Abstract
The effects of vitamin A excess or insufficiency on resistance to Escherichia coli infection and subsequent anti-E. coli immune responses were examined in chicks. Chicks receiving depleted (0 μg/kg), sufficient (0.85 mg/kg) or excess (1000 mg/kg) levels of vitamin A in their feed were inoculated by a subcutaneous injection of pathogenic E. coli (1 x 109 and 2 x 109 cfu per chick). Susceptibility to E. coli was determined by mortality, morbidity and immune responses (antibody production and T lymphocyte proliferation). Excess or insufficient vitamin A led to increased susceptibility of chicks to E. coli infection; this was accompanied by depressed immune responses. Chicks receiving excess vitamin A were more sensitive to E. coli than vitamin A-depleted chicks. This was reflected in higher mortality and morbidity rates and in severely depressed immune responses. In contrast to chicks receiving excess vitamin A, T lymphocyte responses (though not antibody responses) of vitamin A-depleted chicks achieved levels similar to those of vitamin A-sufficient birds with a lag period of 6 to 10 d. Therefore, reduction in resistance to E. coli infection, resulting from vitamin A excess or deficiency, probably was compounded by a delayed immune response.
Original language | English |
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Pages (from-to) | 395-400 |
Number of pages | 6 |
Journal | Journal of Nutrition |
Volume | 121 |
Issue number | 3 |
DOIs | |
State | Published - 1991 |
Keywords
- Chicks
- E. coli
- Immune response
- Infection
- Vitamin A