Milk production by grazing cows given different types of diet in late pregnancy

Abstract

Three experiments were carried out to examine the effects of different types of diet in late pregnancy on subsequent milk production of cows grazing pasture. In experiment one, 17 sets of monozygous twin heifers were fed equal quantities, of metabolizable energy (ME) of either hay or a mixture of hay and grain (1:1). In experiment two, 13 sets of twin heifers were fed equal quantities of ME as either hay or pasture. In experiment three, 22 pairs of mature cows were given equal quantities of ME as either pasture or a mixture of pasture and hay (1:2). In all experiments the amounts fed were estimated to provide for foetal and mammary development and maintain the dam's tissue reserves. No significant differences were obtained in subsequent milk production. The results show that yield and composition of milk of cows fed solely on pasture during lactation was not affected by the type of diet offered in late pregnancy, if fed at levels near maintenance. At this feeding level, hay or mixtures of hay and grain are suitable alternatives to pasture for dairy cows in late pregnancy.