RESUMO
The present study aimed to estimate covariance components of milk fatty acids (FA) and to compare the genomic estimated breeding values under general and heat-stress effects. Data consisted of 38,762 test-day records from 6,344 Holstein cows obtained from May 2012 through January 2018 on 4 dairy herds from Brazil. Single-trait repeatability test-day models with random regressions as a function of temperature-humidity index values were used for genetic analyses. The models included contemporary groups, parity order (1-6), and days in milk classes as fixed effects, and general and thermotolerance additive genetic and permanent environmental as random effects. Notably, differences in heritability estimates between environments (general and heat stress) increased (0.03 to 0.06) for unsaturated FA traits, such as unsaturated, monounsaturated, and polyunsaturated, at higher heat-stress levels. In contrast, heritability estimated between environments for saturated FA traits, including saturated FA, palmitic acid (C16:0), and stearic acid (C18:0) did not observe significant differences between environments. In addition, our study revealed negative genetic correlations between general and heat-stress additive genetic effects (antagonistic effect) for the saturated FA, C16:0, C18:0, and C18:1, which ranged from -0.007 to -0.32. Spearman's ranking correlation between genomic estimated breeding values ranged from -0.27 to 0.99. Results indicated a moderate to strong interaction of genotype by the environment for most FA traits comparing a heat-stress environment with thermoneutral conditions. Our findings point out novel opportunities to explore the use of FA milk profile and heat-stress models.
Assuntos
Lactação , Leite , Animais , Brasil , Bovinos , Ácidos Graxos , Feminino , Resposta ao Choque Térmico/genética , Lactação/genética , GravidezRESUMO
The objectives of this study were to characterize the allelic and genotypic frequencies of polymorphisms in the µ-calpain and calpastatin genes, and to assess their association with meat tenderness and animal growth in Nellore cattle. We evaluated 605 Nellore animals at 24 months of age, on average, at slaughter. The polymorphisms were determined for the molecular markers CAPN316, CAPN530, CAPN4751, CAPN4753, and UOGACAST1. Analyses of meat tenderness at 7, 14, and 21 days of maturation were performed in samples of longissimus thoracis obtained between the 12th and 13th rib and sheared using a Warner Bratzler Shear Force. Significant effects were observed for meat tenderness at days 7, 14, and 21 of maturation for the marker CAPN4751, at day 21 for the marker CAPN4753, and at days 14 and 21 for the marker UOGCAST1. For genotypic combinations of markers, the results were significant for the combination CAPN4751/UOGCAST1 in the three maturation periods and CAPN4753/UOGCAST1 at days 14 and 21 of maturation.
Assuntos
Proteínas de Ligação ao Cálcio/genética , Calpaína/genética , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Animais , Bovinos , Frequência do Gene , Marcadores Genéticos , Genótipo , Carne Vermelha/análiseRESUMO
The continuous trait age at subsequent rebreeding (ASR) was evaluated using survival analysis in Nellore breed cows that conceived for the first time at approximately 14 months of age. This methodology was chosen because the restricted breeding season produces censored data. The dataset contained 2885 records of ASR (in days). Records of females that did not produce calves in the following year after being exposed to a sire were considered censored (48.3% of the total). The statistical model used was a Weibull mixed survival model, which included fixed effects of contemporary groups (CG) and period and a random effect of individual animal. The effect of contemporary groups on ASR was significant (P < 0.01). Heritabilities obtained for ASR were 0.03 and 0.04 in logarithmic and original scales, respectively. These results indicate that the genetic selection response for subsequent reproduction of 2-year-old Nellore breed females is not expected to be effective based on survival analysis. Furthermore, these results suggest that environmental improvement is fundamental to this important trait. It should be highlighted that an increase in the average date of birth can produce an adverse effect in the future, since this cannot be compensated by genetic improvement.
Assuntos
Cruzamento , Reprodução/genética , Seleção Genética , Análise de Sobrevida , Fatores Etários , Animais , Bovinos , Meio Ambiente , Feminino , FenótipoRESUMO
Meat quality is being increasingly demanded by consumers in recent years. Several factors can affect meat quality, ranging from animal traits such as breed and genetic heritage to pre- and post-slaughter processes. This study investigated the influence of Nellore bulls on carcass and meat quality traits. We used 475 young uncastrated males, the progeny of 54 bulls, to evaluate characteristics of the following carcass traits: hot carcass weight, rib-eye area, and fat thickness. We also evaluated the following beef quality traits: marbling, color, drip loss, cooking loss, and shear force at 0, 7, and 14 days of aging. Bulls had a significant influence (P≤0.05) on rib-eye area, fat thickness, marbling, drip loss at 14 days of aging and color at all aging periods. Based on these results, the use of bulls with high breeding values for these traits can provide important advances in carcass traits and meat quality in breeding programs of Nellore cattle that are raised in tropical conditions.
