Effect of Low Levels of Dietary Protein on Growth, Protein Utilisation and Body Composition of Broiler Chicks from One to Twenty-Six Days of Age

Abstract

A trial was conducted to study the effect of lowering dietary crude protein (CP) with optimal amino acids profile on growth and whole body composition of broilers from 1 to 26 days of age. Four isocaloric (Metabolisable energy = 2925 kcal/kg) experimental broiler diets with CP levels of 23 (control), 22, 21 and 20% were formulated. Digestible lysine was maintained at 1.1% of the diet. A total of 1,760 day-old, Hubbard broiler chicks were randomly divided into 16 experimental units of 110 chicks and each diet was offered to 4 experimental units at random. Weight gain, feed intake and feed conversion ratio were not significantly affected by any of the treatment groups during the experimental period. Whole body composition and protein utilisation of broilers were also unaffected by the reduction in dietary CP content. However, total protein intake was decreased ( P<0.001) and protein efficiency ratio was increased ( P<0.001) linearly with low CP diets. Economics of different experimental diets fed to birds revealed that maximum economic returns were observed in 20% CP diet. The results suggested that dietary CP level could be reduced to 20% during starter period without any harmful effect on broiler performance when supplemented with critical amino acids.