Genetic parameters and environmental factors influencing weaning weight in livestock production
Keywords:
Genetic parameters, Environmental factors, Weaning weight, Animal productionAbstract
This is a review paper that focuses on genetic parameters and various environmental factors affecting weaning weight in animal production. Animal production is affected by both genetic and non-genetic factor, and level of weaning weight performance depends on their interaction. The estimates of direct heritability of weaning weight vary from medium to high which makes it a suitable selection candidate trait, however cognisance should be taken of the antagonism of genes controlling direct and maternal effects. The variation in genetic parameter estimates may be due to a variety of factors which include breed differences, management, data preparation and methods of estimation. Estimates of genetic parameters for weaning weight is partly model dependent and ignoring of maternal genetic effect in the model leads to overestimation of direct heritability. Whilst genetics is a major influence on weaning weight, there are also a large number of environmental, nutritional and management factors that impinge on weaning weight of an individual. Estimation of reliable estimates of genetic parameters for weaning weight need to take into account the adjustment of performance data for environmental factors hence this will increase the accuracy of selection of breeding animals. An understanding of environmental factors which affect weaning weight will direct changes in the breeding and management programs to minimise influences which reduce production efficiency. Most environmental factors are significant source of variation for weaning weight and play an important role in expression of genetic potential. Management system is one of the many factors which could affect weaning weight in livestock since in a farm situation young ones will be subjected to the same season, parity, climatic conditions in terms of availability of feed, medication and vaccination. The review paper therefore, concludes that a number of environmental factors affect weaning weight can directly obscure recognition of genetic potential of individuals.
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