THE CHEMICAL-COMPOSITION, DIGESTIBILITY AND ENERGY VALUE OF FERMENTEDAND UREA-TREATED WHOLE CROP WHEAT HARVESTED AT 3 STAGES OF MATURITY

The metabolizable energy (ME) content, digestibility in viva and chemi cal composition of fermented and urea-treated whole crop wheat (WCW) f orage harvested were measured at different maturities. Over 2 years, t wenty-four wheat forages (cv. Slepjner, Hussar and Cadenza) were harve sted at 376, 516 and 632 g dry matter (DM) kg(-1 )in Year 1 and 341, 4 67 and 544 g DM kg(-1) in Year 2 (Cuts 1, 2 and 3 respectively). Forag es were conserved In 200-iota barrels with or without a formic acid-ba sed additive and with urea in Cuts 2 and 3 (20 or 40 g kg(-1) DM). Che mical composition, digestibility in vivo and energy losses in faeces, urine and methane were measured in wethers fed 12 g DM kg(-1) live wei ght. Respective ranges in pH, crude protein, water-soluble carbohydrat es, starch and neutral detergent fibre plus amylase (NDFA) contents we re 3.8-8.5, 89-394, 2-43, 23-424 and 306-655 g kg(-1) DM. ME content, digestible organic matter content (DOMD) and digestibilities of starch and NDFA ranged between 8.4 and 15.7 MJ kg(-1) DM, 558 and 708 g kg(- 1 )DM, 0.901 and 0.999 and 0.362 and 0.693 respectively. Predicted met hane energy losses were poorly correlated with measured values (r(2) < 0.45) in both years, but this accounted for less than 0.1 MJ ME kg(-1 ) DM. Significant (P < 0.05) effects of maturity on the ME/DOMD ratio were observed and ascribed to differences in the extent of fermentatio n. Therefore, treatment application and maturity exert considerable in fluence on the ME content of WCW.