The effect of degree of grass wilting prior to ensiling on performance andenergy utilisation by lactating dairy cattle

Thirty lactating Holstein Friesian cows were used in a three treatment rand omised block design experiment to investigate the influence of degree of gr ass wilting prior to ensiling on animal performance and energy utilisation. The three forage treatments were produced from perennial ryegrass swards e ither ensiled directly or mown, conditioned, spread and tedded to ensure ra pid wilting, and ensiled following 30 or 52 h to achieve dry matter (DM) co ncentrations in the silages of 193, 286 and 437 g/kg respectively. All sila ges were offered in ad libitum quantities for a 5-week period and in additi on all cows received 10 kg/d of a concentrate containing 206 g CP/kg DM. To tal diet digestibility data were recorded on four cows/treatment and methan e outputs on two cows/treatment during the final week of the experiment. Th e daily intake of silage DM increased with increased wilting - 7.2, 7.3, an d 8.4 (s.e.m. 0.44) kg DM - but milk yield was highest with the unwilted si lage - 23.3, 20.5 and 21.7 (s.e.m. 0.80) kg/d - for the unwilted, medium an d high levels of wilting respectively. Wilting had no effect on the yield o f milk fat or protein but the nutrient utilisation studies suggested that t he overall efficiency of metabolisable energy conversion to milk energy out put was reduced with increasing degree of wilting. (C) 2000 Elsevier Scienc e B.V. All rights reserved.