Urea treatment of whole‐crop triticale at four growth stages: effects on chemical composition and on in vitro digestibility of cell wall

Abstract

AbstractThe objective of this study was to evaluate the preservative and upgrading potential of urea added to whole‐crop triticale. Triticale, harvested at different growth stages according to Feekes' scale (10.51, 10.54, 11.1 and 11.2), was ensiled with four levels of urea (0, 30, 60 and 90 g kg−1 dry matter (DM)) and stored in plastic bags for 60 days. Data were analysed as a factorial design with growth stage and urea level as the main factors. Urea was extensively hydrolysed (more than 90% of added urea). Urea breakdown was not affected by urea level (P > 0.05) but decreased significantly with growth stage (P < 0.001). Microbial activity measured by pH, volatile fatty acid production and total non‐structural carbohydrate concentration was significantly reduced by the urea level. Urea treatment significantly (P < 0.001) increased water‐soluble and ammonium nitrogen; more than 85% of the added nitrogen was retained. Application of urea at a rate of 60 and 90 g kg−1 DM significantly (P < 0.05) reduced the neutral detergent fibre (NDF) content and increased (P < 0.05) the NDF and acid detergent fibre in vitro digestibility. Whole‐crop triticale harvested at later growth stages (approximately 60% DM) can be effectively preserved and upgraded by ensiling with 60–90 g urea kg−1 DM. Copyright © 2006 Society of Chemical Industry