The influence of the duration of the “subjective day” under intermittent LED lighting on the daily rhythm of oviposition and the productivity of hens

Lighting is the key factor affecting oviposition time. The oviposition time is directly related to ovulation, which occurs 5 hours after reaching the peak concentration of luteinizing hormone in the blood, which depends on the lighting regime. This paper studies the impact of the “subjective day” duration under intermittent LED lighting on the daily rhythm of oviposition and the productivity of hens of the productive flocks of cross SP-789. The “subjective day” lasted 16 hours per day for group 1, 15 h for group 2, 14 h for group 3 and 13 h for group 4. It was established that the shorter the duration of the “subjective day”, the earlier the hens begin and finish laying. So, in groups 1, 2, 3, and 4, hens began laying eggs at 4 a.m., 3 a.m., 2 a.m., and 1 a.m. and ended at 6 p.m., 4 p.m., 4 p.m., and 3 p.m. with an average time of laying eggs of 8.67; 7.36; 5.36 and 5.27 h, respectively. In groups 1, 2, 3, and 4 the livability of hens, weight of eggs, egg production and yield of egg weight per the initial laying hen, feed consumption for 10 eggs and 1 kg of egg weight were 98.0, 97.0, 99.0, 99.0%; 60.0, 59.9, 60.4, 59.7 g; 123.9, 124.1, 130.3, 126.1 pcs, 7.48, 7.47, 7.97, 7.63 kg; 1.37, 1.36, 1.32, 1.36, and 2.28, 2.26, 2.18, 2.26 kg, respectively.

LC-MS/MS Analysis Elucidates a Daily Rhythm in Orexin A Concentration in the Rat Vitreous Body

Orexins are two neuropeptides synthesised mainly in the brain lateral hypothalamic area. The orexinergic system provides arousal-dependent cues for a plethora of brain centres, playing a vital role in feeding behaviour, regulation of the sleep–wake cycle and circadian rhythms. Recently, orexins were found to be produced in the retina of an eye; however, their content in the vitreous body and possible daily pattern of expression have not yet been explored. In this manuscript, we describe the development and validation of a liquid chromatography with tandem mass spectrometry (LC-MS/MS) method designed for quantitative bioanalysis of orexin in the rat vitreous body. Orexin was extracted from vitreous body samples with a water:acetonitrile:formic acid (80:20:0.1; v/v/v) mixture followed by vortexing and centrifuging. Separation was performed on a reverse-phase HPLC column under gradient conditions. Orexin was analysed via multiple-reaction monitoring (MRM) in the positive electrospray mode. The total analysis time for each sample was less than 5.0 min. Once the method was fully optimised, it was then validated, following the 2018 FDA guidance on bioanalytical method validations. The calibration curves for orexin (1–500 ng/mL) were constructed using a linear regression with a 1/x2 weighting. The lower limit of quantitation for orexin was 1.0 pg/mL for the vitreous body. Intra-day and inter-day estimates of accuracy and precision were within 10% of their nominal values, indicating that the method is reliable for quantitation of orexin in the rat vitreous body. From the physiological perspective, our results are the first to show daily rhythm of orexin synthesis by the retina with possible implications on the circadian regulation of vision.

Daily Rhythm of Fractal Cardiac Dynamics Links to Weight Loss Resistance: Interaction with CLOCK 3111T/C Genetic Variant

The effectiveness of weight loss treatment displays dramatic inter-individual variabilities, even with well-controlled energy intake/expenditure. This study aimed to determine the association between daily rhythms of cardiac autonomic control and weight loss efficiency and to explore the potential relevance to weight loss resistance in humans carrying the genetic variant C at CLOCK 3111T/C. A total of 39 overweight/obese Caucasian women (20 CLOCK 3111C carriers and 19 non-carriers) completed a behaviour–dietary obesity treatment of ~20 weeks, during which body weight was assessed weekly. Ambulatory electrocardiographic data were continuously collected for up to 3.5 days and used to quantify the daily rhythm of fractal cardiac dynamics (FCD), a non-linear measure of autonomic function. FCD showed a 24 h rhythm (p < 0.001). Independent of energy intake and physical activity level, faster weight loss was observed in individuals with the phase (peak) of the rhythm between ~2–8 p.m. and with a larger amplitude. Interestingly, the phase effect was significant only in C carriers (p = 0.008), while the amplitude effect was only significant in TT carriers (p < 0.0001). The daily rhythm of FCD and CLOCK 3111T/C genotype is linked to weight loss response interactively, suggesting complex interactions between the genetics of the circadian clock, the daily rhythm of autonomic control, and energy balance control.

Measuring Salivary Cortisol in Wild Carnivores

ABSTRACTSalivary hormone analyses provide a useful alternative to fecal and urinary hormone analyses in non-invasive studies of behavioral endocrinology. Here, we use saliva to assess cortisol levels in a wild population of spotted hyenas (Crocuta crocuta), a gregarious carnivore living in complex social groups. We first describe a novel, non-invasive method of collecting saliva from juvenile hyenas and validate a salivary cortisol assay for use in this species. We then analyze over 260 saliva samples collected from nearly 70 juveniles to investigate the relationships between cortisol and temporal and social variables in these animals. We obtain evidence of a bimodal daily rhythm with salivary cortisol concentrations dropping around dawn and dusk, times at which cub activity levels are changing substantially. We also find that dominant littermates have lower cortisol than either subordinate littermates or singletons, but that cortisol does not vary with age, sex, or maternal social rank. Finally, we examine how social behaviors such as aggression or play affect salivary cortisol concentrations. We find that inflicting aggression on others was associated with lower cortisol concentrations. We hope that the detailed description of our methods provides wildlife researchers with the tools to measure salivary cortisol in other wild carnivores.HIGHLIGHTSWe validated methods for collecting and analyzing saliva from wild carnivores.We documented a bimodal daily rhythm in juvenile spotted hyena salivary cortisol.Cortisol varied among juvenile hyenas based on litter size and intra-litter rank.Inflicting aggression on others was associated with lower cortisol concentrations.