author(s)
Ashutosh Dubey, Asit Jain, Rajkumar Gadpaylae, Deepti Kiran Bara, Aayush Yadav, Vikas Kumar and Jyotimala Sahu

abstract
The phenotypic expressions of quantitative traits viz. milk production, egg production are under the control of large number of genes which interacts together to express a particular trait. There expressions depend not only on the genotype, but also due to interaction of genotype with an environment. The genotype of a trait, in turn, depends on both additive and non-additive type of gene action. For low heritability and complex traits such as fitness/survival or reproductive traits, the additive genetic variance does not show much of the impact. For a breeding program to be effective, mate selection along with appropriate breeding method is important to control inbreeding depression and to get maximum heterosis due to non-additive type of gene action. These methods includes various type of out breeding programs such as crossbreeding, recurrent selection, recurrent reciprocal selection, etc., mainly in species with short generation intervals like swine and poultry.