Effects of short day (16L:8D) length on broilers: some physiological and welfare indices.
Bildiriler > Tam Metin Bildiri
Yazarlar: Sezen ÖZKAN, Zişan Servet YALÇIN, YAVUZ AKBAŞ, Figen KIRKPINAR, Yakut GEVREKÇİ, L. Türkmut
EPC 2006 - 12th European Poultry Conference, Verona, Italy, 10-14 September, 2006., , , Uluslararası, Tam Metin Bildiri
Özet
The aim of the present study was to evaluate the effects of continuous or short day length on body weight, plasma melatonin, triiodothyronine (T3), and thyroxine (T4) levels, H:L ratios, walking ability, and duration of tonic immobility in broilers. Day-old male broilers (176 chicks) were reared at floor pens in two identical rooms (4 pens/room) with a density of 16 chicks/m. Two lighting schedules were applied; continuous (C) (24 L) or short day (16L:8D) (SD), to chicks from 2 to 42 d. Body weights (BW) were recorded at 0, 21, and 42 d. Blood samples were obtained to measure melatonin concentration at 21 and 42 d at the middle of the light and dark periods. During the day-time (light) sampling, blood was also withdrawn to measure T3, T4, H:L ratios. Tonic immobility was obtained on the same days. SD significantly reduced early (21 d) growth (P 20 lux) used in the experiment. However, SD resulted in lower lameness as reflected by birds with gait score 0 (P<0.05) at 42 d. In conclusion, SD resulted in reduced body weight at 21 d, however broilers attempted to compensate growth retardation by 42 d of age. It could be concluded that a clear diurnal rhythm of melatonin, when taking together with reduced lameness, was welfare advantage of SD.