Assuntos
Peso Corporal/genética , Cruzamento , Carne , Tecido Adiposo/metabolismo , Fatores Etários , Animais , Composição Corporal/genética , Bovinos , Masculino , FenótipoRESUMO
We looked for possible associations of SNPs in genes related to protein turnover, with growth, feed efficiency and carcass traits in feedlot Nellore cattle. Purebred Nellore bulls and steers (N = 290; 378 ± 42 kg body weight, 23 months ± 42 days old) were evaluated for daily feed intake, body weight gain (BWG), gross feed efficiency, feed conversion ratio, partial efficiency of growth, residual feed intake (RFI), ultrasound backfat, rump fat, and ribeye area. Genotypes were obtained for SNPs in the growth hormone receptor (GHR-1 and GHR-2); calpain (CAPN4751); calpastatin (UoGCAST); ubiquitin-conjugating enzyme 2I (UBE2I-1 and UBE2I-2); R3H domain containing 1 (R3HDM1-1, -2, -3, and -4), ring finger protein 19 (RNF19); proteasome 26S subunit, non-ATPase, 13 (PSMD13); ribosomal protein, large, P2 (RPLP2); and isoleucine-tRNA synthetase 2, mitochondrial (IARS2) genes. Allelic substitution, additive and dominant effects were tested and molecular breeding values were computed. CAPN4751, GHR-1 and -2, IARS2, R3HDM1-4, and UoGCAST were found to be normally segregating polymorphisms. Additive and dominance effects were observed on BWG, feed efficiency and carcass traits, although dominant effects predominated. Significant allelic substitution effects were observed for CAPN4751, GHR-1 and -2, and UoGCAST on BWG, gross feed efficiency, RFI, and carcass traits, under single- or multiple-marker analyses. Correlations between molecular breeding values and phenotypes were low, excepted for RFI, based on allelic substitution estimates obtained by stepwise linear regression. We conclude that SNPs in genes related to protein turnover are related to economically important traits in Nellore cattle.
Assuntos
Ração Animal , Polimorfismo de Nucleotídeo Único/genética , Biossíntese de Proteínas/genética , Proteólise , Alelos , Animais , Composição Corporal , Bovinos , Metabolismo Energético/genética , Genótipo , Masculino , Carne , Fenótipo , Aumento de PesoRESUMO
Given the important role of leptin in metabolism, we looked for a possible association of leptin and leptin receptor polymorphisms with carcass and growth traits in Nellore cattle. We examined associations of leptin and leptin receptor SNPs with ultrasound carcass (longissimus dorsi muscle area (ribeye area), backfat thickness and rump fat thickness and growth traits (weaning weight adjusted to 210 days of age, yearling weight adjusted to 550 days of age, weight gain of weaning to yearling and scrotal circumference adjusted to 550 days of age) of 2162 Bos primigenius indicus (Nellore) animals. Allele and genotypic frequencies were calculated for each marker. Allele substitution, additive and dominance effects of the polymorphisms were also evaluated. Some alleles of the molecular markers had low frequencies, lower than 1%, in the sample analyzed, although the same polymorphisms described for B. p. taurus cattle were found. Due to very low allelic frequencies, the E2JW, A59V and UASMS2 markers were not included in the analysis, because they were almost fixed. E2FB was found to be significantly associated with weight gain, ribeye area and backfat thickness. The promoter region markers, C963T and UASMS1, were also found to be significantly associated with ribeye area. T945M was significantly associated with weight gain. We conclude that the leptin and receptor gene markers would be useful for marker-assisted selection.
