Nellore Cattle Research Articles

Characterization of novel lncRNA muscle expression profiles associated with meat quality in beef cattle.

The aim of this study was to identify novel lncRNA differentially expressed (DE) between divergent animals for beef tenderness and marbling traits in Nellore cattle. Longissimus thoracis muscle samples from the 20 most extreme bulls (of 80 bulls set) for tenderness, tender (n = 10) and tough (n = 10) groups, and marbling trait, high (n = 10) and low (n = 10) groups were used to perform transcriptomic analysis using RNA‐Sequencing. For tenderness, 29 lncRNA were DE (p‐value ≤ 0.01) in tough beef animals in relation to tender beef animals. We observed that genic lncRNAs, for example, lncRNA_595.1, were overlapping exonic part of the PICK gene, while lncRNA_3097.2 and lncRNA_3129.5 overlapped intronic part of the genes GADL1 and PSMD6. The lncRNA associated with PICK1, GADL1, and PMD6 genes were enriched in the pathways associated with the ionotropic glutamate receptor, gamma‐aminobutyric acid synthesis, and the ubiquitin–proteasome pathway. For marbling, 50 lncRNA were DE (p‐value ≤ 0.01) in high marbling group compared with low marbling animals. The genic lncRNAs, such as lncRNA_3191.1, were overlapped exonic part of the ITGAL gene, and the lncRNA_512.1, lncRNA_3721.1, and lncRNA_41.4 overlapped intronic parts of the KRAS and MASP1 genes. The KRAS and ITGAL genes were enriched in pathways associated with integrin signaling, which is involved in intracellular signals in response to the extracellular matrix, including cell form, mobility, and mediates progression through the cell cycle. In addition, the lincRNAs identified to marbling trait were associated with several genes related to calcium binding, muscle hypertrophy, skeletal muscle, lipase, and oxidative stress response pathways that seem to play a role important in the physiological processes related to meat quality. These findings bring new insights to better understand the biology mechanisms involved in the gene regulation of these traits, which will be valuable for a further investigation of the interactions between lncRNA and mRNAs, and of how these interactions may affect meat quality traits.

Relationships of the Microbial Communities with Rumen Epithelium Development of Nellore Cattle Finished in Feedlot Differing in Phenotypic Residual Feed Intake.

Simple SummarySeveral data have been published in the literature on the feed efficiency of cattle, measured through residual feed intake, in which the focus is to reduce production costs and improve cattle producer’s profit margins. Most of this variation in animal intake has been attributed to changes in animal metabolism, such as the rate of short-chain fatty acids absorption by the rumen epithelium, hepatic and mitochondrial metabolism, feeding behavior, and content of empty body fat. All these factors impact the anabolism/catabolism of substrates reaching the blood system. However, studies evaluating the composition of the rumen microbial community of animals differing in residual feed intake are scarce, and, therefore, this study aimed to compare the ruminal microbial communities, rumen morphometrics, feeding behavior, feedlot performance, and carcass characteristics of Nellore cattle, ranked by residual feed intake. Our results suggest that ruminal microbial community was not affected across different groups of residual feed intake, suggesting that differences in the efficiency of Nellore animals are associated with other factors.The objective of this study was to examine the relationships among ruminal microbial community, rumen morphometrics, feeding behavior, feedlot performance, and carcass characteristics of Nellore cattle, classified by residual feed intake (RFI). Twenty-seven Nellore yearling bulls with an initial body weight (BW) of 423.84 ± 21.81 kg were fed in feedlot for 107 d in individual pens to determine the RFI phenotype. Bulls were categorized as high RFI (>0.5 SD above the mean, n = 8), medium RFI (±0.5 SD from the mean, n = 9), and low RFI (<0.5 SD below the mean, n = 10). At harvest, whole rumen content samples were collected from each bull to evaluate ruminal microbial community, including bacteria and protozoa. The carcass characteristics were determined by ultrasonography at the beginning and at the end of the experimental period, and behavior data were collected on d 88. As a result of ranking Nellore bulls by RFI, cattle from low-RFI group presented lesser daily dry matter intake (DMI), either in kilograms (p < 0.01) or as percentage of BW (p < 0.01) than high-RFI yearling bulls, resulting in improved gain:feed (G:F). However, variables, such as average daily gain (ADG), final BW, hot carcass weight (HCW) and other carcass characteristics did not differ (p > 0.05) across RFI groups. The eating rate of either dry matter (DM )(p = 0.04) or neutral detergent fiber (NDF) (p < 0.01) was slower in medium-RFI yearling bulls. For ruminal morphometrics an RFI effect was observed only on keratinized layer thickness, in which a thinner layer (p = 0.04) was observed in low-RFI Nellore yearling bulls. Likewise, Nellore yearling bulls classified by the RFI did not differ in terms of Shannon’s diversity (p = 0.57) and Chao richness (p = 0.98). Our results suggest that the differences in feed efficiency of Nellore bulls differing in phenotypic RFI should be attributed to metabolic variables other than ruminal microorganisms and epithelium, and deserves further investigation.

