Genetic and Non-Genetic Parameters for Milk Production Traits of Dairy Cattle: A Review

The estimation of genetic and non-genetic parameters for milk production traits is an important tool for the definition and evaluation of selection programs. Results from various studies indicated that research should be intensified to identify and utilize animals with greater genetic potential. Performance traits like milk yield are considerably affected by environmental factors, which, in addition to genetic differences, are responsible for the marked variation between breeds, herds, and animals within the same breed. Some researchers reported a high value, whereas others reported a low to moderate heritability value. The contradictory results may be associated with differences in local breed, number, and composition of used animals in the estimation procedures and differences in methods and software used in genetic parameter estimation. Knowledge of genetic and phenotypic parameters is required for planning efficient breeding programs in animal husbandry. By knowledge of heritability estimates, animal geneticists can determine whether or not a particular trait can be improved by selection, by improvement of management practices, or both. Selection for yield traits has been successful and has improved the efficiency of dairy production. Genetic parameter estimation of indigenous cattle has been scanty in Ethiopia except for limited research activities that have been done in research centers, universities, and some state farms. Even though the country has more than 27 indigenous characterized breeds, only a few of them (Boran, Arsi, Fogera, and Barka) have estimated their performance for cross-breeding purposes. Since livestock is in the hands of farmers and characterized by having a small fragmented population and absence of pedigree history, performance testing, and the selection and breeding program/have not been performed over the years. Estimation of phenotypic performance and genetic parameters over time is necessary, because of changes in management, increased number of herds, and herd size, Ethiopia, imports semen from other countries.