Determination of the reproductive behavior of dairy cows, post-partum, by means of radio immunoassay (RIA) techniques

The main objective of this trial was to determine the post-partum ovaric activity in dairy cattle recently introduced in the Ecuadorian subtropic. On this trial, progesterone levels in milk of 114 post-partum cows from 6 different farms were determined. The progesterone level in milk was analyzed by RIA and the milk sampling was done according to established protocol. Additional data about management, nutritional condition and health of the animals were also taken in each farm. In the Santo Domingo valley, the ovaries of post-partum cows, with a good nutritious diet, start functioning after 54.21 days with a range of 10 to 161. The duration of the first oestral cycle was 24.07 with the range of 6 to 29 days. Fifty six cows (49.12 percent) remained pregnant up to the end of the trial and the average of interval calving was 409. 95 - 115. 69 days. In the area, there is high incidence of ovaric hypofunctions ( 30.70 percent) and return of anoestrus ( 14.03 percent). heats of the cows were observed ( 62.90 percent) by the farmers, but they were determined by progesterone levels, through RIA technique