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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2007-0304v1 86/13_suppl/21    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Negrão, J. A. Search for Related Content PubMed PubMed Citation Articles by Negrão, J. A.

Hormone release and behavior during suckling and milking in Gir, Gir x Holstein, and Holstein cows^1,2

University of São Paulo (USP), Faculty of Animal Sciences and Food Engineering (FZEA), Basic Science Department, Pirassununga, Brazil 13630-970

³ Corresponding author: jnegrao{at}usp.br

There are several different milking management systems in Latin America, because Gir cattle are reputed to be easily stressed and not well adapted to machine-milking. This paper, therefore, provides an overview of hormone release and behavior during suckling and milking in Gir cows and their cross-bred offspring. Several experiments were performed to study oxytocin release during exclusive suckling or exclusive hand- and machine-milking, oxytocin, and prolactin release during a mixed suckling-milking system and oxytocin release after weaning. Cortisol concentrations and behavior were also examined. Concentration of oxytocin, released during suckling, and both types of milking were high, but the maximum concentration measured during suckling was significantly greater than that observed during exclusive milking. In the mixed suckling-milking system, the greatest oxytocin and prolactin releases were measured during suckling. Cortisol concentrations measured before, during, and after milking demonstrated that Gir x Holstein and Holstein cows were not stressed. On the other hand, although Gir had greater concentrations of cortisol, the percentage of residual milk for Gir cows was less than for dairy cows exposed to different stressful situations. In general, Gir cows and their crossbred offspring adapted to machine-milking, although these breeds can react negatively to milkers. Gir, Gir x Holstein, and Holstein cows all had similar cortisol levels during and after milking.

Key Words: cortisol • Gir • milk ejection • milking • oxytocin • prolactin

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				G. E. Dahl The Eighth International Workshop on the Biology of Lactation in Farm Animals: Introduction J Anim Sci, March 1, 2008; 86(13_suppl): 1 - 2. [Full Text] [PDF]