Changes in chemical composition in male XXXX during growth.

@entity1522 @entity233 @entity535 @entity2569 @entity367 @entity2596 @entity2574
In growing animals, requirements for many nutrients (and energy) are determined by the retention of these nutrients. During growth, this retention changes in an absolute way and also between nutrients and energy, resulting in changing nutrient requirements. The objective of this study was to describe the changes in chemical composition in male growing @entity233 . The serial slaughter technique was used to determine the composition of @entity1522 , lipid, ash, and water in feather-free body (FFB) and feathers in male @entity233 offered feed ad libitum from 1 to 15 wk of age. Allometric relations were used to describe changes in body composition. The feather content in the body decreased from 6% at 1 wk of age to less than 3% at 15 wk of age. The water and protein content in FFB decreased with increasing FFB mass, with allometric scalars (b) of, respectively, 0.967 and 0.970, whereas the lipid content increased with increasing FFB mass (b = 1.388). The water, protein, and ash content in fat-free FFB was constant and represented, respectively, 71.6, 24.2, and 4.2% of the fat-free FFB mass. The @entity535 content of FFB protein was relatively constant and only the @entity2569 content decreased between 1 and 15 wk of age, whereas the Ile content increased. Feathers were mostly composed of protein, and the protein content did not change during growth. During growth, the Lys, Met, Trp, His, Tyr, @entity2574 , and @entity367 contents in feather protein decreased, whereas the @entity2569 , @entity2596 , and Ser contents increased. The contribution of feathers to whole-body @entity535 retention ranged from 5% for His to 33% for @entity2569 . On average, the weight gain of FFB contained 21.3% protein and 12.7% lipid, corresponding to an energy content of 10.1 kJ/g. The weight gain of feathers contained 87.4% protein, corresponding to an energy content of 20.4 kJ/g. The results of the present study can be used in a factorial approach to determine nutrient requirements in growing @entity233 .
