Increasing the number of grazing days achieved by dairy cows

Extending the grazing season has positive implications for profit margins, as grazed grass is the cheapest feed available. Two of the biggest limitations when extending the grazing season are poor soil conditions and wet weather. Allowing animals restricted access to pasture may be a method of achieving an increased number of grazing days (Chilibroste et al., 2007). The objective of this study was to examine the effect of restricting pasture access time on dry matter intake (DMI), grazing behaviour and milk production. Fifty-two (20 primiparous and 32 pluriparous) Holstein-Friesian spring calving dairy cows (mean calving date 31 January) were balanced for lactation number (2.4; s.d. 1.43), milk yield (24.5 (s.d. 4.53) kg), body-weight (509, (s.d. 69.5) kg) and body condition score (3.31, s.d. 0.331) in a randomised block design with 4 treatments. The study was conducted from 25 February to 25 March, 2008. The four treatments were: full-time access to pasture (22H; control); 4.5 h pasture access after both milkings (2 × 4.5H); 3 h pasture access after both milkings (2 × 3H); 3 h pasture access after both milkings plus silage supplementation (3 kg of dry matter (DM) per cow) by night (2 × 3HS). Cows on all treatments were offered a daily herbage DM (above 4 cm) allowance of 15 kg cow−1 day−1 and supplemented with concentrate (3 kg DM per cow per day). Treatment groups grazed separate farmlets for the duration of the study so that effects on subsequent grass re-growth could be established. Pre- and post-grazing sward heights were measured daily. Milk yield was recorded daily,