Biomass yield and feeding value of rye, triticale, and wheat straw produced under a dual-purpose management system
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Dual-purpose management of winter cereals for grazing and grain production provides highly nutritive forage for ruminants in the spring and may positively affect straw feeding value. A 2-yr study investigated the effect of spring defoliation of triticale, wheat, and rye at the tillering and stem elongation stages on total biomass, grain yields, and straw quality. Furthermore, straws of spring-defoliated and undefoliated (control) cereal crops were evaluated for nutritional value and voluntary intake as a means of assessing the efficiency of dual-purpose management systems from the winter feeding context as well. The feeding study consisted of 9 total mixed rations (TMR), each containing 35% triticale, rye, or wheat straw obtained under 3 spring-defoliation regimens. The TMR were individually fed to fifty-four 1-yr-old Anatolian Merino ewes for 28 d. Defoliation of the crops at tillering did not affect the total biomass production or grain yields. However, biomass and grain yields were reduced (P < 0.01) by 55 and 52%, respectively, in crops defoliated at stem elongation. Straw of spring-defoliated cereals had less NDF and ADF concentrations (P < 0.01) but greater CP (P < 0.01), nonfiber carbohydrates (P < 0.01), and ME concentrations (P < 0.01) compared with straw from undefoliated crops. The increase in the nutritive value of straw led to greater nutrient digestion (P < 0.01) and intake of DM and OM of ewes (P < 0.01). However, sheep live weight gain did not differ among treatments (P > 0.77). This study indicated that straw feeding value and digestibility can be increased through spring defoliation.