Postpartum reproductive function in Finnish Ayrshire and Friesian cows after three subsequent parturitions.

The postpartum reproduction functions of 84 Finnish Ayrshire and Friesian cows were studied on an experimental farm. The cows were divided according to type of feed into 2 groups of equal size: a hay-urea group and a silage group. The duration of the study was 3 years. Eighty-four cows were followed during their first postpartum period, 63 during 2 and 57 during 3 consecutive post partum periods. The cows were examined clinically by rectal palpation, and milk samples for progesterone assay were taken 3 times a week between calving and first insemination. External signs of heat were checked 3 times a day by the herdsmen. Intervals from calving to completed uterine and cervical involution, appearance of first palpable follicle, onset of first luteal function and onset of regular ovarian function were recorded. Intervals from calving to the first observed heat and to pregnancy were measured and the rate of successful pregnancies at the first insemination was calculated. Least squares methods were used for evaluation of the effect of individual cow, breed, parity/year and type of feed on postpartum reproductive function. The cows in the herd seemed to have equal reproductive functions which were influenced by the conditions during each year/parity rather than by the breed or type of feed. Individual cow effect was significant for the rapidity of uterine involution. Breed had no significant effect on any of the parameters studied. The effect of type of feed alone was not significant for any parameter, but when studying the intervals from calving to uterine involution and initiation of luteal function differences between the feed groups were noted within parity/year. The percentage of cows showing heat before the first dioestrus (luteal phase) increased with parity/year, and the first dioestrus was shorter than the second. The percentage of cows showing postoestrous bleeding increased with number of oestrous cycles post partum.