Article contents
A comparative evaluation of functions for partitioning nitrogen and amino acid intake between maintenance and growth in broilers
Published online by Cambridge University Press: 18 September 2007
Summary
The results from three types of study with broilers, namely nitrogen (N) balance, bioassays and growth experiments, provided the data used herein. Sets of data on N balance and protein accretion (bioassay studies) were used to assess the ability of the monomolecular equation to describe the relationship between (i) N balance and amino acid (AA) intake and (ii) protein accretion and AA intake. The model estimated the levels of isoleucine, lysine, valine, threonine, methionine, total sulphur AAs and tryptophan resulting in zero balance to be 58, 59, 80, 96, 23, 85 and 32 mg/kg live weight (LW)/day, respectively. These estimates show good agreement with those obtained in previous studies. For the growth experiments, four models, specifically re-parameterized for analysing energy balance data, were evaluated for their ability to determine crude protein (CP) intake at maintenance and efficiency of utilization of CP intake for producing gain. They were: a straight line, two equations representing diminishing returns behaviour (monomolecular and rectangular hyperbola) and one equation describing smooth sigmoidal behaviour with a fixed point of inflexion (Gompertz). The estimates of CP requirement for maintenance and efficiency of utilization of CP intake for producing gain varied from 5·4 to 5·9 g/kg LW/day and 0·60 to 0·76, respectively, depending on the models.
- Type
- Modelling Animal Systems Paper
- Information
- The Journal of Agricultural Science , Volume 146 , Issue 2: Modelling Animal Systems , April 2008 , pp. 163 - 170
- Copyright
- Copyright © Cambridge University Press 2007
References
REFERENCES
- 13
- Cited by