Dl. De Brabander et al., Evaluation of the physical structure of fodder beets, potatoes, pressed beet pulp, brewers grains, and corn cob silage, J DAIRY SCI, 82(1), 1999, pp. 110-121
The physical structure of fodder beets, raw potatoes, ensiled pressed sugar
beet pulp, ensiled brewers grains, and corn cob silage was evaluated in di
ets containing concentrates and either corn silage or grass silage as the r
oughage source. In one series of experiments, the chewing activity of eight
cows was measured over 4 d. The beet pulp and fodder beets were added to t
he two roughage sources at two ratios [20:80 and 35:65, dry matter (DM) bas
is]. Potatoes, brewers grains, and corn cob silage were fed in a fixed amou
nt (5 to 6 kg of DM) with corn silage. The chewing indexes (eating and rumi
nating time per kilogram of DM ingested) for fodder beets and beet pulp ave
raged 34.3 and 32.3 min/kg of DM, respectively, and were hardly affected by
the nature of the roughage or by the inclusion ratio. The chewing indexes
for potatoes, brewers grains, and corn cob silage were 23.7, 56.6, and 41.6
min/kg of DM, respectively. In another series of experiments using 8 to 11
cows, the ratio of roughage to concentrates was lowered weekly by 5 percen
tage units, and the critical roughage portion of the diet was determined (i
.e., the amount just before a lack of physical structure was observed). The
roughage source was either fed alone or supplemented with about 4 kg of DM
of the experimental feed. The critical roughage portion of the diet decrea
sed when the experimental feeds were added; the decrease was greatest with
ensiled pressed beet pulp and was lowest with corn cob silage.