Department of Animal Science, Università degli studi di Padova, Viale dell'Università 16, 35020 Legnaro (PD), Italy.
Meat Sci. 2011 Oct;89(2):133-42. doi: 10.1016/j.meatsci.2011.03.025. Epub 2011 Apr 8.
A trial was carried out on double-muscled Piemontese bulls to evaluate the effects of two rations differing in crude protein density (HP=14.5% DM and LP=10.8% DM) and top dressed or not with 80 g/d of rumen protected CLA (rpCLA) for a long period (336 d) on meat quality traits and CLA content. Forty-eight bulls were fed one of the four experimental diets based on corn silage and cereals and were slaughtered at an average age and body weight (BW) of 562 ± 18 d and 668 ± 56 kg, respectively. After slaughter the 5th rib cut was dissected into Longissimus thoracis (LT), other muscles (OM), inter-muscular fat (IF), cover fat (CF), and bones. Muscles and fatty tissues were analyzed for proximate composition and fatty acid (FA) profiles. Rib was composed by 81.1, 3.7, 1.6 and 13.6% of muscles, IF, FC and bone, respectively; LT and OM contained only 0.8 and 1.4% of lipid, respectively. The treatments did not influence these values, but rpCLA increased, compared to control, both c9,t11-CLA and t10,c12-CLA concentrations in all the tissues (P<0.01); t10,c12-CLA concentration was increased much more in muscles (+20 times) than in fatty tissues (from +0.2 to +0.9 times). This suggests that in the muscle this isomer is preferentially stored and/or less combusted with respect to other fatty acids. Low protein rations did not exert any influence on carcass and meat quality, as on growth performance, but reduced nitrogen excretion, their use for improving the environmental impact (process quality) of this meat production system is recommended.
对双肌皮尔蒙特公牛进行了一项试验，以评估两种粗蛋白密度（HP=14.5% DM 和 LP=10.8% DM）的日粮以及是否用 80 克/天的瘤胃保护 CLA（rpCLA）对肉质特性和 CLA 含量的影响。48 头公牛饲喂基于玉米青贮和谷物的四种实验日粮之一，并在平均年龄和体重（BW）分别为 562±18 天和 668±56 公斤时屠宰。屠宰后，将第 5 肋骨切割成胸最长肌（LT）、其他肌肉（OM）、肌间脂肪（IF）、覆盖脂肪（CF）和骨骼。肌肉和脂肪组织分析了其组成成分和脂肪酸（FA）谱。肋骨由 81.1%、3.7%、1.6%和 13.6%的肌肉、IF、FC 和骨骼组成；LT 和 OM 仅分别含有 0.8%和 1.4%的脂质。与对照相比，rpCLA 增加了所有组织中的 c9,t11-CLA 和 t10,c12-CLA 浓度（P<0.01），但处理并没有影响这些值；与其他脂肪酸相比，t10,c12-CLA 浓度在肌肉中增加了 20 倍，而在脂肪组织中增加了 0.2-0.9 倍。这表明，与其他脂肪酸相比，这种异构体在肌肉中更优先储存和/或燃烧更少。低蛋白日粮对胴体和肉质没有任何影响，就像对生长性能一样，但减少了氮排泄，建议将其用于改善这种肉类生产系统的环境影响（过程质量）。
