Received for publication January 30, 1998.
Accepted for publication June 1, 1998.
Supported by state and Hatch funds allocated to the Georgia
Agricultural Stations of The University of Georgia.
To whom correspondence should be addressed: gpesti@uga.
13418-900 Piracicaba SP, Brazil.
FCR = feed conversion ratio.
Further Studies on the Influence of Genotype and Dietary Protein
on the Performance of Broilers
E. R. SMITH,* G. M. PESTI,*
R. I. BAKALLI,* G. O. WARE,
and J.F.M. MENTEN
*Department of Poultry Science and
School of Forest Resources, The University of Georgia, Athens, Georgia 30602
An experiment was conducted to quan-
tify genetic differences in response to dietary protein
level of male vs female broilers. Broilers (1 d old) from a
“high-yield” strain cross (Ross
Ross 208) and a “fast-
growing” strain cross (Peterson
Arbor Acres) were
placed on fresh pine shavings in floor pens. From Day 0
to 18, all birds were fed a 23% CP starter diet. During
Days 18 to 53 male birds were fed either a 16, 18, 20, 22,
24, or 26% CP diet (3,200 kcal ME/kg) and female birds
< 0.05) were noted in the performance of
the different strains. Ross
Ross 208 male birds had a
higher body weight (3.37 vs 3.16 kg), higher feed intake
(7.08 vs 6.78 kg), higher breast yield (31.76 vs 29.25%),
higher carcass yield (73.90 vs 71.85%), and a lower
adjusted feed conversion ratio (FCR; 2.10 vs 2.16 g:g)
Arbor Acres males at 53 d of age. As
compared to Peterson
Arbor Acres females, Ross
Ross 208 female broilers also had a higher body weight
(2.68 vs 2.55 kg), higher breast meat yield (33.61 vs
30.80%), higher carcass yield (75.31 vs 73.91%), and
lower adjusted FCR (1.97 vs 2.04 g:g). Qualitative
confirmed and better qualitative data is presented that
can be used to predict the important output parameters
from the import inputs in broiler production.
: broiler, strain, sex, carcass yield, dietary protein, abdominal fat pad)
1998 Poultry Science 77:1678–1687
Improvements in the genetic composition of broilers
is a compelling reason for producers to reevaluate their
feeding regimens. Geneticists have selected for im-
proved body weight on the assumption that it will
increase the salable product (carcass weight) with the
same or reduced inputs (mainly feed). Different growth
potentials for different strains have been found (Proud-
., 1991; Holsheimer and Veerkamp,
1992). A genetic influence on feed conversion ratios
(FCR; grams feed consumed per gram body weight
change) was found by Hulan
. (1980). Jackson
(1982), Leclercq (1983), Marks and Pesti (1984), and