不同代谢葡萄糖水平饲粮对8~10月龄后备奶牛生长发育、营养物质消化率和血清生化指标的影响

Effects of Different Dietary Metabolizable Glucose Levels on Growth and Development,Nutrients Digestibility and Serum Biochemical Indices of 8 to 10-Month-Old Heifers

本试验旨在研究不同代谢葡萄糖水平饲粮对8～10月龄荷斯坦后备奶牛生长发育、营养物质消化率和血清生化指标的影响。试验选用24头月龄、体重接近的健康荷斯坦后备奶牛,随机分为4组,每组6头牛,分别饲喂代谢葡萄糖水平为86.43（A组）、99.93（B组）、113.59（C组）和126.42 g/kg（D组）的4种试验饲粮,试验期60 d。在试验期开始当天、第30天、第60天测定生长发育指标和血清生化指标;在试验期第21～25天、第51～55天,采用酸不溶灰分（AIA）法进行消化试验,测定营养物质消化率。结果表明：1）随着饲粮代谢葡萄糖水平的提高,后备奶牛平均日增重呈先升高后趋于稳定的趋势,A、B、C、D组平均日增重分别为0.49、0.71、0.87、0.87 kg/d,A组显著低于B组（P〈0.05）,极显著低于C和D组（P〈0.01）。同一时间点各组后备奶牛体高、体斜长、胸围、腹围和管围接近。2）第30天和第60天,A组血清尿素氮含量均显著高于C组（P〈0.05）,第30天,B组血清胰岛素含量极显著低于C组（P〈0.01）。3）饲粮代谢葡萄糖水平对后备奶牛营养物质消化率无显著影响（P〉0.05）。综合得出,饲粮代谢葡萄糖水平为113.59 g/kg时能满足8～10月龄荷斯坦后备奶牛0.8～1.0 kg/d日增重的需要。

This study was conducted to evaluate the effects of different dietary metabolizable glucose （MG） levels on growth and development, nutrients digestibility and serum biochemical indices of 8 to 10-month-old heifers. Twenty-four healthy Holstein heifers with similar month of age and body weight were randomly divided to 4 groups with 6 heifers in each group. Heifers in groups A, B, C and D were fed experimental diets with MG levels of 86.43, 99.93, 113.59 and 126.42 g/kg, respectively. The experimental period lasted for 60 days. On the started day and days 30 and 60 of experimental period, growth and development indices and ser- um biochemical indices were determined; on days 21 to 25 and 51 to 55 of experimental period, digestive trials were carried out by the acid-insoluble ash （AIA） method to determine nutrient digestibility. The results showed as follows ： 1） with the increase of dietary MG level, average daily gain （ADG） tended to increased firstly and then showed stable state. The ADG of groups A, B, C and D was 0.49, 0.71, 0.87 and 0.87 g/kg, re- spectively. The ADG of group A was significantly lower than that of groups B （P〈0.05）, C （P〈0.01） and D （P〈0.01）. Body height, body length, heart height, abdominal circumference and cannon circumference in different groups at the same time point were close. 2） On days 30 and 60, serum urinary nitrogen content of group A was significantly higher than that of group C （P〈0.05） ; on day 30, serum insulin content of group B was significantly lower than that of group C （P〈0.05）. 3 ） The nutrient digestibility of heifers was not signifi- cantly affected by dietary MG level （P〉0.05）. It is concluded that 113.59 g/kg of dietary MG level can meet the requirement of 0.8 to 1.0 kg/d of daily gain of 8 to 10-month-old Holstein heifers.