INRA, UMR1348 Physiologie, Environnement et Génétique pour l'Animal et les Systèmes d'Elevage, F-35590 Saint-Gilles, France.
J Anim Sci. 2013 Apr;91(4):1893-906. doi: 10.2527/jas.2012-5828. Epub 2013 Jan 23.
Cold environment represents an external stress modulating animal growth and energy use. At muscle level, adaptation to cold conditions potentially involves energy homeostasis regulation gauged by the adenosine monophosphate (AMP)-activated protein kinase (AMPK). Our study aimed at evaluating the bare effects of short- and long-term cold exposure on growth performance, carcass traits, and metabolic characteristics of the oxidative semispinalis (SS) muscle and glycolytic LM and to evaluate the reversibility of short-term effects, with a special emphasis on AMPK activity. A total of 84 pigs fed ad libitum and individually housed were submitted after weaning to either Cold (from 23 ± 1 to 15 ± 3°C) or thermoneutral (T; from 28 ± 1 to 23 ± 1°C) temperature up to 24.7 ± 1.6 kg BW (25 BW). Twelve Cold and 12 T piglets were then slaughtered the same day. Eighteen remaining Cold piglets were reared at 12 ± 2°C (CC) whereas 18 Cold and 24 T piglets were reared at 23 ± 4°C (CT and TT, respectively) and slaughtered at 114.3 ± 5.9 kg (115 BW). The LM and SS samples were analyzed to determine glycolytic potential (GP), activities of lactate dehydrogenase (LDH), citrate synthase (CS), and β-hydroxy-acyl-CoA dehydrogenase (HAD) and to quantify AMPK phosphorylation Threonine 172 phosphorylated form of AMPK α1+α2 isoforms (pAMPK) / total AMPK α1+α2 isoforms (AMPK). Despite a greater ADFI (P < 0.001), Cold piglets exhibited less ADG (P < 0.001) and body fatness (P < 0.03) attesting an acute adaptation to a short-term cold exposure. A long-term cold adaptation evaluated on 115 BW pigs increased ADFI (P < 0.001) but did not influence ADG and carcass lean meat content. Cold environment influenced the dynamic of muscle metabolism in a muscle type dependent manner corresponding to an earlier and acute adaptation in SS from 8 kg onward and a belated adaptation in LM from 25 BW to 115 BW. Cold exposure was associated with a progressive increase of muscle oxidative capacity, first in the SS with greater HAD (P = 0.002) and CS activities (P = 0.03) at 25 BW and then both in SS and LM at 115 BW (P < 0.001). Conversely, in LM of CC pigs, increased GP (P < 0.001) and LDH activity (P = 0.03) were observed in addition to increased CS and HAD activities, highlighting the ability of LM to increase both its glycolytic and oxidative metabolism and to diversify its energy substrates. Pigs from CC group exhibited also less pAMPK/AMPK (P < 0.01) specifically in red SS muscle, denoting a reduced metabolic stress of this muscle after a long-term cold adaptation.
寒冷环境代表着一种调节动物生长和能量利用的外部应激因素。在肌肉水平上，适应寒冷条件可能涉及能量稳态调节，由单磷酸腺苷 (AMP)-激活蛋白激酶 (AMPK) 来衡量。我们的研究旨在评估短期和长期寒冷暴露对生长性能、胴体特性以及半棘肌（SS）和糖酵解 LM 氧化代谢特征的影响，并评估短期影响的可逆性，特别强调 AMPK 活性。总共 84 头自由采食并单独饲养的猪在断奶后被置于冷（从 23±1 到 15±3°C）或热中性（T；从 28±1 到 23±1°C）温度下，直到达到 24.7±1.6 kg BW（25 BW）。然后，12 头冷和 12 头 T 仔猪在同一天屠宰。18 头剩余的冷仔猪在 12±2°C（CC）下饲养，而 18 头冷和 24 头 T 仔猪在 23±4°C（CT 和 TT，分别）下饲养，并在 114.3±5.9 kg（115 BW）时屠宰。分析 LM 和 SS 样本以确定糖酵解潜力（GP）、乳酸脱氢酶（LDH）、柠檬酸合酶（CS）和β-羟酰基辅酶 A 脱氢酶（HAD）的活性，并定量 AMPK 磷酸化 Thr172 磷酸化形式的 AMPK α1+α2 同工型（pAMPK）/总 AMPK α1+α2 同工型（AMPK）。尽管冷仔猪的 ADFI 更高（P＜0.001），但 ADG 更低（P＜0.001），体脂更少（P＜0.03），表明其对短期寒冷暴露有急性适应。对 115 BW 猪进行的长期冷适应增加了 ADFI（P＜0.001），但对 ADG 和胴体瘦肉含量没有影响。冷环境以肌肉类型依赖的方式影响肌肉代谢的动态，对应于 8 kg 以上的 SS 更早和更急性的适应，以及 25 BW 到 115 BW 的 LM 延迟适应。冷暴露与肌肉氧化能力的逐渐增加有关，首先是在 SS 中，HAD（P=0.002）和 CS 活性（P=0.03）在 25 BW 时增加，然后在 SS 和 LM 中在 115 BW 时增加（P＜0.001）。相反，在 CC 组的 LM 中，观察到 GP（P＜0.001）和 LDH 活性（P=0.03）增加，同时 CS 和 HAD 活性增加，这突出了 LM 增加其糖酵解和氧化代谢的能力，并使其能量底物多样化的能力。CC 组的猪还表现出较少的 pAMPK/AMPK（P＜0.01），特别是在红色 SS 肌肉中，这表明在长期冷适应后，该肌肉的代谢应激减轻。
