Calving patterns in dairy heifers following single "set-time" inseminations and re-synchrony preceding second inseminations

S.C. Cliff, G.R. Morris, I.S. Hook, K.L. MacMillan

Livestock Improvement Corporation, Private Bag 3016, Hamilton, New Zealand

Proceedings of the New Zealand Society of Animal Production. 1995, 55: 70-71

Records were obtained for 1617 heifers in 26 herds using the GenermateŒ Programme during October 1993. This synchrony programme involved each heifer having a CIDR device inserted to release progesterone for 10 days, as well as oestradiol benzoate (10 mg) at device insertion and half of the normally recommended dose of prostaglandin F2a injected on the sixth day of CIDR treatment. All inseminations were from 50 to 52 h after device removal. Previously used devices were reinserted 16 days later for a period of 5 days to re- synchronise returns-to-service so that second inseminations could be made following detected oestrus only at 48 h (13 herds), or at 48 and 72 h after device removal (13 herds).

On average, 62.0% of all of the treated heifers calved to first inseminations. A further 14.6% calved to second inseminations and 7.5% failed to calve following a further period of natural mating.

The convenience of single set-time inseminating and avoiding the need to provide extra bulls for a short period by using re-synchrony are elements of a synchrony programme which is being recommended and adopted in an increasing number of herds of heifers.

Keywords: NZSAPAB; oestrous synchrony; set-time inseminating; re-synchrony; calving rates; empty rates

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Last Updated 25-01-1997