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Abstract
1. The aim of this study was to evaluate how splitting the dark period (scotoperiod) affects feeding behaviour and associated intestinal measures in broilers.
2. Ross 308 broilers were reared to 37 d in groups given either a daily 8-h continuous scotoperiod (DARK 8) or an intermittent light schedule with two equally spaced 4-h scotoperiods (DARK 4 + 4), which yielded the same total duration of darkness per 24 h.
3. Feeding behaviour was recorded weekly from 24-h video recordings of 24 groups each of 64 birds. Empty intestinal weights as well as their contents were measured weekly at 4 time points (n = 192). Digestive transit time was estimated on d 29 using a chromic oxide marker; production variables and the extent of foot pad dermatitis were also recorded.
4. In the 3 h prior to a scotoperiod, feeding activity increased in chickens from DARK 8 but not DARK 4 + 4. This increase was reflected in a higher relative content of the crop in DARK 8 at this time.
5. Immediately following the scotoperiod, feeding activity peaked and, although the chickens in DARK 4 + 4 expressed more feeding behaviour in the first 20 min after the scotoperiod, the chickens in DARK 8 had overall higher feeding activity across the day. However, DARK 4 + 4 had a higher feed intake and weight gain. The occurrence and severity of foot pad dermatitis was similar between treatments.
6. In conclusion, broilers modify their feeding behaviour according to the prevailing light schedule. Eight consecutive hours of darkness reduced growth, but did not affect overall feed conversion efficiency, and did not appear to exacerbate hunger or foot pad dermatitis to any great extent.
Acknowledgements
The authors would like to thank Gert Nielsen, who was in charge of the daily management of the chickens, and Lars Gildberg for assistance with data collection. This work was partially supported by a grant from the Danish Poultry Levy Fund.