Data were gathered relating to the practice of induction of premature parturition from farms in the central Waikato during spring 1996. A standard two-injection glucocorticoid treatment regime was employed. The reproductive tract of each cow receiving this treatment was examined 3 - 5 days post partum. Additional information relating to cow management was collected by interviewing participating herd-owners. Preliminary data relating to subsequent reproductive performance of a subset of the cows are also presented. Accurate data were obtained for a total of 691 cows on 31 dairy farms. The mean induction rate was 10% (range 2 - 24%) of the cows in each herd. The distribution of the ages of induced cows was skewed, with 25% of cows being 3 yr old. Of the 35% of cows which calved to a single injection of glucocorticoid, 76% were within 30 days of full term based on expected calving dates. Inadequate progress in udder development following the first injection was seen in 11% of cows, of which 78% were more than 30 days premature. Only 56% of cows completed the routine two-injection regime. Dystocia requiring at least moderate intervention occurred in 15 cows (2%). There were no cows with retained foetal membranes (RFM) on 33% of farms, but the overall incidence of RFM in cows receiving routine induction was 14%. No intervention was required for 43% of these, which resolved spontaneously within 48 h of calving. Milk fever was the complication most frequently reported (overall incidence 2.8%) and contributed to 3 of the 6 reported deaths. Preliminary data from 11 farms indicated that 7% of cows were not presented for re-breeding. Only 12% required treatment for anoestrum. The mean calving to 1st service interval was 64 ± 2 days, and 53% had appeared to hold to 1st service.
Proceedings of the New Zealand Society of Animal Production, Volume 57, , 231-233, 1997
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