Pittaluga Alejandro M, Kieffer Justin, Relling Alejandro E
Department of Animal Science, The Ohio State University, Columbus, OH 43210. USA.
Department of Animal Sciences/Interdisciplinary PhD Program in Nutrition, The Ohio State University, Wooster, OH 44692, USA.
Transl Anim Sci. 2023 Jun 27;7(1):txad068. doi: 10.1093/tas/txad068. eCollection 2023 Jan.
One hundred and twenty-one Angus × SimAngus-crossbred steers (body weight () = 159 ± 22 kg) were used to evaluate the effects of different grain inclusion () rates in diets provided to early-weaned calves and steroidal implants () utilization on growth performance and carcass characteristics, particularly intramuscular fat deposition, of beef steers. The experiment was conducted as a randomized complete block design with a 2 × 2 factorial arrangement of treatments, consisting of two GI rates (35% vs. 58%, dry matter () basis), each one associated or not to steroidal implant utilization (no implants vs. 80 mg trenbolone acetate () + 16 mg estradiol followed by 120 mg TA + 24 mg of estradiol). After being early-weaned (124 ± 14 d of age), steers were offered an average of 4.5 kg/d (DM basis) of a concentrate-based diet with a greater or lesser GI rate for 60 d. After being fed a concentrate-based diet with different GI rates for 60 d, steers were fed a common backgrounding diet for 56 d and subsequently fed a common high-grain diet until harvested at a constant final BW (620 kg). Steers were not implanted until the beginning of the backgrounding phase and then re-implanted when initiating the finishing phase. Data were analyzed using PROC MIXED in SAS. There were no GI × SI interactions ( ≥ 0.62) for any of the growth performance parameters throughout the experimental period. Implanted steers tended to have a greater average daily gain ( = 0.10) during the finishing phase than nonimplanted steers. For the 12th rib fat thickness and yield grade (), a GI × SI interaction ( = 0.03) and a tendency for a GI × SI interaction ( = 0.10) was detected, respectively. Nonimplanted steers fed diets with greater GI rates presented the greatest 12th rib fat thickness and tended to have the greatest YG among treatments. No other interactions ( ≥ 0.33) were observed for the hot carcass weight, muscle () area, quality grade, marbling score, and kidney-pelvic-heart fat content. Steers fed diets with lesser GI rates tended to have a greater LM area than steers fed diets with greater GI rates ( = 0.10). Results from this experiment indicate that varying GI rates in diets provided to early-weaned calves and subsequent implantation with steroidal hormones did not affect marbling deposition.
选用121头安格斯×西姆安格斯杂交阉牛（体重（）=159±22千克），评估给早期断奶犊牛提供的日粮中不同谷物添加量（）比例以及使用甾体植入物（）对育肥牛生长性能和胴体特性（尤其是肌内脂肪沉积）的影响。试验采用随机完全区组设计，处理按2×2析因排列，包括两种谷物添加量比例（干物质（）基础下35%对58%），每种比例分别与使用或不使用甾体植入物相关联（不植入对80毫克醋酸群勃龙（）+16毫克雌二醇，随后是120毫克醋酸群勃龙+24毫克雌二醇）。早期断奶（年龄124±14天）后，给阉牛平均每天提供4.5千克/天（干物质基础）的基于精料的日粮，谷物添加量比例有高有低，持续60天。在给阉牛饲喂不同谷物添加量比例的基于精料的日粮60天后，再给它们饲喂普通的育成前期日粮56天，随后饲喂普通的高谷物日粮，直至达到恒定的最终体重（620千克）时屠宰。阉牛直到育成前期开始时才植入，然后在育肥期开始时再次植入。数据使用SAS中的PROC MIXED程序进行分析。在整个试验期内，任何生长性能参数均未出现谷物添加量×甾体植入物互作（≥0.62）。植入甾体的阉牛在育肥期的平均日增重往往高于未植入的阉牛（=0.10）。对于第12肋骨处脂肪厚度和产肉等级（），分别检测到谷物添加量×甾体植入物互作（=0.03）和存在谷物添加量×甾体植入物互作的趋势（=0.10）。饲喂谷物添加量比例较高日粮的未植入阉牛，其第12肋骨处脂肪厚度最大，且在各处理中往往具有最高的产肉等级。对于热胴体重、眼肌（）面积、质量等级、大理石花纹评分和肾-盆腔-心脏脂肪含量，未观察到其他互作（≥0.33）。饲喂谷物添加量比例较低日粮的阉牛，其眼肌面积往往大于饲喂谷物添加量比例较高日粮的阉牛（=0.10）。本试验结果表明，给早期断奶犊牛提供的日粮中改变谷物添加量比例以及随后植入甾体激素，不会影响大理石花纹沉积。
