The article discusses how genetic traits related to disease resistance can be inherited and improved in animals. Traits like mastitis and helminthiasis have high heritability and genetic correlation, making them effective for genetic improvement. Different methods like offspring-parent regression and sib analysis are used to estimate heritability. The study emphasizes the importance of estimated breeding value and repeatability in genetic improvement programs. Examples with ketosis, mastitis, breech strike, and helminthiasis are provided to illustrate these concepts.