Abstract
The present study was conducted to evaluate the effects of dietary marine-derived polysaccharides (MDP) from seaweed Enteromorpha on productive performance, egg quality, antioxidant capacity, and jejunal morphology in late-phase laying hens. A total of 240 Lohmann white laying hens (62 wk of age) were assigned to 4 dietary treatments that included MDP at concentrations of 0, 1,000, 2,500, and 5,000 mg/kg for 6 wk. Each treatment had 6 replicates with 5 cages (2 birds/cage). The results showed that dietary MDP quadratically improved egg production (P < 0.05) during 5 to 6 wk and 1 to 6 wk. There was a linear reduction in cracked egg rate (P < 0.05) with dietary MDP levels increased during 3 to 4 wk and 1 to 6 wk. After 4 wk of feeding trial, the egg shell thickness, yolk color, and Haugh unit showed a linear increase (P < 0.05) in response to increasing dietary MDP levels. Besides, the egg shell breaking strength, egg shell thickness, yolk color, and Haugh unit were improved linearly (P < 0.05) by dietary MDP at the end of the experiment. Moreover, dietary MDP showed a linear and quadratic reduction in serum malondialdehyde (MDA) content (P < 0.05) at the end of third week. At the end of experiment, the activity of total superoxide dismutase in serum was increased quadratically (P < 0.05) by dietary MDP, and dietary MDP quadratically improved the liver catalase (CAT) activity (P < 0.05) and linearly enhanced jejunal CAT activity (P < 0.05), whereas linearly decreased jejunal MDA concentration (P < 0.05). Furthermore, supplemental MDP linearly improved the villus height (P < 0.05) and quadratically increased villus height/crypt depth ratio (P < 0.05) of jejunum. However, dietary MDP had no effect on jejunal trypsin, amylase, and protease activity (P > 0.10). Taken together, these findings provided new insights into the role of MDP in improving the productive performance, egg quality, antioxidant capacity, and jejunal morphology of late-phase laying hens.