The objective of this study was to evaluate the effects of vitamin and micromineral levels adjustment in the test diet on the total collection method for determination of apparent metabolizable energy (EMA) and apparent metabolizable energy corrected by nitrogen retention (EMAn) of soybean meal. Two treatments were compared: the test diet without or with adjustments in the amounts of choline chloride and vitamin-micromineral premix, when 40% of the reference diet was replaced with soybean meal. The traditional total feces collection method was used, with 360 Ross broilers from 15 to 23 days old. The chickens were allotted to batteries as a randomized block design, with two treatments and 12 ten-birds replicates (five males and five females). Mean values and respective standard errors for EMA and EMAn (kcal/kg) of soybean meal, as-fed basis, were of 2,462±29.62 and 2,269±25.80 for the adjusted diet and 2,353±26.18 and 2,191±23.88 for the diet without vitamin and micromineral adjustment. Adjustments of the amounts of choline choride and vitamin-micromineral premix in the test diet led to higher EMA and EMAn compared to the control test diet with no adjustments. Therefore, vitamin and micromineral levels in the test diet should be adjusted to the reference diet in experiments determining the metabolizable energy of feedstuffs used in poultry diets.
chicken; energy; methods; micronutrients; nutrition
