarity cut-off value of 97%, and the bacterial OTUs were classified using the SILVA database. Alpha diversity indices including Shannon, Simpson, Fisher, Chao1, and ACE, were calculated using the phyloseq package, while beta diversity was determined using the vegan package, both in Rstudio. Alpha diversity indices were compared between treatments using a non-parametric Kruskal–Wallis test and Wilcoxon’s post-hoc test. Beta diversity was tested using permutational multivariate analysis of variance (PERMANOVA) based on the Bray-Curtis similarity index. The AMSP and EPSP did not affect measures of alpha diversity (Figure 1), such as Shannon and Fisher indices (P = 0.219) as well as the richness index measured using Chao1 and ACE (P ≥ 0.363). A negative effect of supplementation on alpha diversity (P = 0.004) was only observed with Simpson’s Index of Diversity. Additionally, the supplementation did not change the beta-diversity of the ruminal bacterial community based on Bray–Curtis similarity index (P = 0.510; Figure 2). In conclusion, the addition of phytogenic compounds in the two levels of supplementation showed only a minor impact on the alpha diversity in the rumen of grazing beef cattle.

PSX-13 Effects of Different Supplementations During the Rainy Season on Nitrogen Metabolism of Beef Cattle Steers on Tropical Pasture

Abstract Phytogenic additives are used as food additives in ruminant nutrition due to their potential to alter the nitrogen (N) excretion route and minimize N emissions into the environment. This study aimed to evaluate the effect of two levels of supplementation plus a mixture of phytogenic additives (essential oils, saponins and spices) on the efficiency of N utilization by beef cattle in tropical pastures. The experiment was conducted at the Beef Cattle Sector of UNESP, Jaboticabal-BR, and lasted 84 days. Nine castrated Nelore steers (body weight 262 ± 31.2 kg) cannulated in the rumen were distributed in 3 simultaneous 3 × 3 Latin square designs. The animals were kept in pasture of Urochloa brizantha cv. Marandu during the rainy season. Treatments included ad libitum mineral supplementation (MS) as a control group, mineral supplementation added 0.1% of body weight per day plus Cargill phytogenic mixture (AMSP) and energy-protein supplementation, 0.3% of body weight per day plus Cargill phytogenic mixture (EPSP). Point urine and fecal samples were collected in the last three days of each experimental period. The concentration of total nitrogen in the urine was analyzed by the Kjeldahl procedure. The nitrogen composition of forage, supplements and feces was estimated by near-infrared spectroscopy (NIRS) using a modular FT-NIR spectrometer (NIRFlex N500, Büchi Labortechnik AG, Flawil, Switzerland). Nitrogen retention was calculated using the following equation: NR = N intake (g/d) – [N excretion in feces (g/d) + N excretion in urine (g/d)]. The nitrogen metabolism data were analyzed as a 3 × 3 Latin square with 3 replications, balanced for residual effects. Considering as fixed effect the treatment, and as random effect the Latin square, period, steer, steer × period interaction, and residues corresponding to the model. The data obtained were submitted to ANOVA and Tukey's test (P ≤ 0.05), using the statistical program R, version 3.4.4. The addition of phytogenic additives in the supplements led to decreased (P &amp;lt; 0.036) urinary excretion of N (g/day) from 41.16 g/day to 28.38 g/day and urinary excretion of N (% of N intake) from 30.66% to 23.21%, but did not differ between the different levels of phytogenic supplementation (Table 1). In addition, retained N (% of N intake) was greater (P &amp;lt; 0.01) in animals supplemented with AMSP and EPSP compared with MS, increasing N retention from 26.78% to 33.88%. This study indicates that the different levels of supplementation plus the addition of the phytogenic mixture improved the efficiency of N utilization by decreasing the excretion of N in the urine and increasing the retained N compared with MS supplementation.

