Relationships among milk yield, body weight, and reproduction in Holstein and Czech Fleckvieh cows

The objective of this study was to determine the dynamics and relative body weight (BW) changes after parturition and their relationships to milk yield in Holstein (H) and Czech Fleckvieh (F) cows, and also the relationships between their BW changes in the first 8 weeks of lactation and reproductive performance. A retrospective, observational study comprised analyses of individual cow records from a computerised herd management system. Production, body weight, and reproduction data were collected between December 2004 and February 2009 from F and H cows kept in a single experimental station. A total of 475 calving interval records (F: N = 132; H: N = 343) were included in the analysis. The data were evaluated using the mixed linear model with repeated measures, and parameters were estimated by the REML method. Whereas BW changes in F first-parity cows significantly (P < 0.01) differed from those detected in greater-parity cows during the major part of lactation, no such differences were manifested for H first-parity animals. The average BW change in weeks 1 to 8 was closely correlated with the BW change in the lactation week, with the lowest BW (NADIR) (r > 0.83, P < 0.0001) in both breeds. In H cows, the average BW change in weeks 1 to 8 and in NADIR significantly (P < 0.01) negatively correlated with the length of postpartum anoestrus, days between parturition and conception, days between first service and conception, and calving interval (P < 0.05 and P < 0.01, respectively). In F cows, the only significant correlations were those with days between parturition and first service (P < 0.05 and P < 0.01, respectively). It was concluded that BW changes postpartum might indicate reproduction problems particularly in H cows.