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Fertility of inseminations with two sperm concentrations in oestrus-synchronized cattle

Published online by Cambridge University Press:  02 September 2010

L. J. Boyd ,
G. F. Smith ,
P. D. P. Wood ,
J. Craven ,
D. R. Melrose  and
J. Williamson
L. J. Boyd
Affiliation:
Milk Marketing Board, Thames Ditton, Surrey
G. F. Smith
Affiliation:
Milk Marketing Board, Thames Ditton, Surrey
P. D. P. Wood
Affiliation:
Milk Marketing Board, Thames Ditton, Surrey
J. Craven
Affiliation:
Milk Marketing Board, Thames Ditton, Surrey
D. R. Melrose
Affiliation:
Meat and Livestock Commission, Ridgmount Street, London
J. Williamson
Affiliation:
Meat and Livestock Commission, Ridgmount Street, London
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Summary

Two field trials were conducted to evaluate oestrus synchronization under farm conditions and to determine if increased sperm numbers per insemination would enhance fertility at the first synchronized oestrus. One hundred and seventy-seven previously unmated British Friesian females in 6 dairy herds and 236 suckler cows in 9 beef herds were used. Treated animals received 1·0 mg melengestrol acetate (MGA) daily for 14 days. Treated and control animals were inseminated with either 15 or 60 million sperm per first insemination.

Oestrus was synchronized in 94% of the treated dairy heifers and 66% of the treated suckler cows. Oestrus detection by herdsmen appeared to be much less precise in suckler herds than in the dairy herds.

First inseminations were given during a 21-day breeding period (commencing at withdrawal of MGA) to 97% of treated and 79% of control dairy heifers (P<0·01), and to 77% of the treated and 69% of the control suckler cows (P>0·05). On an average, first inseminations were given 10 days earlier to treated heifers and 7 days earlier to treated suckler cows than to their control counterparts. The 45-day non-return rate to first inseminations was 81% for control and 41% for treated dairy heifers (P< 0·001) and 69% for control and 46% for treated suckler cows (P>0·05).

Oestrus-synchronized animals required significantly more services than control animals during a 30-day breeding period. However, there was no difference between treated and control animals in the non-return rate to one or more services given during the prescribed 30-day breeding period.

Insemination with 15 or 60 million live sperm had no effect on the non-return rate of treated or control animals.

Type
Research Article
Information
Animal Production , Volume 17 , Issue 2 , October 1973 , pp. 163 - 168
Copyright
Copyright © British Society of Animal Science 1973

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References

REFERENCES

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