Effect of supplementing limiting amino acids on growth performance and carcass traits of Gramasree male chicks fed with low protein diets

An experiment was conducted to study the effect of reduced dietary crude protein (CP) diet supplemented with limiting amino acids on growth performance and carcass traits of Gramasree male birds up to eight weeks of age. A total of 280 day-old chicks were allotted randomly under five dietary treatments each with four replicates of 14 chicks under completely randomized design. The different dietary treatments viz., control diet (T1) was formulated as per ICAR (2013) nutrient requirements for Indian improved native birds with 21 per cent CP and 2800 kcal/kg Metabolizable energy (ME) using corn, soya bean meal, wheat bran and de-oiled rice bran. Treatment diets T2, T3, T4 and T5 were formulated by reducing CP content to 20, 19, 18, and 17 per cent, respectively with isocaloric value of 2800 kcal/kg ME and supplemented with methionine, lysine, threonine and tryptophan to meet the daily requirements. Weekly body weight and feed consumption were recorded. For the carcass study, two birds from each replicate were randomly selected and slaughtered humanely at eighth week of age. The results showed that the final body weight and cumulative weight gain were comparable among the treatments. The lowest cumulative feed intake and feed conversion ratio (FCR) were observed in 17 per cent CP containing treatment (T5), which was not significantly different from rest of the groups. The mean per cent breast meat yield, giblet yield, dressing yield and ready-to-cook yield were comparable among the five dietary treatments. The mean abdominal fat content in birds fed with 18 and 17 per cent (T4 and T5) were significantly (p<0.05) higher than the other treatment groups.The overall results indicated that the dietary CP of Gramasree male chicks can be lowered up to 17 per cent with the supplementation of methionine, lysine, threonine and tryptophan without affecting the growth performance of birds.

Keywords: Low CP diet, limiting amino acids, Gramasree chicks, carcass trait