Additional daily artificial illumination during winter has been reported to increase growth rates in both cattle and sheep.

In an experiment conducted at Seale-Hayne College between September 22, 1982 and March 29, 1983, 20 Hereford x Friesian heifer calves (approximately 7 days of age at the start of the trial) were randomly allocated to either a natural daylength treatment or an artificially supplemented 16L:8D photoperiod. Animals were weaned at 5 weeks of age and then fed on a restricted concentrate ration (2.5 kg/head/day) with hay provided ad libitum. Body weight, girth and height at shoulder measurements were taken at 2-week intervals. Hair samples (4 cm2) were taken from the mid-flank on January 13.