The influence of shade on milk production of Holstein-Friesian cows in a tropical upland environment

Abstract

Sixteen Holstein-Friesian animals, comprising 8 multiparous cows and 8 first-lactation heifers, were divided into 2 equal groups which had access to either tree shade or no shade. All animals were in the first third of lactation and were subjected to treatment for 8 weeks in summer 1985. Average maximum monthly temperatures ranged from 26.2 to 28.22¦ over the experimental period. The provision of shade increased (P< 0.01) milk yield; however, there was a significant (P<0.05) interaction between response to shade and cow parity. Mean daily milk yields for multiparous cows were 19.2 and 17.2 kg/cow (P< 0.01) and 16.3 and 15.9 kg/cow (P> 0.05) for heifers in the shade and no shade groups respectively. Cows without shade incurred a significant decrease (P< 0.05) in solids-not fat yield, lactose percentage and lactose yield, and a significant increase ( P < 0.05) in somatic cell count. The composition of milk from heifers without shade was no different from that from heifers with shade. Rectal temperature was higher (P < 0.01) in animals without shade (mean 40.0¦C) than in animals with shade (mean 39.4¦C). The highest mean maximum rectal temperature of 41.6¦C was recorded in the noshade group. It was concluded that shade is essential if milk yield and milk composition are to be maximised in this environment.