RESULTS AND DISCUSSION
The trial was conducted during early autumn
and ambient temperatures varied from an average
low of 10.5°C at night to an average high of
20.5°C during the day. The FF diet used in the
trial was a conventional starter and grower diet
readily available to small growers and contained
63.5% corn, 30.5% soybean meal, and 2.5%
fishmeal. In contrast, based on selection data,
the feeds chosen by FC birds at the end of the
finisher period included a higher level of grain
and fishmeal and a lower level of soybean meal
(89% grain, 7% soybean meal, and 1.2% fishmeal;
Table 2). Therefore, the FC diet was much
lower in protein compared with the FF diet, 13.2
compared with 20.75% by the end of the trial
(Table 3). Weekly weight gain was significantly
different between treatments at 6 (P < 0.001), 8
(P < 0.001), and 10 wk (P < 0.05) of age. Weight
gain peaked at 7 wk for FF but peaked later for
FC, at 8 wk; the delay was perhaps a result of
birds learning to self-select (Figure 1; Table 4).
Mortality was less than 2% in both treatments.
Final live weights did not differ between
treatments (P > 0.05); however, carcass yield
and breast yields were higher in the birds from
the FF treatment (P < 0.05; Table 5). The higher
breast meat yield (7%) was most likely due to
the higher protein level and amino acid supplements
in the formulated feed. Specifically, the
FF diet contained a synthetic dl-methionine