Corriher V A, Hill G M, Andrae J G, Froetschel M A, Mullinix B G
Department of Animal and Dairy Science, University of Georgia, Tifton 31793, USA.
J Anim Sci. 2007 Oct;85(10):2762-71. doi: 10.2527/jas.2007-0015. Epub 2007 May 25.
Cow and calf performance was determined in a 2-yr, 2 x 2 factorial, grazing experiment using Coastal or Tifton 85 (T85) replicated Bermudagrass pastures (4 pastures each; each pasture 4.86 ha), without or with aeschynomene creep-grazing paddocks (n = 4, 0.202 ha each, planted in May of each year, 13.44 kg/ha). On June 10, 2004, and June 8, 2005, 96 winter-calving beef "tester" cows and their calves were grouped by cow breed (9 Angus and 3 Polled Hereford/group), initial cow BW (592.9 +/- 70.1 kg, 2-yr mean), age of dam, calf breed (Angus, Polled Hereford, or Angus x Polled Hereford), calf sex, initial calf age (117 +/- 20.1 d, 2-yr mean), and initial calf BW (161.3 +/- 30.4 kg) and were randomly assigned to pastures. Additional cow-calf pairs and open cows were added as the forage increased during the season. Forage mass was similar for all treatment pastures (P > 0.70; 2-yr mean, 6,939 vs. 6,628 kg/ha, Coastal vs. T85; 6,664 vs. 6,896 kg/ha, no creep grazing vs. creep grazing). Main effect interactions did not occur for performance variables (P > 0.10; 2-yr means), and year affected only the initial and final BW of the calves and cows. The 91-d tester calf ADG was greater for calves grazing T85 than Coastal (0.94 vs. 0.79 kg; P < 0.01), and for calves creep grazing aeschynomene compared with calves without creep grazing (0.90 vs. 0.82 kg; P < 0.03). Calf 205-d adjusted weaning weights were increased for calves grazing T85 compared with Coastal (252.9 vs. 240.3 kg; P < 0.01) and for calves with access to creep grazing (249.9 vs. 243.3 kg; P < 0.05). The IVDMD of esophageal masticate from pastures had a forage x creep grazing interaction (P < 0.05; Coastal, no creep grazing = 57.4%; Coastal, creep grazing = 52.1%; T85, no creep grazing = 59.1%; T85, creep grazing = 60.0%), and IVDMD was greater (P < 0.05) for T85 than for Coastal pastures. Cows were milked in August 2004, and in June and August 2005, with variable milk yields on treatments, but increased milk protein (P < 0.05) for cows grazing T85 compared with Coastal pastures in August each year, contributing to increased calf gains on T85 pastures. These results complement previous research with T85 and indicate increased forage quality and performance of cattle grazing T85 pastures. Calf gains on T85 pastures and for calves on creep-grazed aeschynomene paddocks were high enough to influence the efficiency of cow-calf operations.
在一项为期两年的2×2析因放牧试验中，测定了奶牛和犊牛的生产性能。试验使用海岸雀稗或蒂夫顿85（T85）重复百慕大草牧场（每个品种4个牧场；每个牧场4.86公顷），设有或不设有合萌爬牧围场（n = 4，每个0.202公顷，每年5月种植，13.44千克/公顷）。2004年6月10日和2005年6月8日，96头冬季产犊的肉牛“测试”母牛及其犊牛按母牛品种（每组9头安格斯牛和3头无角海福特牛）、初始母牛体重（592.9±70.1千克，两年平均值）、母牛年龄、犊牛品种（安格斯牛、无角海福特牛或安格斯×无角海福特牛）、犊牛性别、初始犊牛年龄（117±20.1天，两年平均值）和初始犊牛体重（161.3±30.4千克）进行分组，并随机分配到各牧场。随着季节中牧草量的增加，补充了额外的母牛 - 犊牛对和空怀母牛。所有处理牧场的牧草量相似（P>0.70；两年平均值，海岸雀稗与T85分别为6939对6628千克/公顷；无爬牧与有爬牧分别为6664对6896千克/公顷）。生产性能变量未出现主要效应交互作用（P>0.10；两年平均值），年份仅影响犊牛和母牛的初始及最终体重。与采食海岸雀稗的犊牛相比，采食T85的犊牛91天测试期平均日增重更高（0.94对0.79千克；P<0.01），与未进行合萌爬牧的犊牛相比，进行合萌爬牧的犊牛平均日增重更高（0.90对0.82千克；P<0.03）。与采食海岸雀稗的犊牛相比，采食T85的犊牛205天校正断奶体重增加（252.9对240.3千克；P<0.01），且有合萌爬牧机会的犊牛断奶体重增加（249.9对243.3千克；P<0.05）。牧场食管咀嚼物的体外干物质消化率存在牧草×合萌爬牧交互作用（P<0.05；海岸雀稗，无爬牧 = 57.4%；海岸雀稗，有爬牧 = 52.1%；T85，无爬牧 = 59.1%；T85，有爬牧 = 60.0%），T85牧场的体外干物质消化率高于海岸雀稗牧场（P<0.05）。在2004年8月以及2005年6月和8月对母牛进行挤奶，各处理的产奶量不同，但每年8月采食T85牧场的母牛产奶蛋白质增加（P<0.05），这有助于采食T85牧场的犊牛增重。这些结果补充了之前对T85的研究，并表明采食T85牧场的牛群，其牧草质量和生产性能有所提高。采食T85牧场的犊牛增重以及在合萌爬牧围场的犊牛增重足以影响母牛 - 犊牛养殖的效率。
