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Abstract

This study examines the photoperiodic effect on growth and immune responses of the pearl Guinea fowl. Keets used for this investigation were subjected to different photoperiod levels: 12HL:12HD, 14HL:10HD, 16HL: 8HD, and 18HL:6HD using a white bright LED Energy saving bulbs of 120 watts with light intensity of 5.60 lux and kept from day-old to eight weeks in a completely randomized design. Findings from this study showed that, at starter and grower phases the weight of the birds and feed consumed increased (P<0.05) with increasing levels of photoperiod. Birds subjected to 12HL: 12HD had the poorest (P<0.05) feed conversion ratio as compared to all the other treatment groups at all stages of growth. Birds subjected to 18HL: 6HD had the lowest (P<0.05) mortality rate followed by 16HL: 8HD and 14HL:10HD, while birds on the 12HL:12HD treatment recorded the highest (P<0.05) percentage mortality rate. Basophil level was highest (P<0.05) among birds subjected to 12HL: 12HD and lowest among all the other treatment levels which had similar mean values. Birds subjected to 16HL: 8HD and 12HL: 12HD recorded the highest (P<0.05) monocyte levels in the blood. The levels of PCV, RBC, WBC, albumin, cholesterol, globin, and total serum protein in the blood increased (P<0.05) with increasing levels of photoperiod. As the levels of photoperiod increased, blood pH, Cl- and K+ also increased. In conclusion, increasing photoperiodic levels up to 18HL: 6HD promotes rapid growth, ensures better feed utilization, reduces mortality rate and maintains good health in Guinea fowls.