Effect of the Age of Chickens on the True Metabolizable Energy Values of Feed Ingredients

Abstract

White Leghorn male 4-week-old chicks and adult roosters were used to determine the effect of age on the true metabolizable energy (TME) and nitrogen-corrected true metabolizable energy (TMEn) value of ground yellow corn, dehulled soybean meal, wheat shorts, high-glucosinolate rapeseed meal, and dehydrated alfalfa meal. The TME and TMEn values of each ingredient were calculated from its gross energy value and the regression of energy voided as excreta on the weight of feed consumed. Variable intakes of corn and soybean meal were obtained with chicks by feeding different amounts of the feedstuffs and with roosters by varying the duration of the feeding period. Variable intakes of the other ingredients were obtained by the force feeding of the birds.The TME values of the feedstuffs in kcal/g of dry matter for chicks and roosters, respectively, were as follows: corn, 3.93 and 3.98; soybean meal, 3.24 and 3.11; wheat shorts, 3.12 and 3.07; rapeseed meal, 2.24 and 2.50; alfalfa meal, 1.22 and 1.38. The TMEn values of the feedstuffs for chicks and roosters, respectively, were as follows: corn, 3.76 and 3.88; soybean meal, 2.85 and 2.87; wheat shorts, 2.92 and 2.94; rapeseed meal, 1.99 and 2.24; alfalfa meal, 1.14 and 1.28. The TME values of soybean meal and rapeseed meal for chicks were 104% (P<.05) and 90% (P<.05), respectively, of the values obtained with roosters. The TMEn values of corn and rapeseed meal for chicks were 97% (P<.05) and 89% (P<.01), respectively, of the values for roosters. The TME and TMEn values of the other feedstuffs were not affected (P>.05) by the age of the bird.It appears that, with the exception of high-glucosinolate rapeseed meal, TME values obtained with adult roosters can be used in the formulation of diets for young growing birds.