Substitution and production responses when lactating dairy cows graze a white clover pasture supplemented with maize silage

Abstract

Friesian cows (16) in late lactation grazed pure white clover (Trifolium repens cv. Haifa) swards for 32 days in autumn and were supplemented with maize (Zea mays) silage. Four groups of 4 cows were offered either 19 or 39 kg dry matter (DM)/cow.day of white clover with either 0 or 4.4 kg DM/cow.day of maize silage. All cows were individually fed maize silage and grazed the pasture as individual groups according to treatment. When maize silage was fed, total intake increased, this occurring to a greater degree at the low pasture allowance. The level of substitution of silage for pasture was 0.14 and 0.40 kg DM reduction in pasture intake per kg DM of maize silage eaten at the low and high allowances, respectively. At the low pasture allowance, milk yields were 10.1 and 13.7 kg/cow. day when 0 and 4.4 kg DM/cow.day of maize silage were fed, respectively, and were 15.5 and 15.9 kg/cow.day at the high pasture allowance. Liveweight and body condition increased as plane of nutrition increased but there were no effects of feeding on milk fat or protein contents. Feeding maize silage had little effect on any rumen or faecal variable although there was generally less ammonia nitrogen in rumen fluid when cows were supplemented with maize silage.