Selenium (Se) is an essential trace element with diverse physiological functions related to cellular homoeostasis, body metabolism and antioxidant defence. Se is an integral constituent of at least 25 selenoproteins in the body that regulate cellular redox and antioxidant defence enzymes systems control free radicles of reactive oxygen species . Dietary Se plays key role in immunity, growth and fertility in chickens, which require optimum levels in their diets to maintain high reproductive and productive performance of birds. In the last decade, dietary supplementation with selenium nanoparticles (SeNPs) has enhanced the growth performance, feed conversion ratio, reproductive performance, egg production, immune response and antioxidant status, as well as improved the quality of meat and eggs and promoted microflora. Se has been shown to increase relative weights of immune-related organs (burse and thymus) to enhance immunity. Feeding Se-NPs can improve antioxidant status and glutathione peroxidase activities in both broilers and layers. Use of Se-NPs at 0.9 mg/kg diet in broilers improved the intestinal health via increasing the population of beneficial bacteria and producing short-chain fatty acids. This review focuses on the significance of SeNPs in poultry industry and provides insights about its comparative advantages over conventional sources of Se in poultry diets.

SUMMARY The key objective of poultry husbandry is to provide safe and nutritious food for the growing population. The technique of delivering various nutrients, nutraceuticals, vaccines, immunostimulants, phytochemicals and medicinal herbs via the in ovo route is gaining wide attention among scientists worldwide for improving poultry productivity, boosting immune response and safeguarding the health. Embryonic growth in poultry has been manipulated through direct administration of biological compounds into embryonated eggs during the mid and late phase of incubation. This shows potential to enhance hatchability, superior nutritional status, higher chick quality, improve post-hatch performance and ultimately reduce the challenges associated with infections and oxidative stress, as well as minimize the use of synthetic antibiotic growth promoters in poultry production. In the last two decades, several studies have demonstrated that the in ovo supplementation of herbs and their derivatives, such as chicoric acid, rosmarinic acid, astragalus polysaccharides boost immunity, upregulates antioxidant defense, and improves the health status and production output of poultry birds, making herbal compounds an alternative to antibiotic growth promoters. In ovo injection of herbs and their phytochemicals has shown diverse advantages, including improvements in weight gain, feed efficiency, growth rate, decreased morbidity and mortality of embryos, boosted immunity, and improved health status of poultry birds. Furthermore, in ovo injection of herbal compounds has shown better protection against a number of infectious pathogens than post-hatch supplementation. The current review aimed to provide a promising insight for the promotion of in ovo technology in order to supply natural biological compounds/phytochemicals directly into the developing embryo to achieve an improvement in post-hatch growth, immune responses, antioxidant defense and highlights the future of in ovo technology as a strategy to minimize the use of AGPs and improve the health status and production performance of poultry.

Tibial dyschondroplasia (TD) is an important long bone defect of broiler chickens that disturbs the proximal growth plate and is characterized by non-vascularized cartilage, a distended growth plate and lameness. Celastrol, a medicinal root extract from the plant Tripterygium wilfordii, is reported widely as a well-known heat-shock protein 90 (Hsp90) inhibitor. Recently, Hsp90 inhibition in chondrocyte differentiation and growth-plate vascularization were effective in restoring the morphology of the growth plate. The present study was aimed at investigating Hsp90 inhibition in TD using celastrol. The broiler chicks were divided into three groups; Control; TD induced (40 mg/kg thiram) and celastrol treatment. Hsp90, vascular endothelial growth factor and Flk-1 expressions were evaluated by quantitative real-time polymerase chain reaction and the protein levels of Hsp90 were measured by Western blot analysis. Antioxidant enzymes were determined to assess the liver damage caused by thiram and the protective effects of the medicine were evaluated by levels of serum biomarkers. The expression levels of Hsp90 and vascular endothelial growth factor mRNA transcripts were increased while Flk-1 receptor was decreased in TD-affected chicks. Celastrol therapy inhibited Hsp90 mRNA and protein levels and up-regulated the expressions of receptor Flk-1 in TD-affected tibial growth plates significantly (P < 0.05) in addition to rectifying the damaging effects of thiram on the liver by decreasing the levels of aspartate aminotransferase, alanine aminotransferase and malondialdehyde and correcting the oxidative imbalance. In conclusion, administering celastrol to dyschondroplastic chicks prevented un-vascularized growth plate, lameness and reinstated angiogenesis. Celastrol may be efficacious for the treatment of TD through the inhibition of Hsp90 expression and limiting the liver damage caused by thiram in broiler chickens.

Ruminants serve as one of the most important reservoirs for pathogenic Escherichia coli. Infection with E. coli, a foodborne enteropathogen, can lead to asymptomatic infections that can cause life-threatening complications in humans. Therefore, from a clinical and human health perspective, it is important to know which virulence genes, phylogenetic groups, serogroups, and antibiotic resistance patterns are present in E. coli strains in yaks with diarrheic infections. Two-hundred and ninety-two rectal swabs were collected from diarrheic yaks in Qinghai Plateau, China. The antimicrobial sensitivity of each resulting isolate was evaluated according to the disk diffusion method, and different PCR assays were performed for the detection of virulence genes and different phylogroups. Additionally, strains were allocated to different serogroups based on the presence of O antigen via the slide agglutination method. Among the E. coli isolates tested, most of the isolates were multidrug resistant (97%) and harbored at least one virulence gene (100%). We observed ten virulence genes (sfa, eaeA, cnf1, etrA, papC, hlyA, aer, faeG, rfc, and sepA), of which sfa was the most commonly found (96.9%). Significant positive associations between some resistance phenotypes and virulence genes were observed (P < 0.05, OR > 1). The majority of the E. coli isolates belonged to phylogroup A (79.5%), and the others belonged to phylogroups B1 (7.5%), D (4.1%), B2 (5.8%), and F (0.7%). Among all the E. coli strains tested, serogroups O91 and O145 were the most prevalent, accounting for 15.4 and 14.4%, respectively. Our results suggest that yaks with diarrhea serve as a reservoir of pathogenic E. coli carrying various virulence genes and resistance phenotypes. Therefore, clinicians and relevant authorities must ensure the regulatory use of antimicrobial agents and prevent the spread of these organisms through manure to farm workers and food-processing plants.