The Contents of progesterone(P) and oestradiol(E_2) in the milk of 50 Chinese Holstein cows were measured within 23 days after delivery and 12 days during oestrus with radioactive immunity.

• 用放射免疫法测定了50头荷斯坦牛产后23d内及发情前后12d内乳中的孕酮(P)和雌二醇(E2)的含量。