Can vitamin C elevate laying hen performance, egg and plasma characteristics under normal environmental temperature?

The aim of this study was to investigate the effects of vitamin C on laying hen performance, egg quality and some blood parameters under thermal neutrality condition. A total of 192 laying hens (20-week-old) were used by completely randomize design. The treatments, from 20 to 35 weeks of age, included four levels of vitamin C: 0 (control), 250, 500 and 750 mg/kg diet. Birdʹs performance, egg characteristics, plasma glucose, calcium and uric acid were assayed at 28 and 35 weeks of age. Laying hen performance was similar among treatments (P>0.05). Greater albumen index and Haugh unit were obtained by fed 750 mg vitamin C/kg diet compared to other treatments at 28 weeks of age (P<0.05). Increased yolk height was attained by diet supplemented with 500 mg vitamin C/kg diet at this age (P<0.05). Shape index was improved (P<0.05) by 250 and 500 mg vitamin C/kg diet at 35 weeks of age. Higher yolk index was achieved by 500 mg vitamin C/kg diet at 28 and 35 weeks of age (P<0.05). Plasma uric acid was decreased by 250 mg vitamin C/kg diet compared with control diet (P<0.05). The results of the current study have shown that diets supplemented with vitamin C can improve some egg characteristics and decrease plasma uric acid, but have similar effects on performance.