Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Ave, Wooster 44691
Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Ave, Wooster 44691.
Poult Sci. 2014 Jun;93(6):1484-94. doi: 10.3382/ps.2013-03813.
The effect of the timing of an immediate posthatch feed restriction on broiler pectoralis major muscle development was studied by applying a 20% feed restriction either the first or second week after hatch. Pectoralis major muscle morphological structure and the expression of the myogenic transcriptional regulatory factors, myogenic determination factor 1 (MyoD), myogenic regulatory factor 4 (MRF4), and myogenin, were measured. Broiler chicks at hatch were divided into a full-fed (control) group and a 20% feed restriction treatment administered either the first or second week posthatch. At the end of the feed restriction, the chicks were placed on a full feed ad libitum diet with no further restrictions. Muscle fiber diameter and fiber bundle size of the pectoralis major muscle were smaller in the wk 1 restricted group than the control group by 7 d of age. By 15 d of age through the duration of the study, d 43, both endomysial and perimysial connective tissue spacing were diminished in the wk 1 feed-restricted group. The expression of MyoD, MRF4, and myogenin was affected by the wk 1 feed restriction. The expression of MyoD and MRF4 was significantly increased during the first week posthatch. Both of the genes have been shown to be expressed during proliferation especially MyoD, which is required for muscle cell proliferation. In contrast, myogenin expression was significantly decreased. Myogenin expression is required for differentiation to occur. The morphological changes and gene expression changes observed with the wk 1 feed restriction were eliminated by moving the 20% feed restriction to wk 2, which is after the period of maximal myogenic satellite cell mitotic activity. Taken together, these results demonstrate that the timing of early posthatch feed restrictions to chicks is critical for the morphological development of the pectoralis major muscle and the expression of genes required for muscle satellite cell proliferation and differentiation.
研究了出雏后立即进行限饲对肉鸡胸大肌发育的影响，方法是在出雏后第 1 周或第 2 周进行 20%的限饲。测量了胸大肌形态结构和肌源性转录调节因子肌源性决定因子 1（MyoD）、肌调节因子 4（MRF4）和肌生成素的表达。出雏的肉鸡雏鸡分为全饲（对照）组和出雏后第 1 周或第 2 周进行 20%限饲处理组。限饲结束时，将小鸡置于自由采食的全饲日粮中，不再进行限制。第 1 周限饲组的胸大肌肌纤维直径和纤维束大小在 7 日龄时比对照组小。到研究结束时，第 43 天，第 1 周限饲组的肌内和肌周结缔组织间隙都减小了。MyoD、MRF4 和肌生成素的表达受第 1 周限饲的影响。MyoD 和 MRF4 的表达在出雏后第 1 周显著增加。这两种基因都在增殖期表达，尤其是 MyoD，它是肌肉细胞增殖所必需的。相反，肌生成素的表达显著降低。肌生成素的表达是分化所必需的。第 1 周限饲引起的形态变化和基因表达变化通过将 20%的限饲推迟到第 2 周而消除，第 2 周是肌卫星细胞有丝分裂活动的高峰期之后。总之，这些结果表明，出雏后早期限饲对小鸡的时间安排对胸大肌的形态发育和肌肉卫星细胞增殖和分化所需基因的表达至关重要。
