Modulatory Role of Vitamin A on Individual and Diurnal Fluctuations in Rectal Temperature of Black Harco Pullets

Experiments were performed with the aim of determining the effect of vitamin A administration on rectal temperature (RT) fluctuations in pullets during the hot-dry season. RTs of 29 experimental and 20 control Black Harco pullets were measured hourly for 3 days, 3 days apart, from 06:00 h to 19:00 h with a clinical thermometer. The experimental pullets received vitamin A administered orally at a daily dose of 1,200 IU/kg, while the control pullets were given only water. The lowest hourly RT of 40.82 ± 0.09 oC was obtained in experimental pullets at 06:00 h and 07:00 h, while the highest value of 41.18 ± 0.04 oC was recorded at 15:00 h and 16:00 h (P < 0.001). In control pullets, the RT rose significantly from 41.00 ± 0.08 oC at 06:00 h to the maximum value of 41.73 ± 0.04 oC at 16:00 h (P < 0.001). The maximum RT value in experimental pullets was lower (P < 0.001) than that of the control pullets. It is concluded that vitamin A, by reducing the RT values, ameliorated the thermally stressful effect of the hot-dry season in pullets.