Department of Animal Sciences, University of Missouri, Columbia 65211, USA.
J Anim Sci. 2011 Nov;89(11):3580-6. doi: 10.2527/jas.2010-3303. Epub 2011 May 27.
A total of 54 finishing barrows (initial BW = 99.8 ± 5.1 kg; PIC C22 × 337) reared in individual pens were allotted to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement of treatments with 2 levels of ractopamine (0 and 7.4 mg/kg) and 3 levels of dietary energy (high: 3,537, medium: 3,369, and low: 3,317 kcal/kg of ME) to determine the effects of feeding ractopamine and various dietary energy levels on the fatty acid profile of 4 carcass fat depots (jowl, belly, subcutaneous loin, and intramuscular) and the predictive relationships of calculated iodine value (IV) between these 4 fat depots. Carcasses were sampled for fat tissues at the anterior tip of the jowl, posterior to the sternum on the belly edge, three-quarters the distance around the LM (subcutaneous fat; SC), and within the LM (intramuscular fat; IMF). Feeding ractopamine diets reduced (P < 0.05) total SFA in SC and IMF and increased (P = 0.04) total MUFA in SC. Also, feeding ractopamine diets increased (P < 0.01) the IV of IMF. Total MUFA of belly fat was reduced (P < 0.05) when the low-energy diet was fed compared with the high-energy diet. Jowl fat total MUFA was reduced (P < 0.05) and total PUFA was increased (P < 0.05) when the medium-energy diet was fed compared with the high- and low-energy diets. Iodine values, independent of treatment, were 60.97, 64.51, 55.59, and 58.26 for belly, jowl, IMF, and SC fat depots, respectively. The IV correlations within fat depots were not consistent across dietary treatments because of the effect of treatments on carcass fatty acid characteristics. Feeding ractopamine diets shifted the fatty acid profile from SFA to MUFA in the SC depot. Feeding ractopamine diets did not change belly fat profiles, thus avoiding the potential negative effect of softening belly fat, which is detrimental to processing value. The IV of one fat depot may not be a good indication of IV of other fat depots because of weak correlation coefficients and the apparent influence of dietary treatment.
总计 54 头育肥阉公猪（初始 BW=99.8±5.1kg；PIC C22×337）在单个围栏中饲养，根据 2×3 因子处理设计，分为 6 种饲粮处理组之一，饲粮中分别添加 0 和 7.4mg/kg 的莱克多巴胺，以及 3 种能量水平（高能：3537kcal/kg 的 ME；中能：3369kcal/kg 的 ME；低能：3317kcal/kg 的 ME），以确定添加莱克多巴胺和不同饲粮能量水平对 4 个胴体脂肪组织（颈肉、腹部、皮下腰肉和肌肉内）脂肪酸组成的影响，以及这些脂肪组织间碘价（IV）的预测关系。在颈肉前缘、胸骨后腹部边缘、LM 周围 3/4 处（皮下脂肪；SC）和 LM 内（肌肉内脂肪；IMF）取样脂肪组织。添加莱克多巴胺饲粮降低了 SC 和 IMF 中的总饱和脂肪酸（P＜0.05），增加了 SC 中的总 MUFA（P=0.04）。此外，添加莱克多巴胺饲粮增加了 IMF 的 IV。与高能饲粮相比，低能饲粮降低了腹部脂肪的总 MUFA（P＜0.05）。与高能和低能饲粮相比，中能饲粮降低了颈肉脂肪的总 MUFA（P＜0.05），增加了总多不饱和脂肪酸（P＜0.05）。不论处理方式如何，碘价分别为 60.97、64.51、55.59 和 58.26，用于腹部、颈肉、IMF 和 SC 脂肪组织。由于处理对胴体脂肪酸特性的影响，不同处理方式之间脂肪组织内的 IV 相关性不一致。添加莱克多巴胺饲粮将 SC 中的脂肪酸组成从 SFA 转移到 MUFA。添加莱克多巴胺饲粮没有改变腹部脂肪的组成，因此避免了腹部脂肪变软的潜在负面影响，这对加工价值不利。由于相关系数较弱以及饲粮处理的明显影响，一个脂肪组织的 IV 可能不能很好地指示其他脂肪组织的 IV。
