Vincent A, Louveau I, Gondret F, Tréfeu C, Gilbert H, Lefaucheur L
J Anim Sci. 2015 Jun;93(6):2745-58. doi: 10.2527/jas.2015-8928.
Improving feed efficiency is a relevant strategy to reduce feed cost and environmental waste in livestock production. Selection experiments on residual feed intake (RFI), a measure of feed efficiency, previously indicated that low RFI was associated with lower feed intake, similar growth rate, and greater lean meat content compared with high RFI. To gain insights into the molecular mechanisms underlying these differences, 24 Large White females from 2 lines divergently selected for RFI were examined. Pigs from a low-RFI ("efficient") and high-RFI ("inefficient") line were individually fed ad libitum from 67 d of age (27 kg BW) to slaughter at 115 kg BW (n = 8 per group). Additional pigs of the high-RFI line were feed restricted to the daily feed intake of the ad libitum low-RFI pigs (n = 8) to investigate the impact of selection independently of feed intake. Global gene and protein expression profiles were assessed in the LM collected at slaughter. The analyses involved a porcine commercial microarray and 2-dimensional gel electrophoresis. About 1,000 probes were differentially expressed (P < 0.01) between RFI lines. Only 10% of those probes were also affected by feed restriction. Gene functional classification indicated a greater expression of genes involved in protein synthesis and a lower expression of genes associated with mitochondrial energy metabolism in the low-RFI pigs compared with the high-RFI pigs. At the protein level, 11 unique identified proteins exhibited a differential abundance (P < 0.05) between RFI lines. Differentially expressed proteins were generally not significantly affected by feed restriction. Mitochondrial oxidative proteins such as aconitase hydratase, ATP synthase subunit α, and creatine kinase S-type had a lower abundance in the low-RFI pigs, whereas fructose-biphosphate aldolase A and glyceraldehyde-3-phosphate dehydrogenase, 2 proteins involved in glycolysis, had a greater abundance in those pigs compared with high-RFI pigs. Antioxidant proteins such as superoxide dismutase and glutathione peroxidase 3 at the mRNA level and peroxiredoxin-6 at the protein level were also less expressed in LM of the most efficient pigs, likely related to lower oxidative molecule production. Collectively, both the transcriptomic and proteomic approaches revealed a lower oxidative metabolism in muscle of the low-RFI pigs and all these modifications were largely independent of differences in feed intake.
提高饲料效率是降低畜牧生产中饲料成本和环境废弃物的一项相关策略。对残余采食量（RFI）（一种饲料效率的衡量指标）的选择试验先前表明，与高RFI相比，低RFI与较低的采食量、相似的生长速度以及更高的瘦肉含量相关。为深入了解这些差异背后的分子机制，对来自2个RFI差异选择品系的24头大白母猪进行了研究。来自低RFI（“高效”）和高RFI（“低效”）品系的猪从67日龄（体重27千克）开始自由采食，直至体重达到115千克时屠宰（每组n = 8）。对高RFI品系的额外猪只进行限饲，使其采食量与自由采食的低RFI猪相同（n = 8），以独立于采食量研究选择的影响。在屠宰时采集的腰大肌中评估了全基因组和蛋白质表达谱。分析涉及猪商业微阵列和二维凝胶电泳。RFI品系之间约有1000个探针差异表达（P < 0.01）。这些探针中只有10%也受限饲影响。基因功能分类表明，与高RFI猪相比，低RFI猪中参与蛋白质合成的基因表达更高，与线粒体能量代谢相关的基因表达更低。在蛋白质水平上，11种独特鉴定的蛋白质在RFI品系之间表现出丰度差异（P < 0.05）。差异表达的蛋白质通常不受限饲的显著影响。线粒体氧化蛋白如乌头酸水合酶、ATP合酶亚基α和肌酸激酶S型在低RFI猪中的丰度较低，而参与糖酵解的2种蛋白质果糖二磷酸醛缩酶A和甘油醛 - 3 - 磷酸脱氢酶在低RFI猪中的丰度高于高RFI猪。抗氧化蛋白如超氧化物歧化酶和谷胱甘肽过氧化物酶3在mRNA水平以及过氧化物酶体增殖物激活受体γ辅激活因子1α在蛋白质水平在最高效猪的腰大肌中也表达较少，这可能与较低的氧化分子产生有关。总体而言，转录组学和蛋白质组学方法均显示低RFI猪肌肉中的氧化代谢较低，并且所有这些修饰在很大程度上独立于采食量差异。
