Pantnagar Journal of Research

Abstract

Genetic improvement of animals for production traits especially the milk yield has always been a topic of concern for researchers all over the world. The concept of analyzing 305 days milk yield has now become obsolete. Developed countries had already started using test day (TD) model in their regular breeding program however in developing countries it is still an emerging concept and therefore extends further opportunities in areas of newer researches. The data of animal breeding can be analyzed by several analyzing methods like the repeatability model, the multiple trait model and the most recent random regression model (RRM). Random regression model is generally used for the analyzing longitudinal data that can be measured several times on trajectory of an individual. RRM allows drawing a personalized lactation curve for each cow with fixed regression explaining the general shape of lactation curve for all animals belonging to the same sub class and random regression describing the deviation which allows each cow to have differently shaped lactation curve and account for random genetic and permanent environmental effects. The article tries to gather all the information related to the past researches and future prospect of random regression model in genetic evaluation of cattle.