Effect of betaine supplement on broiler performance during an experimentalcoccidial infection

A trial was conducted to investigate the effects of betaine as a feed suppl ement, given singly and in combination with the ionophore coccidiostat nara sin, on broiler performance during an experimental coccidial infection. Fiv e hundred and sixty female Ross broiler chickens were kept in floor pens an d given a wheat-based diet. At 10 d of age, 420 chickens were individually inoculated with a mixture of Swedish chicken Eimeria isolates containing E. acervulina, E. praecox, E. maxima, and E, tenella. Remaining birds were ke pt as uninoculated controls. The effects of betaine (0 or 1.0 g/kg) and nar asin (0 or 70 ppm) added to the basal diet were evaluated. Overall, betaine as a single feed supplement improved live weight by 5.7, 5.4, and 5.6% at 22, 29, and 36 d, respectively, but had no positive effect in combination w ith narasin. A longer withdrawal period of the coccidiostat (10 vs 5 d) did not affect live weight, but significantly increased feed intake by 9.6% an d feed conversion ratio by 12.6%, irrespective of betaine supplement. Inocu lated birds had a 10% lower live weight than uninoculated chickens. Perform ance of uninoculated birds was similar to that of inoculated birds treated with narasin, except at 7 d after inoculation, when live weights of uninocu lated birds were significantly higher. Chickens given coccidiostat had less Clostridium perfringens in their ceca, but the prevalence was not altered by betaine supplement. There was no difference in intestinal lesion scores between inoculated chickens given coccidiostat or not, despite the better p erformance of chickens given coccidiostat. Betaine did not affect Eimeria o ocyst output or intestinal lesion scores.