ABSTRACT A trial was conducted to investigate the
effects of betaine as a feed supplement, given singly and
in combination with the ionophore coccidiostat narasin,
on broiler performance during an experimental coccidial
infection. Five hundred and sixty female Ross broiler
chickens were kept in floor pens and given a wheatbased
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
kept as uninoculated controls. The effects of betaine (0
or 1.0 g/kg) and narasin (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 with narasin. A longer