Effects of melatonin on hematologic and biochemical changes and the effects of circadian rhythm on hematologic changes in donkeys (Equus asinus) subjected to packing during the hot‐dry season

Abstract

Background: Melatonin is a hormone with antioxidant and anti-inflammatory properties and may alleviate the effects of stress on hematologic and biochemical analytes in working donkeys that pack (load-carry). Objectives:We aimed to evaluate the effects of melatonin administration on hematologic and biochemical responses in donkeys subjected to packing during the hot-dry season. We also examined its effects on circadian rhythms. Methods:Ten male Nubian pack donkeys with (Packing + Melatonin; P + M) and without melatonin (Packing-Melatonin; P-M) administration were included. Blood samples were collected before, immediately after (15 min), and from 16 h to over 27-h postpacking at 3-h intervals for hematologic and total protein analyses. Serum from blood samples collected before and immediately after packing was analyzed for muscle enzyme activities and electrolyte concentrations. Student's t-test, one-way ANOVA, and online cosinor analysis were used for statistical analyses.