The opioid peptide leucine enkephalin modulates hypothalamic-hypophysial axis in the cichlid fish Oreochromis mossambicus

In vertebrates, opioid peptides are thought to be involved in the regulation of reproduction; however, the significance of enkephalins in testicular function remains unclear. We examined the influence of δ-opioid receptor agonist leucine enkephalin (L-ENK) on the hypophysial-testicular axis of the cichlid fish Oreochromis mossambicus. Treatment with a low dose of L-ENK (60 µg) caused a significant increase in the numbers of primary and secondary spermatocytes and early and late spermatids, concomitant with intense immunolabelling of testicular androgen receptors, but did not significantly alter serum luteinizing hormone (LH) and 11-ketotestosterone (11-KT) levels compared to those of controls. Nevertheless, treatment with a high dose of L-ENK (200 µg) caused a significant reduction in the numbers of secondary spermatocytes as well as late spermatids associated with marginal immunolabelling of androgen receptors and significantly lower concentrations of serum 11-KT and LH compared to controls. In addition, the serum cortisol level was not affected in low-dose L-ENK-treated fish, but its level was significantly increased in the high-dose L-ENK-treated group. Together, these findings indicate that a low dose of L-ENK stimulates the germ cells at the meiosis stage and promotes further stages of spermatogenesis, whereas a high concentration of L-ENK inhibits spermatogenesis at the advanced stages. This effect appears to be mediated through the suppression of testicular steroidogenesis and the reduction of LH release in the pituitary gland of tilapia. The findings also suggest that elevated L-ENK levels in teleosts may exert their inhibitory influence on the hypophysial-testicular axis via glucocorticoids.

The Effect of Low Temperature on Laying Performance and Physiological Stress Responses in Laying Hens

The present study investigated the effect of low temperature on laying performance, egg quality, body temperature, yolk malondialdehyde, yolk corticosterone, and serum biochemistry in laying hens. A total of 40 laying hens (Hy-Line Brown) aged 36 weeks were housed in one of two environmental chambers kept at 12 ± 4.5 °C (low temperature) or 24 ± 3 °C (normal temperature) for 4 weeks. Low vs. normal temperature significantly increased (p < 0.05) live body weight, feed intake, and feed conversion ratio in laying hens. Skin surface temperature, but not rectal temperature, was decreased in laying hens exposed to low vs. normal temperature. Hens exposed to low temperature laid an intense eggshell color compared with those raised in a normal temperature. Malondialdehyde concentrations in yolk were increased in low-temperature-exposed laying hens compared with those at normal temperature conditions, but this effect was only noted on day 7, post the low-temperature exposure (p = 0.04). Finally, low vs. normal temperature increased the concentrations of total cholesterol and triglyceride in serum. Collectively, this study indicates that exposure to low temperature in laying hens initially disrupted antioxidant system and altered lipid metabolism in laying hens without inducing stress responses.

Haematological parameters of laying hens under different group size

The relevance of this study lies in its potential implications for poultry farming practices and animal welfare. Understanding the impact of group size on the blood parameters of hens can provide valuable insights for optimising their health and well-being in farming environments. The aim of the study was an analysis of haematological parameters of laying hens under the influence group size with the same stoking density in analogous cages by design. Hens were kept for 34 weeks in cages of multilevel batteries at different group sizes: I group-93 birds, II group-52 birds, III group-17 birds and IV group-9 birds. The study analysed blood samples from laying hens at 18 and 52 weeks of age. Results showed that reducing the group size from 93 to 52 birds led to a haematological status within the physiological norm, characterized by increased heterophils and decreased monocyte levels. Whereas, the decrease in group size to 17 birds was accompanied by a decrease in the hens' blood content of thrombocytes, an increase of heterophile, a decrease of monocytes and lymphocytes within the physiological norm, as well as an increase in the heterophiles to lymphocytes ratio.

