José Bento Sterman Ferraz

Correlação genética entre perímetro escrotal e algumas características reprodutivas na raça Nelore

Data of scrotal circumference and female reproductive traits were analyzed to estimate heritabilities and genetic correlations. Data were obtained from 11 farms by the same company, located in the States of Sao Paulo, Mato Grosso do Sul and Goias. Variance components were estimated by restricted maximum likelihood using two-trait animal models. For traits with repeated measures, two mathematical models were used: including or not the permanent environment of the cow. Analyses that not included the permanent environment of the cow showed the following heritabilities 0.51, 0.12, 0.17, 0.06 and 0.13 for scrotal circumference (SC), age at first calving (AFC), days to calving (DC), calving interval (CI) and gestation length (GL), respectively. In these analyses, the genetic correlations were: -0.22 (SC x AFC), -0.04 (SC x DC), 0.10 (SC x CI) and ¾0.04 (SC x GL). When permanent environment of the cow were included in the model, heritabilities of DC (0.07) and GL (0.06) were smaller, indicating that models without permanent environment of the cow can overestimate the additive genetic variance of these two traits. However, the CI parameters did not change with the inclusion of permanent environment of the cow in the model. The scrotal circumference showed favorable genetic correlations with AFC, DC and GL, but the values in overall were low. These results allow utilizing SC as a selection criterion to improve the female fertility efficiency.

Parâmetros genéticos de longevidade e produtividade de fêmeas da raça Nelore

In order to estimate the (co)variance components, heritabilities and genetic correlations of longevity and herd life in females, informations of 56,413 births of females from a Nellore cattle herd, from 1950 to 2000, under different rearing and management conditions, were used. It was studied from calf: weaning weight (W205C), yearling weight (W365C), weight in 550 days (W550C), from cows: weaning weight (W205), yearling weight (W365) and weight in 550 days (W550), age at first calving (AFC), calving interval (CI), herd life (RL), longevity (LONG), reproductive efficiency (RE), index production (IP), index of metabolic production (IMP), sum of index production (SIP), sum of index metabolic production (SIMP). The analysis were performed using the MTDFREML software, estimating (co)variance components, assuming animal model. Direct genetic, maternal and permanent environmental effects were analyzed. Fixed effects of farm, feeding program, rearing condition, birth calf year, birth calf season and calf sex, were also analyzed. Heritability estimates showed similar results among the different analyses, higher (0.24 to 0.75) for W205, W365, W550, W205C, W365C, W550C, IP, IMP, AFC, RL, LONG and lower (0 to 0.10) for RE, CI, SIP and SIMP. Some correlations between maternal genetic effect and the growth traits were negative. In general, estimates of genetic and phenotypic correlations among LONG and growth traits were negative, suggesting genetic antagonism between LONG and early maturity, between the LONG and reproductive and productive traits were positive, suggesting the significant effect of reproductive and productive traits on LONG.

Additive genetic relationships between scrotal circumference, heifer pregnancy, and stayability in Nellore cattle

Scrotal circumference data from 47,605 Nellore young bulls, measured at around 18 mo of age (SC18), were analyzed simultaneously with 27,924 heifer pregnancy (HP) and 80,831 stayability (STAY) records to estimate their additive genetic relationships. Additionally, the possibility that economically relevant traits measured directly in females could replace SC18 as a selection criterion was verified. Heifer pregnancy was defined as the observation that a heifer conceived and remained pregnant, which was assessed by rectal palpation at 60 d. Females were exposed to sires for the first time at about 14 mo of age (between 11 and 16 mo). Stayability was defined as whether or not a cow calved every year up to 5 yr of age, when the opportunity to breed was provided. A Bayesian linear-threshold-threshold analysis via Gibbs sampler was used to estimate the variance and covariance components of the multitrait model. Heritability estimates were 0.42 ± 0.01, 0.53 ± 0.03, and 0.10 ± 0.01, for SC18, HP, and STAY, respectively. The genetic correlation estimates were 0.29 ± 0.05, 0.19 ± 0.05, and 0.64 ± 0.07 between SC18 and HP, SC18 and STAY, and HP and STAY, respectively. The residual correlation estimate between HP and STAY was -0.08 ± 0.03. The heritability values indicate the existence of considerable genetic variance for SC18 and HP traits. However, genetic correlations between SC18 and the female reproductive traits analyzed in the present study can only be considered moderate. The small residual correlation between HP and STAY suggests that environmental effects common to both traits are not major. The large heritability estimate for HP and the high genetic correlation between HP and STAY obtained in the present study confirm that EPD for HP can be used to select bulls for the production of precocious, fertile, and long-lived daughters. Moreover, SC18 could be incorporated in multitrait analysis to improve the prediction accuracy for HP genetic merit of young bulls.

