Agriculture Reference
In-Depth Information
55
g, the concentrations of Lys, Met+Cys and
Thr required in the feed would be 7.17 g/kg
(
k
= 0.0023), 6.89 g/kg (
k
= 0.0025) and 5.93 g/kg
(
k
= 0.0034), respectively.
Depending on the ingredients available,
and their prices, the marginal cost of each
amino acid will vary, but not all amino acids
need necessarily be limiting in the feed and
hence their marginal costs may not be realis-
tic. It is not necessary to attempt to restrict all
the essential amino acids to their lower bound-
ary as defined using the Reading model ap-
proach: only those amino acids that are limit-
ing in the formulation would be at the lower
boundary, while all others should be unlim-
ited. In feed formulations for laying hens that
are based on maize and soybean meal, Met+Cys
are the first limiting amino acids.
In conclusion, the Reading model is a
strategic tool that may be used to estimate the
optimum amino acid intakes for laying hens
under different genetic and economic circum-
stances. The values of the coefficients derived
in the trials reported here add further evi-
dence that these coefficients have biological
meaning and that they can be universally
applied for the purpose of defining the opti-
mum economic intakes of amino acids.
Acknowledgements
We would like to acknowledge the Fundação
de Apoio a Pesquisa do Estado de São Paulo
(FAPESP) for financing the research and for
providing student scholarships. We also
thank the Programa de Estudante Convenio
de Pós Graduação (PEC-PG) for providing a
scholarship.
References
Bonato, M.A., Sakomura, N.K., Siqueira, J.C., Fernandes, J.B.K. and Gous, R.M. (2011) Maintenance
requirements for methionine & cysteine and threonine for poultry.
South African Journal of
Animal Science
41,
209-222.
Bowmaker, J.E. and Gous, R.M. (1991) The response of broiler breeder hens to dietary lysine and
methionine.
British Poultry Science
32,
1069-1088.
Burnham, D. and Gous, R.M. (1992) Isoleucine responses in broiler chickens. The requirement for
maintenance.
British Poultry Science
33,
59-69.
D'Mello, J.P.F. (2003) Responses of growing poultry to amino acids. In: D'Mello, L.P.F. (ed.)
Amino
Acids in Poultry Nutrition
, 2nd edn. CAB International, Wallingford, UK. pp.
237-263.
EFG Software (2003) Amino acid optimizer. Available at:
www.efgsoftware.net
(accessed October 2013).
Fisher, C. and Morris, T.R. (1970) The determination of the methionine requirement of laying pullets
by a diet dilution technique.
British Poultry Science
11,
67-82.
Fisher, C., Morris, T.R. and Jennings, R.C. (1973) A model for the description and prediction of the
response of laying hens to amino acid intake.
British Poultry Science
14,
469-484.
Gous, R.M. and Morris, T.R. (1985) Evaluation of a diet dilution technique for measuring the response
of broiler chickens to increasing concentrations of lysine.
British Poultry Science
26,
147-161.
Gous, R.M., Griessel, M. and Morris, T.R. (1987) Effect of dietary energy concentration on the response
of laying hens to amino acids.
British Poultry Science
28,
427-436.
Huyghebaert, G. and Butler, E.A. (1991) Optimum threonine requirement of laying hens.
British
Poultry Science
32,
575-582.
McDonald, M.W. and Morris, T.R. (1985) Quantitative review of optimum amino acid intakes for young
laying pullets.
British Poultry Science
26,
253-264.
MDIC (2012) Estudo da Viabilidade Técnica e Econômica destinado à implantação do Parque Produtivo
Nacional de Aditivos da Indústria de Alimentação de Animais de Produção. Available at:
http://
www.desenvolvimento.gov.br/arquivos/dwnl_1347635101.pdf
(accessed
21
March 2013).
Morris, T.R. (1983) The interpretation of response data from animal feeding trials. In: Haresign, W. (ed.)
Recent Advances in Animal Nutrition
. Butterworths, London, pp.
12-23.
Morris, T.R. (1999)
Experimental Design and Analysis in Animal Sciences
. CAB International,
Wallingford, UK.
Morris, T.R. (2004) Nutrition of chicks and layers.
World's Poultry Science Journal
60,
5-18.
