Effect of Exogenous Melatonin and Different Photoperiods on Differential Leucocyte Count in Chhotanagpuri Ewe

Abstract

Forty-two healthy, non-pregnant, non-lactating Chhotanagpuri ewe, having body weight ranging from 14.11 ± 0.09 to 15.38 ± 0.06 kg,
were selected and isolated from rams 2 months before melatonin administration. The selected animals were allocated randomly into
seven groups each of 6 animals, viz., Group-I [Normal control], Group-II [Long day (LD) control], Group-III [LD + melatonin administration
3 mg/day orally], Group-IV [(LD + melatonin administration s/c @ 1 mg/day], Group-V [Short day (SD) control], Group-VI [SD + melatonin
administration 3 mg/day orally] and Group-VII [SD + melatonin administration s/c @ 1 mg/day]. Rams were then introduced into
each group after completion of exogenous administration of melatonin for one month. Blood samples without anticoagulant in vials
were collected from each animal at day-0 (a day before the start of experiment), 30th, 60th, 90th, 120th and 150th of the experiment.
Among different periods, lymphocyte % in the third and fourth months of the experiment was significantly (p <0.05) lower in all groups
(group-I to VII) in comparison to day-0, first, and second months. In the fifth month, lymphocyte % was significantly (p <0.05) higher
in group III, IV, VI, and VII compared to the third and fourth months of the experiment. Neutrophil % in the third and fourth months of
the experiment was significantly (p <0.05) higher in all groups in comparison to 0 days, first, and second months. In the fifth month,
neutrophil % was significantly (p <0.05) lower in group III and VI than in the third and fourth months. Monocyte % was significantly
(p <0.05) higher in group III and IV than group VII at first month. In the third month, monocyte % was significantly (p <0.05) higher in
group IV and VI than in group I and group II.