Photic and non-photic entrainment on daily rhythm of locomotor activity in goats

Real-Time Measurement of the Daily Total Locomotor Behavior in Calves Reared in an Intensive Management System for the Possible Application in Precision Livestock Farming

Housing confinement, adaptation to different light/dark conditions, and social deprivation could modify the amount of total locomotor behavior of calves recommended for their psychophysical health. Total locomotor behavior was recorded by means of an activity data logger every 5 min for 6 consecutive days. To do that eight clinically healthy 30-day-old Holstein calves living in calf boxes under natural photoperiod and environmental conditions were enrolled. ANOVA (analysis of variance) showed a statistical effect of the day of monitoring and animal. In the temporal distribution of the resting-activity frequency, it was observed that the calves presented periods of total locomotor behavior with the existence of two peaks, one between 06:00-07:00 and another between 17:00-18:00, which corresponds to time of food intake. In all animals, a diurnal daily rhythm of total locomotor behavior was observed during time of monitoring. Intrasubject and intersubject variabilities were statistically different in mesor, amplitude, and robustness of rhythm. In conclusion, the total locomotor behavior showed a diurnal daily rhythmicity in 30-day-old calves. The characteristics of rhythm were different from individual to individual and from day to day. The recorded intersubject variability must be taken in consideration during the monitoring of farm animals and justifies the application of the device to each animal, as precision livestock farming suggests.

Amplitude of the daily pattern of rest – activity in different species of Leopardus kept in captivity

Closer examination of the diurnal or nocturnal nature of wildlife species improves the knowledge necessary for landscape identity and biodiversity preservation. The aim of this study was to evaluate the daily rhythmicity of total locomotor activity in wild felids of several species of Leopardus of similar body weight housed in captivity: Geoffroy’s cat (Leopardus geoffroyi), ocelot (Leopardus pardalis), oncilla (Leopardus tigrinus) and margay (Leopardus wiedii). Twenty-four felids, six animals for each species, were housed under a natural light/dark cycle. The activity was recorded for thirteen consecutive days by means of an actimeter attached to a neck collar. Using cosinor rhythmometry, circadian rhythmic parameters (mesor, amplitude and acrophase) were assessed and compared among the several species. The daily and individual chronobiological variations of rest and activity showed a well-defined pattern. A nocturnal daily rhythmicity of locomotor activity was observed in Geoffroy’s cat, ocelot, oncilla and margay. The acrophase was observed shortly after midnight in margay and Geoffroy’s cat, and early at night in oncilla and ocelot. Our results improve the knowledge about the circadian system in wild animals. They can be a contribution to understanding the adaptive behaviour of wild felid species kept in zoological parks and rehabilitation agencies in providing the proper care for these animals

Clock genes determination in whole blood in goats housed under a long light cycle

An innate 24 h circadian clock drives various behavioral processes via expression of clock genes that regulate circadian rhythmicity and temporal signals. Elucidating the gene expression in goats may contribute to improving the knowledge of the regulation of circadian rhythms in this species. Five nonpregnant and nonlactating Maltese goats with no evidence of disease were kept in an indoor pen under the natural long photoperiod (05:05-20:56 h) and natural environmental temperature (23°C and 60% RH). They were fed an Alfalfa hay and concentrate mixture provided twice a day; water was available ad libitum. Blood samples were collected every 4 h over a 48 h period into PAX gene Blood RNA Tubes and stored at -80°C until processing. Clock genes (Clock; Cry1; Cry2; Per2; Per3) were determined using real-time quantitative polymerase chain reaction. During the experimental period, locomotor activity was monitored by an actigraphy-based data logger that records a digitally integrated measure of motor activity as a means to assess indices of discomfort during study and stability of the circadian rhythm. All of the tested genes showed daily rhythmicity in their expression in whole blood. Differences in their circadian parameters were observed. Mesor and amplitude were statistically different among the tested gene (Mesor: F_(4.30) = 205.30; p < .0001; amplitude: F_(4.30) = 104.80; p < .0001), with each gene showing its acrophase at a different time of day (F_(4.30) = 81.17; p < .0001), and differences were observed between the two days of monitoring (F_(1.30) = 10.25; p = .003). The application of two-way analysis of variance (ANOVA) on robustness of rhythm values did not show statistical differences among the tested genes (F_(4.30) = 1.83; p = .14) and between the two days of monitoring (F_(1.30) = 1.16; p = .28). Locomotor activity data recording were in accordance with the data reported in literature, indicating the absence of discomfort or alteration of circadian rhythms during the experimental period. Our results support the presence of a cyclic transcription of clock genes in whole blood of healthy goats housed under a long light natural photoperiod and natural environmental conditions.

