The digestibility and acceptability to sheep of chopped or milled barley straw soaked or sprayed with alkali

Abstract

SUMMARYThe main objective of the experiments described was to compare the effects of milling straw and/or soaking or spraying it with sodium hydroxide on its digestibility and acceptability to sheep. Some preliminary trials were made in the laboratory to compare different alkali treatments with respect to losses of organic matter, chemical composition and digestibility in vitro.In a feeding trial of Latin-square design, involving six sheep, the following treatments of barley straw were compared: C, chopped; M, coarsely-milled; OIL, chopped and soaked in 1·5% NaOH (9 g NaOH/100 g straw); CIH, chopped and soaked in 3·0% NaOH (18 g/100 g straw); CS, chopped and sprayed with 16 % NaOH (8 g/100 g straw); MS, milled and sprayed with 16 % NaOH. After treatments OIL and CIH the straw was washed; this caused losses of organic matter of 28 and 32%, respectively. For CS and CM the excess NaOH was neutralized by addition of 7·4 ml propionic acid/100 g straw.The straws were given with supplements of purified soya protein, minerals and vitamins. The digestibility of energy for the straw was (%): C, 40·4; M, 39·1; CIL, 65·0; CIH, 64·4; CS, 57·3; MS, 60·2. Dry-matter intake (g/kg W0·75 per day) was: C, 26·7; M, 36·2; CIL, 37·1; CIH, 44·2; CS, 48·4; MS 53·6.