Norman Thomas C, DeHaan Erin R, Francis Forest L, Rusche Warren C, Smith Zachary K
Department of Animal Science, South Dakota State University, Brookings, SD 57007, USA.
Animals (Basel). 2024 Feb 8;14(4):567. doi: 10.3390/ani14040567.
The objective of the study was to determine the influence that initial BW has on growth performance responses, efficiency of dietary net energy (NE) utilization, and carcass traits in feedlot steers. Charolais×Red Angus steers ( = 70) selected from a larger single-source group were used in a 209-d growing-finishing feedlot experiment. Steers were assigned to two groups based on initial BW (light initial weight, LIW = 273 ± 16.0 kg; heavy initial weight, HIW = 356 ± 14.2 kg) and allotted into 10 pens ( = 7 steers per pen; 5 pens per experimental group) the within pen standard deviation for LIW was from 14.1 kg to 20.9 kg and for HIW was from 13.7 kg to 16.0 kg. Steers were fed a common diet once daily. Experimental data were analyzed as a randomized complete block design with pen as the experimental unit. LIW steers had a greater cumulative HH change ( = 0.04). A treatment × day interaction ( = 0.05) was observed for HH with HIW steers having a greater HH at all time points. Final BW and carcass-adjusted (HCW/0.625) BW were greater for HIW steers by 13.1% and 13.4% respectively ( ≤ 0.01). HIW steers had a greater DMI ( = 0.01) compared to LIW. Cumulative ADG was greater for HIW by 3% ( = 0.04). LIW steers had better feed conversion ( = 0.01). HIW steers had greater ( ≤ 0.05) HCW, marbling scores, and yield grade (YG), with decreased REA/HCW ( 0.01) compared to LIW. The distribution of USDA Yield Grade was altered by initial BW ( = 0.04). No differences were detected ( ≥ 0.22) for the distribution of Quality grade nor liver abscess prevalence and severity. Regression coefficients did not differ between LIW and HIW for urea space calculations of empty body water, fat, or protein ( ≥ 0.70). A quadratic response was noted for empty body fat (EBF), empty body water (EBH20), and carcass protein (CP). In conclusion, HIW steers had greater growth, but poorer feed efficiency compared to LIW steers. Steers with a HIW produced fatter carcasses with a greater degree of marbling.
本研究的目的是确定初始体重对育肥牛生长性能反应、日粮净能（NE）利用效率和胴体性状的影响。从一个较大的单一来源群体中挑选出70头夏洛莱×红安格斯育肥牛，用于一项为期209天的育肥试验。根据初始体重将育肥牛分为两组（轻初始体重组，LIW = 273 ± 16.0千克；重初始体重组，HIW = 356 ± 14.2千克），并分配到10个围栏中（每个围栏7头牛；每个实验组5个围栏），LIW组围栏内标准差为14.1千克至20.9千克，HIW组为13.7千克至16.0千克。育肥牛每天喂一次普通日粮。实验数据采用以围栏为实验单位的随机完全区组设计进行分析。LIW组育肥牛的累积热增耗变化更大（P = 0.04）。观察到热增耗存在处理×天数交互作用（P = 0.05），HIW组育肥牛在所有时间点的热增耗都更大。HIW组育肥牛的末重和胴体校正体重（HCW/0.625）分别比LIW组高13.1%和13.4%（P≤0.01）。与LIW组相比，HIW组育肥牛的干物质采食量更大（P = 0.01）。HIW组的累积平均日增重比LIW组高3%（P = 0.04）。LIW组育肥牛的饲料转化率更好（P = 0.01）。与LIW组相比，HIW组育肥牛的胴体重、大理石花纹评分和产量等级（YG）更高（P≤0.05），而眼肌面积与胴体重的比值降低（P 0.01）。初始体重改变了美国农业部产量等级的分布（P = 0.04）。在质量等级分布、肝脓肿患病率和严重程度方面未检测到差异（P≥0.22）。在计算空腹体重的水分、脂肪或蛋白质的尿素空间时，LIW组和HIW组的回归系数没有差异（P≥0.70）。观察到空腹脂肪（EBF）、空腹水分（EBH2O）和胴体蛋白质（CP）呈二次反应。总之，与LIW组育肥牛相比，HIW组育肥牛生长速度更快，但饲料效率更低。HIW组育肥牛的胴体更肥，大理石花纹程度更高。
