The utilization of the products of green-crop fractionation by pigs and ruminants

Abstract

Fibrous green crops can be separated by mechanical methods into two fractions: a highquality fibrous feedstuff for ruminants and a liquid rich in protein, sugars and minerals for non-ruminants. The yields of crude protein (CP) (nitrogenx6.~5) which can be obtained from grasses and legume crops are substantially greater than for other methods of crop or animal production (Davys, 1973) (Table I), and the concentration of protein in grass and legume crops when harvested at an immature stage of growth is greater than that required by the most productive ruminant animals. Results from various experiments (Greenhalgh, Reid 8z Aitken, 1971; Maguire & Brookes, 1973; A. S. Jones, M. Kay, A. Cadenhead & A. Macdearmid, unpublished results) show that the concentration of CP in the dry matter (DM) of green crops harvested frequently (4-5 cutdyear) is greater than that required by highly productive beef and dairy animals (Agricultural Research Council, 1965). Developments in the mechanical processing of green crops make possible the extraction of protein from many plant species hitherto not utilized in agricultural systems. Several types of processing equipment have been used for the fractionation of green crops, the most widely used being the pulper and belt-press, the screw-press and sugar-cane rollers. Throughout the history of greencrop fractionation several species of plants have been investigated as possible alternative sources of protein to the twenty to thirty plant species currently considered as major protein-producing crops (see Pirie, 1971). Table I. Yields of edible crude protein (nitrogenx6.25) produced under various fanning systems (UK) (a@ D a y , 1973) Animals crops Leaf protein Upland grazing Intensively reared Dairyherd Wheat grain Potato (Solanurn tuberosum L.) Field bean (ViCiOfabo L.) Lucerne (Medicago ~ ~ t i o o L.) OT Clover (Trifolium sp.) Cocksfoot (Dactylir glumeruta L.) Wheat and Mustard (Brasaica ap.) Yield 5*150