Effects of oestrus synchronisation and fixed-time artificial insemination on the reproductive performance of dairy heifers

Authors: Burton LJ, Xu ZZ
Publication: New Zealand Veterinary Journal, Volume 47, Issue 3, pp 101-104, Jun 1999
Publisher: Taylor and Francis

Animal type: Cattle, Livestock, Production animal, Ruminant
Subject Terms: Artificial insemination, Reproduction - female, Breed/breeding, Husbandry/husbandry procedures, Reproduction - hormones, Treatment/therapy, Animal remedies/veterinary medicines, Endocrine/autocrine/paracrine, Reproduction, Oestrus/oestrous, Reproduction - male, Animal production/wastage
Article class: Scientific Article

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Abstract: AIM: To compare the reproductive performance of heifers after oestrus synchronisation and fixed-time artificial insemination with non-synchronised heifers bred by herd sires.
METHODS: Heifers from 10 spring-calving herds were randomly divided into two groups by herd, breed and age. Heifers in one group (the synchronised group, n = 478) were synchronised with a combination of progesterone, oestradiol benzoate and PGF_2α, and inseminated 50-54 hours after progesterone treatment. Returns to first service were resynchronised with progesterone treatment 16-21 days after the fixed-time artificial insemination. Heifers in the other group (the control group, n = 470) did not receive any treatment and were bred by herd sires.
RESULTS: The conception rate of synchronised heifers to the fixed-time artificial insemination was 51.2% and to the artificial insemination after resynchronisation 40.4%. The pregnancy rate at the end of the breeding season was lower (p<0.001) for the synchronised (92.9%) than for the control (97.2%) group. The interval from start of breeding to calving was earlier for synchronised (295.9 ± 22.5 days, mean ± s.d.) than for control (298.5 ± 17.3 days) heifers.
CONCLUSION: Results from this study indicate that the oestrus synchronisation programme used in the present study can reduce reproductive performance by increasing the empty rate compared with natural mating.
KEY WORDS: Oestrus synchronisation, fixed-time artificial insemination, reproductive performance, dairy heifer.

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