Assuntos
Bovinos/crescimento & desenvolvimento , Bovinos/genética , Leptina/genética , Carne , Polimorfismo de Nucleotídeo Único/genética , Característica Quantitativa Herdável , Receptores para Leptina/genética , Alelos , Animais , Frequência do Gene/genética , Estudos de Associação Genética , Marcadores Genéticos , Genótipo , UltrassomRESUMO
Information about the Brazilian beef cattle industry is provided and th e effects of massive use of genetically superior bulls, semen and embryos is simulated to show their important contribution to that industry, as a way to improve the low productivity levels observed in Brazil, one of the leaders in beef exports in the world. Any in crease on the use of better genetics will cause a very significant economic impact in the Brazilian beef industry. Amounts as high as US$ 342 million/yr may be reached in the near future with the growing utilization of fixed time artificial insemination (FTAI), considering only the direct effects of weaning and yearling weights. These values will be even higher if reproductive traits are considered as selection criteria. The indirect effects, which are clearly underestimated in this simulation study, are much more important than the direct ones. The increase on the income of the industry coul d reach significant amounts, without the need of opening new areas for cattle grazing or destroying forests and devastating the environment.(AU)
Assuntos
Animais , Embrião de Mamíferos/embriologia , Sêmen/citologia , Bovinos/classificação , Inseminação Artificial/veterináriaRESUMO
Information about the Brazilian beef cattle industry is provided and th e effects of massive use of genetically superior bulls, semen and embryos is simulated to show their important contribution to that industry, as a way to improve the low productivity levels observed in Brazil, one of the leaders in beef exports in the world. Any in crease on the use of better genetics will cause a very significant economic impact in the Brazilian beef industry. Amounts as high as US$ 342 million/yr may be reached in the near future with the growing utilization of fixed time artificial insemination (FTAI), considering only the direct effects of weaning and yearling weights. These values will be even higher if reproductive traits are considered as selection criteria. The indirect effects, which are clearly underestimated in this simulation study, are much more important than the direct ones. The increase on the income of the industry coul d reach significant amounts, without the need of opening new areas for cattle grazing or destroying forests and devastating the environment.
Assuntos
Animais , Embrião de Mamíferos/embriologia , Sêmen/citologia , Bovinos/classificação , Inseminação Artificial/veterináriaRESUMO
We analyzed single nucleotide polymorphisms in calpain, leptin, leptin receptor, and growth hormone receptor genes and their association with color, drip and cooking losses of longissimus muscle at 7, 14 and 21 days postmortem in 638 purebred Nellore bulls slaughtered between 22 and 26 months of age. Meat samples were vacuum-packed and aged at 4°C. The single nucleotide polymorphisms T945M, GHR2, E2FB, and CAPN4751 were evaluated. All genotypic classes were observed; however, the T/T genotype of T945M and E2FB was found at a low frequency. A significant association of E2FB with drip loss (a measure of water-holding capacity) was detected at seven days of meat aging. CAPN4751 had an additive effect on red and yellow color intensities. The T allele of CAPN4751 was found to be positively associated with improved meat color, but not with meat tenderness, differing from a previous report indicating that it is associated with meat tenderness. We conclude that the potential for use of CAPN4751 as a marker for these meat quality traits requires further research.
Assuntos
Composição Corporal/genética , Calpaína/genética , Bovinos/genética , Leptina/genética , Carne , Animais , DNA/análise , DNA/genética , Marcadores Genéticos , Genótipo , Gado/genética , Carne/análise , Músculo Esquelético , Fenótipo , Polimorfismo de Nucleotídeo Único , Receptores para Leptina/genética , Receptores da Somatotropina/genéticaRESUMO
We examined whether single-nucleotide polymorphisms (SNPs) in the calpain (CAPN) and calpastatin (CAST) genes, described from Bos primigenius taurus, are polymorphic in Nellore cattle. We also looked for a possible association of linkage disequilibrium of this polymorphism with tenderness of the longissimus dorsi muscle after 7, 14 and 21 days of postmortem aging in 638 purebred Nellore bulls. Meat tenderness was measured as Warner-Bratzler shear force. Additive and dominance effects were tested for SNPs of the three genotypic classes; the substitution effect was tested for SNPs with missing genotypic classes. Genotypic and gene frequencies were also calculated for the different SNPs. An increase in tenderness was observed from 7 to 21 days; the average values for shear force at 7, 14 and 21 days of aging were 5.92 +/- 0.06, 4.92 +/- 0.05, and 4.38 +/- 0.04 kg, respectively. All markers showed polymorphism, but there was no CC genotype for CAPN316, and few animals showed the AA genotype for CAPN530. The alleles CAPN4751, UOGCAST1, and WSUCAST were found to have additive and dominance effects for shear force at 7, 14 and 21 days, while CAPN316 showed a substitution effect for shear force at 7 and 21 days. An additive-by-additive epistatic interaction was observed between CAPN4751 and markers on the CAST gene. In conclusion, these markers should be considered for use in breeding programs.