The role of photoperiod regimens on regulating the immune response in male broilers

الملخص EN

Day length changes markedly across the year.

In many mammals and birds, these photoperiodic variations are associated with physiological modulation including immune function.

However, the influence of this environmental variable on poultry physiology is less clear, and the potential underlying mechanisms are unknown.

To address this issue, the effects of different photoperiod regimens on the immune function and the mechanism that regulates the immune response in male broilers were examined.

A total number of 450 one-day-old male broilers were divided randomly into three equal groups.

The broilers were exposed to continuous light, 23 h light : 1 h darkness (23 L: 1D) in the first group ; non-intermittent restricted light, 12 h light : 12 h darkness (12L : 12D) in the second group ; and intermittent light, 2 h light : 2 h darkness (2L : 2D) in the third group.

At 6 weeks of age, blood samples were collected to measure peripheral lymphocyte activation and antibody titer against bovine serum albumin (BSA).

At the same age, broilers were slaughtered and the spleens were removed to measure splenocyte Interleukin-2 (IL-2) and the phosphorylation of Protein Kinase B (PKB also called Akt).

The results indicated that intermittent light regimen induced phosphorylation of Akt and significantly stimulated the peripheral T and B-lymphocyte proliferation compared to the other two regimens.

Furthermore, the secretion of Splenocyte IL-2 and anti-body production against BSA were significantly enhanced by intermittent light regimen in comparison with the other two groups.

In contrast, no significant differences were observed between constant light regimen and non-intermittent restricted light regimen.

Taken together, these data suggest that intermittent photoperiod regimen modulates positively the immune response by up-regulating the phosphorylation protein kinase Akt.