Effect of urea on growth, food utilisation and body composition of chicks

1. A study was made of the effect of urea, added to chick diets of different protein contents with or without added methionine, on growth and body composition. 2. In chicks fed on diets containing urea, concentrations of urea were higher in the blood and digestive tract but not in the excreta, as compared with chicks fed on diets containing soyabean as the only source of protein. 3. Urea-nitrogen was utilised better for growth when the diets were supplemented with methionine rather than unsupplemented. 4. Body fat content was decreased with the increase in protein content of the diet. Addition of urea decreased body fat less than an equivalent amount of protein. 5. There was no correlation between body fat and body weight in groups fed on diets containing 189 or 216 g protein/kg, but there was a significant correlation between these variables in groups fed on diets containing 292 g protein/kg or either concentration of urea. This phenomenon was much more pronounced in diets not supplemented with methionine.