Chemical composition, rumen degradability, and digestibility coefficients o
f whole cardoon (Cynara cardunculus L.) seed were studied on two different
samples. Ruminal degradability of whole seed was determined by using the ny
lon bag technique in three rumen fistulated wethers. Four wethers were used
to perform digestibility studies on a basal diet (0.5 hay and 0.5 concentr
ate) and three diets more where cardoon seed was included at rates of 0.1,
0.2, and 0.3 at the expense of the basal diet in a 4 x 4 Latin-square desig
n. Additionally, the effects of three substitution rates (0, 0.1, and 0.25)
on rumen fermentation patterns and fibrolytic activity, measured by the in
sacco degradation of the lucerne hay included in the diets, were establish
ed using a 3 x 3 Latin-square design with three rumen fistulated wethers. C
rude protein (CP), ether extract (EE) and neutral detergent fibre (NDF) con
tents of whole cardoon seed were 225, 250, and 338 g kg(-1) DM, respectivel
y, the last being highly lignified (acid detergent lignin (ADF) = 104 g kg(
-1) DM) as consequence of its high hull proportion (45%). Rumen DM degradab
ility of whole seed was 56.8%, while CP degradability was 82.9%. Diet diges
tibility coefficients were maximum for 8.1 substitution rate, except for EE
, that showed a linear and quadratic increase through all diets. The estima
tes of seed digestibility obtained by the substitution and extrapolation me
thods were only similar for the 0.3 substitution rate. Digestibility coeffi
cients (%) obtained by substitution at this level were 83.8 for CP, 82.8 fo
r EE, 20.3 for NDE 56.1 for OM, and 59.2 for energy. Seed inclusion in diet
s up to a 25% had not effect on rumen fermentation patterns or on ruminal f
ibrolytic activity, in spite of the high content of fat rich in unsaturated
fatty acids (85.5% of total fatty acids) of this seed. (C) 2000 Elsevier S
cience B.V. All rights reserved.