本试验研究了宰前2周添加钙和维生素D3对黄羽肉鸡肌肉嫩度的影响。试验采用2×3因子随机试验设计，选用1440只43日龄的黄羽肉鸡（母鸡），随机分为9组，每组4个重复，每个重复40只鸡。预饲1周后在基础日粮（含钙0.8%、维生素D3 1 000 IU/kg）中添加钙与维生素D3水平分别为：钙，0.0%、0.4%、0.8%；维生素D3，0、1 000、2 000 IU/kg。鸡饲养至63日龄结束。结果表明，在黄羽肉鸡宰前2周添加钙与维生素D3对黄羽肉鸡的生长性能无显著影响（P>0.05）。添加维生素D3对黄羽肉鸡肌肉嫩度无显著影响（P>0.05），添加0.4%钙显著提高黄羽肉鸡肌肉嫩度（P<0.05），添加维生素D3能协同钙提高肌肉嫩度，但钙的添加剂量超过0.4%时维生素D3协同作用效果下降。单独添加维生素D3对Ca-ATP酶活性及肌钙蛋白降解度无显著影响（P>0.05）；添加0.4%的钙，Ca-ATP酶活性趋于提高，肌钙蛋白降解度趋于降低，钙蛋白酶抑制蛋白的基因表达显著提高（P<0.05）。由此可知，黄羽肉鸡饲料中添加0.4%钙能提高肌肉嫩度，单独添加维生素D3不能改善肌肉嫩度但是可以协同钙提高肌肉嫩度。

The present study was to investigate the effects of supplementation of Ca and vitamin D3 in the basal diet on muscle tenderness of yellow chickens two weeks before slaughter. A total of 1 440 yellow chickens (43 days old) were used in this experiment. They were allotted to 9 groups on the basis of body weight in a 2×3 factors design; each treatment consisted of 4 replicates with 40 chickens in each replicate. The supplemental levels of Ca and vitamin D3 were as follows, Ca: 0.0%, 0.4%, 0.8%; VD3: 0, 1 000, 2 000 IU/kg Results showed that supplementation of Ca and vitamin D3 had no significant effect on growth performance of yellow chickens (P>0.05). Supplementation of vitamin D3 had no significant effect on muscle tenderness of yellow chickens (P>0.05). Supplementation of 0.4% Ca increased the muscle tenderness (P<0.05), and vitamin D3 had an associative effect with Ca, but when the supplemental level of Ca was more than 0.4%, the associative effect of vitamin D3 decreased. Supplementation of vitamin D3 had no significant effect on the activity of CaATPase and the degradation extent of troponin (P>0.05) Supplementation of 0.4% Ca increased the calpastatin gene expression （P<0.05） and had a trend to increase the activity of CaATPase and the degradation extent of troponin. It was concluded that supplementation of 0.4% Ca increased the muscle tenderness of yellow chickens, and supplementation of vitamin D3 had no effect on the muscle tenderness, but it had a cooperative effect with Ca.