Agriculture Reference
In-Depth Information
17
Responses of Broilers to Amino
Acid Intake
D.C.Z. Donato, N.K. Sakomura* and E.P. Silva
Universidade Estadual Paulista, Jaboticabal, São Paulo, Brazil
Abstract
The main objective of this research was to measure the responses of broilers to methionine + cysteine
and to threonine intake, to determine their efficiencies of utilization for growth and their intake for
optimum response in the starter, grower and finisher phases. Six dose-response trials were conducted
with male and female Cobb broilers in these three phases of growth. Measurements included body
weight gain, digestible amino acid intake, feed conversion ratio, the proportion of feathers in the pro-
tein deposited and the amino acid and lipid deposition in the body. The efficiency of utilization of the
amino acids studied was calculated by linear regression of amino acid deposition and the amino acid
intake for each phase. Despite the differences between sexes and phases, the efficiency of utilization
remained unchanged, being 0.56 and 0.73 for methionine + cysteine and threonine, respectively. The
methionine + cysteine intakes estimated for optimum feed conversion ratio were
231
mg/day and 524 mg/
day in the starter and grower phases, respectively, for both males and females, and 923 mg/day and
1053 mg/day for females and males, respectively, in the finisher phase. For threonine these intakes
were
184
mg/day, 612 mg/day and 823 mg/day in the three phases, for both males and females.
Introduction
broilers, since their productivity depends
mainly on an efficient conversion of feed
protein into muscle protein (Costa
et al
.,
2001). However, now that synthetic amino
acids are being produced on a commercial
scale by industries, nutritionists have re-
duced levels of dietary crude protein and
now formulate diets in order to meet the
specific needs for essential amino acids.
Therefore, it is of importance to know how
broilers respond to the intake of specific
amino acids so that the optimum economic
intakes of these amino acids can be deter-
mined. Maintenance requirements and the
To maintain the increasing production and
productivity of broilers, in addition to health
care and management, nutrition is of great
importance. All nutrients should be supplied
in sufficient quantities so that nutrient defi-
ciencies do not occur, as these lead to low
productivity, and excesses should be avoided
as these lead to an increased cost of produc-
tion, the excretion of waste products into the
environment and losses in productivity.
Protein is considered to be one of the
most important nutrients in the feed of
