Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2002
Publication Date: 3/20/2002
Citation: ALLEN, P.C., FETTERER, R.H. EFFECTS OF DIETARY VITAMIN E ON CHICKENS INFECTED WITH EIMERIA MAXIMA: OBSERVATIONS OVER TIME OF PRIMARY INFECTION. AVIAN DISEASES. 46:839-846. 2002. Interpretive Summary: Eimeria maxima is one of the more pathogenic species of coccidia (protozoa) that parasitizes the chicken digestive tract. Its presence in poultry flocks accounts for a major portion to the overall 4000 million annual cost of coccidiosis to that poultry industry. Because the chick host responds to infection with E. maxima by producing harmful free radicals that can cause oxidative damage to the host tissues, it was hypothesized that feeding a high level of vitamin E, a potent antioxidant, might lessen the pathology of E. maxima infection. Two trials were conducted to contrast effects of feeding a low (25ppm) and a high (225 ppm) level of stabilized vitamin E (acetate ester of vitamin E) from on day of age to chickens that were then infected with E. maxima at three weeks of age. The high dietary level of vitamin E increased plasma concentrations of vitamin E 4- to 6- fold, but it did not improve weight gains during infection, and did not consistently affect parasite reproduction as measured by lesion scores and oocyst shedding. Plasma vitamin E decreased during infection in a pattern and degree similar to those of cartenoids, suggesting malabsorption of this form of vitamin E occurs during the acute phase of E. maxima infection, reducing its bioavailability to infected tissues.
Technical Abstract: Two trials were conducted to define temporal changes in plasma a-tocopherol (AT) caused by infection with Eimeria maxima in chickens that consumed either low (25 ppm) levels of dietary DL-a-tocopheryl acetate (VE-AC) from one day of age. In both trials, rates of weight gain were depressed between days 5 and 7 post inoculation (PI), and were not influenced by the level of dietary VE-AC. Plasma AT was consistently depressed at 5 and 7 days PI in chickens consuming either level of dietary AT. The pattern and degree of plasma AT depression correlated with those of plasma carotenoids. Plasma levels of nitrite + nitrate were significantly increased at 5 and 7 days PI. Also, there were no consistent effects of dietary AT on lesion scores or number of oocysts shed. These results are in general accord with findings of earlier experiments, and it is concluded that feeding high levels of VE-AC to broiler chicks from one day of age is not effective in mitigating the pathology including weight gain depression and development of mucosal lesions during E. maxima infections, or in modifying immune response events associated with phagocytosis as indexed by plasma nitrite + nitrate. The likely basis for the ineffectiveness of feeding diet high in this form of vitamin E is that it is malabsorbed during E. maxima infection in the same manner as carotenoids, and becomes less biologically available to infected tissues during the acute phase of infection.