In vivo determination of domestic quail (Coturnix japonica) muscle development by ultrasonography as a function of energy levels.

The aim was to evaluate the growth and meat production and some meat quality characteristics of domestic quail (Coturnix japonica) as a function of metabolizable energy (ME) levels in the diet and to adjust predicting equations in ratio to area pectoralis major muscle of the carcass through the ultrasound. Two hundred and seventy mixed sex quail from 7 to 49 days old were distributed in three treatments (7 to 21 days old, diets with 2700; 2900 and 3100 kcal ME/kg; from 21 to 49 days, diets with 2900, 3050 and 3200 kcal of ME/kg), with five replications per treatment. Ultrasonography was performed at 21; 35 and 49 days of age in the pectoralis major muscle to determine prediction equations through multiple linear regression. Feed intake (FI) and feed efficiency (FE) were linearly influenced (P < 0.05) by energy levels in both phases evaluated. Regarding sensory analysis, there was no interference of ME levels on sensory attributes. The equation for predicting breast area was Y = 0.00271ME + 0.25411Age-9.58002, R = 74.25%. It is concluded that increasing the energy level of the feed from 2700 to 3100 kcal ME/kg reduces FI and improves the FE of quail. The increase in carcass fat from 35 days of age does not harm the physical and sensory characteristics of the meat. The ultrasonography in vivo of the M. pectoralis major, considering the age and energy level of the diet, made it possible to predict the pectoral muscle are a with higher reliability.