Prediction of metabolizable energy in poultry feedstuffs basis on their chemical composition

Determination and knowledge quality and nutrient content in poultry feed resources are necessary for proper use of them in scientific poultry diet. In order to prepare chemical composition tables of feedstuffs in the country, this research was carried out on the most consuming poultry feed resources including corn, wheat, barley grains and wheat bran, produced in Iran. All of the samples were analyzed for crud protein, crud fiber ether extract and gross energy by the standard methods. Therefore, this sample examined for metabolizable energy by the Sibbald method (1976). Mean values of crud protein content of corn, wheat, barley grain and wheat bran were 8/68, 11/28, 10/41 and 16/9 percent respectively. The highest CV belonged to corn grain (7/32 %) and the less CV was that of barley grain (4/93%). Average value of ether extract content of corn, wheat barley grain and wheat bran were 3/03, 1/25, 1/13 and 2/65 percent. The CV of the barley (19/53%) was the highest and of wheat bran (8/68%) was the lowest. Mean values content of crud fiber of corn, wheat, barley grain and wheat bran were 3/6, 3/86, 6/75 and 11/04 percent respectively. The barley grain had the highest CV (16/88%) and wheat grain had the lowest CV (10/47%). Means of gross energy content of corn, wheat, barley and wheat bran were 4/33, 4/29, 4/29, and 4/48 (kcal/g) respectively. The highest CV belonged to corn grain (1/11 %) and the less CV was that of wheat bran (0/21%). The mean values AME content of corn grain, wheat, barley grain and wheat bran were 3/13, 2/84, 2/36 and 1/46 (kcal/g) respectively. The highest CV belonged to wheat bran (16/87%) and the lower CV was that of corn grain (7/34 %). Means values of AMEn content of corn, wheat, barley grain and wheat bran were 3/36, 3/18, 2/88 and 11/04 (kcal/g) respectively. The wheat bran had the highest CV (14/91 %) and corn grain had the lowest CV (6/06%). The TME values of corn, wheat, barley grain and wheat bran were 3/90, 3/42, 3/13 and 2/56 (kcal/g). The high CV belonged to corn grain (18/47 %) and the lower CV was that of wheat bran (8/1%). Mean values of TMEn content of corn, wheat barley grain and wheat bran were 3/62, 3/39, 3/14 and 2/12 (kcal/g) respectively. The wheat bran had the highest CV (16/1%) and corn grain had the lowest CV (7/8 %). Since biological methods of evaluating metabolisable energy content of feedingstuffs used for poultry takes considerable amount of time and finance, the indirect method of predicting metabolisable energy based on its chemical composition has been increasingly used. The latter method is based on correlation coefficient that exists between metabolisable energy content of feedingstuffs and their chemical composition. Colorimetric, Polarizer, Copper and Acid hydrolysis methods were applied to determine starch content and Colorimetric method to determine free sugars (glucose, fructose and sucrose) of above cereals. To determine the metabolisable energy content of above feedingstuffs the prediction formula of Carpenter and Clegg (1956), Sibbald et al (1963), Janssen et al (1979-1989) and European Economic Committee (EEC) were used and compared with each others. Also the effect of different starch analysis methods on each metabolisable energy prediction method was evaluated. The results showed that there was significant difference (P0.01) between metabolisable energy prediction methods applied. Apart from Janssen et al (1979-1989) formula there was significant effect (P 0.01) of starch analysis methods on predicting formulas. As for metabolisable energy content of each cereal, wheat grain showed highest metabolisable energy (15.54 MJ/Kg) by Carpenter and Clegg formula, while highest starch value (67.58%) with Colorimetric method, barley grain showed highest metabolisable energy (15.16 MJ/Kg) by Carpenter and Clegg formula, while highest starch value(57.25%) with Acid hydrolysis, corn grain showed highest metabolisable energy (16.82 MJ/Kg) by Carpenter and Clegg formula, while highest starch value(72.54%) with Copper method. Janssen et al (1979-1989) formula gave lowest metabolisable energy valueswheat grain (13MJ/Kg), barley grain (12.01MJ/Kg) and corn grain (13.7MJ/Kg) respectively. Correlation coefficient between metabolisable energy prediction formulas for each one of cereal showed that Carpenter and Clegg formulary had high correlation (P 0.01) with any of Sibbald et al (1963) and European Economic Committee (EEC) ones.