Analysis of lactation specific demographic parameters and effect of involuntary culling and mortality on lifetime performance in Karan Fries cows

Abstract

Disposal at an early stage shortens the breeding and productive life of dairy animal and affects the farm economics. Present study was aimed at estimating various demographic parameters and studying the parity wise disposal in Karan Fries cows. Data was spread over a period of 30 years (1981 to 2010), the information consisted of disposal records of 1813 adult Karan Fries cattle maintained at National Dairy Research Institute (NDRI) herd. Parity wise disposal pattern (upto fifth parity), revealed that the average parity wise culling and disposal rates were 26.08% and 31.96%, respectively. Involuntary culling accounted for the major cause of culling in the Karan Fries herd. Highly significant difference in lifetime performance of cows affected with different disposal causes was observed, in comparison to normal crossbred cows culled due to older age. Highly significant unfavourable effect of involuntary culling on lifetime performance of Karan Fries cows was observed. Estimates of parity wise demographic parameters indicated that stayability (L_x) of cows upto fourth parity was less than half (33%) of the total cows that entered the herd during first parity. The average survival (P_x) and disposal rate (Q_x) were around 70% and 30% for most of the parities. Lactation specific herd structure indicated that the more than half (62%) of the cows belong to first two parities and the lactation wise disposal was highest in the first and second parity due to the voluntary culling of the cows for low milk production in the early parities. Expected herd life (E_x) had a declining trend with increase in lactation number.