Effects of Different β-Carotene Level on Milk Yield and Quality of Cows

The purpose of this research is to study the effects of β-carotene supplements on cow's milk production and the milk quality.32 Holstein cows with the same age,body weight,body condition,parturition,and milking at 200 days in milk were divided into 4 experimental groups.Group I received the basal diet as the control;group II,Ⅲ,Ⅳ received the β-carotene supplement of 300 mg/d,600 mg/d,900 mg/d.The basal diet composed of corn silage,alfalfa meal,wheat straw and concentrates.The results indicated that the addition of β-carotene in the diet of cows could improve the milk production and quality,the milk production of group Ⅳ increased by 11.03% compared with that of control group(P0.05),the milk fat percentage of group Ⅲ and Ⅳ increased by 6.34% and 9.36% respectively compared with that of control group(P0.05),the milk protein percentage of group Ⅳ increased by 2.05% compared with control group(P0.05).There were no significant differences among all groups(P0.05).