Effect of different diets and buffer pH on conjugated linoleic acid content of rumen cultivate liquor | 日粮与缓冲液pH对奶牛瘤胃液CLA含量的影响

صينى. 研究体外培养条件下日粮与缓冲液pH对奶牛瘤胃液共轭亚油酸（CLA）含量的影响，筛选能提高奶牛瘤胃CLA含量的最佳条件。选择日粮中粗料比例、精料中植物油种类及比例、棉粕质量分数与豆粕质量分数比值（以下简称棉粕与豆粕比例）、缓冲液pH值、硫酸铜作为影响因素，采用五因素二次正交旋转组合设计，对泌乳荷斯坦奶牛瘤胃液进行体外培养，测定奶牛瘤胃中CLA含量。各因素对CLA含量的影响作用从大到小依次为：pH值平方项＞粗料比例＞植物油种类及其比例平方项（达1%显著水平）＞粗料比例与pH值交互项（达2.5%显著水平）＞棉粕与豆粕比例平方项＞pH值（达5%显著水平）。在其他条件一定时，日粮中添加5%葵花籽油、粗料比例为70%、棉粕与豆粕质量分数分别为14%与11%、pH值为7.0时，奶牛瘤胃液CLA的含量最高。日粮中粗料比例、植物油种类及其比例、缓冲液pH值、棉粕与豆粕比例是影响奶牛瘤胃液CLA含量的主要因素，筛选得到了提高奶牛瘤胃中CLA含量的最佳条件。

إنجليزي. In this experiment the rumen liquor was collected and cultivated to study the effect of different diets on conjugated linoleic acid content of rumen cultivate liquor in vitro to select the best factors to increase the CLA content of rumen liquor. The five factors quadratic rotary combination design was used and conjugated linoleic acid content of rumen cultivate liquor was detected. Effect orders of various factors on CLA content are: the square terms of pH valueforage additionthe square terms of vegetable oil (P0.01)the interaction terms of forage addition and pH value (P0.025)the square terms of nitrogen ratiopH value (P0.05). The proportion of rumen cultivate liquor conjugated linoleic acid was greatest with 5% sunflower oil diet, 70% forage, 11% soybean meal and 14% cottonseed meal in diets with pH 7.0. The main factors to enhance CLA content of cultivate liquor were percentage of forage, percentage of soybean meal and cottonseed meal, sunflower oil in diets and buffer pH. The best factors to increase the CLA content of rumen liquor was the supplementation with 5% sunflower oil, 70% forage, 11% soybean meal and 14% cottonseed meal in diets with pH 7.0.