Determination of the proteins and carbohydrates fractions and estimative of the energy value of forages and by-products in Brazilian Northeast

Abstract

The present study aimed to characterize the carbohydrates and proteins fractions and to estimate the energetic value of native and adapted forages and agro industry by-products produced in Brazilian Northeast. To obtain the carbohydrates fractions, according with CNCPS system, were calculated the total carbohydrates, its fractions B2, C and the soluble neutral detergent components. For the determination of nitrogenous fractions, were analyzed the non-protein nitrogenous compounds, soluble and insoluble nitrogen in borate-phosphate buffer, protein nitrogen insoluble in neutral detergent and acid detergent. To the estimative of TDN, were used the equations proposed by NRC (2001). The by-products analyzed carbohydrates fractions varied from 19.35 to 58.52%; 9.95 to 61.44% and 15.35 to 70.06, for A+B1, B2 and C, respectively. In the forages, the fractions A, B1, B2, B3 and C of nitrogenous compounds presented variation from 9.84 to 42.33%; 1.58 to 11.47%; 48.63 to 80.10%; 0.70 to 6.13% and 0.43 to 2.86%, respectively. The estimated TDN of the forages varied from 48.30 to 65.42%, while for the by-products varied from 31.41 to 128.9%. The fractionation of nitrogen compounds and carbohydrates are simple methodologies and should be common practices in laboratories of feed evaluation.