Context Many indices of feed efficiency for livestock have been proposed, but most are associated with differences in body composition and consequently affect meat quality. Aims This study aimed to assess meat quality and lipid profile of intramuscular fat of Texel crossbred lambs classified by residual intake and gain (RIG). Methods Seventy-seven non-castrated male Texel crossbred lambs (1/4 Pantaneira and 3/4 Texel) were assessed in a 2-year study. First year: Forty-seven lambs with initial bodyweight of 29.9 ± 5.5 kg. Second year: Thirty lambs with an initial bodyweight of 22.4 ± 3.3 kg. Lambs were confined in individual stalls for 70 days for the assessment of individual dry matter intake and average daily gain, being then slaughtered. The muscle Longissimus lumborum was removed for analyses. The RIG was obtained by: RIG = (−1 × residual feed intake) + residual gain. The data of meat quality and lipid profile from both years were grouped and analysed in a completely randomised design. Animals were classified into three RIG classes based on the s.d. of RIG variable. Efficient (n = 20) and inefficient (n = 22) animals were classified adopting ± 0.5 s.d. from RIG mean, and animals between these two groups were classified as intermediate (n = 35). Key results No significant differences were observed between RIG classes regarding instrumental characteristics and proximate composition of the Longissimus lumborum muscle. We observed no differences between RIG classes for concentrations of saturated (SFA), monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA), as well as for the total sum of SFA, MUFA, and PUFA of intramuscular fat, with 40.9, 54.1, and 5.1% of total FA, respectively. The MUFA:SFA ratio, PUFA:SFA ratio, atherogenic and thrombogenic index were also not influenced by RIG classes. Conclusions There were no differences in meat quality and lipid profile of intramuscular fat between animals classified based on RIG. Implications Improvements provided by using RIG to identify efficient and faster-growing lambs could assist in reducing feed and labour investments in the production system through an early slaughter without having negative impacts on meat quality.

中文翻译：

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按残留摄入量和增重分类的 Texel 杂交羔羊肌肉内脂肪的肉质和脂质特征

背景 已经提出了许多牲畜饲料效率指标，但大多数与身体成分的差异有关，从而影响肉质。目的 本研究旨在评估 Texel 杂交羔羊的肉质和肌肉内脂肪的脂质特征，这些羔羊按残留摄入量和增重 (RIG) 分类。方法 在为期 2 年的研究中评估了 77 只未阉割的雄性 Texel 杂交羔羊（1/4 Pantaneira 和 3/4 Texel）。第一年：47 只羔羊，初始体重为 29.9 ± 5.5 kg。第二年：三十只羔羊，初始体重为 22.4 ± 3.3 kg。羔羊被关在各个畜栏内 70 天，以评估个体干物质摄入量和平均日增重，然后进行屠宰。取出腰最长肌进行分析。RIG 是通过以下方式获得的：RIG = (-1 × 剩余采食量) + 剩余增重。将这两年的肉质和脂质分布数据分组并以完全随机的设计进行分析。根据 RIG 变量的 sd，将动物分为三个 RIG 类别。高效 (n = 20) 和低效 (n = 22) 动物按 RIG 平均值± 0.5 sd 进行分类，这两组之间的动物被归类为中间 (n = 35)。主要结果 RIG 类别之间在器械特性和腰最长肌的近似组成方面没有观察到显着差异。我们观察到饱和 (SFA)、单不饱和 (MUFA) 和多不饱和脂肪酸 (PUFA) 的浓度以及肌内脂肪的 SFA、MUFA 和 PUFA 总和的 RIG 类别之间没有差异，分别为 40.9、54.1 ，和 5。分别占总 FA 的 1%。MUFA:SFA 比率、PUFA:SFA 比率、致动脉粥样硬化和血栓形成指数也不受 RIG 类别的影响。结论 基于 RIG 分类的动物之间的肉质和肌肉内脂肪的脂质特征没有差异。影响 通过使用 RIG 来识别高效和快速生长的羔羊，可以通过早期屠宰帮助减少生产系统中的饲料和劳动力投资，而不会对肉质产生负面影响。