Combined Use of Milk Progesterone Profiles, Clinical Examination and Oestrus Observation for the Study of Fertility in the Post-Partum Period of Dairy Cows

Abstract

Three different criteria were used to study the fertility of 50 cows: 1. Clinical investigation of ovaries and uterus at two-weekly intervals. 2. Daily observation of oestrus, three times a day. 3. Determination of milk progesterone every second or every third day. From the combination of clinical data and progesterone profiles it was found that 26% of the animals were abnormal according to both criteria. This group could be subdivided into three categories: delayed start (later than day 30 after parturition) of luteal activity (12%), prolonged (lasting longer than 20 days) luteal activity (6%) and irregular luteal activity (8%). Three animals (6%) which were clinically diagnosed to be abnormal (retained placenta or peritonitis) had normal progesterone profiles. On the other hand, one animal (2%) which appeared to be clinically normal had an abnormal progesterone profile. Two animals with follicular cysts were treated with Nymfalon (progesterone + HCG), one with a pyometra was treated with Cloprostenol (PGF2α) and one cow showing anoestrus was treated with GnRH. In all these cows the effectiveness of the treatment was confirmed by the corresponding progesterone profile. From the combined data of oestrus observations and progesterone profiles it was found that 48% of the animals showed at least one silent oestrus (the start of the first progesterone rise was not taken into consideration). 27% of a total of 110 oestrous periods, as expected from the progesterone profiles (excluding the start of the first progesterone rise), were apparently silent, since they were not observed despite frequent oestrus observations. One animal was never seen in oestrus, although there was some (delayed) luteal activity. Although 88% of the animals had started luteal activity earlier than day 30 after parturition, only 36% had shown oestrus at that time.