Wpływ kondycji krów rasy polskiej holsztyńsko-fryzyjskiej przed porodem i na początku laktacji na wskaźniki płodności

This study examined the effect of the body condition of Polish Holstein-Friesian cows in the last month before calving and in the first week of lactation and of the rate of the body condition loss in the early lactation on basic fertility indicators. Body condition of a total 327 cows was evaluated using the 5-point BCS scale. Five fertility indices were included. The fertility indicators analysed depended less on the BCS of cows in the last month before calving and in the first week of lactation, and more on the size of body condition loss and its duration. Scores of over 3.5 both before parturition and at the start of lactation were associated with the longest service periods and with the lowest percentage of conceptions after one insemination procedure. The length of the days open and calving intervals and the number of services per conception increased as the length of the decline in BCS after parturition increased. The most favourable values for the fertility indicators analysed can be expected in cows whose BCS before parturition and at the start of lactation was 2.75-3.5. A smaller energy deficit with a shorter duration after parturition was also more favourable for these traits.