Effect of pressure toasting on the rumen degradability and intestinal digestibility of whole and broken peas, lupins and faba beans and a mixture of these feedstuffs
Jo. Goelema et al., Effect of pressure toasting on the rumen degradability and intestinal digestibility of whole and broken peas, lupins and faba beans and a mixture of these feedstuffs, ANIM FEED S, 76(1-2), 1998, pp. 35-50
The effects of pressure toasting of whole and broken peas, lupins and faba
beans on in situ degradability of protein and starch and intestinal digesti
bility of protein were studied. To test for associative effects on rumen de
gradability and intestinal digestibility after toasting, a mixture of peas,
lupins and faba beans was examined and results were compared with weighted
averages of separately processed feedstuffs. Pressure toasting for 3 min a
t 132 degrees C decreased in situ protein degradability of peas, lupins and
faba beans and in situ starch degradability of peas and faba beans, especi
ally when broken versus whole seeds were processed. Undegraded intake prote
in (%UIP) increased after toasting whole or broken seeds from 25% to 44% an
d 52% for peas, from 22% to 47% and 51% for lupins and from 20% to 48% and
57% for faba beans, respectively. Undegraded intake starch (%UISTA) increas
ed from 39% to 50% and 53% after toasting whole and broken peas and from 33
% to 53% and 60% for toasted whole and broken faba beans, respectively. Tot
al tract protein digestibility, measured after 12 h rumen and subsequent in
testinal incubation, remained unchanged for peas and faba beans, but decrea
sed from 99% to 98% for toasted whole lupins and to 97% for toasted broken
lupins. For toasted whole and broken faba beans, pressure toasting increase
d %UISTA from 33% to 53% and 60%, respectively. After pressure toasting, wa
shable fractions (W) of all legume seeds decreased for both constituents, t
he fractional rate of degradation (k(d)) Of protein decreased, while the k(
d) of starch increased. It was concluded that protein degradability decreas
ed after pressure toasting, without seriously affecting its total tract pro
tein digestibility. Toasting a mixture of peas, faba beans and lupins resul
ted in higher starch degradabilities than expected, based on the separately
treated feedstuffs. The k(d)'s Of the mixtures were higher than expected:
5.49 versus 4.29% h(-1) for whole seeds and 5.01 versus 4.18% h(-1) for bro
ken seeds, respectively. Consequently, %UISTA was lower than expected (47%
vs. 51% for whole seeds and 50% vs. 57% for broken seeds). (C) 1998 Elsevie
r Science B.V.