Mahdie Nikbakhetzadeh; Heydar Zarghi; َAbolghasem Golian
Volume 22, Issue 1 , March 2020, , Pages 105-116
Abstract
The aim of this study was to investigate the effect of finisher diet nutrient density and slaughter age on energy and protein retention efficiency of broiler chickens. Three hundred 23-day-old Cobb-500 male broiler chickens were assigned in a 5×2 factorial arrangement of completely randomize ...
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The aim of this study was to investigate the effect of finisher diet nutrient density and slaughter age on energy and protein retention efficiency of broiler chickens. Three hundred 23-day-old Cobb-500 male broiler chickens were assigned in a 5×2 factorial arrangement of completely randomize design with 10 treatments, 6 replicates and 5 birds each. The experimental treatments included five nutrient levels of finisher diets (102.5, 100, 97.5, 95, and 92.5% levels of nutrient composition recommendations stated by the Cobb-500 Commercial Management Guide) and two slaughtered ages (38 and 46 days of age). As increased dietary nutrient density significantly and l inearlyincreased weight gain, feed efficiency, energy and protein retention efficiency and decreased maintenance energy requirements per unit of weight gain (P<0.05). By increasing slaughter age from d38 to d46, above indices significantly deteriorated (P<0.05). The highest residual feed intake belonged to birds fed the finisher diet with 97.5% of strain recommendation nutrients level. Dietary nutrient density level for optimal weight gain, feed efficiency, and energy and protein retention efficiency by linear broken line models were estimated 101.7, 98.7, 97.7 and 99.5% of strain recommendation, respectively. Whereas, these values were 2.3-5.5 percent less than those estimated by the quadratic broken-line model. As a conclusion, residual feed intake methodology can be a viable alternative to measure dietary energy efficiency. Formulation broiler finisher diet with nutrients concentration lowers than 97.5% of strain recommendation is not suitable.
fatemeh fouladvand; Ali Kiani; seyed davood sharifi; Arash Azarfar
Volume 21, Issue 2 , July 2019, , Pages 247-259
Abstract
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). ...
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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.