Moriel P, Johnson S E, Vendramini J M B, McCann M A, Gerrard D E, Mercadante V R G, Hersom M J, Arthington J D
North Carolina State University, Mountain Research Station, Waynesville 28786.
Virginia Tech University, Department of Animal and Poultry Sciences, Blacksburg 24061.
J Anim Sci. 2014 Aug;92(8):3598-609. doi: 10.2527/jas.2014-7751. Epub 2014 Jun 19.
Brahman × British crossbred steers (n = 40 and 38 in yr 1 and 2, respectively) were used to evaluate the effects of calf management systems following early weaning (EW) on growth performance, muscle gene expression, and carcass characteristics. On the day of EW (d 0), steers were stratified by BW and age (95 ± 14 kg; 74 ± 14 d) and randomly assigned to a control treatment that was normally weaned (NW) on d 180 (n = 10 steers/yr) or to 1 of 3 EW treatments: 1) EW and limit fed a high-concentrate diet at 3.5% of BW (as-fed basis) in drylot until d 180 (EW180; n = 10 steers/yr), 2) EW and limit fed a high-concentrate diet at 3.5% of BW (as-fed basis) in drylot until d 90 and then grazed on bahiagrass pastures until d 180 (EW90; n = 10 steers/yr), or 3) EW and grazed on annual ryegrass pastures until d 60 (yr 1; n = 10 steers) or 90 (yr 2; n = 8 steers) and then on bahiagrass pastures until d 180 (EWRG). Early-weaned steers on ryegrass and bahiagrass pastures were supplemented with high-concentrate diet at 1.0% of BW (as-fed basis) until d 180. From d 180 to 270 (yr 1), all EW steers remained in their respective treatments, whereas NW steers were provided high-concentrate diet at 1.0% of BW (as-fed basis) on bahiagrass pastures. In yr 1, feedlot finishing period began on d 270. In yr 2, the study was terminated on d 180. In both years, EW180 steers were heaviest (P < 0.0001) on d 180. On d 180 of yr 1, EWRG steers were lightest (P < 0.0001) and EW90 steers were heavier (P = 0.05) than NW steers, whereas EW90, EWRG, and NW steers had similar BW on d 180 of yr 2 (P ≥ 0.14). On d 90, muscle PPARγ mRNA expression tended (P = 0.07) to be greater for EW180 steers and was greater (P = 0.008) for EW90 vs. EWRG steers but similar (P = 0.25) between EW180 and NW steers. On d 180, PPARγ mRNA was greater (P ≤ 0.06) for EW180 vs. NW, EW90, and EWRG steers. From d 274 to 302, EW180 steers had the least ADG (P ≤ 0.09), whereas EW90 steers had similar (P = 0.19) ADG compared with EWRG steers but greater (P = 0.03) ADG than NW steers. At slaughter, carcass characteristics did not differ (P ≥ 0.22) among treatments. In summary, EW steers provided a high-concentrate diet in drylot for at least 90 d were heavier at the time of normal weaning than NW steers and EW steers grazed on ryegrass pastures for 60 to 90 d and supplemented with concentrate at 1.0% of BW. Feeding a high-concentrate diet immediately after EW enhanced the muscle PPARγ expression but did not enhance marbling at slaughter.
婆罗门牛与英国杂交阉牛（第1年和第2年分别为40头和38头）用于评估早期断奶（EW）后犊牛管理系统对生长性能、肌肉基因表达和胴体特性的影响。在早期断奶当天（第0天），根据体重和年龄（95±14千克；74±14天）对阉牛进行分层，并随机分配至对照组，对照组在第180天正常断奶（NW）（每年10头阉牛），或3种早期断奶处理中的1种：1）早期断奶，在干栏中按体重的3.5%（风干基础）限量饲喂高浓度日粮直至第180天（EW180；每年10头阉牛），2）早期断奶，在干栏中按体重的3.5%（风干基础）限量饲喂高浓度日粮直至第90天，然后在巴哈雀稗牧场上放牧至第180天（EW90；每年10头阉牛），或3）早期断奶，在一年生黑麦草牧场上放牧至第60天（第1年，10头阉牛）或第90天（第2年，8头阉牛），然后在巴哈雀稗牧场上放牧至第180天（EWRG）。在黑麦草和巴哈雀稗牧场上的早期断奶阉牛，在第180天之前按体重的1.0%（风干基础）补充高浓度日粮。从第180天至270天（第1年），所有早期断奶阉牛维持各自的处理方式，而正常断奶阉牛在巴哈雀稗牧场上按体重的1.0%（风干基础）饲喂高浓度日粮。在第1年，育肥期在第270天开始。在第2年，研究在第180天结束。在两年中，EW180阉牛在第180天体重最重（P<0.0001）。在第1年的第180天，EWRG阉牛体重最轻（P<0.0001），EW90阉牛比正常断奶阉牛重（P=0.05），而在第2年的第180天，EW90、EWRG和正常断奶阉牛的体重相似（P≥0.14）。在第90天，EW180阉牛的肌肉PPARγ mRNA表达趋于更高（P=0.07），EW90阉牛的表达高于EWRG阉牛（P=0.008），但EW180和正常断奶阉牛之间相似（P=0.25）。在第180天，EW180阉牛的PPARγ mRNA高于正常断奶阉牛、EW90阉牛和EWRG阉牛（P≤0.06）。从第274天至302天，EW180阉牛的平均日增重最低（P≤0.09），而EW90阉牛与EWRG阉牛的平均日增重相似（P=0.19），但高于正常断奶阉牛（P=0.03）。屠宰时，各处理间的胴体特性无差异（P≥0.22）。总之，在干栏中提供至少90天高浓度日粮的早期断奶阉牛，在正常断奶时比正常断奶阉牛以及在黑麦草牧场上放牧60至90天并按体重1.0%补充精料的早期断奶阉牛更重。早期断奶后立即饲喂高浓度日粮可增强肌肉PPARγ表达，但未提高屠宰时的大理石花纹程度。
