[1]The State Key Laboratory of Animal Nutrition;
College of Animal Science and Technology;
China Agricultural University;
Beijing 100193;
People’s Republic of China;
[1]The State Key Laboratory of Animal Nutrition;
College of Animal Science and Technology;
China Agricultural University;
Beijing 100193;
People’s Republic of China;
[1]The State Key Laboratory of Animal Nutrition;
College of Animal Science and Technology;
China Agricultural University;
Beijing 100193;
People’s Republic of China;
[1]The State Key Laboratory of Animal Nutrition;
College of Animal Science and Technology;
China Agricultural University;
Beijing 100193;
People’s Republic of China;
Ascorbic acid; Antioxidant capacity; Immunity; L-gulonolactone oxidase; Old laying hens;