THE FEEDING VALUE OF STRAW FROM DIFFERENT GENOTYPES OF BARLEY WHEN GIVEN TO AWASSI SHEEP

Barley straw constitutes up to half of the dry-matter intake of Awassi sheep in areas of Syria where the rainfall is 200 to 350 mm. The genotype of barley planted could therefore, through the nutritive value of its straw, significantly affect flock production levels. Selection of suitable barley genotypes may have greater economic potential as a means of improving roughage feeding quality in these areas than chemical or physical processing. The voluntary intake and digestibility of the unsupplemented straw of three genotypes of barley was evaluated with Awassi castrated male sheep. The voluntary organic-matter (OM) intakes of hand-harvested Beecher, Arabic Abied and ER/Apam straw were 22.2, 34.7 and 27.0 g/kg M0.75 per day and OM digestibility coefficients were 0.39, 0.44 and 0.42. The factors affecting voluntary intake and digestibility appeared to be the proportions of leaf and stem. Beecher straw had less leaf and more stem than the other two genotypes. The chemical composition and in vitro cellulase digestibility of the leaf indicated that it had a higher potential feeding value than stem. ER/Apam appears to be an example of a genotype which under dry environmental conditions combines higher barley grain yields with more acceptable straw feeding value than several other genotypes evaluated.