The effects of different pelleting temperatures on the activity of cel
lulase, bacterial amylase, fungal amylase, and pentosanase were tested
. Samples of a commercial barley-wheat-soybean diet containing differe
nt enzyme preparations were pelleted at 60, 70, 80, 90, and 100 C (pel
let temperature measured at the die outlet) through a die containing h
oles 2.5 mm in diameter. Enzymatic analyses were conducted on either s
oluble substrates or by measuring the ability of the tested enzymes to
decrease the viscosity of the diet. Measurements made on soluble subs
trates suggest that cellulase, fungal amylase, and pentosanase maintai
ned activity when being pelleted at temperatures up to 80 C and bacter
ial amylase maintained activity at temperatures up to 90 C. Pentosanas
e and amylases showed little or no effect on the viscosity of the diet
. Cellulase addition decreased the viscosity at all temperature levels
, even after being pelleted at 90 and 100 C (P < 0.05). No cellulolyti
c activity was detected on the soluble substrate after these pelleting
temperatures. Measurements on a soluble substrate might therefore not
always reflect the true stability of a preparation because the abilit
y of a carbohydrase to decrease the viscosity of the digesta is import
ant to its effect in the gastrointestinal tract. Measurements on solub
le substrates suggest that cellulase, fungal amylase, and pentosanase
can be pelleted at temperatures up to at least 80 C and bacterial amyl
ase up to 90 C without a considerable loss in analyzed activity.