Small genetic variation affecting mRNA isoforms associated with marbling and meat color in beef cattle.

The aim of this study was to identify mRNA isoforms and small genetic variants that may be affecting marbling and beef color in Nellore cattle. Longissimus thoracis muscle samples from 20 bulls with different phenotypes (out of 80 bulls set) for marbling (moderate (n = 10) and low (n = 10) groups) and beef color (desirable (n = 10) and undesirable (n = 9) group) traits were used to perform transcriptomic analysis using RNA sequencing. Fourteen and 15 mRNA isoforms were detected as differentially expressed (DE) (P-value ≤ 0.001) between divergent groups for marbling and meat color traits, respectively. Some of those DE mRNA isoforms have shown sites of splicing modified by small structural variants as single nucleotide variant (SNV), insertion, and/or deletion. Enrichment analysis identified metabolic pathways, such as O2/CO2 exchange in erythrocytes, tyrosine biosynthesis, and phenylalanine degradation. The results obtained suggest potential key regulatory genes associated with these economically important traits for the beef industry and for the consumer.

Use of tannin extract as a strategy to reduce methane in Nellore and Holstein cattle and its effect on intake, digestibility, microbial efficiency and ruminal fermentation.

This study was carried out to evaluate the use of tannin extract from Acacia mearnsii as a strategy to reduce methane (CH4 ) in two distinct cattle genotypes and its effect on intake, digestibility, microbial efficiency and ruminal fermentation. Four Nellore (Bos indicus) and four Holstein (Bos taurus) dry cows fitted with rumen cannula were assigned to two 4 × 4 Latin square design, in a 2 × 4 factorial arrangement, where each genotype represented a square receiving four tannin levels (commercial extract of A.mearnsii) in the diet (0%, 0.5%, 1.0%and 1.5% of dry matter). Tannin levels used did not cause a reduction in feed intake or rumen passage rate for both genotypes (p > 0.05), although there was a linear reduction in the degradation rate and ruminal disappearance of diet (p < 0.05). The increase in tannin levels reduced the amount of entodiniomorph protozoa in the Nellore cattle (p < 0.05). There was no change in N retention or microbial efficiency (p > 0.05), despite the linear reduction of nutrient digestibility and the synthesis of microbial nitrogen (p < 0.05). The ruminal CH4 production was reduced (p < 0.05) without reducing the short-chain fatty acidproduction. The threshold of 0.72% of tannin in the diet was estimated as the starting point for the reduction of ruminal CH4 production with long-term efficacy. Therefore, the use of low levels of tannin extract from A. mearnsii is a potential option to manipulate rumen fermentation in Nellore and Holstein cattle and needs to be further investigated.

