Calving patterns and herd production in seasonal dairy herds
K.L. Macmillan
Ruakura Animal Research Station, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1979, 39: 168-174
Calving patterns, mean calving dates and production of milkfat
were compared in three groups of identical twins of differing
productivity. Within-set differences in calving date were used to
assess differences in production which may arise because of variations
in the calving patterns. For cows producing an average of 0.84 kg milk
fat per cow per day during October, the 12-day difference in mean
calving date resulting from the "first" or earlier calving members of
each set having a more concentrated calving pattern than the "second"
calvers was associated with a 12 kg milkfat difference in favour of the
group of "first" calvers (163 kg vs. 151 kg). This production
difference arose in early lactation. Production differences in the
other two groups of identical twins in favour of the "first" calvers
also arose largely in early lactation, but this difference was
influenced by the productive ability of the cows.
These results are discussed in terms of the effect which aspects of herd
fertility may have on the subsequent season's calving pattern and
production.
Keywords: NZSAPAB;
Last Updated 12-09-1998
