Effect of dietary energy and amino acids on meat yield and gastrointestinal tract development of naked neck broilers in hot climate

Abstract

An investigation was conducted to study the requirements of energy and critical amino acids for growth, meat yield and digestive tract development of naked neck broilers during summer (room temperature minimum 29.6 degree to 33.9 degree C and maslnium 34.3-39. degree C). Day-old naked neck chicks (192) were distributed in 24 groups of8 each. Eight diets (4 dietary regimens-DR with different levels of energy and limiting amino acids x 2 meal type-with fish-meal or all vegetable meal) were formulated following NRC (1994) recommendations of crude protein (23% CP) and metaboliozable energy, 3200 ME and limiting amino acid concentration (DR 1) , 100% AA of NRC (1994) and 3200 kcal ME without protein in consideration (DR 2). 108% AA of NRC standard and 3000 kcal ME (DR3), 94% AA of NRC (1994) and 3000 kcal ME (DR 4) with FM and without FM (all VM), Each diet was fed to 3 replicated groups of birds during starter (0-3 week) and finisher (4-6 week) phases. During starting phase, the birds fed DR 2 had higher body weight than those in dietary regimens D3 or D4, while at 6 week of age body weights accrued in D1 and D2 were higher than those in D3 or D4. Additional amino acids at 3000 kcal/kg based diet did not improve growth. There was no difference in the weight of digestive organs between treatments or energy levels. The weight of caeca was higher in all VM based diets than FM based diets. Carcass traits differed due to dietary regimens being higher at D2. Cut-up parts did not differ signiicantly due to dietary regimens. As the prediction equations in the present study were highly significant, there is a possibility of manipulating the breast and leg meat yield by altering dietary amino acid content.