Suckling induced cortisol secretion in young beef cows.
The profiles of plasma cortisol concentration in response to suckling were determined in 10 young, postpartum beef cows between days 25 and 85 postpartum. Two trials, comprised of five cows each, were conducted in the fall (I) and spring (II), respectively. In both trials, plasma cortisol rose within 10 minutes after suckling began and was significantly higher than pre-suckling concentrations (P<.01). Over the next 30 minutes in trial I and 40 minutes in trial II, the cortisol level progressively fell back to the pre-suckling levels. This profile was qualitatively similar among the days postpartum on which the cows were bled. Neither the profile nor the peak concentration after suckling changed significantly (P>.10) as days postpartum lapsed. Finally, there was a significant difference (P<.01) in mean plasma cortisol between the cows in trial I compared to the cows in trial II.
Ellicott
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Extension Animal Science Department University of Georgia, Athens, Ga. 30602 USA; Department of Animal and Dairy Sciences University of Georgia, Athens, Ga. 30602 USA.
Henricks
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Gimenez
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Kiser
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