Evaluation of protein quality of poultry feedingstuffs. 3. Expeller-processed oilseed cakes

Abstract

SummaryA study was made to evaluate the protein quality of groundnut cake (GN), mustard cake (MS) and cottonseed cake (CS) and to find a suitable laboratory test for predicting the protein quality of these cakes for chicks. Different oilseed cakes varied considerably in their crude protein, true protein and crude fibre content. The nitrogen solubility was higher in GN (87·7%) followed by MS (78·7%) and CS (60·9%). A similar trend was evident with regard to in vitro protein digestibility. The GN protein was, however, lower in available lysine (2·54%) than MS (3·97%) or CS (3·19%). The albumin, globulin, prolamin and glutelin fractions accounted for 74·1, 57·0 and 48·0% in GN, MS and CS, respectively. The nitrogen solubility, globulin content and modified relative nutritive value (RNV) correlated (P < 0·05) with gross protein value (GPV). The accuracy and precision of various regression equations for predicting the quality of protein in GN, MS and CS are discussed.