| Issue |
Reprod. Nutr. Dev.
Volume 42, Number 4, July-August 2002
|
|
|---|---|---|
| Page(s) | 373 - 380 | |
| DOI | https://doi.org/10.1051/rnd:2002032 | |
DOI: 10.1051/rnd:2002032
Effect of calf suckling on oxytocin, prolactin, growth hormone and milk yield
in crossbred Gir
Holstein cows during milking
João Alberto Negrãoa and Pierre-Guy Marnetb
a USP/FZEA, FAPESP, Cx. Postal 23, 13630-970, Pirassununga/SP, Brazil
b UMR production du lait, INRA/ENSAR, Rennes, France
(Received 18 April 2002; accepted 20 July 2002)
Abstract
This study evaluated the effect of different milking managements on oxytocin,
prolactin and growth hormone release in Gir
Holstein cows. Six cows were suckled
by their calves, before and after milking (SM group); another six cows were submitted
to exclusive milking (M group). High OT levels were observed during suckling of the
SM group, however both groups had similar levels of OT during milking. The SM
group presented PRL levels significantly higher than the M group, however only
during suckling. For GH levels, the SM group showed higher levels than the M group,
however this difference was significant only during the first suckling, cleaning of
the teats and at the beginning of machine milking. Despite these results, SM cows
produced more milk (milking plus suckling) than M cows, however milk obtained by
milking was similar for both groups.
Key words: cows / crossbred / milking / suckling / hormone
Correspondence and reprints: João Alberto Negrão
e-mail: jnegrao@usp.br
© INRA, EDP Sciences 2002