本试验旨在探讨饲粮不同非纤维性碳水化合物和中性洗涤纤维比(NFC/NDF)条件下,诱导奶山羊发生亚急性瘤胃酸中毒(SARA)过程中瘤胃上皮细胞胰岛素样生长因子Ⅰ(IGF-Ⅰ)及胰岛素样生长因子Ⅰ受体(IGF-ⅠR)的基因表达量的变化。选用12只泌乳期关中奶山羊为试验动物,试验分4期进行,每期15d,依次饲喂NFC/NDF分别为1.02(Ⅰ期)、1.24(Ⅱ期)、1.63(Ⅲ期)、2.58(Ⅳ期)的4种饲粮,以逐渐增加饲粮精料的方式诱导奶山羊发生SARA,并采用实时定量PCR(qRT-PCR)法对瘤胃上皮细胞中IGF-Ⅰ及IGF-ⅠR的基因表达量的变化进行相对定量分析。结果表明:随着饲粮NFC/NDF的升高,IGF-Ⅰ及IGF-ⅠR的基因表达量均出现不同程度的增加,Ⅱ期、Ⅲ期和Ⅳ期IGF-Ⅰ的基因表达量分别是Ⅰ期的1.70、2.71和9.61倍,IGF-ⅠR的基因表达量分别是Ⅰ期的1.88、3.09和10.19倍。饲粮NFC/NDF为2.58(即SARA期)时,与Ⅰ期相比,IGF-Ⅰ和IGF-ⅠR的基因表达量均出现极显著增加(P<0.01)。结果提示,以提高饲粮NFC/NDF的方法逐渐诱导SARA,IGF-Ⅰ及IGF-ⅠR的基因表达量显著提高,SARA发生后,它们的表达量有大幅增加。
The objective of this study was to investigate the changes of expressions of insulin-like growth factor Ⅰ (IGF-Ⅰ) and insulin-like growth factor Ⅰ receptor (IGF-ⅠR) genes in the ruminal epithelium of dairy goats in the process of inducing subacute rumen acidosis (SARA) under the condition of different dietary ratios of non-fiber carbohydrate and neutral detergent fiber (NFC/NDF). This study was designed for four experimental periods with twelve lactating Guanzhong dairy goats, and 15 days in each period. Goats were fed 4 diets with different NFC/NDF (1.02, 1.24, 1.63 and 2.58, respectively). The induction of SARA was conducted by the gradual increase of dietary NFC/NDF, and expressions of IGF-Ⅰ and IGF-ⅠR genes were quantitatively analyzed by quantitative real-time PCR (qRT-PCR). The results showed as follows:expressions of IGF-Ⅰ and IGF-ⅠR genes were both increased with the gradual increase of dietary NFC/NDF. The expression of IGF-Ⅰ gene in periods Ⅱ, Ⅲ and Ⅳ was 1.70, 2.71 and 9.61 times of that in period Ⅰ, respectively, and the expression of IGF-ⅠR gene in periods Ⅱ, Ⅲ and Ⅳ was 1.88, 3.09 and 10.19 times of that in period Ⅰ, respectively. Compared with period Ⅰ, expressions of IGF-Ⅰ and IGF-ⅠR genes significantly were increased when NFC/NDF reache 2.58 (P<0.01). In conclusion, induction of SARA using the method of increasing dietary NFC/NDF can significantly increase expressions of IGF-Ⅰ and IGF-ⅠR genes, and they are increased sharply after SARA occurs.
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