1Buccione k, Schroeder A C, Eppig J. Interactions be- tween somatic cells and germ cells throu-ghout mammali- an oogenesis[J].J Biol Reprod, 1990,43: 543-547.
2D Buskirk D, Faulkner D B, Hurley W L, et al. Growth, reproductive performance, mammary develop- ment, and milk production of beef heifers as influenced by prepuberty dietary energy and administration of bovine somatotropin[J]. J AnimSci, 1996,74: 2649-2662.
3Barb C R. The brain-pituitary-adipocyte axis: Role of leptinin modulating neuro endocrine function[J]. J Anim Sci,1999, 77:1249-1257.
4Broderick G A, Clayton M K. A statistical evaluation of animal and nutritional factors influencing concentrations of milk urea nitrogen[J]. J Dairy Sci, 1997,80: 2964 -2971.
5Butler W R, Calaman J J, Beam S W. Plasma and milk area nitrogen in relation to pregnancy rate in lactating Jairy cattle[J]. Journal of Animal Science, 1996, 74:858 -865.
7Moley K H, Schreiber J R. Ovarian follicular growth, ovulation and atresia endocrine, paracrine and autocrine :egulation[J]. J Adv Exp Med Biol, 1995, 377: 103 -119.
8Johnson R G,Young A J. The association between milk urea nitrogen and DHI production variables in western commercial dairy herds[J]. J Dairy Sci, 2003, 86(9) : 3008 -3015.
9Kauffman A J, St-Pierre N R. The relationship of milk urea nitrogen to urine nitrogen excretion in Holstein and Jersey cows[J]. J Dairy Sci, 2001,84:2284-2294.
