Daily rhythms of behavioral and hormonal patterns in male dromedary camels housed in boxes

Abstract

BackgroundDaily rhythmicity has been observed for a number of hormonal and behavioral variables in mammals. It can be entrained by several external factors, such as light-dark cycle and scheduled feeding. In dromedary camels, daily rhythmicity has been documented only for melatonin secretion and body temperature. In this study, the daily rhythmicity of behavioral repertoire, cortisol and testosterone levels was investigated in captive male camels.MethodsSix clinically healthy male dromedary camels (Camelus dromedarius) were used. The animals were housed in single boxes for 24 h daily and fed twice a day. Over a period of 48 h, behavioral observations were made and blood samples taken every two hours. The data were analyzed using diurnality index, conisor analysis and PROC mixed procedure.ResultsThe diurnality index for rumination and lying down was close to 0 (respectively, 0.09 and 0.19), while the indices for stereotypy, standing, feeding and walking were close to 1 (respectively, 0.74, 0.84, 0.92 and 0.85). Cosinor analysis revealed daily rhythmicity for all behaviors and for cortisol levels (acrophase at 12:57) but not for testosterone. Rumination and lying down (inactive behaviors) reached a peak during the scotophase, whereas feeding, walking and stereotypy (active behaviors) reached a peak during the photophase around midday. Cortisol level and expression of stereotypies peaked before and after food distribution and were negatively correlated (r = − 0.287, P = 0.005). Testosterone levels and expression of sexual behaviors were stimulated by the visual and olfactory contacts with the females and were positively correlated (r = 0.164, P = 0.040). Testosterone was also negatively correlated with cortisol (r = − 0.297; P = 0.003).DiscussionThese preliminary results provided new knowledge about the daily rhythm of behaviors in camels housed in boxes, suggesting that camels exhibit diurnal behavior pattern in the maintenance conditions outlined in the study. Daily rhythmicity seemed to be entrained not only by the light-dark cycle but also by scheduled feeding. The rise in stereotypy after food distribution could be due to the persistence of feeding motivation and frustration after the ingestion of food. Therefore, feeding practices should be improved to satisfy the foraging and feeding motivation of these camels. Behavioral and hormonal daily patterns in camels should be taken in consideration to adapt the management system, giving the animals more freedom during the light period and a diet richer in fiber, so as to improve reproductive performance, health and welfare.

Validation of locomotion scoring as a new and inexpensive technique to record circadian locomotor activity in large mammals

“…In addition to the conception of a reliable technique for recording daily LA rhythm in large animals, the present study also emphasizes the diurnal pattern of LA in the camel and the goat, as was also demonstrated in other species (Bertolucci et al., 2008; Piccione et al., 2005, 2008a, 2010; Aube et al., 2017). This observed diurnal pattern is very close to that of diurnal laboratory animals (Garcia-Allegue et al., 1999; Schumann et al., 2005).…”

Do Camels (Camelus dromedarius) Need Shaded Areas? A Case Study of the Camel Market in Doha

“…In agreement with studies in cattle, the time camels spend ruminating is about 8.3 h per day, peaking in the morning between 9:00 and 11:00 a.m. and in the night between 2:00 and 4:00 a.m. [ 41 ]. It seems, therefore, that only camels of Group 1 in the shade could express rumination in line with their natural daily rhythms [ 11 , 41 ]. In domestic ruminants, normal rumination patterns are disrupted in case of distress, diets high in carbohydrates, and stressful events [ 40 ].…”

“…Despite this growing interest, scientific knowledge regarding camel behavior and welfare is still scarce. Few studies have been carried out to assess the effects of housing systems in camels [ 9 , 10 , 11 ]. In particular, confinement and lack of social interaction were found to affect the well-being of these animals [ 9 , 10 ].…”

“…Male dromedary camels housed in single stalls had higher blood cortisol levels and showed more stereotypic behavior than the subjects who were housed in open paddocks and interacted with females [ 9 , 10 ]. The freedom of movement and the olfactory contact with females permitted the expression of sexual behaviors and increased testosterone levels in male camels [ 11 ]. The literature therefore suggests that management choices, including space allowance, are critical for camel welfare [ 12 ].…”

Effects of Stocking Density on Some Behavioral and Some Blood Biochemical Parameters in Camel during the Rut Period

“…Testosterone is the most important sex hormone, which regulate most of the reproductive functions such as the activity of sex accessory glands, spermatogenesis and libido of male animals [31], reduction in the testosterone levels in the HSD could be attributed to elevated cortisol level and stress [4].…”