A collaborative study on the determination of cyst(e)ine in feedingstuffs

Work was carried out at eight laboratories to assess the Moore1 and Spencer and Wold2 procedures for the determination of cyst(e)ine in casein, fishmeal, extracted leaf protein concentrate, groundnut, soya bean and wheat. Variation between duplicate hydrolyses within laboratories was similar by both methods (mean coefficients of variation 4.3 and 5.0 %) and smaller than the variation between laboratories (mean coefficients of variation 14.8 and 14.3%). Both methods appear to provide a satisfactory means of estimating cyst(e)ine in feedingstuffs with the exception of casein, but the Moore1 method is preferred because methionine is estimated at the same time.