Variations in reproductive hormones during estrus cycle in local beef cattle from Jilin of China.

[Objective] To provide a theoretical basis for improving reproductive efficiency of domestic beef cattle in Jilin of China.[Method] China Red Steppe cattle,Yanbian yellow cattle and Simmental cattle in Jilin Province were used for detection.The levels of progesterone(P4),estradiol(E2),follicle-stimulating hormone(FSH) and luteinizing hormone(LH) in serum and urine during estrus cycle were determined.[Result] The levels of P4 and E2 were significantly different between pregnant cattle and non-pregnant cattle on Day 21 post estrus(P 0.01).The level of LH on estrus day was significantly different from that on the other days of estrus cycle(P 0.05).[Conclusion] It is feasible to detect P4 level for diagnosis of estrus and early pregnancy in beef cattle.