FAILURE OF A 16 h L:8 h D or AN 8 h L:16 h D PHOTOPERIOD TO INFLUENCE LACTATION OR REPRODUCTIVE EFFICIENCY IN SOWS

Abstract

Forty-one sows were divided into two groups where animals were either exposed to a long photoperiod (16 h L:8 h D) or a short photoperiod (8 h L:16 h D) 1 mo before parturition. One month prior to the following parturition, sows were switched to the opposite light treatment and maintained on this treatment until the following estrus. Birth weight and litter size at birth of piglets conceived under natural lighting (15.4 h L) did not significantly differ from piglets conceived under a 16 h L or 8 h L photoperiod. Litter size at weaning and weight of piglets did not significantly differ for receiving a 16 h L or an 8 h L regime followed by the opposite treatment. The length of time to return to heat from weaning to next estrus was unaffected by photoperiod. The results from this experiment indicate that photoperiods of 16 h L:8 h D or 8 h L:16 h D have no influence on reproductive efficiency or lactation in sows. Key words: Light, photoperiod, production, swine, sows