commercial hatchery. Birds were randomly assigned to
1 of 4 treatment groups: nonmedicated control (Table 1),
11 ppm virginiamycin, 0.2% butyric acid, or 0.4% butyric
acid, respectively, both as a mixture of glycerides.2 The
product contains 25 to 30% monoglycerides in the 1 or
3 position, 50 to 55% diglycerides in the 1 or 3 position,
and 15 to 25% triglyceride. There were 35 birds per pen
and 6 replicate pens per treatment. Butyric acid and
antibiotics were added to the basal diet by substituting at
the expense of corn. Birds were maintained at a brooding
temperature of 32°C for 5 d, and then the environmental
temperature was gradually reduced to 22°C in keeping
with normal brooding practice. The lighting schedule
was 23 h/d from d 0 to 4; 12 h/d from d 4 to 14; 15 h/
d from d 14 to 18; 18 h/d from d 18 to 25; and 23 h/d
from d 25 to 42. Birds were vaccinated against coccidiosis
at 1 d of age using gel-spray coccidiosis vaccine.3 Birds
were managed under the guidelines of the Canadian
Council on Animal Care (1993) and with the approval
of the University of Guelph Animal Care Committee.
Feed and water were available ad libitum. Birds were
individually weighed on d 20 and 42. The starter diet
(crumble) was fed until d 20. The grower/finisher diet
(pellet) was fed from d 20 to 42. On d 42 of the trial, 8
birds from each treatment were selected at random