Effect of dietary crude proteins on the reproductive function in the postpartum dairy cow

The study was conducted on 216 dairy cows. Samples of feeds distributed to cows were collected monthly for the purpose of determining their content in dry matter, energy, crude proteins and mineral matter. Milk samples were c ollected weekly for every cow from newly calved cows until confirmation of pregnancy by rectal palpation at least 2 months after artificial inseminati on. These samples were used for progesterone assays in skimmed milk, in ord er to assess the interval between calving and return to ovarian activity [C -ROA], calving and first insemination [C-11], calving and conception [CC] a nd number of inseminations per conception (nI/C). Results have shown a sign ificant negative correlation between the duration of [C-ROA] and [CC] inter vals and the dietary content in crude proteins (r = - 0.720, p < 0.05 and = - 0.914, p < 0.01 respectively).