Reprod. Nutr. Dev.
Volume 46, Number 1, January-February 2006
|Page(s)||77 - 85|
|Published online||27 January 2006|
Milk yield, residual milk, oxytocin and cortisol release during machine milking in Gir, Gir × Holstein and Holstein cowsJoão Alberto Negrão and Pierre-Guy Marnet
(Received 26 January 2005; accepted 14 October 2005; published online 27 January 2006)
Abstract - This study evaluated the effect of exclusive machine milking on oxytocin (OT) and cortisol (CORT) release, and on milk yield and residual milk in Gir (group Gir), Holstein (group Hol) and crossbred animals (group GirHol). Six animals from each group were submitted to experimental milkings. As expected, milk yield was significantly higher in the Hol group than in the groups GirHol and Gir, and group GirHol produced more milk than the Gir group. In contrast, all groups exhibited significant but similar levels of OT, although OT increased more rapidly during milking for the groups Hol and GirHol than for the Gir group. In addition, CORT levels measured during and after milking were significantly influenced by the group. The Gir group showed higher levels of CORT than the groups GirHol and Hol. The lower performances of the Gir breed can not be explained by a less efficient milk ejection reflex because all cows studied released enough OT and had an effective milk ejection.
Key words: zebu / crossbred / milking / oxytocin / cortisol
Corresponding author: João Alberto Negrão firstname.lastname@example.org
© INRA, EDP Sciences 2006