Teagasc, Animal & Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork P61 C996, Ireland.
Teagasc, Animal & Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork P61 C996, Ireland.
Animal. 2021 Sep;15(9):100335. doi: 10.1016/j.animal.2021.100335. Epub 2021 Aug 13.
Extending the grazing season in pasture based systems of dairy production can increase farm profitability; poor weather and soil conditions can reduce the number of grazing days. The study objectives were to (i) examine the effect of restricted access to pasture in the autumn on the milk production, grazing behaviour and DM intake (DMI) of late lactation spring-calving dairy cows and (ii) establish the effect of alternating restricted and continuous access to pasture on dairy cow production, DMI and grazing behaviour. Cows were randomly assigned to one of four grazing treatments: (i) 22 h (full-time) access to pasture (22H; control); (ii) Two 5-h periods of access to pasture (2×5H); (iii) Two 3-h periods of access to pasture (2×3H); and (iv) alternating between full-time and 3-h access to pasture with no more than three continuous days on any one regime, e.g. Monday - full-time access, Tuesday - 2x3H access, Wednesday - 2x3H access; Thursday - full-time access, etc. (2×3HV). Restricted access to pasture was offered after a.m. and p.m. milking. Swards of similar quality and pregrazing herbage mass were offered. Treatment had no effect on milk yield (13.2 kg/day), milk fat (48.2 g/kg), protein (39.0 g/kg) or lactose content (42.6 g/kg) and milk solid yield (1.15 kg/day). Similarly, there was no effect of treatment on final BW (483 kg) or final BCS (2.66). There was no significant difference in DMI (15.1 kg DM/cow/day) between treatments. There was an effect on daily grazing time, 22H cows (565 min/cow/day) grazed for longest time, however, when the 2x3HV treatment had full-time access to pasture, they had a similar grazing time (543 min/cow/day) to the 22H cows and were similar to the 2x3H treatment on days with restricted access to pasture (357 min/cow/day). The 22H and 2x5H animals had similar grass DMI/min (29.2 g/min), the 2x3HV were higher (33.9 g/min) but were similar to the comparable treatment when offered 2x3H access time (41.6 g/min) and when offered 22H access time (27.7 g/min). The results from this study show how when offered a grass only diet of autumn pasture grazing behaviour can be modified by restricting pasture access time without reducing dairy cow production in late lactation at low production levels. There was also no effect of alternating access time between 22H and 2x3H on milk production and DMI in the 2x3HV treatment. Restricted access time to pasture in autumn may be a strategy which farmers can use to extend the grazing season.
延长牧场系统中奶牛养殖的放牧季节可以提高农场的盈利能力；恶劣的天气和土壤条件会减少放牧天数。本研究的目的是：（i）研究秋季限制牧场放牧对泌乳后期春季产奶牛的产奶量、放牧行为和干物质采食量（DMI）的影响；（ii）确定限制和连续放牧对奶牛生产、DMI 和放牧行为的影响。奶牛被随机分配到以下四种放牧处理之一：（i）22 小时（全时）放牧（22H；对照）；（ii）两次 5 小时放牧（2×5H）；（iii）两次 3 小时放牧（2×3H）；（iv）全时和 3 小时放牧交替进行，任何一种方案都不超过连续三天，例如，周一 - 全时放牧，周二 - 2x3H 放牧，周三 - 2x3H 放牧；周四 - 全时访问等（2×3HV）。在早晚挤奶后提供限制放牧。提供质量和放牧前牧草质量相似的草地。处理对产奶量（13.2 公斤/天）、乳脂（48.2 克/公斤）、蛋白质（39.0 克/公斤）或乳糖含量（42.6 克/公斤）和乳固体产量（1.15 公斤/天）没有影响。同样，处理对最终体重（483 公斤）或最终体况评分（2.66）也没有影响。处理间的 DMI（15.1 公斤 DM/奶牛/天）无显著差异。放牧时间有影响，22H 奶牛（565 分钟/奶牛/天）的放牧时间最长，然而，当 2x3HV 处理可以全天放牧时，它们的放牧时间与 22H 奶牛相似（543 分钟/奶牛/天），与限制放牧时的 2x3H 处理相似（357 分钟/奶牛/天）。22H 和 2x5H 动物的牧草 DM/分钟采食量相似（29.2 克/分钟），2x3HV 较高（33.9 克/分钟），但当提供 2x3H 访问时间（41.6 克/分钟）和提供 22H 访问时间（27.7 克/分钟）时，与可比处理相似。本研究结果表明，在秋季提供仅草地的放牧时，如何通过限制放牧时间来改变放牧行为，而不会降低低产奶牛在泌乳后期的产奶量。在 2x3HV 处理中，22H 和 2x3H 之间交替访问时间对产奶量和 DMI 也没有影响。秋季限制牧场放牧时间可能是农民延长放牧季节的一种策略。
