Variation in the metabolizable energy values of diets and dietary components fed to adult roosters.
Two experiments were conducted to measure the variability of the M.E. values of diets and dietary ingredients fed to adult S.C.W.L. roosters. The first experiment was concerned  with the variability between birds and days, the acclimatization to dietary change and the effect of the nitrogen correction. The standard error of the mean dietary M.E. value appropriate to an individual bird on one day was found to be 0.073 kcal./g. Increasing the number of days of excreta collection reduced this value slightly faster than did increasing the number of birds. The results suggest that the dietary acclimatization period should be at least 48 hr. The nitrogen correction was very small and of doubtful value. The second experiment comprised 5 bioassays in each of which 6 different samples of grain were fed at 3 levels of dietary inclusion (25, 50 and 75%) to birds drawn from the population used in the first experiment. The standard error of the mean dietary M.E. value was in agreement with the earlier value. The variance of ingredient M.E. values increased as the level of dietary inclusion decreased. Standard deviations of the mean M.E. value of an ingredient predicted from the data of the first experiment were in agreement with actual values observed in the second experiment. It is concluded that the adult rooster is suitable for use in bioassays designed to measure the M.E. values of diets and ingredients.
D000064:Acclimatization; D000821:Animal Feed; D000818:Animals; D002645:Chickens / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism; D002523:Edible Grain; D004734:Energy Metabolism; D006799:Housing, Animal; D008297:Male; D008894:Milk Proteins / Q000378:metabolism; D008903:Minerals / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D014815:Vitamins / Q000378:metabolism
D004041:Dietary Fats; D008894:Milk Proteins; D008903:Minerals; D014815:Vitamins; D009584:Nitrogen