Determination of energy requirement for maintenance and growth of growing turkey using comparative slaughter technique and relative growth index

The aim of this study was to determine energy requirement for maintenance (MEm) and to estimate efficiency of energy utilization for gain (kg) using comparative slaughter technique (CST) and relative growth index (RGI: gain/BW0.75) in growing turkey chicks from one to four kg of live body weight (LBW). Forty male turkey chicks (24 days of age, 800 ± 93 g LBW) were fed a standard diet (12.3 MJ ME) up to 4 kg of LBW. Apparent metabolizable energy (AME, and AMEn), nutrient digestibility of the diet, and energy balance were determined at two and three kg of BW. In CST, twenty chicks were randomly killed at four stages (five birds at each stage) at 1119 ±60, 2539 ±93, 3528 ±68, 3957 ±82 g of body weight, and the chemical composition of carcass were measured. Maintenance energy requirement (MEm) and efficiency of energy utilization for gain were determined by linear regression in CST. In RGI, the MEm and energy for growth were estimated by a regression of ME intake and relative daily gain. The results showed that in CST, MEm and efficiency of energy utilization for gain were 450 (kJ/kg BW0.75/d), and 56% respectively. In RGI, the MEm and energy for growth were 3.66 (kJ/g BW0.75/d), and 10.4 kJ per g gain. In conclusion, using RGI method is recommended to estimate energy requirement for maintenance and growth in growing turkey due to its simplicity.