Entrainment of circadian rhythms of locomotor activity by ambient temperature cycles in the dromedary camel

In the dromedary camel, a well-adapted desert mammal, daily ambient temperature (T_a)-cycles have been shown to synchronize the central circadian clock. Such entrainment has been demonstrated by examining two circadian outputs, body temperature and melatonin rhythms. Locomotor activity (LA), another circadian output not yet investigated in the camel, may provide further information on such specific entrainment. To verify if daily LA is an endogenous rhythm and whether the desert T_a-cycle can entrain it, six dromedaries were first kept under total darkness and constant-T_a. Results showed that the LA rhythm free runs with a period of 24.8–24.9 h. After having verified that the light–dark cycle synchronizes LA, camels were subjected to a T_a-cycle with warmer temperatures during subjective days and cooler temperatures during subjective nights. Results showed that the free-running LA rhythm was entrained by the T_a-cycle with a period of exactly 24.0 h, while a 12 h T_a-cycle phase advance induced an inversion of the LA rhythm and advanced the acrophase by 9 h. Similarly, activity onset and offset were significantly advanced. All together, these results demonstrate that the Ta-cycle is a strong zeitgeber, able to entrain the camel LA rhythm, hence corroborating previous results concerning the T_a non-photic synchronization of the circadian master clock.

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

Background

The locomotor activity (LA) rhythm, widely studied in rodents, has not been fully investigated in large mammals. This is due to the high cost and the brittleness of the required devices. Alternatively, the locomotion scoring method (SM), consisting of attribution of a score to various levels of activity would be a consistent method to assess the circadian LA rhythm in such species.

New method

To test this, a SM with a score ranging from 0 to 5 has been developed and used in two domestic large mammals, the camel and the goat. One minute interval scoring was performed using visual screening and monitoring of infra-red camera recording videos and carried out by two evaluators.

Results

The SM provides a clear daily LA rhythm that has been validated using an automate device, the Actiwatch-Mini. The obtained curves and actograms were indeed highly similar to those acquired from the Actiwatch-Mini. Moreover, there were no statistical differences in the period and acrophase. The period was exactly of 24.0h and the acrophases occurred at 12h05 ± 00h03 and 12h14 ± 00h07 for the camel and at 13h13 ± 00h09 and 12h57 ± 00h09 for the goat using SM and Actiwatch-Mini respectively.

Comparison with existing methods

Compared to the automatic system, the SM is inexpensive and has the advantage of describing all types of performed movements.

Conclusions

The new developed SM is highly reliable and sufficiently accurate to assess conveniently the LA rhythm and specific behaviors in large mammals. This opens new perspectives to study chronobiology in animal models of desert, tropical and equatorial zones.

Circadian rhythms of melatonin and behaviour in juvenile sheep in field conditions: Effects of photoperiod, environment and weaning

Entrainment of circadian rhythms (CR) to the light dark cycle has been well described under controlled, experimental conditions. However, studies in rodents have reported that rhythms in the laboratory are not always reproduced under field conditions. The aim of this study was to characterise the CR of sheep maintained under conditions of standard UK farm animal husbandry and to investigate the effects of environmental challenges presented by season, weaning and changes in housing on CR. Male sheep (n = 9) were kept at pasture, or group housed in barns, under natural photoperiod for one year. CR in locomotor activity were monitored using accelerometry, and 24 h patterns in plasma cortisol and melatonin were measured every 4 h by ELISA. CR was measured before and after weaning, in summer and winter, and at pasture and by barn housing. Cosinor analysis revealed high amplitude, diurnal rhythms in locomotor activity that were disrupted by weaning and by barn housing. Rhythms in winter showed an interrupted night time activity pattern, but only when the sheep were kept at pasture. Cortisol and melatonin secretion followed typical circadian patterns in winter and summer. The CR of the sheep under the field conditions of this study were strikingly robust under basal conditions, but easily disrupted by environmental challenges. Interrupted patterns of activity during the long nights of wintertime, not previously reported for sheep kept in experimental conditions were recorded. Based on these findings, we propose that animals require exposure to more complex environments than the laboratory in order to exhibit their true circadian phenotype.

Acupuncture Improves Sleep Conditions of Minipigs Representing Diurnal Animals through an Anatomically Similar Point to the Acupoint (GV20) Effective for Humans

Acupuncture, an alternative medicine, has been widely applied for people with sleep disturbances; therefore, the effects should be evaluated objectively. Micro-minipigs (MMPigs), the smallest miniature pigs for animal experiments, were used. Acupuncture was performed at two different points: Dafengmen is located on the head and is an anatomically similar point to human-Baihui (GV20), an effective acupoint for sleep disturbances in humans; pig-Baihui is on the back. The procedure was performed as follows: shallow, within 5 mm depth for several seconds; deep, 10–20 mm depth for 20 min. The sleep conditions were evaluated by actigraph, and the amount of catecholamine in pooled urine after acupuncture treatment. MMPigs with deep acupuncture at Dafengmen showed significantly efficient values on actigraph and catecholamine analysis as compared with untreated MMPigs. The effective acupoint for sleep conditions in the porcine model is at an anatomically similar point to humans, rather than the point determined by traditional Chinese medicine.