8Chew B P. Role of carotenoids in the immune response [J]. J Dairy Sci,1993,76(9) :2804-2811.
9Rajiv C, Harjit K. Plasma antioxidant vitamin status of periparturient cows supplemented with ot-tocopherol and 13-carotene[ J]. Anim Feed Sci and Technol,2004,114 ( 1/2/3/4 ) : 279-285.
10Bendich A. Beta-carotene and the immue response [ J 1. Proc Nutr Soc,1991,50(2) : 263-274.