The effects of the duration of the artificial photoperiod on the growth parameters and behaviour of heavy pigs

In order to evaluate the productive and behavioural effects of two artificial photoperiod lengths, 56 barrows (initial BW 112.5 kg) were homogeneously allocated to two groups: group A in which animals were exposed to a 14-hour light period (70 lux) followed by 10 hours of darkness (14L:10D) and group B in which, in compliance with current legislation, pigs were exposed to a 8-hour light period (8L:16D). Pigs were restricted-fed and they were slaughtered at about 160 kg BW. The longer light period (group A) resulted in an improvement of growth and feed conversion (P<0.01). Pigs belonging to group A spent more time resting in sternal recumbency (P<0.01) and showed a reduction of some abnormal behaviours such as standing inactive (P<0.01), sitting and over investigation (sniffing) of the floor (P<0.001). From our data it is suggest that a daily 14- hour lighting time improved growth parameters and welfare condition of heavy pigs.