Effect of tannin extract associated with two levels of non-protein nitrogen in the supplement on performance, ruminal parameters, and microbial diversity of grazing Nellore cattle during the growing phase at dry season

The objective of this study was to evaluate the effects of tannin extracts (TE) with two levels of nonprotein nitrogen in protein-energy supplements on the intake, apparent total tract digestibility, ruminal and blood parameters, rumen microbial diversity, and performance of grazing Nellore cattle during the growing phase in the dry season. In experiment 1 (Exp. 1), eight ruminally cannulated Nellore steers [293 ± 5.6 kg of body weight (BW)] were used in a double 4 × 4 Latin square design in a 2 × 2 factorial arrangement. In experiment 2 (Exp. 2), sixty-four Nellore bulls (294 ± 15.2 kg of BW; blocked by initial BW) at eighteen months old were distributed in 16 paddocks in a 2 × 2 factorial arrangement as follows: urea at 30 g/kg (UR3) or 50 g/kg (UR5) as feed supplement without TE or with TE (7 g/kg as feed supplement). The animals were fed daily with protein-energy supplements at 3 g/kg of BW, and the paddocks consisted of Urochloa brizantha cv. Marandu grass. In Exp. 1, the total intake, forage intake, and apparent total tract digestibility were similar among the treatments. A TE × Urea interaction trend was observed for supplement intake in kg/day (P = 0.05) or % of BW (P = 0.09), with lower intake in UR3 without TE than UR3 with TE while no effect of TE at UR5. The NH3-N concentration was higher in steers supplemented with TE (P = 0.02). The NH3-N concentration was higher in animals fed UR5 than in those fed UR3 at 6 h after supplementation (P < 0.01). Animals supplemented with TE had a lower Simpson index (P = 0.01), lower total ruminal ciliate protozoa counts (P = 0.02), and higher richness estimators (P < 0.05). In Exp. 2, the animal performance was not influenced by the Urea, TE or their interaction (P ≥ 0.230). The use of 30 or 50 g/kg urea in the protein-energy supplements during the dry season does not alter animal performance, metabolic changes make it flexible. TE use alters the microbial population but does not affect performance. Thus, the use of supplements with a higher nonprotein nitrogen amount is a useful strategy for improving the cost-benefit ratio in protein-energy supplements for beef cattle during the dry season. However, higher blood urea correlates with increased N excretion in the environment, and further studies are needed to verify these possible impacts.

Performance and economic analysis of Nellore cattle finished in feedlot during dry and rainy seasons

We aimed at evaluating the animal performance and economic variables of Nellore cattle finished in feedlot during the dry and rainy seasons. A total of 1,908 Nellore animals with an average age of 24 months were used. These animals were separated into two groups: 1,021 animals, with an average body weight of 400 kg, wereconfined for 100 days in the dry season and 887 animals, with an average body weight of 356 kg, were confined for 126 days in the rainy season. All animals received the same diet in the two studied seasons. Diets fed during adaptation had a roughage to concentrate ratio of 30:70 (dry matter basis). The amount of concentrate was gradually increased until reaching a roughage toconcentrate ratio of 10:90. We used a completely randomized design with two treatments (dry and rainy season) and six replications per treatment.The feedlot pens were considered as the experimental unit. The performance variables were analyzed to identify the differences between the seasons. Also, correlations between variables were calculated. The economic analysis was done using the operating cost methodology andcomparing the weighted averages between economic variables. Animals confined on both seasons (dry and rainy) showed the same performance. There was a positive correlation between days of confinement with administrative cost, depreciation and opportunity cost. A negative correlation was observed between profit and the equilibrium point. The arroba cost was higher in the rainy season. However, sale values for the animals in rainy season were high, which surpassed the higher production cost compared to the dry season and resulted in a higher profitability. We conclude that Nellore cattle could be confined all year round in an economically viable way.

Signatures of selection in Nelore cattle revealed by whole-genome sequencing data.

