Huang Zhongzuo, Yu Xiaoxiao, Jiang Zongyou, Tang Gaojian, Gao Shaoqi, Xiang Yifan, Luo Yicheng, Ye Boping, Li Yating, Song Pengkang, Xin Yu, Du Min, Zhao Junxing, Wang Bo
State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
College of Animal Science, Shanxi Agricultural University, Taigu 030801, China.
Anim Nutr. 2024 Sep 28;19:215-225. doi: 10.1016/j.aninu.2024.08.006. eCollection 2024 Dec.
This study investigated whether vitamin A (VA) administration during the neonatal stage could increase the number of intramuscular adipocytes in Hu sheep by promoting vascularity. A total of 56 newborn male Hu sheep were divided into four groups and received intramuscular injections of either 0, 7500 IU retinoic acid (RA), 7500 IU VA, or a combination of 7500 IU VA and 5 mg SU5416 (an angiogenic inhibitor), at 1, 7, 14, and 21 days of age. At 15 days of age, 6 sheep from each group were randomly selected and sacrificed for intramuscular adipogenic capacity analysis. The remaining 8 sheep in each group were raised until they were 8 months old. VA-treated sheep exhibited an increase in preadipocytes, elevated expression of adipogenic genes (CCAAT enhancer binding protein alpha [] and CCAAT enhancer binding protein beta []) and angiogenic genes (vascular endothelial growth factor A []), and stromal vascular fraction cells in the longissimus dorsi (LD) muscle with enhanced adipogenic capacity ( ＜ 0.05). These effects were entirely negated by SU5416. Upon slaughter, VA increased final weight, carcass weight, and average daily gain ( ＜ 0.05) but did not affect feed intake at 21 to 32 weeks ( = 0.824). VA increased the number of intramuscular adipocytes in the LD and semitendinosus (ST) muscle ( ＜ 0.05) without changing the adipocyte number of the omentum, perirenal and subcutaneous fats ( ＞ 0.05). VA injections also increased intramuscular triglyceride (TG) content ( = 0.016) without changing the omentum fat weight or subcutaneous fat thickness ( ＞ 0.05), but it did increase the perirenal fat weight ( = 0.011). Consistently, SU5416 mitigated the effects of VA on intramuscular TG content and adipocyte count, correlating with a decrease in vascularity. In contrast, RA injections didn't affect the intramuscular fat ( = 0.744) but reduced the TG content of the omentum and perirenal fat ( ＜ 0.05). In conclusion, intramuscular injections of VA but not RA at the neonatal stage improved the growth performance of Hu sheep, increasing the number of intramuscular adipocytes and marbling by promoting angiogenesis.
本研究调查了在新生阶段给予维生素A（VA）是否能通过促进血管生成来增加湖羊肌肉内脂肪细胞的数量。将56只新生雄性湖羊分为四组，在1、7、14和21日龄时分别肌肉注射0、7500 IU视黄酸（RA）、7500 IU VA或7500 IU VA与5 mg SU5416（一种血管生成抑制剂）的组合。在15日龄时，从每组中随机选取6只羊并处死，用于肌肉脂肪生成能力分析。每组其余8只羊饲养至8月龄。VA处理的羊表现出前体脂肪细胞增加，脂肪生成基因（CCAAT增强子结合蛋白α[ ]和CCAAT增强子结合蛋白β[ ]）和血管生成基因（血管内皮生长因子A[ ]）的表达升高，背最长肌（LD）中的基质血管分数细胞增加，脂肪生成能力增强（ ＜0.05）。SU5416完全消除了这些影响。屠宰时，VA增加了最终体重、胴体重量和平均日增重（ ＜0.05），但在21至32周时对采食量没有影响（ =0.824）。VA增加了LD和半腱肌（ST）中肌肉内脂肪细胞的数量（ ＜0.05），而网膜、肾周和皮下脂肪的脂肪细胞数量没有变化（ ＞0.05）。VA注射还增加了肌肉内甘油三酯（TG）含量（ =0.016），而网膜脂肪重量和皮下脂肪厚度没有变化（ ＞0.05），但确实增加了肾周脂肪重量（ =0.011）。一致地，SU5416减轻了VA对肌肉内TG含量和脂肪细胞计数的影响，这与血管生成减少相关。相比之下，RA注射对肌肉内脂肪没有影响（ =0.744），但降低了网膜和肾周脂肪的TG含量（ ＜0.05）。总之，新生阶段肌肉注射VA而非RA可改善湖羊的生长性能，通过促进血管生成增加肌肉内脂肪细胞数量和大理石纹。
