Scenario of Genetic Selection and Its Impact on Bovine Mastitis
Ahmad Arif, Muneeb U Rehman, Showkat Ahmad Bhat, Bilal Ahmad Mir, Rahil Razak Bhat, Manzoor R Mir, Sheikh Bilal, Ishraq Hussain.
Abstract Ever since their original domestication, farm animals have been undergoing human managed selection. Originally, selection was limited to docility and manageability, but in the last few decades breeding programmes have focused on the genetic improvement of production traits, in terms of milk yield, growth rate etc. Genetic selection together with preventive health care, hygiene and veterinary treatment is the most important approved combat strategies against mastitis. The potentiality of genetic selection as a possible mode of resistance to mastitis is by the fact that the disease is in part genetically determined; although little information is known about the genes that transfer resistance. The importance of genetic selection for resistance to mastitis is exacerbated by the deteriorating genetic base for resistance to mastitis with intense selection for production traits, which is due to an unfavourable genetic correlation between milk yield and mastitis. Therefore there is need for accurate selection criteria in genetic selection for resistance to mastitis balanced against genetic improvement of other traits. The consequences of selection and breeding can be judged on the basis of its impacts on health and the welfare of individual offspring and future generations. Many genetic studies showed an unfavourable genetic correlation between milk yield and incidence of ketosis, lameness, metabolic stress, mastitis, reduces fertility and longevity. In this review we will discuss selection for high yield traits and their consequences; and need for formulating future breeding goals that include not only production traits but also traits concerning to fertility, longevity, animal welfare etc.