Impact of Variability Factors on Hair Cortisol, Blood Count and Milk Production of Donkeys

SIMPLE SUMMARY: The recent interest in donkey milk has led changes in donkey farm management; however, little is still known about the effect of farm management on donkey health and welfare. The measurement of hair cortisol is a new method to assess stress in animals. Furthermore hair cortisol measurement in dairy donkeys has not previously been done. In addition, only a few studies have investigated physiological ranges of donkey blood parameters. We analysed changes in milk quality, blood parameters and mane hair cortisol in relation to lactation phase, parity and season. Hair cortisol was higher in the peri-partum period while milk yield and composition and blood parameters changed according to parity or season. This study represented a first effort to better understand the biochemical processes occurring in lactating jennies, and their physiological and wellbeing status. ABSTRACT: The increased interest in donkeys because of their milk has led to changes in their farm management. Little is known about the effect of the farming systems on donkey health and welfare. Measuring hair cortisol concentrations is an emerging method to assess stress in animals. To the best of our knowledge, no cortisol assessment has been done on dairy donkeys; similarly, only a few studies have investigated donkey haematological values. The aim of this study was to evaluate the effects of the lactation phase, parity and season on blood parameters, milk yield and quality and hair cortisol in dairy donkeys. Individual samples of milk, blood and mane hair were taken from twenty jennies at 1, 6 and 10 months after parturition. Higher values of hair cortisol were found in the first sampling, suggesting temporary stress during the peri-parturition. The parity influenced the number of blood cells, which was lower in the pluriparous jennies. The season affected milk quality and mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. The latters might represent the adaptation to the environmental conditions. This study contributes to a better understanding of the biochemical processes occurring in lactating jennies, and to their physiological and wellbeing status.