Effects of retinol and retinol esters on performance, egg quality traits and vitamin a levels in serum and egg of laying quails

Effects of Retinol and Retinol Esters on Performance, Egg Quality Traits and Vitamin A Levels in Serum and Egg of Laying Quails This study was conducted to determine the effects of retinol and retinol esters supplementations in laying quail diet on performance and egg quality parameters as well as vitamin A levels in serum and egg. In the study, a total of 300 Japanese quails (200 females and 100 males; Coturnix coturnix japonica) aged 8 eight weeks old were used. They were divided into one control group and four treatment groups, each consisting of 60 quails. The control group was fed with basal diet containing vitamin premix without retinol and carotene. The diets of the treatment groups were formulated to provide dietary supplementation of retinol and retinol esters [as retinyl acetate (R-acetate), retinyl palmitate (R-palmitate) and retinyl propionate (R-propionate), 3300 IU/kg]. The experiment was conducted for eight weeks. The results of the study showed that there were no changes in experimental groups in terms of initial and final body weight, feed intake, egg weight, egg external and internal quality parameters in the 4th and 8th weeks except egg yolk color index in the 8th week (p>0.05). Egg production in all experimental groups during the whole research was higher than those in control group (p<0,01). Feed conversion ratio in all experimental groups was lower than those in control group during the whole research (p<0,01). In this study, serum β-carotene and malondialdehyde (MDA; p<0.01) levels were decreased in all experimental groups, whereas serum retinol level was increased (p<0,001) in the same groups. Serum antioxidant activity (AOA) level in R-palmitate and R-propionate groups was higher than those in control, retinol and R-acetate groups (p<0,001). In the 4th and 8th weeks of this study, no significant difference was found among the groups in terms of the egg yolk carotene level (p>0.05). Yolk retinol level in R-palmitate and R-acetate groups was higher than those in control and R-propionate groups (p<0,001). Egg yolk MDA level in experimental groups was lower than those in control group on day 8th, 15th and 30rd of storage (p<0,05). In conclusion, it was considered that retinol and retinol esters supplementation into laying quail's diets had positive effects on some performance and quality traits, these supplements had a preventive effect on lipid oxidation in serum and egg, however the discrepancies in retinol ester supplemented to diet had different effects on vitamin A level in serum and egg and supplementation of R-palmitate and R-acetate into the diet might be more effective to increase vitamin A level in egg. Key words: Retinol, retinol esters, performance, egg quality, laying quail