Changes in the skin characteristics of Nellore steers during the rearing phase in hot climate pasture supplemented with protein sources

We hypothesized that the protein source in supplements and the insolation and ambient temperature changes in different seasons could cause changes in the skin of Nellore steers during the rearing phase on warm-climate pasture. The objective of this study was to evaluate the effects of replacing true protein (soybean meal) with NPN (extruded urea) in the supplement on the skin characteristics of steers grazing on Marandu grass pastures. Thirty-six Nellore steers with an average initial weight of 250.0 kg and 15 months of age were used. Skin biopsies were performed at three different times: summer, autumn, and winter. The protein source has effects on the length of the glandular portion, number of follicles, and gland area in steers during the rearing phase at different seasons of the year. In the summer, the skin presented a higher compact structure, while in the autumn and winter, the skin presented a sparser arrangement. Skin from steers that received soybean meal in supplement had a more significant number of follicles in the summer and a smaller area and length of sweat glands. The dermis thickness of steers supplemented with soybean meal was greater than that of urea supplemented. The epidermis thickness and dermis of the steers' skin were greater at the autumn (April). Sweat gland depth was greater in autumn (April) and winter (July) than in summer (December). The protein source in the supplement alters the skin characteristics by increasing of dermis thickness of Nellore steers during the growth phase. The insolation and ambient temperature changes in different seasons alter the skin structure by increasing the epidermis and dermis thickness, sweat glands depth, and glands area of the skin of steers during the growth phase.

Doses of orange (Citrus sinensis) essential oil for Nellore steers fed with a forage-based diet

The aim was to evaluate whether the doses of orange essential oil supplementation impact on dry matter intake (DMI), ruminal fermentation parameters, apparent nutrient digestibility, and methane production in Nellore steers fed with forage-based diet. A total of 32 rumen-cannulated Nellore steers (initial BW= 335±25 kg; age= 20±1 month) were assigned to individual pens in a randomized complete block design. Within block, steers were randomly assigned to treatments: CON= diet without orange essential oil (EO); 100EO= CON diet plus 100 mg orange EO/kg DM diet; 200EO= CON diet plus 200 mg orange EO/kg DM diet; and 500EO= CON diet plus 500 mg orange EO/kg DM diet. The main active compounds of the orange EO used were limonene (88.0 %) and myrcene (5.79 %). The experimental period lasted 28d, with 22d for adaptation and 6d for sample collection. From d23 to 27, samples of haylage, concentrate, and total fecal production were collected to determine the total tract apparent nutrient digestibility. Ruminal fluid was obtained from d28 at 0, 6, and 12 h after feeding to determine ruminal fermentation parameters and methane production. The difference was considered significant when P ≤ 0.05. No treatment effects were detected (P>0.05) to DMI or specific nutrient intake. The increasing levels of EO did not affect (P>0.05) the total apparent nutrient digestibility. No treatment effects were detected (P>0.05) for ruminal fermentation parameters in vivo. In ex situ, there was a treatment effect for acetate, total short-chain fatty acids (SCFA), methane, and relative energy loss (REL). For acetate, an increasing linear effect was observed for treatments that received EO for the variables production (g/kg) (P = 0.002) and gross energy (MJ/kg) (P = 0.002), with a higher concentration for the 500EO. For the total production of SCFA, there was an increasing linear effect of treatment with a higher concentration for 500EO for the variables production (g/kg) (P = 0.001) and gross energy (MJ/kg) (P = 0.001). For methane, a quadratic treatment effect was observed for the variables production (g/kg) (P = 0.045) and gross energy (MJ/kg) (P = 0.046), with lower concentrations for the 200EO. There was a decreasing linear treatment effect for REL(%) (P<0.001). The results for the use of orange EO as a manipulator of ruminal fermentation were promising and the dose of 500 mg/kg of DM showed a greater capacity to increase the energy efficiency of fermentation, with greater production of acids and lower production of methane, without affecting the voluntary intake of steers.

