The effects of maternal vitamin E supplementation on the antioxidant status of chicks were investigated. Female breeder chicks were fed corn-soybean growing diets without supplemental vitamin E for a 17-wk developmental period. After 17 wk, the birds were randomly assigned to 5 treatments and fed corn-soybean diets supplemented with 0, 40, 80, 120, and 160 mg/kg vitamin E (all-rac-α-tocopherol acetate), respectively. Blood samples were collected and pullets were artificially inseminated at 35 wk of age. Eggs laid beginning on d 2 after insemination were placed in an incubator. At the time of hatching, 12 chicks from each treatment were randomly sampled and killed. Livers and brains of chicks were collected for the subsequent evaluation of antioxidant status. Plasma vitamin E concentrations increased linearly (P < 0.001; r = 0.997) with the increase in supplemental vitamin E, but those in egg yolk reached a plateau at 120 mg/kg supplemental vitamin E. The malondialdehyde (MDA) concentration, an indicator of lipid peroxidation, of chick brain decreased linearly (P < 0.01; r = −0.909) with the increase in supplemental vitamin E. Pullets given 160 mg/kg supplemental vitamin E had lower plasma MDA concentrations than those given 0 mg/kg (P < 0.05). Similar results were found for the reactive oxygen species levels, an indicator of oxidative stress, of chick brain and liver. For antioxidant enzymes, chicks of pullets given 120 mg/kg supplemental vitamin E had higher (P < 0.05) activities of liver catalase than those given 0–80 mg/kg. Chicks of pullets given 160 mg/kg supplemental vitamin E had higher (P < 0.05) activities of brain superoxide dismutase than those given 0–40 mg/kg. These results indicated that maternal supplementation with high levels of vitamin E (120–160 mg/kg) enhances antioxidant capability and depresses oxidative stress in chicks.

1. One-day-old Taiwan native male chicks were fed with maize–soybean rearing diets without supplemental vitamin E to 23 weeks of age. From 23 to 52 weeks of age, the cockerels (n = 90) were assigned at random to 5 dietary treatments and fed with maize–soybean diets supplemented with 0, 20, 40, 80 and 160 mg/kg of vitamin E (dl-α-tocopherol acetate). Pullets (225) of the same age were fed with standard diets throughout. 2. They were artificially inseminated with one dose of 0·04 ml/bird intact and 5-fold diluted pooled semen at 31 to 43 weeks of age and at 49 weeks of age, respectively. 3. The criteria evaluated included: semen quality, fertility and maximum and effective duration of fertility, blood characteristics, body and testes weight. 4. Supplemental vitamin E did not affect cockerels’ effective duration of fertility and percentage of fertility. However, when pullets were inseminated with diluted semen, supplementing 160 mg/kg vitamin E increased the maximum duration of fertility at 49 weeks of age. 5. Cockerels receiving 40 to 160 mg/kg supplements had higher sperm viability and motility after 39 weeks of age and those fed 80 mg/kg had higher sperm concentration at 39 weeks of age. 6. Cockerels receiving supplements of more than 40 mg/kg vitamin E had higher body weight gain. 7. Plasma cholesterol and testosterone were not affected by supplemental vitamin E. However, plasma luteinising hormone (LH) concentration was lower in cockerels fed 160 mg/kg. 8. Lack of supplemental vitamin E over 39 weeks was associated with lower semen quality but did not reduce the proportion of fertile eggs laid by inseminated hens, perhaps because the insemination dose compensated for low sperm quality. We found that the maximum duration of fertility might be improved by supplementing 160 mg/kg vitamin E at 49 weeks of age.