Effects of dim light at night on milk yield, milk composition and endocrine profile of lactating dairy cows

Abstract

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 lx (CONTROL) or 40 to 60 lx (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-LIGHTat night, and treatment effects on milk and milk component yields were not detected.