Nelore cattle breed was farmed worldwide due to its economic importance in the beef market and adaptation to the tropics. In Brazil, purebred Nelore animals (PO) receive a certificate from the breeders' association based on the animal's genealogy and morphological characterization. The top 20 to 30% of the superior animals are eligible to receive the Special Certificate of Identification and Production (CEIP), meaning animals from this category were selected and evaluated in a breeding program to improve economically important traits. We used whole-genome sequencing and approaches based on haplotype differentiation and allelic differentiation to detect regions of selection signatures in Nelore cattle by comparing animals from PO and CEIP categories. From a total of 150 animals, a hierarchical clustering analysis was performed to choose the more unrelated animals from each category (16 PO and 40 CEIP). The hapFLK statistic was performed, and extensions of hapFLK values were investigated considering continuous regions with significant q-values. The Weir and Cockerham's Fst estimator (wcFst) was computed using the GPAT++ software library. The total of 82,326 SNPs with hapFLK values passed the FDR control (q-value<0.05), and 718 segments were target as signatures of selection. A total of 1713 highly differentiated genomic regions were identified based on the segmentFst approach. The signatures of selection were spread across the genome. Annotation of overlapping selection signature regions between the two methods revealed 118 genes in common. A variant located within the 3' region of the BOLA-DRB3 gene was found as a promising candidate polymorphism. Within genomic regions that deserves attention, we found genes previously associated with adaptation to tropical environments (HELB), growth and navel size (HMGA2), fat deposition and domestication (IRAK3), and feed efficiency and postmortem carcass traits (GABRG3). The genes BOLA-DQA2, BOLA-DQB, BOLA-DQA5, BOLA-DQA1, BOLA-DRB3, ENSBTAG00000038397 on chromosome 23 are part of the Bovine Major Histocompatibility Complex (MHC) Class II gene family, representing good candidates for immune response and adaptation to tropical conditions. The BoLA family genes and the interaction of ROBO1 with SLIT genes appeared in the enrichment results. Genomic regions located in intronic regions were also identified and might play a regulatory role in traits under selection in PO and CEIP subpopulations. The regions here identified contribute to our knowledge regarding genes and variants that have an important role in complex traits selected in this breed.

Investigating potential causal relationships among carcass and meat quality traits using structural equation model in Nellore cattle

The objective of this study was to investigate potential causal relationships among hot carcass weight (HCW), longissimus muscle area (LMA), backfat thickness (BF), Warner-Bratzler shear force (WBSF), and marbling score (MB) traits in Nellore cattle using structural equation models (SEM). The SEM fitted comprises the following links between traits: WBSF → LMA, WBSF → HCW, HCW → LMA, BF → HCW, and BF → MB, where the arrows indicate the causal direction between traits, with structural coefficients posterior means (posterior standard deviation) equal to −0.29 cm2/kg (0.09), 0.43 kg/kg (0.29), 0.10 cm2/kg (0.006), 1.92 kg/mm (0.28), and 0.03 score-grade/mm (0.006), respectively. The final SEM revealed some important putative causal relationships among the traits studied here. The implied causal effects suggest that interventions on meat tenderness and fat content would affect overall growth and muscle deposition. Knowledge regarding potential causal relationships inferred among the traits studied here can have important implications for the genetic selection and management of Nellore cattle for improvement of carcass and meat quality.

Prediction ability for growth and maternal traits using SNP arrays based on different marker densities in Nellore cattle using the ssGBLUP.

