莫能菌素对高比例精料补饲条件下采食暖季型牧草断奶犊牛生长及生理参数的影响。
Effects of monensin inclusion into increasing amount of concentrate on growth and physiological parameters of early-weaned beef calves consuming warm-season grasses.
机构信息
IFAS/Range Cattle Research and Education Center, University of Florida, Ona, FL.
Department of Animal Science, Texas A&M University, College Station, TX.
出版信息
J Anim Sci. 2018 Dec 3;96(12):5112-5123. doi: 10.1093/jas/sky374.
Two experiments evaluated the effects of concentrate amount and monensin inclusion on growth and physiological parameters of early-weaned beef calves consuming warm-season grasses in drylot (Exp. 1) and pastures (Exp. 2). In both experiments, treatments consisted of two concentrate DM amounts (1 or 2% of BW) and two inclusion rates of monensin (0 or 20 mg of monensin/kg of total DM intake). In Exp. 1, 48 Angus × Brahman crossbred early-weaned (EW) beef calves (initial age = 90 ± 13 d; initial BW = 83 ± 12 kg) were distributed in 12 drylot pens (four calves per pen; three pens per treatment) and provided stargrass (Cynodon nlemfuensis) hay (9% CP and 52% IVDOM) at amounts to ensure 10% DM refusals for 56 d. In Exp. 2, 36 Angus × Brahman crossbred EW heifer calves (initial BW = 171 ± 15 kg) were randomly allocated into one of 12 bahiagrass (Paspalum notatum) pastures on a continuous and fixed stocking rate (1 ha and three heifers per pasture; three pastures per treatment) and received daily supplementation of their respective treatments for 84 d. In both experiments, effects of monensin inclusion × concentrate amount were not detected for any variable (P ≥ 0.14), but overall ADG and plasma IGF-1 concentrations were greater (P ≤ 0.05), whereas fecal coccidia egg counts tended (P = 0.09; Exp. 1) or were less (P = 0.05; Exp. 2) for calves offered concentrate with vs. without monensin inclusion. Calves offered concentrate at 2% of BW had greater (P ≤ 0.05) overall ADG (Exps. 1 and 2), herbage mass (Exp. 2 only), in vivo apparent digestibility, total DMI and plasma concentrations of glucose and IGF-1 (Exp. 1 only), less forage DM intake (Exp. 1 only), and no effects on fecal coccidia egg counts (Exps. 1 and 2) compared to calves offered concentrate at 1% of BW. Increasing concentrate amount is an effective management practice to increase ADG and decrease forage DMI in early-weaned calves consuming warm-season grasses, whereas the decrease in fecal coccidia egg count and additional ADG provide evidence that monensin should be supplied to early-weaned calves grazing warm-season pastures and receiving concentrate at 1% of BW or above.
两个实验评估了浓缩物的数量和莫能菌素的添加对在干草场（实验 1）和牧场上（实验 2）食用暖季草的早期断奶肉牛的生长和生理参数的影响。在两个实验中，处理包括两种浓缩物 DM 量（BW 的 1%或 2%）和两种莫能菌素添加率（总 DM 摄入量的 0 或 20mg 莫能菌素/kg）。在实验 1 中，48 头安格斯×婆罗门杂交早期断奶（EW）肉牛（初始年龄=90±13d；初始 BW=83±12kg）被分配到 12 个干草场围栏（每栏 4 头；每处理 3 栏），并提供了星状草（Cynodon nlemfuensis）干草（9%CP 和 52%IVDOM），以确保 56 天内有 10%的 DM 被拒绝。在实验 2 中，36 头安格斯×婆罗门杂交早期断奶（EW）小母牛（初始 BW=171±15kg）被随机分配到 12 个巴哈草（Paspalum notatum）牧场上的一个连续和固定的饲养率（每公顷和每牧场三头小母牛；每处理三个牧场），并在 84 天内每天补充各自的处理。在两个实验中，莫能菌素添加×浓缩物量对任何变量都没有影响（P≥0.14），但总体 ADG 和血浆 IGF-1 浓度更高（P≤0.05），而粪便球虫卵计数则倾向于（P=0.09；实验 1）或较少（P=0.05；实验 2）对于提供浓缩物和不提供浓缩物的小母牛。与提供 1% BW 浓缩物的小母牛相比，提供 2% BW 浓缩物的小母牛具有更高的总体 ADG（实验 1 和 2）、牧草质量（仅实验 2）、体内表观消化率、总 DMI 和血糖和 IGF-1 的血浆浓度（仅实验 1）、更少的牧草 DM 摄入量（仅实验 1），粪便球虫卵计数无影响（实验 1 和 2）。与提供 1% BW 浓缩物的小母牛相比，增加浓缩物的量是提高早期断奶肉牛暖季草采食量和降低牧草 DM 摄入量的有效管理措施，而粪便球虫卵计数的减少和额外的 ADG 提供了证据，即莫能菌素应供应给放牧暖季牧场并接受 1% BW 或以上浓缩物的早期断奶小母牛。
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