Three models on estimates of variance components and fixed effects on weaning weight of slow growing rabbits population were compared. Measures on weaning weight (W-weight) from 86 progeny of 4 bucks mated with 12 does (3 dams/buck) were collected and sex (Sex), number of progeny weaned (N-weaned), Parity and age at weaning (W-age) were registered. Variance components of W-weight concerned buck-, doe-, error-, phenotipic-, additive genetic-, maternal-, and environmental- variance. Buck- and doe- random components were estimated by REML (REstricted Maximum Likelihood) in a nested design. Analysis was carried out by use of three different mixed models in which (fixed) effects of Sex, number of progeny weaned (N-weaned), Parity and age at weaning (W-age) were considered. In model-1 Sex and Parity were concerned as class variables and W-age as a covariate. In model-2 Sex and N-weaned were concerned as class variables and W-age as a covariate. In model-3 Sex was concerned as a class variable and N-weaned and W-age as covariates. In all models Sex do not showed significant differences. Parity and W-age denoted significant influences in model-1. N-weaned was found significant as a class variable (model-2) and as a covariate (model-3). Heritability (h2) estimates were: model-1=0.31, model-2=0.65 and model-3>1.00, respectively. Sex does not influence W-weight. All models results in estimates of heritability with high standard errors, subjecting need to repeat estimation on more extended data. Model-1, resulted in a more reliable estimate of h2 with respect to others models in which, some variance components were found negatives.
Estimation of Influence of Genetic and Environmental Factors on Slow Growing Rabbit Population: I. Preliminary Study.,
LEOTTA, ROBERTO;PACI, GISELLA
2007
Abstract
Three models on estimates of variance components and fixed effects on weaning weight of slow growing rabbits population were compared. Measures on weaning weight (W-weight) from 86 progeny of 4 bucks mated with 12 does (3 dams/buck) were collected and sex (Sex), number of progeny weaned (N-weaned), Parity and age at weaning (W-age) were registered. Variance components of W-weight concerned buck-, doe-, error-, phenotipic-, additive genetic-, maternal-, and environmental- variance. Buck- and doe- random components were estimated by REML (REstricted Maximum Likelihood) in a nested design. Analysis was carried out by use of three different mixed models in which (fixed) effects of Sex, number of progeny weaned (N-weaned), Parity and age at weaning (W-age) were considered. In model-1 Sex and Parity were concerned as class variables and W-age as a covariate. In model-2 Sex and N-weaned were concerned as class variables and W-age as a covariate. In model-3 Sex was concerned as a class variable and N-weaned and W-age as covariates. In all models Sex do not showed significant differences. Parity and W-age denoted significant influences in model-1. N-weaned was found significant as a class variable (model-2) and as a covariate (model-3). Heritability (h2) estimates were: model-1=0.31, model-2=0.65 and model-3>1.00, respectively. Sex does not influence W-weight. All models results in estimates of heritability with high standard errors, subjecting need to repeat estimation on more extended data. Model-1, resulted in a more reliable estimate of h2 with respect to others models in which, some variance components were found negatives.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
