The scientific literature on the effects of supplementary light on the
behaviour, performance and production of cattle was reviewed.
Research into the effects of extended photoperiod on animal behaviour and
performance has demonstrated that the behaviour of farm animals, milk production, growth rate and voluntary food intake can be positively affected by giving extra light to the animals.
The effects of extended photoperiod on cattle behaviour and performance
was studied in a series of four experiments using steers, heifers and dairy cows.
Investigations were also made of the preferences for light and darkness on bullocks.
Supplementary light had no major effects on the growth rate or feed intake
of steers. Steers spent less time sleeping and more time standing with
supplementary light and produced leaner carcases.
Supplementary light increased lean percent and reduced fat percent in
heifers. It also increased the time heifers spent lying but reduced the time spent
sleeping.
Supplementary light was applied to lactating dairy cows during conditions of
increasing and decreasing natural daylength. During decreasing daylength
supplementary light increased the time cows spent lying down and considerably
reduced feed intake, milk production, live weight and body condition, so that lights were installed in the feeding area for the second period of the trial, which partially restored intake and live weight. During increasing daylength supplementary light did not affect lying time, had less effect on feed intake and no effect on milk production or live weight.
Bullocks were given the opportunity to control their lighting schedule. They
preferred to spend a slightly larger proportion (53 .7%) of their activities in the light rather than in the dark. Feeding was the most dominant activity in the light,
whereas ruminating was the least observed behaviour exhibited when the light was on.
It is concluded that providing growing cattle in winter with supplementary
light can in particular reduce body fatness in both steers and heifers in winter and decrease the time cattle spend sleeping, but that there were no major effects on growth rate or feed intake.