This study aimed to investigate the prediction ability for growth and maternal traits using different low-density customized SNP arrays selected by informativeness and distribution of markers across the genome employing single-step genomic BLUP (ssGBLUP). Phenotypic records for adjusted weight at 210 and 450days of age were utilized. A total of 945 animals were genotyped with high-density chip, and 267 individuals born after 2008 were selected as validation population. We evaluated 11 scenarios using five customized density arrays (40k, 20k, 10k, 5k and 2k) and the HD array was used as desirable scenario. The GEBV predictions and BIF (Beef Improvement Federation) accuracy were obtained with BLUPF90 family programs. Linear regression was used to evaluate the prediction ability, inflation, and bias of GEBV of each customized array. An overestimation of partial GEBVs in contrast with complete GEBVs and increase of BIF accuracy with the density arrays diminished were observed. For all traits, the prediction ability was higher as the array density increased and it was similar with customized arrays higher than 10k SNPs. Level of inflation was lower as the density array increased of and was higher for MW210 effect. The bias was susceptible to overestimation of GEBVs when the density customized arrays decreased. These results revealed that the BIF accuracy is sensible to overestimation using low-density customized arrays while the prediction ability with least 10,000 informative SNPs obtained from the Illumina BovineHD BeadChip shows accurate and less biased predictions. Low-density customized arrays under ssGBLUP method could be feasible and cost-effective in genomic selection.

Changes on meat fatty acid profile, cholesterol and hepatic metabolism associated with antioxidants and canola oil supplementation for Nellore cattle

This study investigated the effect of canola oil supplementation associated with vitamin E and selenium on cholesterol and liver metabolism and meat fatty acid profile of Nellore cattle. Forty-eight Nellore bulls were randomly assessed to were randomly distributed in a 2 × 2 factorial arrangement: two levels of oil in the diet (no inclusion and 3% canola oil, defined as NO and OIL, respectively) and two levels of antioxidants in the diet (no inclusion and 2.5 mg of Se/kg of dry matter (DM) + 500 UI of vitamin E/kg of DM, defined as NA and ANT, respectively). Blood samples were collected at the beginning (day 0) and at days 28, 56 and 84 of the finishing periods for selenium, total cholesterol and its fractions and triglycerides quantification. After slaughter, liver samples were obtained from each animal to analyze the activity of reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione peroxidase (GSH-Px) and TBARS (substances reactive to 2-thiobarbituric acid). Additionally, 5 g of Longissimus thoracis (LT) were collected for evaluation of cholesterol, ethereal extract and fatty acids profile. Serum selenium concentration has a quadratic increase by antioxidant treatments according to the days on feed. Animal fed ANT presented a better liver antioxidant status, improving the activity of GSSG, GSH-Px, decreasing GSH, TBARS values and decreased the cholesterol concentration in the LT. As well as, decreased cholesterol and LDL-cholesterol in blood serum. Addition of 3% canola oil in diets for cattle improved fatty acid profile in meat and associated with antioxidants (selenium and vitamin E) increased antioxidants status and promoted reducing the cholesterol concentration in meat and serum. Supplementation with canola oil increased unsaturated, decreased saturated fat, increased the amount of n-3 and conjugated linoleic acid (CLA) meat content, and improved the n6/n-3 ratio. As consequence, the supplementation with canola oil and antioxidants in Nellore cattle diet can be a potential strategy to provide meat for human consumption with better lipids content in beef meat, with higher n-3 and lower cholesterol, which might impact positively the meat consumers health.

Economic Viability Analysis of an Oral Anthelmintic Treatment for Cattle in Feedlot

The economic viability of a commercial oral anthelmintic suspension containing 10% fenbendazole was evaluated in Angus x Nelore cattle in a feedlot. Two groups of 37 animals (treated and non-treated) were formed. A random-block design was used based on initial weight, egg count per gram of feces (EPG) and carcass grade. EPG counts and the determination of weight were performed on Days 0, 42 and 122. Carcass grade and yield were determined on the day of slaughter. Economic viability was evaluated using cost-effectiveness, sensitivity and financial analyses, considering three economic scenarios: most likely (M), optimistic (O) and pessimistic (P). The anthelmintic achieved 99.89% efficacy regarding EPG reduction. The animals exhibited an increase of 20.7 kg in live weight, 20.2 kg in live weight gain and 0.166 kg in daily weight gain (p &lt; 0.05). No effects were found on yield or carcass grade (p &gt; 0.05). The genus Haemonchus predominated at the onset of the study, whereas only the genus Cooperia was found after treatment. A net return of 14.60 USD per animal was found in the treated group, which remained viable under O, M and P scenarios, with respective differences of 18.92%, 12.86% and 91.15% in gross profit. The treatment was financially superior under all scenarios (real, M, O and P), with reductions of 1.89, 1.04, 0.48 and 16.39 years for the recovery of the initial investment. These results demonstrate the importance of economic analysis methods in the evaluation and selection of anthelmintics.

