Determination Of Net Energy Of Sorghum And Sunflower Seed Meal For Layer-type Chicks At 2-4 And 5-8 Weeks Of Age

Accurate evaluation of feed efficiency is of great significance for rational selection of feed materials,optimization of feed formula and reduction of feed cost.Metabolizable energy system is widely used in poultry nutrition.Metabolizable energy system underestimates the effective energy of energy feedstuff and overestimates the effective energy of protein feedstuff.The net energy system takes into account the loss of heat increment on the basis of metabolizable energy and reflects the energy used for maintenance and production of poultry.Therefore,the net energy system can reflect the effective energy value of feedstuff more accurately than the metabolizable energy system.In this study,an open respiratory calorimetric chamber was used for energy metabolism test.The metabolizable energy and net energy values of sorghum and sunflower meal for layer-type chicks aged 2 to 4 weeks and 5to 8 weeks were determined by indirect calorimetric method combined with nesting algorithm.In experiment 1,the metabolizable energy and net energy values of sorghum and sunflower seed meal were measured in layer-type chicks aged 2 to 4 weeks.A total of 180 1-day-old Jingfen No.6 layer-type chicks with similar initial body weight were randomly divided into 3 groups with 4 replicates per group and 15 chicks per replicate.The chicks were fed with basal diet,sunflower meal diet(20% sunflower meal replaced the basal diet)and sorghum diet(50% sorghum replaced the basal diet),respectively.At 17 days of age,6 chicks were selected from each replicate of each diet group,in total of 24 chicks.The experimental chicks were transfered into a respiratory calorimeter chamber with 6 chicks in each metabolic chamber and there were 4 metabolic chambers for one experimented diet.After 3 days of acclimation,the chicks underwent respiratory calorimetry for 3 consecutive days,and then fasting for 3 days.The initial and final weights of the chickens were recorded.The results showed that the metabolism of sorghum and sunflower seed meal can value were 12.25 MJ/kg and 7.76 MJ/kg,respectively;The net energy values were 10.6 MJ/kg and 6.63 MJ/kg for sorghum and sunflower seed meal,respectively.The net energy/ME values were 87% and85% for sorghum and sunflower seed meal,respectively.In experiment 2,the metabolizable energy and net energy values of sorghum and sunflower seed meal were measured in layer-type chicks aged 5 to 8 weeks.A total of 180 1-day-old Jingfen No.6 layer-type chicks with similar initial body weight were randomly divided into 3 groups with 4 replicates per group and 15 chicks per replicate.The chicks in 3groups were fed basal diet,Kwai seed meal diet(20% kwai seed meal substituted for basal diet)and sorghum diet group(50% substituted for basal diet),respectively.At 41 days of age,6 chicks were selected from each replicate of each diet group,in total of 24 chicks.The experimental chicks were transfered into a respiratory calorimeter chamber with 6 chicks in each metabolic chamber and there were 4 metabolic chambers for one experimented diet.After 3 days of acclimation,the chicks underwent respiratory calorimetry for 3 consecutive days,and then fasting for 3 days.The initial and final weights of the chickens were recorded during the period of respiratory calorimetry.The results showed that the metabolizable energy values of sorghum and sunflower meal were 12.85 MJ/kg and 8.25 MJ/kg,respectively.The net energy values were 11.21 MJ/kg and 6.64 MJ/kg for sorghum and sunflower seed meal,respectively.The NE/ME values were 87% and 81%,respectively.The results of this study showed that the effective energy values of sorghum and sunflower seed meal were significantly affected by age,and the AME and NE values increased with age.The net energy of sorghum and metabolizable energy of sunflower seed meal were significantly affected by age.