AN EXPERIMENT ON THE APPARENT ABSORPTION RATE OF METHIONINE-ZN(Met-Zn) BY HOLSTEIN-FRIESIAN DAIRY COWS
Huang Yude;Zhu Guosheng; Lu Guoquan;Qiao Kexing and Zhang Jiutao(Bureau of Animal Production,Zhangqiu,Shandong Province, Veterinary Station,Zhangqiu,Neighbourhood Service Centre of Dairy Cow,Zhangqiu)
The apparent absorption rate of Met-Zn in dairy cows was estimated through the analysis of feeds and feces, A total of 12 cows were equally divided into 3 groups,each fed similar ration according to milk production with added Met-Zn to the amounts of 6mg/kg, 20mg/kg and 60mg/kg of Zn to the ration,respectively. results showed that the apparent absorption rates werc 85. 02%,73. 29% and 64. 66% for the groups in the above order.And the Zn concentration in milk did not increase proportionately with the amounts of Met-Zn added to the ration.The apparent absorption rate of Zn in the milk decreased when the amount of Met-Zn in the ration increased. It was suggested that 20ms/kg may be the appropriate amount to add to the cow ration.