Genetic parameters for traditional and novel ultrasound carcass traits in Nellore cattle.

The objective of this study was to contribute to genetic improvement for carcass quality in Nellore cattle by estimating genetic parameters for carcass characteristics measured by traditional and novel ultrasound adjusted for body weight. Records of 19,910 Nellore breed animals born between 2001 and 2015 as part of a genetic improvement program were evaluated for this purpose. The (co)variance components and genetic parameters for yearling weight (YW), slaughter conformation at yearling age (SCY), ribeye area (REA), REA adjusted for 100kg of body weight (REA100), REA adjusted for 450kg of body weight (REA450), subcutaneous fat thickness over the loin (SFTL) and the rump (SFTR), intramuscular fat (IF), and height × width ratio of the sirloin steak (RATIO) were estimated using the restricted maximum likelihood (REML) method and the three-trait animal model. The estimated heritability values were 0.39 (YW), 0.33 (SCY), 0.31 (REA), 0.42 (REA100), 0.38 (REA450), 0.31 (RATIO), 0.17 (SFTL), 0.27 (SFTR), and 0.41 (MAR). The genetic correlations between REA and YW (0.43) and SCY and YW (0.78), respectively, suggested that selecting for REA or SCY could result in an increase in body weight. Because of its moderate and negative correlation with YW, REA100 was ineffective as a muscling indicator (- 0.38). The indicators REA450 and RATIO had a - 0.12 and 0.11 low correlation with YW, respectively. Thus, it is concluded that REA450 and RATIO were the best indicators of muscling, with heritability of medium magnitude, making the selection viable, as well as having a low correlation with body weight.

Early growth, backfat thickness and body condition has major effect on early heifer pregnancy in Nellore cattle.

The aim was to evaluate the association between growth, carcass and visual scores traits with precocious calving in Nellore cattle. Birth weight (BW), weight at 120, 210, 365 and 450 days of age, pre and post-weaning average daily gain, rib eye area, backfat thickness (BF), rump fat thickness and visual scores obtained at 18 months were used for the analysis. Records from 700 females born between 2009 and 2015, exposed to mating starting at 11 months of age were analyzed. Discriminant analyzes were performed with the software Statistica. BW and BF showed the highest (P>0.01) discrimination value for early heifer pregnancy (EP). Extreme intrauterine growth retardation can result in slower growth, which reflects in the worst reproductive performance, confirmed by the variation in BW between precocious and conventional heifers. The results also demonstrate that the level of body fat affects begin of puberty. Bone structure, musculature, depth, tail insertion and rump scores presented the highest discrimination value for EP. These traits can be used as selection tools to improve sexual precocity in female Nellore cattle. The results obtained in this study would support farmers to guide the heifer management and decisions in order to enhance the EP.

