Estimates of protein fractions of various heat-treated feeds in ruminant production

Abstract

Leaves of Cassava (Manihot esculenta Crantz) (CLM), Sesbania (Sesbania grandiflora) (SG), Leucaena (Leucaena leucocephala) (LL), Gliricidia (Gliricidia sepium) (GS) and Water hyacinth (Eichorniacrassipes) (WH) were subjected to heating at 60 (control), 100 or 140°C for 2 hours. The experimental treatments were laid out in a 5x3 factorial arrangement with 3 replications. The protein fractions of the leaves were estimated using The Cornell Net Carbohydrate and Protein System (CNCPS) model. Heating the leaves to temperatures of 140°C for 2 hours reduced the proportion of the protein in the A (NPN) and B2 (some fraction B2 escapes to the lower gut) fractions and increased the B3 (slowly rumen degradable fraction). The highest value for the B3 fraction was in water hyacinth (44% of the total crude protein) while in the other leave it was less than 10%. By contrast, the B2 fraction was low in water hyacinth (less than 20%) and high in the other leaves and especially in cassava leaf meal where it accounted for 66% of the total crude protein. The implication from these findings is that the B2 fraction may be a better indicator of the probable bypass protein value of leaves than the B3 fraction.