Linhagem materna: Qual a sua influência em características pré e pós desmama em bovinos da raça Nelore?

The present work had as objective to evaluate the effects of the introduction of the maternal lineage (Lc), representing the mitochondrial inheritance, in the model of genetic evaluation on birth weight (BW), weight for 120 days (W120), weaning weight (WW), weight at 12 month (W12), weight at 18 month (W18), weight gain from weaning to 18 month (WG18), scrotal perimeter (SP) and temperament (TEMP) of a Brazilian Nelore herd. Two models had been used for raise a comparison among of estimates the (co)variances components and genetic parameter, been the first equal one to currently used in the genetic evaluations of this herd, and second included the random effect of maternal lineage. Amongst the analyzed characteristics, the maternal lineage effect was significant (P<0.05) for W18 and SP only it, where this effect was responsible for 3% and 7%, respectively, of phenotypic variance could be explained by Lc effect. For besides characteristics, however not significant, this effect was responsible for 1% and 9% of phenotypic variance.

Maltodextrina em rações de leitões desmamados com diferentes pesos: Desempenho e morfometria intestinal

Two trials were conducted: in the first trial, 96 weaning pigs at the age of 21 days were used, in a block design, with a 2 x 2 factorial arrangement (two sources of carbohydrate and two weaning weight classes). In the second trial, 48 pigs were used, in a block design, with 2 x 2 x 2 x 3 factorial arrangement (two weaning weight classes x two sources of carbohydrate x two portions of the small intestine x three slaughter periods). The effects of the replacement of lactose by maltodextrin in diets of weaning pigs, with different weights, were evaluated on daily feed intake, daily weight gain, feed:gain ratio, villus height, crypt depth and thickness of the mucosa. In the first trial, from 0 to 17 days and from 0 to 29 days after weaning, effects of weight classes were detected on daily weight gain and daily feed intake. In the second trial, maltodextrin resulted in an increase in the average thickness of the intestinal mucosa and in average crypt depth, only in lighter animals. Maltodextrin can be used as an alternative to lactose in diets of weaning pigs.

Phenotypic plasticity of composite beef cattle performance using reaction norms model with unknown covariate

The objective of the present study was to determine the presence of genotype by environment interaction (G × E) and to characterize the phenotypic plasticity of birth weight (BW), weaning weight (WW), postweaning weight gain (PWG) and yearling scrotal circumference (SC) in composite beef cattle using the reaction norms model with unknown covariate. The animals were born between 1995 and 2008 on 33 farms located throughout all Brazilian biomes between latitude -7 and -31, longitude -40 and -63. The contemporary group was chosen as the environmental descriptor, that is, the environmental covariate of the reaction norms. In general, higher estimates of direct heritability were observed in extreme favorable environments. The mean of direct heritability across the environmental gradient ranged from 0.05 to 0.51, 0.09 to 0.43, 0.01 to 0.43 and from 0.12 to 0.26 for BW, WW, PWG and SC, respectively. The variation in direct heritability observed indicates a different response to selection according to the environment in which the animals of the population are evaluated. The correlation between the level and slope of the reaction norm for BW and PWG was high, indicating that animals with higher average breeding values responded better to improvement in environmental conditions, a fact characterizing a scale of G × E. Low correlation between the intercept and slope was obtained for WW and SC, implying re-ranking of animals in different environments. Genetic variation exists in the sensitivity of animals to the environment, a fact that permits the selection of more plastic or robust genotypes in the population studied. Thus, the G × E is an important factor that should be considered in the genetic evaluation of the present population of composite beef cattle. © The Animal Consortium 2012.