Doses of lemongrass (Cymbopogon citratus) essential oil for Nellore steers fed with a forage-based diet

The aim was to evaluate whether doses of lemongrass essential oil supplementation affect DMI, apparent nutrient digestibility and methane production in Nellore steers fed forage-based diets. According to their initial fasting BW, 32 Nellore steers (BW = 332±19 kg; age = 19±1 months) rumen cannulated and castrated, were allocated in individual pens in a randomized complete block design. The treatments were randomly assigned to the animals: CON= forage-based diet without addition of lemongrass EO; 200EO= CON diet plus 200 mg/kg lemongrass EO; 400EO= CON diet plus 400 mg/kg lemongrass EO; or 600EO= CON diet plus 600 mg/kg lemongrass EO. The experimental diets contained 95% Tifton-85 haylage and 5% ground corn. The experimental period lasted 21 days, 15 days for diet adaptation and 6 days for sample collection. Samples of haylage, concentrate and total feces production were collected from day 15 to 20, to determine the total apparent digestibility of nutrients. On the 21st day at 0, 6 and 12 h after feeding, rumen fluid was collected to determine the parameters of rumen fermentation and methane production. Significant effects were adopted when P ≤ 0.05. The main active compounds of the EO of lemongrass used were geranial (42.5%) and neral (30.49%). No treatment effects were detected for DM and nutrient intake. The increasing EO levels of lemongrass did not affect the apparent digestibility of nutrients. There was an increasing linear effect (P < 0.05) of treatment in the in vivo analysis, where the highest dose had the highest valerate concentration. There was no effect for any other variables in vivo. Effects on fermentation parameters were identified in the ex situ technique. For acetate, there was a quadratic treatment effect with higher values for the 400EO for the variable production (g/kg day; P = 0.02) and gross energy (Mcal/kg day; P = 0.02). There was linear increase for butyrate production (g/kg day; P = 0.04) and gross energy (Mcal/kg day; P = 0.04). There was a quadratic effect with higher values for the 400EO for production (g/kg day; P = 0.02) and gross energy (Mcal/kg day; P = 0.02) of SCFA. There was a quadratic effect for REL (P = 0.01), with lower loss in the 400EO. There was no treatment effect for propionate (P ≥ 0.97) and methane production (P ≥ 0.19). In conclusion, 400 mg/kg lemongrass EO optimized ruminal fermentation, minimizing energy loss due to methane emissions.

Efficiency of Amino Acid Utilization in Nellore Cattle Grazing Low-Quality Forage Supplemented with Different Sources of Nitrogen.

This study aimed to evaluate the effects of supplementation with non-protein nitrogen (NPN) or ruminal undegradable protein (RUP) on intake, digestibility, and amino acid (AA) use efficiency of Nellore cattle grazing during the dry season. Eight Nellore steers (12 ± 2 months old) were used in quadruplicate Latin squares (2 × 2). The animals were placed on Urochloa brizantha cv. Xaraés under continuous grazing. The treatments included the following: (1) urea supplementation (NPN) and (2) supplementation of corn gluten meal 60 (CGM, RUP). Animals supplemented with CGM showed higher intakes of dry matter (DM) supplement, total AA, essential AA, and individual AA. The supplementation did not affect the total AA digestibility, total AA flux, and the AA fluxes of microbial origin and RUP from the diet (p > 0.05). The ruminal microorganism origin flux of total AA to the duodenum was 44.5% and 52.7% for animals supplemented with NPN and CGM, respectively. Animals supplemented with CGM showed an increase in blood concentrations of isoleucine (+19.09 μmol/L), cystine (+27.29 μmol/L), and albumin (+0.11 g/dL) (p < 0.05), but this increase was not accompanied by an improvement in N use efficiency of steers (p > 0.05). RUP supplementation via CGM can be an efficient nutritional strategy to enhance the intake and absorption of AA by Nellore cattle grazing low-quality forage during the dry season.