Selection criteria for frame score and its association with growth-, reproductive-, feed efficiency- and carcass-related traits in Nellore cattle

Context A frame score prediction equation developed specifically for Nellore cattle could be an auxiliary tool to improve mating decisions on the basis of feed resources and production-system objectives. Aims Estimate genetic parameters for frame by using a prediction equation developed for Nellore cattle and genetic associations between frame score (FRAME) and growth-, reproductive-, carcass- and feed efficiency-related traits, and five bioeconomic indexes. Methods Birth weight (BW), adjusted weight at 120 (W120), 210 (W210) and 450 (W450) days of age, adult weight (AW), age at first calving (AFC), probability of precocious calving (PPC30), stayability (STAY), accumulated cow productivity (ACP), adjusted scrotal circumference at 365 (SC365) and 450 (SC450) days of age, rib eye area (REA), subcutaneous backfat thickness (BFT), rump fat thickness (RFT), intramuscular fat percentage (IMF), residual feed intake (RFI) and dry-matter intake (DMI) were included in the analyses. Frame score was calculated using the multiple linear regression (MLR) prediction method. The estimation of genetic parameters was performed using a linear animal model, except for PPC30 and STAY, which were estimated through a threshold animal model. The correlated response in FRAME considering selection for growth-, reproductive-, carcass- and feed efficiency-indicator traits were obtained in the context of single-trait selection and a multiple-trait context. Key results Heritability estimated for FRAME was moderate (0.30 ± 0.09). Frame score showed moderate genetic correlations with growth traits, BW (0.51 ± 0.08), W120 (0.41 ± 0.07), W210 (0.35 ± 0.07) and W450 (0.29 ± 0.08). The genetic correlation estimates between FRAME and RFT was high (−0.84 ± 0.02), but low with ACP (0.25 ± 0.08) and RFI (0.10 ± 0.13). In the single-trait and multi-trait contexts, there was a lower correlated gain for FRAME when the selection was applied for traits commonly measured in beef cattle breeding programs. Conclusion Selection to increase growth traits would lead to an increase in frame size and herd nutritional requirements, and it would reduce the carcass fatness level and early heifer sexual precocity. FRAME could be an alternative trait to monitor calf birth weight. Implications Selection for FRAME is feasible, and the most suitable frame score value depends on the production system objectives and feed resources.

Research Article Identification of SNPs and changes in protein coding of genes associated with beef quality in Nellore cattle

Research Article Identification of SNPs and changes in protein coding of genes associated with beef quality in Nellore cattle

Ajuste e parâmetros genéticos da curva de crescimento em bovinos da raça Nelore Mocho

ABSTRACT This study was undertaken to compare different non-linear models for fitting growth curves of Polled Nellore animals as well as to estimate genetic parameters for the components of the growth curve. The study involved body weight-age data of 6,717 Polled Nellore cattle from birth to 650 days of age, which belonged to the Brazilian Association of Zebu Breeders (ABCZ), corresponding to the period from 1980 to 2011. Four non-linear models (Brody, Bertalanffy, Logistic, and Gompertz) were fitted and compared by the adjusted coefficient of determination (R2adj), mean absolute deviation of residuals (MAD), root mean square error (RMSE), Akaike information criterion (AIC), and Bayesian information criterion (BIC). To estimate the genetic parameters and genetic values of asymptotic weight (A), integration constant (B), and maturation rate (K), the Bayesian inference method was adopted. The Brody model showed the lowest values of MAD, RMSE, AIC, and BIC and the highest R2adj. Heritability estimates for parameters A, B, and K were 0.11, 0.16, and 0.30, respectively, whereas genetic correlations were 0.01 (A-B), -0.91 (A-K), and 0.24 (B-K). The Brody model provided the best fit. The K parameter shows enough genetic variability for selection in the herd. Heavier animals in adulthood tend to exhibit lower growth rates. Despite the low heritability estimate of parameter A, there were genetic gains, indicating that selection is being efficient on asymptotic weight.

