Animal Feed Science and Technology, 27 (1989) 117-125 117 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands Yield, Composition and Nutritive Value of Leaf Protein Concentrates from Mixed Forages of Cereals and Legumes ELZBIETA PISULEWSKA 1, PIOTR HANCZAKOWSKI 2 and PAWEL PISULEWSKI2 1Agricultural University, Department of Agronomy, Al. Mickiewicza 21, Krak6w (Poland) 2Institute of Animal Production, Department of Animal Nutrition and Physiology, 32-083 Balice (Poland) ( Received 3 March 1988; accepted for publication 16 March 1989 ) ABSTRACT Pisulewska, E., Hanczakowski, P. and Pisulewski, P., 1989. Yield, composition and nutritive value of leaf protein concentrates from mixed forages of cereals and legumes. Anim. Feed Sci. Technol., 27: 117-125. Leaf protein concentrates (LPC) were produced from high- and low-legume (high-cereal) mix- tures of forage. The forages were obtained by sowing seed mixtures containing either 60% legume and 40% cereal or 60% cereal and 40% legume (air dry matter). The legumes used were vetch and pea, and the cereals were wheat, triticale and barley. Average green- and dry-matter yield was highest for high-legume mixtures containing vetch. Barley-containingmixtures gave higher yields than those containing wheat or triticale. The LPC were analysed for their gross composition and amino-acid content. Biological value and true digestibility of LPC protein were estimated in rats using the Thomas-Mitchell balance method. Protein content of LPC was low (32.3-46.7% dry matter basis). All concentrates were poor in sulphur amino acids and their content of basic amino acids was unexpectedly low. Protein extracted from low-legume forages was higher in biological value than that from high-legume forages, while true digestibility did not differ significantly. It can be concluded that increasing the proportion of legume in mixed (legume-cereal) forages increases the yield of green and dry matter per unit area, but significantly decreases nutritive value of extracted protein. INTRODUCTION Leaves are the most abundant source of protein. Unfortunately, factors such as their high fibre and water content limit their utilization by non-ruminants. Leaf protein can be mechanically extracted from leaves by the process pro- posed by Pirie (1942). Leaf protein concentrates (LPC) are produced by grinding green matter, expressing the juice and coagulating protein dissolved in this juice. Such concentrates contain ~ 50% of protein and are practically 0377-8401/89/$03.50 © 1989 Elsevier Science Publishers B.V.