INFLUENCE OF AN EXTENDED PHOTOPERIOD ON SOW AND LITTER PERFORMANCE

The influence of an extended photoperiod on sow and litter performance was studied using 136 multiparous sows, randomly assigned to one of four treatments. From 1 week before parturition, until the end of lactation, two groups were exposed to a long (16 h) photoperiod and the other two groups to a short (8 h) photoperiod. Half the litters from sows in each photoperiod treatment were provided with creep feed ad libitum from 7 days post-partum, while the remaining litters depended totally on sows' milk. Litter growth and survival during lactation were not significantly influenced by an extended photoperiod or by creep feeding. A non-significant reduction in weaning-to-estrus interval was observed for sows exposed to 16 h light (4.9 vs. 5.3 days; P > 0.05) and a greater proportion of these sows were mated within 7 days of weaning (88.4 vs. 77.1%; P > 0.05). In a second experiment, two additional groups of 34 sows each were provided with a "skeleton" photoperiod (8 h L:8 h D:2 h L:6 h D or 8 h L:4 h D: 8 h L: 4 h D) for the same duration, but neither sow nor piglet productivity was affected. It would appear that an extended photoperiod during lactation has no significant influence on sow or litter productivity. © 1990.