Sugar beets (Beta vulgaris var. altissima) are grown around
the globe and are a valuable option in modern crop rotation
strategies. Last year, US farmers harvested 29.9 million tons
of sugar beets on 1.3 million acres. Over the past 10 years,
sugar beets accounted for more than 53% of US sugar
production.
Sugar beets are tubers that grow in the ground much like
garden beets, carrots or turnips. In autumn, farmers "campaign"
or harvest the sugar beets by unearthing the tubers and
trucking them to processing plants, where they are dumped in
mountainous piles waiting their turn to be processed. First,
dirt and debris are sifted and washed from the surface and the
sugar beets are sliced into cossettes (chips). These cossettes
are then steeped and (or) washed with hot water in
countercurrent flow diffusers to extract the sugar. The
extracted juice is further processed to produce granulated
sugar suitable for the sweetener market and the residue (pulp)
is dried. For ease of transportation and handling, most of the
fibrous beet pulp is milled into 3/8-inch diameter pellets.
The gray, speckled pellets are sold primarily into the
livestock feed market and have found favor in dairy cattle and
horse diets as "dried plain beet pulp" (Section 60.36; AAFCO
2005 Official Publication). Some beet fiber has begun to find
its way into human foods with such disparate applications as
decorative sprinkles on baked goods to supplemental fiber
laxatives. This latter application is where beet pulp has found
favor in petfoods, as a supplemental fiber source to promote
bowel regularity, stool consistency and overall
gastrointestinal (GI) health.
There has been some confusion by consumers regarding beet pulp.Regularity or laxation from fibers is attributed, among
other things, to "bulking" and water-binding capacity in the
lower GI. These combine to increase GI luminal contents and
stimulate gut motility. One would predict that beet pulp, with
its high concentration of total dietary fiber (TDF >65%) and
substantial water-holding capacity (>6 g H2O/g DM), would
fulfill this role quite nicely. This was confirmed in early dog
nutrition work in which a linear increase in wet fecal
excretion and defecations per day resulted from increasing
levels of beet pulp in the diet (Fahey, et al., 1990). A
similar effect was demonstrated in the cat (Sunvold, et al.,
1995b). Contrary to what often occurs with supplemental fiber
sources, elevated levels of beet pulp (12.5% and 7.5% in the
dog and cat, respectively) were not reported to negatively
affect palatability.
The challenge is that digestibility declines with the
inclusion of beet pulp beyond about 5% of the diet. However,
compared to non-fermentable fibers like cellulose, this
decrease in digestibility is much smaller (Muir, et al., 1996).
An offset to this negative is that beet pulp is fermented to a
limited degree in the colon. Results from in vitro fermentation
of beet pulp with dog and (or) cat fecal inoculum ranked beet
pulp more fermentable than cellulose, and about a third as
fermentable as extremely-fermentable substrates like guar gum
(Sunvold, et al., 1995a). Thus, it is often described as
"moderately" fermentable.
This results in a slight shift in the fermentation end
products to a greater proportion of the short-chain fatty acid,
butyrate. Butyrate is a key fuel for the coloncyte.
Improvements in colonocyte microstructure health were credited
to this change in fermentation end products when dogs were fed
beet pulp-containing diets (Hallman, et al., 1995) and would
tend to refute some of the anecdotal claims that beet pulp
causes "plugging" of the intestinal villi. Additionally, beet
pulp has found favor as a key ingredient in hairball remedies;
as a way to attenuate the glycemic response in diabetic diets;
as an energy diluent in "Lite" diets; and has been claimed to
improve gut immune response.
There has been some confusion by consumers regarding beet
pulp; primarily as it relates to the name and the plant's
origin. First, consumers have confused beet pulp with the
common red beet. Because of this confusion, beet pulp has been
blamed for red stains around the mouth of light colored dogs
and carpet stains due to inappropriate elimination. However,
both of these faults are misdirected, as beet pulp really has
no pigment, especially not red. Secondly, some consumers have
mistakenly assumed that a substantial amount of sugar remains
with the pulp and they don't want sugar in their pet's diet.
However, this concern is not well founded, as only trace
amounts of sugar remain with the pulp. Bloat and villi plugging
have also errantly been blamed on beet pulp without good
cause.
Beet pulp has found favor as a key ingredient in hairball remedies.A great deal of research and information has been published
regarding the merits of moderately-fermentable fiber from beet
pulp in companion animal diets. Despite this effort, there are
some consumers who consider beet pulp as less than desirable
due to its perception as a low-grade filler, livestock feed or
their misplaced health concerns. Further, long-term clinical
studies which directly demonstrate that beet pulp is superior
to other fiber sources on GI health are lacking and might
improve consumer acceptance of functional fibers, like beet
pulp, in their pets' diets.