Illumination or guiding light during night hours in the resting area of AM-barns

Introduction

It is a common practice to have full illumination day and night in AM-barns. It is however questioned whether cows prefer/need guiding light/darkness during night hours. The aim was to investigate if dairy cows actively choose light or dark area for resting during night hours.

Material and methods

The study was conducted in an AM research barn with a DeLaval VMS™ milking station. The cow traffic system during the study was forced traffic with 2 by-pass gates. The resting area of the barn was divided into 2 identical sections by screening. Each section of the resting area had 25 available cubicles. 46 cows, Swedish Red and White, were used in the study.
The study was divided into 3 periods. Period 1 with full lightning in both parts of the resting area. Period 2 and 3 with one half of the resting area with full lighting (app. 200 lux), while the other had guiding light (5 – 7 lux) from 23:00h to 05:00h. After 3 weeks the lighting in the two sections was reversed. Manual identification of every cow in the resting area was performed every 12:th minute during 48 consecutive hours in period 1 and 2 x 48h in period 2 and 3.

Results and discussion

The cows distributed equally in both sections of the resting area during the whole experiment and no effect of level of illumination could be seen on herd level. In all periods there were free cubicles in both sections during both day and night time.
Although no effect could be seen on herd level, a number of individual cows seemed to prefer the light or the dark side and followed the changes, but there were no relation between ranking order and choice of light.
The results of the studies did not reveal obvious preference for a special side because of the illumination. But there are results in the study indicating that individual cows might have preferences for a lighter or darker resting area.

Corresponding author:

G. Pettersson Department of Animal Nutrition and Management
Swedish University of Agricultural Sciences
Kungsängen Research Centre,
S-753 23 Uppsala, Sweden
Tel.: +46-18-671647
Fax: +46-18-672946
Session “Welfare aspects”

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