Nanotechnology innovations for increasing the productivity of poultry and the prospective of nanobiosensors

Nanotechnology is an innovative, promising technology with a great scope of applications and socioeconomic potential in the poultry industry sector. Nanoparticles (NPs) show the advantages of high absorption and bioavailability with more effective delivery to the target tissue than their bulk particles. Various nanomaterials are available in different forms, sizes, shapes, applications, surface modifications, charges and natures. Nanoparticles can be utilised in the delivery of medicines, targeting them to their right effective site in the body and, at the same time, decreasing their toxicity and side effects. Furthermore, nanotechnology can be beneficial in the diagnosis of diseases and prevention of them and in enhancing the quality of animal products. There are different mechanisms through which NPs could exert their action. Despite the vast benefits of NPs in poultry production, some concerns about their safety and hazardous effects should be considered. Therefore, this review article focuses on NPs' types, manufacture, mechanism of action and applications regarding safety and hazard impact.

Selenium and/or vitamin E upregulate the antioxidant gene expression and parameters in broilers

BACKGROUND

In contrast to free radicals, the first line of protection is assumed to be vitamin E and selenium. The present protocol was designed to assess the roles of vitamin E and/or a selenium-rich diet that affected the blood iron and copper concentrations, liver tissue antioxidant and lipid peroxidation, and gene expression linked to antioxidants in the liver tissue of broilers. The young birds were classified according to the dietary supplement into four groups; control, vitamin E (100 mg Vitamin/kg diet), selenium (0.3 mg sodium selenite/kg diet), and vitamin E pulse selenium (100 mg vitamin/kg diet with 0.3 mg sodium selenite/kg diet) group.

RESULTS

The results of this experiment suggested that the addition of vitamin E with selenium in the broiler diet significantly increased (P ≤ 0.05) serum iron when compared with the other groups and serum copper when compared with the vitamin E group. Moreover, the supplements (vitamin E or vitamin E with selenium) positively affected the enzymatic activity of the antioxidant-related enzymes with decreased malondialdehyde (MDA),which represents lipid peroxidation in broiler liver tissue. Moreover, the two supplements significantly upregulated genes expression related to antioxidants.

CONCLUSION

Therefore, vitamin E and/or selenium can not only act as exogenous antioxidants to prevent oxidative damage by scavenging free radicals and superoxide, but also act as gene regulators, regulating the expression of endogenous antioxidant enzymes.

Efficacy of hepatoprotectors in prophylaxis of hepatosis of laying hens

Hepatoses of laying hens are quite common in poultry farms as a result of improper practices of poultry maintenance consisting in excessive number of protein feeds for provision of high productivity. The objective of the study was preventive efficacy of Gep-A-Stress hepatoprotectors (carnitine hydrochloride, D L methionine, sorbitol, choline chloride, magnesium sulfate heptahydrate) and Hepasan VS (L-carnitine hydrochloride, sorbitol, choline chloride, magnesium sulfate hepahydrate, betaine hydrochloride, L-arginin) against hepatosis of laying hens. To determine the efficacy of Hep-A-Stres and Hepasan-VS hepatoprotectors during production tests (n = 4,500), we monitored the parameters of survival rate (the final number of individuals as percentage of the initial number) and egg productivity of laying hens. We determined that after 30 days of using the hepatoprotectors, the content of overall protein in blood serum of laying hens of the first and the second experimental groups decreased by 21.4% and 18.9% compared with the parameters prior to providing the hepatoprotectors and by 26.3% and 23.3% compared with the control group after receiving the drug. The urea contents in blood serum increased by 19.0% and 10.5%. Compared with the control, the activity of alanine aminotransferase decreased by 43.7% and 24.1% in the first experimental group and by 23.4% and 14.9% in the second. The activity of aspartate aminotransferase in blood serum of the experimental groups decreased by 10.7%. The cholesterol concentration decreased by 50% and 58.3%. The content of triaglycerols decreased by 24.1% and 8.9% respectively. The concentrations of high-density lipoproteins after 30 days of the experiment decreased by 33.3% and 77.8% respectively, the content of low-density lipoproteins decreased by 61.3% and 40.4% and 42.3%. Population maintenance equaled respectively 97.1%, 98.3% and 98.1%. At the end of the experiment, the egg productivity of laying hens of the first and second groups increased by 4% and 3.6% compared with the control. Therefore, intake of the hepaprotectors by laying hens stimulated their metabolism, positively influenced the blood parameters, survival and egg productivity. The conducted studies confirm the benefits of using hepatoprotectors for the prohylaxis of hepatosis of hens.