Effect of dietary supplementation of taurine on productive performance, egg quality, and liver health in aged laying hens

The current study aimed to investigate the effect of increasing supplementation of taurine in diets on productive performance, egg quality, and liver health in aged laying hens. A total of three hundred twenty 75-week-old Hy-Line Brown laying hens were randomly allotted to 1 of 4 dietary treatments with 8 replicates and 10 hens per replicate in a 12-week feeding trial. A corn-soybean meal-based basal diet was formulated and feed-grade taurine was then supplemented to the basal diet at the supplemental levels of 2.5, 5.0, or 10.0 g/kg. Results indicated that increasing supplementation of taurine in diets decreased (linear, P < 0.05) egg weight, egg mass, and feed intake in aged laying hens. Moreover, increasing supplementation of taurine in diets exhibited a quadratic relationship (P < 0.05) with broken and shell-less egg production. However, hen-day egg production and feed conversion ratio were not affected by increasing supplementation of taurine in diets. Increasing supplementation of taurine in diets decreased (linear, P < 0.01) egg yolk color, but tended to increase eggshell strength (linear, P = 0.08). The hepatic malondialdehyde concentrations were decreased (linear, P < 0.01) by increasing supplementation of taurine in diets. However, expression levels of genes related to hepatic taurine metabolism were not affected by increasing supplementation of taurine in diets. In conclusion, increasing supplementation of taurine in diets decreases egg weight and egg yolk color, but improves eggshell strength in aged laying hens. Increasing supplementation of taurine in diets may have positive effects on the liver health, particularly by decreasing oxidative stress in aged laying hens.