| Popis: |
Background Light management plays an important role in broiler growth and behavior. Constant light in early post hatch stage has been a common practice for improving feed intake and body weight gain in broiler chickens, while whether and how constant light in early life affects the behavior in broiler chickens is rarely reported. Results In this study, newly hatched chickens were kept in either constant light (24L:0D, LL) or natural photoperiod (12L:12D, LD) for 7 days and maintained in constant light thereafter from 8 d to 21 d of age. Constant light did not affect chicken body weight, while increased average daily feed intake (ADFI) in 7 d and 21 d and every week feed conversion ratio (FCR). Constant light exposure in early life induces depressive-like behaviors, which was associated with higher corticosterone (CORT), lower melatonin and 5-hydroxytryptamine (5-HT) plasma. Concurrently, constant light exposure increased the mRNA expression of clock related genes and suppressed the expression of antioxidative genes in the hippocampus of both 7- and 21-day-old chickens. Moreover, brain derived neurotrophic factor (BDNF)/extracellular signal-regulated kinase (ERK) pathway in hippocampus was suppressed by constant light exposure. Conclusions These findings imply that constant light exposure in early life disrupts hippocampal expression of clock genes and BDNF/ERK pathway, which contributes to depressive-like behaviors in the chicken. |
