Lowe B K, Gerlemann G D, Carr S N, Rincker P J, Schroeder A L, Petry D B, McKeith F K, Allee G L, Dilger A C
Department of Animal Science, University of Illinois at Urbana-Champaign, Urbana 61801.
Department of Animal Science, University of Missouri, Columbia 65211.
J Anim Sci. 2014 Aug;92(8):3715-26. doi: 10.2527/jas.2013-7515. Epub 2014 Jul 8.
Effects of feeding ractopamine (RAC; 5 mg/kg) to physically castrated (PC) and immunologically castrated (IC) pigs on carcass characteristics, cutting yields, and loin quality were evaluated using 285 carcasses. Male pigs were randomly assigned to sex treatments (PC and IC) at birth and fed the same nursery diets before allotment into 32 pens with 22 pigs per pen in a grow-finish barn. Pigs in the PC group were physically castrated at approximately 5 d of age, and pigs in the IC group were administered Improvest at 11 and 18 wk of age. Diet treatments (control or RAC) were initiated on study d 87. Pigs were marketed at 12 d (4.5 wk post-second Improvest dose), 19 d (5.5 wk post-second Improvest dose), and 33 d (7.5 wk post-second Improvest dose) following the start of final diet treatments. Three carcasses per pen were selected for evaluation of cutting yields and loin quality. Data were analyzed using PROC MIXED in SAS with fixed effects of sex, diet, market group, and their interaction; carcass (N = 285) was the experimental unit. Carcasses from RAC-fed pigs were heavier (P < 0.01) and had deeper (P = 0.02) loins than control-fed carcasses. Carcasses from IC pigs were similar (P = 0.22) in weight but had less (P < 0.01) fat and shallower (P = 0.02) loins when compared to PC carcasses. There were differences (P < 0.05) among market groups for carcass weights, fat depths, loin depths, and estimated carcass leanness. For cutting yields, RAC-fed carcasses had greater (P ≤ 0.03) bone-in lean and total carcass cutting yields than control-fed carcasses while there were no differences (P > 0.05) between RAC-fed and control-fed carcasses when evaluating LM color, marbling, firmness, pH, drip loss, and tenderness. Carcasses from IC pigs had greater (P < 0.05) boneless lean yields, bone-in lean yields, and total carcass cutting yields than PC carcasses. There were minimal differences (P < 0.05) in LM marbling, firmness, composition, and tenderness between PC and IC pigs. There was an interaction (P = 0.03) between sex and diet for LM composition. Control-fed PC loins had more (P < 0.01) lipid than all other treatment combinations. Market group had effects (P < 0.05) on carcass cutting yields, LM color, marbling and firmness scores, pH, purge loss, composition, and tenderness. The results from this study indicated RAC and immunological castration were additive in terms of improving carcass cutting yields while having minimal effects on pork quality.
使用285头猪的胴体，评估了给物理阉割（PC）和免疫阉割（IC）的猪饲喂莱克多巴胺（RAC；5毫克/千克）对胴体特性、分割产量和腰肉品质的影响。雄性仔猪在出生时随机分配到性别处理组（PC和IC），在分配到育肥舍的32个栏中（每个栏22头猪）之前，饲喂相同的保育日粮。PC组的猪在大约5日龄时进行物理阉割，IC组的猪在11周龄和18周龄时注射免疫去势剂Improvest。日粮处理（对照或RAC）在研究第87天开始。在最终日粮处理开始后的12天（第二次注射Improvest剂量后4.5周）、19天（第二次注射Improvest剂量后5.5周）和33天（第二次注射Improvest剂量后7.5周）对猪进行屠宰上市。每个栏选取3头猪的胴体用于评估分割产量和腰肉品质。数据采用SAS中的PROC MIXED程序进行分析，固定效应包括性别、日粮、上市组及其交互作用；胴体（N = 285）为实验单位。饲喂RAC的猪的胴体比饲喂对照的胴体更重（P < 0.01），腰肉更深（P = 0.02）。与PC猪的胴体相比，IC猪的胴体重量相似（P = 0.22），但脂肪更少（P < 0.01），腰肉更浅（P = 0.02）。上市组之间在胴体重量、脂肪深度、腰肉深度和估计的胴体瘦肉率方面存在差异（P < 0.05）。对于分割产量，饲喂RAC的胴体比饲喂对照的胴体有更高的（P ≤ 0.03）带骨瘦肉和总胴体分割产量，而在评估腰大肌颜色、大理石花纹、硬度、pH值、滴水损失和嫩度时，饲喂RAC和饲喂对照的胴体之间没有差异（P > 0.05）。IC猪的胴体比PC猪的胴体有更高的（P < 0.05）去骨瘦肉产量、带骨瘦肉产量和总胴体分割产量。PC猪和IC猪的腰大肌大理石花纹、硬度、组成和嫩度之间差异极小（P < 0.05）。腰大肌组成在性别和日粮之间存在交互作用（P = 0.03）。饲喂对照的PC猪腰肉的脂质含量比所有其他处理组合都多（P < 0.01）。上市组对胴体分割产量、腰大肌颜色、大理石花纹和硬度评分、pH值、渗出损失、组成和嫩度有影响（P < 0.05）。本研究结果表明，RAC和免疫阉割在提高胴体分割产量方面具有相加作用，而对猪肉品质的影响最小。
