Performance and feed efficiency of heat-stressed lambs of different genotypes in response to dietary lipid sources and residual feed intake status

IF 1.8 3区农林科学 Q2 AGRICULTURE, DAIRY & ANIMAL SCIENCE

Small Ruminant Research Pub Date : 2025-11-01 Epub Date: 2025-09-19 DOI:10.1016/j.smallrumres.2025.107620

G. Halakoo , Yansari A. Teimouri , M. Mohajer , Y. Chashnidel

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Abstract

Although supplementing dietary lipids is a common strategy to mitigate heat stress in livestock, its efficacy may depend on an animal's genetics and inherent metabolic efficiency (Residual Feed Intake; RFI). This study investigated whether performance responses to different lipid sources are co-dependent on the genotype and RFI status of heat-stressed lambs. Initially, 48 male lambs from four genotypes were evaluated for RFI. From this group, 32 lambs, classified as Low-RFI (LRFI) or High-RFI (HRFI), were selected and used in a 2 × 4 factorial arrangement to assess their response to four diets under HS: a control (no fat) and diets supplemented with Calcium Salts of Fatty Acids (CSFA), Beef Tallow (BT), or Canola Oil (CO). The results confirmed the central role of RFI: LRFI lambs were more resilient, exhibiting 12 % lower dry matter intake (P = 0.03), superior nutrient digestibility (P < 0.05), and greater residual weight gain (P = 0.03) compared to HRFI lambs. While all lambs benefited from lipids (highest ADG with CSFA, P = 0.01), a crucial RFI × lipid interaction (P = 0.02) emerged. The results showed that the animal's efficiency status dictated the optimal fat source: CSFA was best for LRFI lambs, while CO was optimal for HRFI lambs. Based on the results, it appears that an animal's response to nutritional support under heat stress is dependent on both its inherent metabolic efficiency (RFI) and genetic makeup. It appears, therefore, that incorporating the RFI trait into sheep selection programs could substantially elevate the strategic importance and efficacy of tailored nutritional interventions.

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不同基因型热应激羔羊生产性能和饲料效率对饲粮脂肪来源和剩余采食量的响应

虽然在饲料中添加脂质是减轻家畜热应激的常用策略，但其效果可能取决于动物的遗传和固有代谢效率（残余采食量；RFI）。本研究探讨了热应激羔羊对不同脂质来源的生产性能反应是否共同依赖于基因型和RFI状态。最初，对来自4种基因型的48只雄性羔羊进行RFI评估。从这组羔羊中选择32只低rfi （LRFI）或高rfi （HRFI）羔羊，采用2 × 4因子安排，评估它们对四种饲粮的反应：对照组（无脂肪）和添加脂肪酸钙盐（CSFA）、牛油（BT）或菜籽油（CO）的饲粮。结果证实了RFI的核心作用：与HRFI羔羊相比，LRFI羔羊的弹性更强，干物质采食量降低12 % (P = 0.03)，营养物质消化率更高（P <； 0.05），剩余增重更大（P = 0.03）。虽然所有羔羊都受益于脂质（CSFA组平均日增重最高，P = 0.01），但出现了关键的RFI与 脂质相互作用（P = 0.02）。结果表明，动物的生产效率状况决定了最佳脂肪源，低脂高脂羔羊以CSFA为最佳脂肪源，高脂低脂羔羊以CO为最佳脂肪源。基于这些结果，动物在热应激下对营养支持的反应似乎取决于其固有代谢效率（RFI）和基因组成。因此，将RFI特性纳入绵羊选择计划可以大大提高量身定制的营养干预的战略重要性和有效性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Small Ruminant Research 农林科学-奶制品与动物科学

CiteScore

3.10

自引率

11.10%

发文量

210

审稿时长

12.5 weeks

期刊介绍： Small Ruminant Research publishes original, basic and applied research articles, technical notes, and review articles on research relating to goats, sheep, deer, the New World camelids llama, alpaca, vicuna and guanaco, and the Old World camels. Topics covered include nutrition, physiology, anatomy, genetics, microbiology, ethology, product technology, socio-economics, management, sustainability and environment, veterinary medicine and husbandry engineering.