The effect of early-spring grazing on the intake and performance of dairy cows managed on two contrasting systems of milk production during the winter.

A study was designed to examine the effects of early-spring grazing on the performance of dairy cows managed on two contrasting systems of milk production during the winter. This four-system study involved 60 autumn-calving Holstein-Friesian dairy cows, comprising 33 multiparous and 27 primiparous animals. Animals were allocated to each of the four systems according to calving date, with primiparous and multiparous animals being allocated separately. From calving until 24 February, animals on forage-based (F-) systems, F-G and F-H, were offered high feed-value silages, supplemented with 6.0 kg concentrates/day [crude protein content, 311 g/kg dry matter (DM)], while animals on concentrate-based (C-) systems, C-G and C-H, were offered medium feed-value silages, supplemented with 12.5 kg concentrate /day (crude protein content, 211 g/kg DM). On 25 February, animals on each of systems F-G and C-G commenced a period of early-spring grazing (-G), with animals initially being given access to pasture for 2 to 3 h per day, increasing to 8 to 9 h per day by 24 March, while continuing to be offered their full winter concentrate allowance during the part of the day when they were indoors. During this 4-week period, animals on systems F-H and C-H continued to be housed (-H). Mean herbage intakes were estimated as 3.4 and 3.6 kg DM / day for animals on systems F-G and C-G, respectively, while animals with access to pasture had significantly lower silage DM intakes than those which did not (P 0.05), but tended to increase the energy balance of the animals, compared to those which did not have access to pasture. In the present study, which involved planes of nutrition relevant to high producing autumn calving animals, the use of early-spring grazing had no beneficial effects on animal performance, although it did reduce silage intake.