Department of Animal Sciences, University of Illinois, Urbana, 61801, USA.
J Anim Sci. 2011 Jul;89(7):2189-99. doi: 10.2527/jas.2010-3640. Epub 2011 Mar 7.
The objective of this experiment was to determine if increasing lysine in the diets of immunologically castrated (IC) male pigs would increase percentage fat free lean and carcass cutting yields when compared with physical castrates. The anti-gonadotropin-releasing factor (GnRF) immunological product (Improvest, Pfizer Animal Health) is used worldwide to immunologically castrate entire male pigs to control boar taint and take advantage of the inherent ability of the entire male to deposit more muscle, less fat, and grow more efficiently than physically castrated males. The immunization process essentially allows the pig to grow as an entire male pig for most of its life and then removes any boar odor (boar taint) before slaughter. Reported lean meat advantages may also provide economic benefits to the domestic meat industry. Approximately 1,200 male pigs [physical castrates, IC males, and entire males] were each assigned to 1 of 4 diet programs which differed in lysine content. In each case, lysine was fed in a conventional step-down program that culminated with the following concentrations in the late finishing diet: physical castrates fed low lysine (0.7%), IC fed low lysine (0.7%), IC fed low/medium lysine (0.8%), IC fed medium/high lysine (0.9%), IC fed high lysine (1.0%), and entire males fed high lysine (1.0%). At 25 wk of age (5 wk post-second injection), pigs were individually weighed and the 2 pigs (n=96) in each pen closest to the median pig BW were selected and slaughtered. The right side of each carcass was dissected into soft tissue, skin, and bone. Proximate composition was determined on the soft tissue to determine percentage fat-free lean. The left side of each carcass was weighed and initially fabricated into ham, loin, belly, and whole shoulder. Each primal piece was weighed again and further fabricated into respective subprimal cuts. Immunological castration did not change (P>0.05) shear force values or ultimate pH when compared with either physical castrates or entire males. Marbling appeared to decrease as dietary lysine was increased among IC males. As expected, IC males had a greater (P<0.05) percentage fat-free lean than physical castrates but less (P<0.05) than entire males. Immunologically castrated males fed diets with medium/high and high lysine had greater (P<0.05) lean cutting yields and carcass cutting yields than physical castrates. Lean cutting yield and carcass cutting yields appeared to increase as dietary lysine was increased among IC males. Overall, immunological castration improved carcass cutability, increased percentage fat free lean, and had no effect on pork quality when compared with physical castrates.
本实验的目的是确定在免疫去势（IC）雄性猪的日粮中添加赖氨酸是否会增加无脂瘦肉的百分比，并与物理去势的猪相比增加胴体切割产量。抗促性腺激素释放因子（GnRF）免疫产品（Improvest，辉瑞动物保健）在全球范围内用于免疫去势整个雄性猪，以控制公猪异味，并利用整个雄性猪沉积更多肌肉、更少脂肪和更高效生长的固有能力，比物理去势的雄性猪生长得更好。免疫过程基本上允许猪在其大部分生命中作为整个雄性猪生长，然后在屠宰前去除任何公猪气味（公猪异味）。据报道，瘦肉的优势也可能为国内肉类行业带来经济利益。大约 1200 头雄性猪[物理去势、IC 雄性和整个雄性]被分配到 4 种不同赖氨酸含量的日粮方案中的 1 种。在每种情况下，赖氨酸都以常规的逐步降低方案喂养，最后在后期育肥日粮中达到以下浓度：物理去势的猪喂养低赖氨酸（0.7%）、IC 喂养低赖氨酸（0.7%）、IC 喂养低/中赖氨酸（0.8%）、IC 喂养中/高赖氨酸（0.9%）、IC 喂养高赖氨酸（1.0%），整个雄性猪喂养高赖氨酸（1.0%）。在 25 周龄（第二次注射后 5 周）时，每头猪单独称重，每栏最接近中间猪 BW 的 2 头猪（n=96）被选择并屠宰。每个胴体的右侧被解剖成软组织、皮肤和骨骼。对软组织进行了近似成分分析，以确定无脂瘦肉的百分比。每个胴体的左侧被称重，最初制成火腿、里脊、腹部和整个肩部。每个主要部分再次称重，并进一步制成各自的次级切割。与物理去势或整个雄性猪相比，免疫去势对剪切力值或最终 pH 值没有改变（P>0.05）。大理石花纹似乎随着 IC 雄性猪日粮中赖氨酸的增加而减少。正如预期的那样，IC 雄性猪的无脂瘦肉百分比高于物理去势猪，但低于整个雄性猪（P<0.05）。用中/高和高赖氨酸喂养的免疫去势雄性猪的瘦肉切割产量和胴体切割产量高于物理去势猪（P<0.05）。随着 IC 雄性猪日粮中赖氨酸的增加，瘦肉切割产量和胴体切割产量似乎增加。总体而言，与物理去势猪相比，免疫去势提高了胴体切割的可操作性，增加了无脂瘦肉的百分比，并且对猪肉质量没有影响。
