D-Glucuronolactone Supplementation Enhances Production Performance, Eggshell Quality, and Liver Health in Laying Hens

The liver of hens bears a very heavy workload in handling lipogenesis as well as carbohydrate, protein, and other nutrient metabolism to maintain a high laying rate. D-glucuronolactone (DGL) is a naturally occurring chemical metabolite produced from glucose and exhibits a hepatoprotective effect as a food ingredient. This study aimed to evaluate the effect of DGL on production performance, egg quality, and liver health in laying hens during their peak period. Four hundred and eighty Hy-Line brown hens (aged 42 weeks), with comparable high-laying performance, were randomly assigned to four groups, with each group consisting of eight replicates. The control group was fed a basal diet, while the treatment groups were supplemented with DGL at 70, 140, and 280 mg/kg in the basal diet, respectively. The results indicated that DGL supplementation significantly increases the laying rate and egg mass of hens (<i>p</i> < 0.05). The brown color of the eggshell was significantly deepened by DGL administration (<i>p</i> < 0.05). Additionally, DGL supplementation significantly decreased the serum levels of aspartate aminotransferase and γ-glutamyl transpeptidase (<i>p</i> < 0.05). The liver index, liver fat, and triglyceride levels in the liver had also significantly decreased (<i>p</i> < 0.05). Liver histopathological results showed that the control group exhibited yellow coloration with large gaps and numerous vacuolar cells, while DGL supplementation improved the compactness of liver parenchyma. Antioxidant activity was enhanced, showing a significant increase in the activity of total antioxidant capacity and catalase in the liver (<i>p</i> < 0.05). The inflammatory response was alleviated, with a significant decrease in expressions of interleukin-β, tumor necrosis factor-α, interferon-α, interleukin-6, and interleukin-8 genes in the liver (<i>p</i> < 0.05). Moreover, DGL supplementation significantly reduced cell apoptosis-related genes, including factor-related apoptosis, Caspase 7, and BCL2 associated X protein in the liver (<i>p</i> < 0.05). Overall, these findings indicate that dietary DGL enhanced the laying performance of hens by maintaining liver health, with the best results achieved at a dose of 280 mg/kg in this trial.