Nutritive value of green forage and crop by-products of Cyn&ra cardunculus

Abstract

The nutritive value of cardoon (Cynara cardunculus L.) green forage (GF), dry leaves (DL) and straw (S) was studied from chemical composition analyses and from voluntary intake, digestibility and rumen degradability estimations obtained using adult wethers. Aptitude For bring ensiled according to the wilting period was also evaluated making silages with fresh forage and after 24 and 94 hours of wilting. Green forage had a high nutritive value, as shown by low levels of fibre and lignin and its very high digestibility (86 % for OM). Nevertheless, its voluntary intake was relatively low (64 g DM.kg(-1) LW0.75), although very variable among animals. Fermentation characteristics of the GF silages were good and wilting reduced silage losses andimproved the duality of silages. Nutritive value of DL was high, but limited only by a moderate crude protein content. Supplemented with urea, it hadan OM digestibility similar to a medium-good quality hay (65.9 % average) and a voluntary intake equivalent to a good quality grass (75.9 g DM.kg(-1)LW0.75). Finally, S was a typical fibrous and low protein forage, but whensupplemented with urea, it had an intake and a digestibility higher than those of cereal straws. Variations in digestibility for OM and energy among the different non-preserved Cynara cardunculus forages showed close relationships with fibre fractions, especially with the acid detergent lignin content.