Principal components and factor analytic models for birth to mature weights in Nellore cattle

A total of 61,528 weight records from 22,246 Nellore animals born between 1984 and 2002 were used to compare different multiple-trait analysis methods for birth to mature weights. The following models were used: standard multivarite model (MV), five reduced-rank models fitting the first 1, 2, 3, 4 and 5 genetic principal components, and five models using factor analysis with 1, 2, 3, 4 and 5 factors. Direct additive genetic random effects and residual effects were included in all models. In addition, maternal genetic and maternal permanent environmental effects were included as random effects for birth and weaning weight. The models included contemporary group as fixed effect and age of animal at recording (except for birth weight) and age of dam at calving as linear and quadratic effects (for birth weight and weaning weight). The maternal genetic, maternal permanent environmental and residual (co)variance matrices were assumed to be full rank. According to model selection criteria, the model fitting the three first principal components (PC3) provided the best fit, without the need for factor analysis models. Similar estimates of phenotypic, direct additive and maternal genetic, maternal permanent environmental and residual (co)variances were obtained with models MV and PC3. Direct heritability ranged from 0.21 (birth weight) to 0.45 (weight at 6 years of age). The genetic and phenotypic correlations obtained with model PC3 were slightly higher than those estimated with model MV. In general, the reduced-rank model substantially decreased the number of parameters in the analyses without reducing the goodness-of-fit. © 2013 Elsevier B.V.

Estimativas de parâmetros genéticos para características de crescimento em ovinos da raça somalis brasileira

The aim of this study was to estimate genetic parameters for growth traits in Somalis Brasileira hair sheep breed. The data used in this study were from the flock of Embrapa Caprinos and Ovinos, located in the city of Sobral - CE, Brazil. Data contained records of 1,120 animals in the pedigree file. The analyzed traits were birth weight (PN), weaning weight (PD), weight gain from birth to weaning (GND) and adult weight (PA). Estimates of (co)variances and genetic parameters were obtained by Derivative Free Restricted Maximum Likelihood Method (DFREML) using the MTDFREML software. The heritabilities were low to moderate in univariate analysis. The maternal heritabilities were higher than direct heritabilities. The heritabilities in multivariate analysis exceeded those in univariate analysis. The values of genetic correlations varied widely.

Nursing regimens: Effects on body condition, return to postpartum ovarian cyclicity in Santa Ines ewes, and performance of lambs

The effects of nursing regimens on the body condition, onset of ovarian cyclicity postpartum and weaning weight of lambs were assessed in Santa Ines ewes. Thirty-two ewes were blocked according to parity, number of lambs, and body weight at lambing and within each block randomly allocated to treatments: continuous nursing (CN), controlled nursing (CN2) with two daily feedings for an hour after the 10th day postpartum, or early weaning (EW) with total separation from the lambs after the 10th day. The animals were evaluated from the 12th day postpartum until the first estrus or until 60th day. The dry matter and nutrients intake did not differ among treatments ( P>. 0.05) but did differ over time ( P<. 0.01). The weight, body condition score, serum concentrations of non-esterified fatty acids and prolactin, the percentages of ewes in estrus, of ewes that ovulated within 60th day and had ovulation silent, the period from lambing to estrus, ovulation and follicle with a diameter ≥5. mm and the maximum follicular diameter did not differ ( P>. 0.05) among the treatments. The percentage of ovulation until 30th day was greater ( P<. 0.05) in the EW group. The percentage of short luteal phases was higher in the CN2 and EW groups ( P=0.07) and normal luteal phases were higher in the CN group ( P=0.01). Lamb weight weaning was lower in the EW group ( P<. 0.05). It is possible to use CN to obtain lambing periods less than eight months in Santa Ines ewes, with the advantages of simpler management and higher lamb weaning weights. © 2013 Elsevier B.V.

Genetic variability for temperament indicators of Nellore cattle

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Produção e composição do leite de ovelhas da raça bergamácia suplementadas com óleo de linhaça (Linum usitatissimum L.)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Associação genética entre características da carcaça e carne com características de crescimento em bovinos Nelore

Pós-graduação em Genética e Melhoramento Animal - FCAV

Estudo de características de desempenho e medidas por escores visuais em bovinos Nelore

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estimativas de parâmetros genéticos para características de crescimento e de carcaça em ovinos de corte

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Parâmetros genéticos de escore de temperamento em bovinos da raça Nelore

Pós-graduação em Zootecnia - FCAV

Análise de genes associados à deposição de gordura em bovinos da raça Nelore

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estimativas de parâmetros genéticos para características de temperamento e de escores visuais em bovinos da raça Nelore

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Interação genótipo ambiente sobre características reprodutivas de fêmeas da raça Nelore

Pós-graduação em Genética e Melhoramento Animal - FCAV