Melatonin modulates tonic immobility and vigilance behavioural responses of broiler chickens to lighting regimens during the hot-dry season

Adverse effects of heat stress during summer on broiler chickens production and antioxidant mitigating effects

Broiler chicken meat is a good source of protein consumed universally, and is one of the most commonly farmed species in world. In addition to providing food, poultry non-edible byproducts also have value. A major advantage of broiler chicken production is their short production cycle, which results in a greater rate of production in comparison to other species. However, as with any production system, there are constraints in broiler production with one of the most pressing being energy requirements to keep the birds warm as chicks and cool later in the growth cycle, as a result of the cost needing mechanical heating and cooling. While this is feasible in more advanced economies, this is not readily affordable in developing economies. As a result, farmers rely on natural ventilation to cool the rearing houses, which generally becoming excessively warm with the resultant heat stress on the birds. Since little can be done without resorting to mechanical ventilation and cooling, exploring the use of other means to reduce heat stress is needed. For this review, we cover the various factors that induce heat stress, the physiological and behavioral responses of broiler chickens to heat stress. We also look at mitigating the adverse effect of heat stress through the use of antioxidants which possess either an anti-stress and/or antioxidant effects.

Myeloperoxidase expression in diencephalon is potentially associated with fear‐related behavior in chicks of laying hen

Preventing feather pecking (FP) in adult laying hens is important for the welfare of intensively poultry farming. Fear-related behavior in growing female layer chicks may predict FP in adult hens. In this study, in two representative laying breeds (White Leghorn [WL] and Rhode Island Red [RIR]) that have different FP frequencies, we identified a candidate gene associated with fear-related behavior in chicks and FP in adult hens. In the tonic immobility test and open-field test, the behavioral activity was lower in WL chicks than in RIR chicks (P < 0.01), suggesting that WL chicks were more fearful than RIR chicks. Based on previous studies, 51 genes that have been found to be differentially expressed in the brain between high- and low-FP populations were chosen, and their expression levels were screened in the chick diencephalon. This analysis revealed that myeloperoxidase (MPO) gene expression level was higher in WL chicks than that in RIR chicks (P < 0.05). Furthermore, STRING analysis predicted the gene network including MPO and MPO-related genes and revealed the association of these genes with fear-related behavior. These results suggest that MPO is potentially associated with fear-related behavior in growing female layer chicks and FP in adult hens.

"I just became like a log of wood … I was paralyzed all over my body": women's lived experiences of tonic immobility following rape

Tonic immobility is considered the last involuntary self-protecting act/mechanism experienced by victims of rape when they are under attack. It is associated with trauma related mental health risks post-rape. Despite this, tonic immobility has not received priority as an area of research on Nigerian female victims of rape. As a result, little has been known about this phenomenon by nurses and other professionals who are involved in the care and management of rape survivors in Nigeria. The limited knowledge about tonic immobility as a phenomenon might have resulted in mismanagement and secondary victimization of rape victims experiencing manifestations suggestive of tonic immobility during or after rape. This study was a qualitative narrative inquiry that explored, analysed, and interpreted the lived experiences suggestive of tonic immobility, and the meaning attached to such experiences by victims. A sample of fourteen Nigerian women who self-identified as rape victims was utilized. Individual semi-structured, in-depth interviews were conducted to generate data. Thematic data analysis revealed four overarching themes: namely (i) Tonic immobility as an Altered Physical State, (ii) Tonic Immobility as Mental Paralysis, (iii) Painful Loss of Self-defence, and (iv) Constant Self-blame. The findings provided an insight into the traumatic experience of raped women and the psychological implication of tonic immobility as extreme defence mechanism. This study will prove invaluable to nurses and other professionals/stakeholders involved in the care and management of rape victims; to help them develop and use appropriate strategies for management and prevention of secondary victimisation.

Changes in feed consumption and water intake among broiler chickens subjected to melatonin treatment during the hot-dry season

