1JOHNSON H D. World animal science [ M ]. New York:Elsevier Science Publ Co. , 1987.
2COPPOCK C E. Energy nutrition and metabolism of the lactating dairy cow [J]. J Dairy Sci, 1985, 68(12) : 3403 -3410.
3ABILAY T A, MITRA R, JOHNSON H D. Plasma cortisol and total progestin levels in Holstein steers during acute exposure to high en- vironmental temperature ( 42 C ) conditions [J]. J Anita Sci,1975, 41(1): 113 -117.
4HOLTER J B,WEST J W, MCGILLIARD M L. Predicting adlibi- turn dry matter intake and yield of Holstein cows [ J ]. J Dairy Sci, 1997, 80:2188-2199.