Análise de alguns critérios de seleção para características de crescimento na raça Nelore

Foram obtidas estimativas de parâmetros geneticos para peso ao nascimento (PN) e ao sobreano (PSOB), ganhos de peso pre- (GPNDES) e pos-desmama (GP345), dias para 160 (D160) e 300kg (D300) de peso vivo, e taxas de crescimento relativo pre- (TCR1) e pos-desmama (TCR2), utilizando 60.470 animais Nelore. Adotou-se o metodo REML, sob modelo animal. Para caracteristicas pre-desmama (PN, GPNDES, D160 e TCR1), o modelo incluiu efeitos aleatorios de animal, aditivo materno, de ambiente permanente de vaca e de residuo, e os efeitos fixos de grupo de contemporâneos (GC) a desmama e das covariaveis idade da vaca ao parto e idade do animal (IA) a epoca da desmama. Para caracteristicas pos-desmama (PSOB, GP345, D300 e TCR2), considerou-se como efeito fixo o GC ao sobreano e como covariavel a IA ao sobreano. As medias observadas± desvios-padrao foram 30,7±3,8kg (PN); 317,2± 49,4kg (PSOB); 155,4± 21,0kg (GPNDES); 119,6± 32,2kg (GP345); 175,7± 34,2 dias (D160); 553,9± 152,7 dias (D300); 913,2± 80,9x10-3%/dia (TCR1); e 140,5± 31,2x10-3%/dia (TCR2). Resultantes das analises conjuntas de duas caracteristicas (GPNDES e cada uma das outras caracteristicas), as estimativas de herdabilidade direta e materna para GPNDES variaram, respectivamente, de 0,11 a 0,20 e de 0,03 a 0,16. Os coeficientes de herdabilidade direta foram 0,24; 0,26; 0,18; 0,15; 0,12; 0,14 e 0,22, respectivamente, para PN, PSOB, GP345, D160, D300, TCR1 e TCR2. Os coeficientes de herdabilidade materna para PN, D160 e TCR1 foram, respectivamente, 0,11; 0,00 e 0,14. As correlacoes geneticas entre GPNDES e as outras caracteristicas foram altas, exceto entre GPNDES e GP345 (0,23).

Análise genética de algumas características reprodutivas e suas relações com o desempenho ponderal na raça Nelore

Aiming to study age at first calving for females exposed to bulls for the first time around 14 months of age (IPP14) or around 26 months of age (IPP26), days to calving (DPP), gestation length (DG) and scrotal circumference (PE) and their relationships with weight traits (birth weight - PESNAS; weaning weight - PESDES; 18 month weight - PESSOB; and weight gain from weaning to 18 months - GP345) in Nellore cattle, data sets varying from 6,030 to 94,637 observations were analyzed. Analyses were processed using two-trait animal models. Heritability estimates for reproductive traits were: 0.18 (IPP14), 0.02 (IPP26), 0.06 (DPP), 0.26 (DG), and 0.46 (PE). Correlations between PE and weight traits indicated that weights were not antagonic to PE. Although genetic correlations between PESDES and reproductive traits of females were low to moderate, in unfavorable direction, it would not be recommended to increase adult size of the animals in those herds to avoid the risk of low reproductive performance. The traits PESSOB and GP345 were not antagonic to sexual precocity and fertility of females, except gestation length.

Genome-wide association analysis of feed intake and residual feed intake in Nellore cattle

BackgroundFeed intake plays an important economic role in beef cattle, and is related with feed efficiency, weight gain and carcass traits. However, the phenotypes collected for dry matter intake and feed efficiency are scarce when compared with other measures such as weight gain and carcass traits. The use of genomic information can improve the power of inference of studies on these measures, identifying genomic regions that affect these phenotypes. This work performed the genome-wide association study (GWAS) for dry matter intake (DMI) and residual feed intake (RFI) of 720 Nellore cattle (Bos taurus indicus).ResultsIn general, no genomic region extremely associated with both phenotypic traits was observed, as expected for the variables that have their regulation controlled by many genes. Three SNPs surpassed the threshold for the Bonferroni multiple test for DMI and two SNPs for RFI. These markers are located on chromosomes 4, 8, 14 and 21 in regions near genes regulating appetite and ion transport and close to important QTL as previously reported to RFI and DMI, thus corroborating the literature that points these two processes as important in the physiological regulation of intake and feed efficiency.ConclusionsThis study showed the first GWAS of DMI to identify genomic regions associated with feed intake and efficiency in Nellore cattle. Some genes and QTLs previously described for DMI and RFI, in other subspecies (Bos taurus taurus), that influences these phenotypes are confirmed in this study.

