Effect of body condition and pregnancy on milk yield and composition in crossbred dairy cattle under tropical conditions

Milk yield and its composition are influenced by flow of substrates from the blood circulation to the mammary tissues. Body condition score (BCS) is an intermediate factor between the feed intake and the productivity status of the animal. Since energy intake does not keep pace with continuously rising milk yield, energy deficit in early lactation leads to a competitive situation among milk yield, fertility and health of the dairy cow as these traits are linked by energy requirement. The present study was designed to investigate the effect of body condition and pregnancy on milk yield and composition in F1 crossbred cows (HolsteinFriesian X local cows). Fifty-eight cows (60 days postpartum) were selected at a large state farm. Pregnancy status was classified as: NP (non-pregnant), T-1 (pregnant trimester-I), T-II (trimester-II) and T-III (trimester-III). Milk yield (MY), milk composition (MC) and BCS were recorded weekly. The study continued up to 9 months postpartum during the year, 2007-2008. Pregnancy significantly affected the MY and MC (P<0.05). There was a linear increase in fat and protein contents with advancing pregnancy whereas lactose showed an opposite trend. NP animals had also lower milk yield compare to pregnant ones. BCS correlated negatively with MPL and animals with moderate BCS showed higher MPL. BCS affected fat and protein contents as well as milk yield. Milk yield was higher with moderate BCS while fat and protein with higher one. BCS correlated negatively with milk yield while positively with fat and protein contents. It was concluded that moderate BCS supported higher milk yield.