CANADIAN JOURNAL OF ANIMAL SCIENCE, vol.88, no.4, pp.609-612, 2008 (SCI-Expanded)
Bal, M. A., Penner, G. B., Oba, M. and Kennedy, A. D. 2008. Effects of dim light at night on milk yield, milk composition and endocrine profile of lactating dairy cows. Can. J. Anim. Sci. 88: 609-612. The objective of this study was to evaluate the effects of night-time light intensity on lactation performance and hormonal profiles in lactating dairy cattle. Twenty-four multiparous lactating dairy cows were exposed to light intensities of 0 to 5 1x (CONTROL) or 40 to 60 1x (DIM-LIGHT) from 1800 to 0400 in a cross-over design with 28-d periods. Contrary to the pre-trial hypothesis, melatonin release was not suppressed by DIM-LIGHT at night, and treatment effects on milk and milk component yields were not detected.