Functional roles of taurine,L-theanine,Lcitrulline,and betaine during heat stress in poultry

Heat stress(HS)is an important environmental stress factor affecting poultry production on a global scale.With the rise in ambient temperature and increasing effects of global warming,it becomes pertinent to understand the effects of HS on poultry production and the strategies that can be adopted to mitigate its detrimental impacts on the performance,health,welfare,immunity,and survival of birds.Amino acids(AAs)have been increasingly adopted as nutritional modifiers in animals to ameliorate the adverse effects of HS.They are essential for protein synthesis,growth,maintenance,reproduction,immunity,stress response,and whole-body homeostasis.However,HS tends to adversely affect the availability,transport,absorption,and utilization of these AAs.Studies have investigated the provision of these AAs to poultry during HS conditions,and variable findings have been reported.Taurine,L-theanine,and L-citrulline are non-essential amino acids that are increasingly gaining attention as nutritional supplements in HS animals.Similarly,betaine is an amino acid derivative that possesses favorable biological properties which contributes to its role as a functional additive during HS.Of particular note,taurine is negligible in plants,while betaine,L-theanine,and L-citrulline can be found in selected plants.These nutrients are barely found in feed ingredients,but their supply has been shown to elicit important physiological roles including anti-stress effects,anti-oxidative,anti-inflammatory,gut promoting,and immunomodulatory functions.The present review provides information on the use of these nutritionally and physiologically beneficial nutrients as functional additives to poultry diets during HS conditions.Presently,although several studies have reported on the positive effects of these additives in human and murine studies,however,there is limited information regarding their utilization during heat stress in poultry nutrition.Therefore,this review aims to expound on the functional properties of these nutrients,their potentials for HS alleviation,and to stimulate further researches on their biological roles in poultry nutrition.

miRNA sequencing analysis of healthy and atretic follicles of chickens revealed that miR-30a-5p inhibits granulosa cell death via targeting Beclin1

Background:The egg production performance of chickens is affected by many factors,including genetics,nutrition and environmental conditions.These factors all play a role in egg production by affecting the development of follicles.MicroRNAs(miRNAs)are important non-coding RNAs that regulate biological processes by targeting genes or other non-coding RNAs after transcription.In the animal reproduction process,miRNA is known to affect the development and atresia of follicles by regulating apoptosis and autophagy of granulosa cells(GCs).Results:In this study,we identified potential miRNAs in the atretic follicles of broody chickens and unatretic follicles of healthy chickens.We identified gga-miR-30a-5p in 50 differentially expressed miRNAs and found that gga-miR-30a-5p played a regulatory role in the development of chicken follicles.The function of miR-30a-5p was explored through the transfection test of miR-30a-5p inhibitor and miR-30a-5p mimics.In the study,we used qPCR,western blot and flow cytometry to detect granulosa cell apoptosis,autophagy and steroid hormone synthesis.Confocal microscopy and transmission electron microscopy are used for the observation of autophagolysosomes.The levels of estradiol(E2),progesterone(P4),malondialdehyde(MDA)and superoxide dismutase(SOD)were detected by ELISA.The results showed that miR-30a-5p showed a negative effect on autophagy and apoptosis of granulosa cells,and also contributed in steroid hormones and reactive oxygen species(ROS)production.In addition,the results obtained from the biosynthesis and dual luciferase experiments showed that Beclin1 was the target gene of miR-30a-5p.The rescue experiment conducted further confirmed that Beclin1 belongs to the miR-30a-5p regulatory pathway.Conclusions:In summary,after deep miRNA sequencing on healthy and atretic follicles,the results indicated that miR-30a-5p inhibits granulosa cell death by inhibiting Beclin1.