The effect of different light / dark rhythm on performance, carcass and some metabolic parameters in broiler chickens

This study was carried out to determine the effect of different rhythmic light / dark programs on broiler performance, carcass characteristics, some metabolic activities and welfare of broiler chickens. Twenty three hours of light / 1 hour dark program was applied in the first week. Then, research groups were arranged as 23 hours light (L) / 1 hour dark (D) (23L: 1D) treated group (Group I); 4L: 2D: 4L: 2D: 4L: 2D: 4L: 2D (4x (4L: 2D)) treated group (Group II); 8L: 4D: 8L: 4D (2x (8L: 4D)) applied group (Group III); continuously 16L: 8D treated group (Group IV). For this purpose, 500 male Ross-308 broiler chicks taken from a commercial company were distributed in to 4 experimental groups with 125 broilers whose first body weight near each other in each group. All groups were arranged with 5 replications. The fattening period was 7-42 days. At the end of the study, 2 chickens from per replicate whose body weight near replicate average, 10 chickens from per group were slaughtered for carcass, blood and bone analysis. All chicks in the study were evaluated for ammonia burns and body temperatures. The lowest live weight was found at the end of fattening (day 42) in Group IV (P <0.001). While live weight gain, feed consumption and feed efficiency values were different among the groups at early ages, these differences were lost towards the end of the research (P>0.05). The live weight gain, feed consumption, feed efficiency and survival were similar among the groups on days 7-42 (P> 0.05). Daily water consumption was significantly lower in Group IV compared to Group I (P <0.05). Water consumption (mL) / feed consumption (g) was similar between groups (P> 0.05). The best uniformity was obtained in Group III (P <0.05) on day 21, and the difference among the groups on the 42nd day was not statistically significant (P> 0.05). The highest breast ratio and the lowest wing ratio were found in Group I (P<0.001). The highest free thyroxine (T4), glucose and uric acid, the lowest serum testosterone was obtained in Group IV (P <0.05). Body temperatures and tibia ash levels were similar among the groups (P> 0.05). The limited illumination programs increased the rate of ammonia burns (P <0.001). As a result, it was determined that performance and welfare of the chickens decreased significantly in the continuous restraint group. Key words: Broiler chicken, light / dark period, performance, carcass, metabolic parameters