Supplementary feeding of forage to grazing dairy cows

Abstract

AbstractGrass silage was offered to continuously stocked dairy cows in two experiments. In the first 12 weeks of the grazing season (Experiment 1) 32 cows were offered grazed herbage only (G), or grazed herbage with a silage supplement offered for 45 min after morning milking (GMS), overnight at a restricted level (GRS) or overnight ad libitum (GAS). The two overnight treatments involved housing the cows between afternoon and morning milking. In late season (Experiment 2) 18 cows were used in a similar experiment lasting 9 weeks to compare treatments G, GMS and GAS. Within experiments the same level of herbage was available to all treatments (mean sward height 9.6 and 7.2 cm in Experiments 1 and 2 respectively).In Experiment 1, offering silage depressed herbage dry matter (DM) intake but had no significant effect on total DM intake. Silage (GMS, GRS, GAS) reduced milk yield but increased milk fat content and fat yield compared with G. In Experiment 2 offering silage depressed herbage DM intake but increased total DM and ME intakes. This led to increased milk yields, fat and lactose contents and liveweight gains, with the greatest benefit obtained when silage was available overnight.Silage was therefore beneficial in maintaining high DM intakes. Also, the substitution of silage for grazed herbage, particularly in Experiment 2, indicated that high stocking rates on grazing land can be maintained throughout the season, when silage is available ad libitum.