Effect of a High Level of Dietary Iodine on Resistance of Broilers to Mycoplasma synoviae

Abstract

In each of 2 trials, 2560 broiler chicks of equal numbers of each sex were housed in a controlled environment house. The house provided 2 chambers of 16 pens each, and chicks were housed 80 per pen on litter with the sexes in separate pens. Birds in 8 pens in each chamber were supplied with diets formulated to be adequate in iodine (I11Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable.) and birds in 8 pens in each chamber were fed the I1 diet supplemented with 500 p.p.m. iodine (I501) for the 22- to 57-day-old period. When the chickens were 31 days old in Trial 1 or 30 days old in Trial 2, those birds in one of the chambers were aerosol exposed to a broth culture of Mycoplasma synoviae (Ms.). Growth, feed, mortality, serum iodine and serum Ms. antibody data were obtained. Carcass condemnation data was obtained at the processing plant at 60 days of age.Mycoplasma synoviae-exposed chickens had significantly lower body weight gain than unexposed controls. These results agree with those in a previous report. Male chickens on the I501 diet had significantly less body weight gain than the comparable males on the I1 diet in 3 of 4 treatment groups, but the I501 diet did not affect body weight gain for the female birds. Neither feed conversion, mortality, nor processing plant condemnation was affected by the I501 dietary treatment. Birds on the I501 diet had serum iodine concentration equal to that reported to be effective in disinfecting water.