Effects of vitamin E and selenium yeast on growth performance and immune function in ducks fed maize naturally contaminated with aflatoxin B-1

摘要

This study was conducted to determine the effects of a combined vitamin E (VE) and selenium yeast (SeY) supplementation on growth performance, blood profiles, relative organ weight, and immune function in ducks fed diets containing maize naturally contaminated with a variety of mycotoxins, but primarily aflatoxin (AFB(1)). A total of 448 ducks were blocked on the basis of sex and body weight, and then randomly assigned to 1 of 4 treatments in a 2 x 2 factorial arrangement with 2 levels of AFB(1) contaminated maize (0 or 100%) and 2 VE and SeY levels (0 IU VE and 0 mg SeY/kg or 50 IU VE and 0.2 mg SeY/kg) for a 28-d study period. There were 7 replications (pens) per treatment and 16 birds per pen. Detectable levels of other toxins were present but that only AFB(1) exceeded limits, and the level of the AFB(1) was 196.8 mu g/kg in the contaminated maize, 130.5 and 142.4 mu g/kg in the 100% contaminated starter diets with or without VE and SeY, respectively, and 152.6 and 157.1 mu g/kg in the 100% contaminated grower diets with or without VE and SeY, respectively. Ducks fed AFB(1) contaminated maize diets had lower (P < 0.05) ADG and ADFI, and greater (P < 0.05) death rates during the whole experiment. The supplementation of VE and SeY increased (P < 0.05) FCR during d 0 to 14 but decreased (P < 0.05) ADFI during d 15 to 28 and 0 to 28. Interactions were observed (P < 0.05) in ducks fed AFB(1) contaminated diets. Feeding AFB(1) contaminated maize diets increased (P < 0.05) the activity of lactate dehydrogenase, whereas the levels of total protein, albumin, and globulin decreased (P < 0.05) at both d 14 and 28. However, VE and SeY had no consistent effects. The lymphocyte proliferation and acid alpha-naphthylacetate esterase positive ratios (ANAE+) were decreased (P < 0.05) by the inclusion of AFB(1) contaminated diets during the whole experiment but benefited from VE and SeY supplementation. Dietary VE and SeY improved (P < 0.05) the levels of interleukin 2 (IL-2) and interleukin 6 (IL-6) throughout the experiment. Avian influenza (H5N1) antibody titer was reduced (P < 0.05) by the inclusion of AFB(1) contaminated maize without VE and SeY supplementation. Ducks fed AFB(1) contaminated maize diets had greater (P < 0.05) relative weights of spleen and bursa of fabricius but lower (P < 0.05) thymus, and the supplementation of VE and SeY increased (P < 0.05) the relative bursa of fabricius weight in the presence of contaminated maize. Interactive effects were observed (P < 0.05) in ANAE+ and IL-2 on d 28 and relative weight of bursa of fabricius. In conclusion, feeding AFB(1) contaminated maize caused adverse effects on growth performance, immunity, and relative immune organ weight in ducks, while dietary addition of VE and SeY partially counteracted the negative effects of AFB(1) on growth and death rate