Some effects of using progesterone and oestradiol benzoate to stimulate oestrus and ovulation in dairy cows with anovulatory anoestrus

K.L. MacMillan, V.K. Taufa, A.M. Day, S. McDougall

Dairying Research Corporation, Private Bag 3123, Hamilton, New Zealand

Proceedings of the New Zealand Society of Animal Production. 1995, 55: 239-241

Anovulatory anoestrus (AA) is a major form of infertility in pasture- fed dairy cows in New Zealand and is most frequently treated by injecting equine chorionic gonadotrophin (eCF) after pre-treatment with progesterone (P4). The effectiveness of this treatment varies between herds. Injecting oestradiol benzoate (ODB) from 24 h to 48 h following PA4 and ODB priming can also induce oestrus and ovulation in AA cows. Two field trials compared responses in 572 cows with AA treated with P4 alone, P4 + eCG and P4 + ODB. The P4 was administered per vaginum for 5 or 7 days using a CIDR device.

An injection of 1 mg ODB at 48 h after device removal in Trial 1 increased the insemination submission rate during the following 4 days from 55% among cows treated with P4, or P4 + eCG to 75%, and reduced the incidence of non-responding cows from 21% to 3%. In Trial 2, the comparable results to ODB treatments were 86% inseminated and 3% not responding.

The increased submission rates were not due to the ODB producing oestrus without ovulation. Consequently, 42% of anoestrous cows treated with ODB conceived during the first week of AB, 75% conceived after 6 weeks of AB and only 5.5% were finally not pregnant. Comparable figures for herdmates treated with P4 but not injected with ODB were 29%, 66% and 12% respectively.

Injecting a low dose of ODB from 24 to 48 h after P4 pre-treatment can be used to successfully treat AA in dairy cows.

Keywords: NZSAPAB; dairy cows; anovulatory anoestrus; progesterone; oestradiol; infertility

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Last Updated 25-01-1997