中文摘要：

试验旨在研究泌乳奶牛TMR中添加不同长度的苜蓿干草对奶牛采食及产奶性能的影响。采用3个3×3拉丁方试验研究了TMR中苜蓿干草长度分别为1、3、5 cm时对3头头胎及6头经产泌乳奶牛的采食及产奶性能的影响。结果表明：TMR中的苜蓿干草长度变化对奶牛的DM采食量无显著影响（P〉0.05）;当苜蓿干草长度从1 cm增加到3 cm和5 cm时,奶牛的NDF、ADF及peNDF摄入量均显著增加（P〈0.05）;3 cm和5 cm长度的苜蓿干草较1 cm的能显著提高奶牛4%FCM产奶量、产奶效率及乳脂率（P〈0.05）。结果提示,泌乳奶牛TMR中苜蓿干草以较长的5 cm为宜;较长的苜蓿干草不影响奶牛的干物质采食量,能增加其有效纤维的摄入量,提高其4%FCM产奶量、产奶效率及乳脂率。

英文摘要：

This experiment was conducted to study the effect of particle length of alfalfa hey in TMR on intake and milk production of lactating dairy cows.In this research,nine Holstein diary cows which parity was 1,2 and 3,respectively,were arranged in triple 3×3 Latin squares to evaluate the effect of particle length of alfalfa hey in total mixed rations on intake and milk production.The results showed that particle length of alfalfa hey in total mixed rations affected little on DMI of all the Holstein dairy cows.But with the increasing of the particle length of alfalfa hey from 1 to 3 and 5 cm,the NDF,ADF and peNDF intake were significantly increased（P 0.05）,and 4% FCM yield,FCM efficiency and milk fat percentage were significantly improved（P 0.05） for the Holstein dairy cows.These results indicated that the proper particle length of alfalfa hey in TMR was 3 to 5 cm,and the longer particle length of alfalfa had no effect on DM intake,but improved peNDF intake,4% FCM yield,milk efficiency and milk fat percentage of the lactating dairy cows.