The experiment was conducted to evaluate changes in feed consumption and water intake among broiler chickens subjected to melatonin treatment during the hot-dry season. A total of 300 broiler chicks were selected and assigned into three groups, by simple random sampling, comprising 100 chicks each: group I was exposed to natural photoperiod of about 12-h light and 12-h darkness cycle (12D/12L), without melatonin supplementation; group II was kept under 24-h continuous lighting (CL), without melatonin supplementation; and group III was raised under 24-h CL and administered daily with melatonin orally at 0.5 mg/kg (CL + MEL). Live weight (LW), feed consumption, and water intake for each group were obtained at weekly intervals over a period of 8 weeks. On day 42 of age, the LW of 2420 ± 50 g/bird was obtained in group III administered with melatonin (CL + MEL), while LW values recorded in the 12D/12L and CL groups not administered with melatonin were 1470.00 ± 30.00 and 1907.00 ± 38.00 g/bird, respectively. The mean weight gain in CL + MEL (345.00 ± 21.01 g) was significantly (P < 0.05) higher than those of the 12D/12L (244.99 ± 18.67 g) and CL (307.48 ± 18.14 g) groups. Feed consumptions were significantly (P < 0.05) different in all the groups. Group II, raised on CL without melatonin supplementation, had the highest feed consumption value of 25.14 ± 0.51 g/bird from day 14, and attained the peak value of 206.77 ± 7.82 g/bird at day 56. The highest overall amount of water intake was recorded in the melatonin-treated group. In conclusion, melatonin administration to broiler chickens enhanced water intake but decreased feed consumption with increase in LW during the hot-dry season.

BMAL1 but not CLOCK is associated with monochromatic green light-induced circadian rhythm of melatonin in chick pinealocytes

The avian pineal gland, an independent circadian oscillator, receives external photic cues and translates them for the rhythmical synthesis of melatonin. Our previous study found that monochromatic green light could increase the secretion of melatonin and expression of CLOCK and BMAL1 in chick pinealocytes. This study further investigated the role of BMAL1 and CLOCK in monochromatic green light-induced melatonin secretion in chick pinealocytes using siRNAs interference and overexpression techniques. The results showed that si-BMAL1 destroyed the circadian rhythms of AANAT and melatonin, along with the disruption of the expression of all the seven clock genes, except CRY1. Furthermore, overexpression of BMAL1 also disturbed the circadian rhythms of AANAT and melatonin, in addition to causing arrhythmic expression of BMAL1 and CRY1/2, but had no effect on the circadian rhythms of CLOCK, BMAL2 and PER2/3. The knockdown or overexpression of CLOCK had no impact on the circadian rhythms of AANAT, melatonin, BMAL1 and PER2, but it significantly deregulated the circadian rhythms of CLOCK, BMAL2, CRY1/2 and PER3. These results suggested that BMAL1 rather than CLOCK plays a critical role in the regulation of monochromatic green light-induced melatonin rhythm synthesis in chicken pinealocytes. Moreover, both knockdown and overexpression of BMAL1 could change the expression levels of CRY2, it indicated CRY2 may be involved in the BMAL1 pathway by modulating the circadian rhythms of AANAT and melatonin.

Betaine and ascorbic acid modulate indoor behavior and some performance indicators of broiler chickens in response to hot-dry season

Heat stress causes lipid peroxidation in poultry, necessitating antioxidant administration. The experiment evaluated the modulating effects of betaine and ascorbic acid (AA) on indoor behavior and some performance parameters of broiler chickens during the hot-dry season. Experimental groups were: Group I (control) was daily given sterile water; Group II, betaine at 250 mg/kg; Group III, AA (50 mg/kg), and Group IV, betaine (250 mg/kg) + AA (50 mg/kg), orally for 42 days. The natural occurring dry-bulb temperature (28.0-37.0 °C), relative humidity (69.0-93.0%), and temperature-humidity index (27.9-36.1 °C) were predominantly outside the thermo-neutral zone for broiler chickens, indicating heat stress conditions. Scan test, used to assess the percentage of birds sitting/lying, panting, feeding, drinking and spreading wings, was performed at 06:00 h, 13:00 h and 18:00 h on each of days 35 and 42. Feed intakes (FD), water consumption (WC), body weight, average daily weight gain (ADG) and feed-to-gain ratio (FGR) were obtained. Betaine+AA reduced (P < 0.05) percentage of birds panting; AA decreased (P < 0.05) percentage of birds spreading wing, compared with control. Finisher phase: betaine and/or AA, decreased FGR, increased ADG (P < 0.05); betaine reduced (P < 0.01) FD compared with control. Grower phase: betaine, either alone or with AA, lowered FGR and FD (P < 0.01); AA reduced (P < 0.01) FD, compared with control. Starter phase: betaine and/or AA decreased WC (P < 0.05); AA lowered FGR, compared with controls. Betaine administration decreased (P < 0.05) FD at 4 week-old, but its administration, either alone or with AA, reduced WC at 1 week-old, compared with control. Overall, betaine and/or AA group lowered FGR compared with controls. In conclusion, administration of betaine and/or AA to broiler chickens modulated indoor behavior, some performance indicators and water consumption during the hot-dry season.