Dietary L-citrulline supplementation modulates nitric oxide synthesis and antioxidant status of laying hens during summer season

Background:L-citrulline(L-Cit),a non-protein amino acid,has been implicated in several physiological functions including anti-inflammatory,anti-oxidative,and hypothermic roles,however,there is a paucity of information with regards to its potential in poultry production.Methods:This study was designed to investigate the effects of dietary L-Cit supplementation on the production performance,nitric oxide production,and antioxidant status of laying hens during summer period.Hy-Line Brown laying hens(n=288,34 weeks old)were allotted to four treatment,6 replicates of 12 chickens each.Dietary treatments of control(basal diets),0.25%,0.50%and 1.00%L-Cit supplementation were fed to chickens for eight(8)weeks.Production performance,free amino acid profiles,nitric oxide production,and antioxidant properties were measured.Blood samples were collected at the 4th and 8th weeks of the experiment.Results:Air temperature monitoring indicated an average daily minimum and maximum temperatures of 25.02°C and 31.01°C respectively.Dietary supplementation with L-Cit did not influence(P>0.05)the production performance,and rectal temperature of laying hens.Egg shape index was increased(P<0.05)with increasing levels of L-Cit.Serum-free content of arginine,citrulline,ornithine,tryptophan,histidine,GABA,and cystathionine were elevated,but taurine declined with L-Cit diets.Plasma nitric oxide(NOx)concentration was highest at 1%L-Cit.Likewise,nitric oxide synthase(NOS)activity for total NOS(tNOS)and inducible NOS(iNOS)were upregulated with increasing L-Cit levels,although,tNOS was not affected at the 4th week.Anti-oxidant enzymes including catalase and superoxide dismutase(SOD)were increased with L-Cit supplementation,however,SOD activity was unchanged at 4th week,while total anti-oxidant capacity increased at the 8th week.L-Cit supplementation attenuated the extent of lipid peroxidation,and also inhibited glutathione peroxidase activity.Conclusion:Dietary L-Cit supplementation modulated systemic arginine metabolism,nitric oxide synthesis,antioxidant defense system,and increased the egg shape index of laying hens during the summer season.1%L-Cit supplementation proved most effective in potentiating these effects and may be adopted for feed formulation strategies.

Effect of microencapsulated watermelon(Citrullus lanatus)intake on plasma amino acids and glycemic response in healthy adults

Watermelon is an L-citrulline-rich fruit that has been used as a supplement to increase L-arginine in plasma,which in turn plays a critical role in the synthesis of nitric oxide,a molecule that regulates vascular tone.Watermelon rind,similar to its pulp,presents a high L-citrulline content,yet a lower concentration of sugar,which would be more convenient for individuals who need to refrain from excessive sugar ingestion(i.e.,diabetics and obese individuals).Further,ingestion of watermelon rind can be a sustainable alternative to increase plasma L-arginine,given that rind of fruits is commonly discarded.Therefore,we evaluated the effect of ingestion of a product derived from watermelon rind and pulp(microencapsulation in spray drier)on plasma amino acids(L-citrulline,L-arginine and L-ornithine),glucose,and insulin.Eleven participants(28.36±5.70 years)were enrolled in a single blind,cross-over and randomized study.They ingested microencapsulated watermelon rind and pulp(containing 4 g of L-citrulline)plasma amino acids,glucose,and insulin were evaluated before and 30,60,90 and 120 min after ingestion.It was observed that both microencapsulated watermelon rind and pulp increased L-citrulline through 120 min and microencapsulated watermelon rind significantly increased L-arginine at 30 min.In addition,microencapsulated watermelon rind and pulp similarly increased plasma glucose and insulin levels.In conclusion,these findings suggest that both microencapsulated watermelon rind and pulp are effective to increase plasma L-citrulline and microencapsulated watermelon rind effectively increases plasma L-arginine.In addition,rind and pulp promote similar changes on plasma glucose and insulin.