assessment of inbreeding depression in a Guzerat dairy herd: effects of individual increase in inbreeding coefficients on production and reproduction

Influences of inbreeding on daily milk yield (DMY), age at first calving (AFC), and calving intervals (CI) were determined on a highly inbred zebu dairy subpopulation of the Guzerat breed. Variance components were estimated using animal models in single-trait analyses. Two approaches were employed to estimate inbreeding depression: using individual increase in inbreeding coefficients or using inbreeding coefficients as possible covariates included in the statistical models. The pedigree file included 9,915 animals, of which 9,055 were inbred, with an average inbreeding coefficient of 15.2%. The maximum inbreeding coefficient observed was 49.45%, and the average inbreeding for the females still in the herd during the analysis was 26.42%. Heritability estimates were 0.27 for DMY and 0.38 for AFC. The genetic variance ratio estimated with the random regression model for CI ranged around 0.10. Increased inbreeding caused poorer performance in DMY, AFC, and CI. However, some of the cows with the highest milk yield were among the highly inbred animals in this subpopulation. Individual increase in inbreeding used as a covariate in the statistical models accounted for inbreeding depression while avoiding overestimation that may result when fitting inbreeding coefficients.

Estimação de parâmetros genéticos em bovinos de corte utilizando os métodos de máxima verossimilhança restrita e Â

The objective of this paper was to compare the estimates of genetic parameters obtained by REML and method Â. Animal model single-trait analyses were performed using a data set of Nellore cattle. Statistical models included fixed effects of contemporary group (herd, year, sex and management groups at weaning and 550 days) and age of animal (covariable-linear effect), and additive genetic and residual random effects. Heritability estimates were 0.36 and 0.39 for weight at 550 days (W550); 0.27 and 0.29 for weight gain from weaning to 550 days (WG345); 0.22 and 0.21 for conformation (CONF); 0.21 and 0.21 for precocity (PREC) and 0.22 and 0.22 for muscling (MUSC), respectively, by REML and method Â. For all heritability estimates, standard errors were lower than or equal to 0.02. The differences in the estimates of genetic trend obtained from the two methods were low for all traits. Spearman rank correlation between breeding values obtained in the analyses using the variance components obtained by REML and method  were equal to 1 for all traits. The results suggest that REML and method  provide similar results and that method  can be used as an alternative to REML in single-trait analyses, mainly due to lower computational requirements.

Influência da interação touro x rebanho na estimação da correlação entre efeitos genéticos direto e materno em bovinos da raça Nelore

Sire x herd interactions were studied in 30,789 records of birth (BW) and weaning weight (WW) and weight gain from weaning to 18 months of age (G345) of Nellore cattle born from 1984 to 1994 in twelve farms located in three states of central and southeastern Brazil, with a total of 48.495 animals in pedigree. Sire x herd interaction was considered as a random effect in single trait and two traits animal models using MTDFREML. This effect was important for BW (6% of the phenotypic variance) and it both affected variance and covariance components and, consequently, genetic parameters. The effect was smaller for WW (around 1% of the phenotypic variance), but influenced the estimates of (co) variance components. For G345, Sire x Herd effect was small. Likelihood tests showed that this effect was significant for all traits. This study showed that genetic correlations between direct x maternal effects are close to zero or even positive if sire x herd interaction is fitted in the model, and always negative if it is not.

Liver transcriptomic networks reveal main biological processes associated with feed efficiency in beef cattle

BackgroundThe selection of beef cattle for feed efficiency (FE) traits is very important not only for productive and economic efficiency but also for reduced environmental impact of livestock. Considering that FE is multifactorial and expensive to measure, the aim of this study was to identify biological functions and regulatory genes associated with this phenotype.ResultsEight genes were differentially expressed between high and low feed efficient animals (HFE and LFE, respectively). Co-expression analyses identified 34 gene modules of which 4 were strongly associated with FE traits. They were mainly enriched for inflammatory response or inflammation-related terms. We also identified 463 differentially co-expressed genes which were functionally enriched for immune response and lipid metabolism. A total of 8 key regulators of gene expression profiles affecting FE were found. The LFE animals had higher feed intake and increased subcutaneous and visceral fat deposition. In addition, LFE animals showed higher levels of serum cholesterol and liver injury biomarker GGT. Histopathology of the liver showed higher percentage of periportal inflammation with mononuclear infiltrate.ConclusionLiver transcriptomic network analysis coupled with other results demonstrated that LFE animals present altered lipid metabolism and increased hepatic periportal lesions associated with an inflammatory response composed mainly by mononuclear cells. We are now focusing to identify the causes of increased liver lesions in LFE animals.