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Poultry diets are typically formulated to meet metabolisable energy (ME) and other nutritional needs. ME does not account for the heat increment (HI) of birds fed diets of differing chemical composition. Formulating for energy needs based on the net energy (NE) system (AME minus HI) accounts for HI differences between diets. HI comprises heat associated with prehension, digestion and metabolism of ingested feed. Minimising the feed HI may therefore improve conversion efficiency of feed energy to energy used for production. Classen (2013), amongst others, has reported that the relationship between ME and digestible amino acids is variable depending on the source of energy in the diet (lipid, carbohydrate, protein) among other factors. De Groote (1974) determined the relative efficiency of energy utilisation from carbohydrate (100%), protein (78%) and lipid (133%). Thus, birds fed diets containing high lipid and low protein may have a lower HI than birds fed high protein, low lipid diets. A study was conducted to determine if low lipid, high protein and high lipid, low protein diets had different HI, NE, NNE:AME (to account for different dietary AME values) and retained energy (RE) in broilers. |
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