摘要
[ Objective]Through study of different diet categories＇ effects on lactating cows＇ feces/urine features and nitrogen emission, and in order to reduce and control the nitrogen emission. [Method112 China Holsteins each with the weight of 514 kg and at the age of 3 to 5 years old are selected for this experiment to carry out test and research on their feces/urine features and nitrogen emission. The cows are divided into 3 groups which are fed with Diet A which takes dry corn straw as forage with forage to concentrate ratio of 40：60, Diet B and Diet C （ both take corn silage as forage） with forage to concentrate ratio of 40：60 and 60：40 respectively. [ ltesult]The results show that diet categories have certain effects on dairy cows＇ output of feces and urine. Feces output of Diet A （straw type） is more than that of Diet B （silage type with low forage to concentrate ratio） which is more than that of Diet C （silage type with high forage to concentrate ratio）. Feces output of Diet A group exceeds that of Diet B and Diet C groups by 6.10% and 10.08% respectively. Feces output of Diet B exceeds that of Diet C by 3.75%. The difference is insignificant （ P 〉 0.05）. In terms of urine output of these three diet groups, Diet C is more than that of Diet B which is more than that of Diet A. Urine output of Diet C exceeds that of Diet B and Diet A by 22.75% and 56.30% respectively. Urine output of Diet B exceeds that of Diet A by 27.33%. The difference is significant（ P 〈 0.05）. At the same time, diet categories have significant effects on dairy cow＇s nitrogen balance. Straw-typed diet＇s milk nitrogen and urinary nitrogen contents as well as nitrogen digestibility are far lower than those of silage-typed diet （ P 〈 0.01 ）. Under conditions of taking corn silage as forage, as diet＇s concentrate refines, nitrogen digestibility and urinary nitrogen both increase remarkably （ P 〈 0.01 ） while fecal nitrogen and milk nitrogen＇s increase is not obvious （P 〉 0.05）.[ Conclusion] Moreover, it shows that Straw-typed diet＇s absorbed nitrogen is mainly discharged through feces. When corn silage is taken as forage, as diet＇s concentrate refines, proportion of fecal nitrogen reduces while that of urinan/nitrogen increases, and fecal nitro clen and urinary nitrogen＇s proportions in total feces/urine nitroqen are basically the same.
[ Objective]Through study of different diet categories＇ effects on lactating cows＇ feces/urine features and nitrogen emission, and in order to reduce and control the nitrogen emission. [Method112 China Holsteins each with the weight of 514 kg and at the age of 3 to 5 years old are selected for this experiment to carry out test and research on their feces/urine features and nitrogen emission. The cows are divided into 3 groups which are fed with Diet A which takes dry corn straw as forage with forage to concentrate ratio of 40：60, Diet B and Diet C （ both take corn silage as forage） with forage to concentrate ratio of 40：60 and 60：40 respectively. [ ltesult]The results show that diet categories have certain effects on dairy cows＇ output of feces and urine. Feces output of Diet A （straw type） is more than that of Diet B （silage type with low forage to concentrate ratio） which is more than that of Diet C （silage type with high forage to concentrate ratio）. Feces output of Diet A group exceeds that of Diet B and Diet C groups by 6.10% and 10.08% respectively. Feces output of Diet B exceeds that of Diet C by 3.75%. The difference is insignificant （ P 〉 0.05）. In terms of urine output of these three diet groups, Diet C is more than that of Diet B which is more than that of Diet A. Urine output of Diet C exceeds that of Diet B and Diet A by 22.75% and 56.30% respectively. Urine output of Diet B exceeds that of Diet A by 27.33%. The difference is significant（ P 〈 0.05）. At the same time, diet categories have significant effects on dairy cow＇s nitrogen balance. Straw-typed diet＇s milk nitrogen and urinary nitrogen contents as well as nitrogen digestibility are far lower than those of silage-typed diet （ P 〈 0.01 ）. Under conditions of taking corn silage as forage, as diet＇s concentrate refines, nitrogen digestibility and urinary nitrogen both increase remarkably （ P 〈 0.01 ） while fecal nitrogen and milk nitrogen＇s increase is not obvious （P 〉 0.05）.[ Conclusion] Moreover, it shows that Straw-typed diet＇s absorbed nitrogen is mainly discharged through feces. When corn silage is taken as forage, as diet＇s concentrate refines, proportion of fecal nitrogen reduces while that of urinan/nitrogen increases, and fecal nitro clen and urinary nitrogen＇s proportions in total feces/urine nitroqen are basically the same.
