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Bromocryptine is effective in reducing milk production in ewes during lactation, but has no additional effect during drying off

Published online by Cambridge University Press:  02 September 2010

N. Buys ,
D. Vanmontfort ,
R. Peeters ,
J. van Isterdael ,
E. Decuypere  and
E. R. Kühn
N. Buys
Affiliation:
Laboratory of Comparative Endocrinology, Catholic University of Leuven, Naamsestraat 61, B-3000 Leuven, Belgium Department of Animal Husbandry, Catholic University of Leuven, Kardinaal Mercierlaan 92E, B-3001 Heverlee, Belgium
D. Vanmontfort
Affiliation:
Department of Animal Husbandry, Catholic University of Leuven, Kardinaal Mercierlaan 92E, B-3001 Heverlee, Belgium
R. Peeters
Affiliation:
Department of Animal Husbandry, Catholic University of Leuven, Kardinaal Mercierlaan 92E, B-3001 Heverlee, Belgium
J. van Isterdael
Affiliation:
Department of Animal Husbandry, Catholic University of Leuven, Kardinaal Mercierlaan 92E, B-3001 Heverlee, Belgium
E. Decuypere
Affiliation:
Department of Animal Husbandry, Catholic University of Leuven, Kardinaal Mercierlaan 92E, B-3001 Heverlee, Belgium
E. R. Kühn
Affiliation:
Laboratory of Comparative Endocrinology, Catholic University of Leuven, Naamsestraat 61, B-3000 Leuven, Belgium
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Abstract

The effect of bromocryptine on milk production was investigated in 32 crossbred ewes (Flemish Milksheep х Suffolk) with one sucking lamb, during lactation and during drying off. After weaning the lambs, all ewes were hand milked twice daily for 3 days. From day 4 onwards, the ewes were divided into four groups with equal mean daily milk production. Ewes of groups A and B were hand milked twice daily during the following 9 days. Ewes of groups C and D were dried off by reducing the milking frequency. They were milked on days 5, 8 and 12. In groups B and D, bromocryptin (1 ml of 1 g/l ethanol 50%) was injected intramuscularly twice daily while control ewes (groups A and C) received 1 ml ethanol 50%. Blood samples were taken by venipuncture prior to each injection and were assayed for prolactin, growth hormone, thyrotropin and cortisol.

Bromocryptine decreased plasma prolactin levels but did not alter growth hormone or cortisol concentrations during lactation or drying off. Thyrotropin levels were elevated by bromocryptine during drying off but were unaffected during galactopoiesis.

During lactation the daily milk production remained unchanged in control ewes while in bromocryptine-treated ewes a proportional decrease of 0·5 was observed. In all ewes the decrease in milk production occurring at drying off could not be accelerated or stimulated by bromocryptine.

It is concluded that prolactin plays an important role in galactopoiesis in ewes but its role is comparatively unimportant compared with other factors during mammary involution.

Keywords

bromocryptineewesmilk productionprolactin
Type
Research Article
Information
Animal Science , Volume 60 , Issue 2 , April 1995 , pp. 203 - 208
Copyright
Copyright © British Society of Animal Science 1995

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