Beef of Nellore cattle has limited tenderization despite pH decline in Longissimus lumborum

Bos taurus indicus temperament is variable and affects beef tenderization. Our objective was to investigate temperament and performance of non–castrated Nellore and identify groups based on Longissimus lumborum (LL) pH decline as well as beef characteristics produced by those groups. We investigated 94 animals with a subset of carcasses (n = 24) selected based on LL pH at 24 h postmortem (pm) to represent two groups: resistant to pH decline (> 5.8 called pH–Res; n = 10) and normal (< 5.7 called pH–Nor; n = 14). Steaks were fabricated from the LL muscle and randomly assigned to aging (2, 7, 14, and 21 days). Sarcomere length, cooking loss, myofibrillar fragmentation index (MFI), and Warner–Bratzler shear force (WBSF) were determined. Data on temperament were investigated in a multivariate approach, while beef data were compared between groups using the analysis of variance. Rectal temperature at the beginning of the finishing phase and total weight gain were greater and related to animals in the pH–Res group (p < 0.01 and p = 0.03, respectively). Temperature and pH decline curves, sarcomere length, and cooking loss revealed that pH–Res produced beef with lower quality compared to the pH–Nor group. Results for MFI and WBSF did not show differences between groups within each time pm; however, overall steaks from pH–Res were tougher (p = 0.06). Incidence of LL pH between 5.8 and 5.9 at 24 h pm did not compromise the tenderization rate or extension; however, it affected the water holding capacity in this population of Nellore cattle.

Analysis of Differences in Meat Quality Characteristics of Different Parts of Brazilian Nellore Cattle

Analysis of Differences in Meat Quality Characteristics of Different Parts of Brazilian Nellore Cattle

Eritrograma e estresse oxidativo em bovinos confinados alimentados com feno de Brachiaria sp. e suplementados com antioxidantes

Abstract Brachiaria sp contains sporidesmin that can be oxidized by lipoperoxidation and cause oxidative stress. In the present study we evaluated the effects of different antioxidants on lipoperoxidation of erythrocytes from Nelore cattle fed with Brachiaria sp hay. The experimental design was entirely randomized, in which 40 whole male cattle were divided into five treatments (G1: control - no supplementation; G2: selenium and vitamin E supplementation; G3: zinc supplementation; G4: selenium supplementation and G5: vitamin E supplementation) and allocated in feedlot pens for 105 days. The samples heparinized and withethylenediaminetetraacetic acid (EDTA) were obtained every 28 days for hematological and oxidative stress evaluation (0, 28 56, 84 and 105 days). In the erythrogram total erythrocyte count, hemoglobin, and hematocrit (Ht) were measured. For the evaluation of oxidative stress, in order to analyze the characteristics of the erythrocyte membrane, the thiobarbituric acid reactive substances (TBARS), total glutathione (GSH-T), glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) were determined. The results showed that regardless of the treatment there was no oxidative stress during the experimental confinement period and that the joint association of selenium and vitamin E in the bovine diet provided a lower incidence of deleterious alterations on erythrocytes.

Phenotypic association between residual feed intake and carcass traits of young nelore bulls

The purpose of this study was to estimate the phenotypic associations between residual food intake (RFI) and carcass traits, evaluated by ultrasonography, of young Nellore bulls. Information about 53 young Nelore bulls, pure origin (PO), participants in the Individual Performance Test of Nelore Bulls, carried out at the Capim Branco experimental farm of the Federal University of Uberlândia (UFU) were used for this purpose. It was evaluated the characteristics of residual feed intake (RFI), rib eye area (REA), marbling (MAR) and fat thickness (FT). In order to estimate the Spearman and Pearson correlation coefficients, the SAS program was used. Regarding the influence of the RFI classes (low RFI, medium RFI and high RFI) on carcass traits, an out analysis of variance was carried out using the least squares method. It was verified that there was no phenotypic association between RFI and the characteristics of REA and MAR, but the relation between FT and the phenotypic association revealed a medium magnitude. However, when evaluating the RFI classes, it was observed that there were no significant differences of the RFI classes with the carcass traits (REA, FT and MAR). It is recommended that new studies are carried out to verify if the selection for RFI does not result in damages to the finishing of carcass in Nelore cattle.