Milk production and grazing behaviour responses of Alpine dairy goats to daily access time to pasture or to daily pasture allowance on temperate pastures in spring

摘要

In a context of price volatility and low feed self-sufficiency of goat farms in Western Europe, grazing may play an important role. Knowledge about the impact of grazing management - particularly daily access time to pasture or pasture allowance - on dairy goats' performance is scarce. Two 3-week trials were carried out in spring with 36 Alpine goats in mid-lactation. In Trial 1, 3 access times to pasture during daytime (AT: 4, 6 or 8 h/day, from 08:00 to 12:00, from 10:00 to 16:00 and from 08:00 to 16:00, respectively) were compared. In each treatment, goats individually received 370 g DM of dehydrated forage (lucerne and maize) after the evening milking, 278 g DM of concentrate twice daily, at each milking, and a daily pasture allowance of 2.0 kg DM/goat, measured at 4 cm above ground level. In Trial 2, 3 daily pasture allowances (PA: 1.6, 2.3 or 3.0 kg DM/goat, measured at 4 cm above ground level) were compared. Goats individually received 278 g DM of concentrate twice daily, at each milking, and access time to pasture was of 13 h/d (from 07:30 to 16:00 and from 17:00 to 21:30). Milk production was similar between medium and high levels of AT or PA, and was lower for the lowest level of AT or PA (-300 g/d at the lowest AT and -500 g/d at the lowest PA). Milk fat and protein concentrations only slightly varied between the different levels of AT or PA. In both trials, goats maintained an intense grazing activity. Grazing time (from 240 to 540 min/d) and proportion of time spent grazing (from 66 to 99%) were mainly affected by AT, and only marginally by PA.