dietary methionine is in keeping with previously
published reports for example,
Boomgaardt and Baker (1973); however,
there was little or no reduction in carcass
fat deposition, an observation often reported
with increased dietary methionine
(Larbier and Leclercq 1980). Failure to
show a significant reduction in carcass fat
deposition may be due to the fact that only
two levels of methionine were used and
hence the differences were not great enough
to demonstrate altered carcass fat levels.
The reduction in abdominal and carcass fat
content noted with the glycine-supplemented
groups (Table 2), is in keeping with
the reduced energy intake and, although
carcass protein content was not measured,
the improved feed:gain ratios would suggest
that the carcass contained a correspondingly
greater amount of carcass protein.
Although methionine and lysine
additions had little effect on carcass fat content,
as did the 247o protein diets, there was
a substantial reduction in carcass fat when
these amino acids were used in combination
with glycine. Again demonstrating that glycine
or nonessential nitrogen acts to reduce
feed intake with the broiler, with a corresponding
change in carcass composition.
Amino acid supplements to the 2O7o protein
basal did not enhance 7-wk body
weight, although the addition of glycine resulted
in reduced gain whether added by itself
or in combination with lysine and methionine
(Table 3). Increasing the protein
content of the diets (treatments 6 and 7)