Page 78 - Small Animal Clinical Nutrition 5th Edition

78 Small Animal Clinical Nutrition

tion sites with pathogens (Gibson et al, 2005). Imbalances in suggesting that adhesion depended on the microorganism.
VetBooks.ir the gut flora have been linked to diseases such as allergy, Various bacteria possessing some of these attributes have been
identified for potential use as probiotics, including bifidobacte-
inflammatory bowel disease and diarrhea. Theoretically, when
normal tolerance to the gut flora is disrupted, an altered
ria, Saccharomyces spp. and lactobacilli.
response may occur in the intestinal immune system, which Table 5-7 summarizes the benefits attributed to probiotics
may initiate and maintain inflammatory bowel disease or trig- and their potential mechanisms (Teitelbaum and Walker, 2002).
ger the development of allergic responses (Fedorak and There is much literature with varying results about feeding
Madsen, 2004; Macfarlane et al, 2005). Also, many pathogens probiotics to people and other non-human animals for GI
in the GI tract, including C. perfringens, C. difficile, Salmonella health, immune health, diarrhea, inflammatory conditions,
spp. and Escherichia coli cause diarrhea (Marks and Kather, allergic conditions, cancer and many other disorders. As with
2003). According to human and veterinary literature, the gut prebiotics, many studies have not used dogs and cats. Four
flora changes with age (Buddington, 2003; Benno et al, 1992; studies in dogs that examined four different microorganisms
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Reuter, 2001). Molecular techniques currently available for (fed between 1 x 10 to 1 x 10 cfu/day): Lactobacillus GG,
microbial characterization such as fluorescent in situ hybridiza- Enterococcus faecium, Lactobacillus acidophilus DSM 13241 and
tion and denaturing gradient gel electrophoresis (DGGE) can Bacillus CIP 5832, gave mostly neutral results (Benyacoub et al,
be used to identify major groups of bacteria. Using DGGE, 2003; Baillon et al, 2004; Biourge et al, 1998; Westermarck et
investigators identified Bacteroides spp., fusobacteria, lactobacil- al, 2005). E. faecium was the most promising organism studied;
li and streptococci in the canine GI tract (Simpson et al, 2002). this organism improved circulating specific anti-canine distem-
Although not quite as abundant, bifidobacteria are thought to per virus IgG (Benyacoub et al, 2003). However, use of
be important for GI health. Bifidobacteria produce short-chain Enterococcus as a probiotic must be evaluated cautiously because
fatty acids that decrease intestinal pH and inhibit growth of it was shown to significantly enhance adhesion of C. jejuni to
pathogenic bacteria. Bifidobacteria are also thought to produce the canine intestine in in vitro adhesion studies, making it a
antibacterial substances that are active against clostridia, E. coli potential risk factor for infection and carriage (Rinkinen et al,
and other pathogenic bacteria. Studies have shown that bifi- 2003a). Many stability challenges exist for incorporating probi-
dobacteria are found at higher levels in breast fed babies (Hoy otics into pet food (Weese and Arroyo, 2003). In this study,
et al, 1990) and are found at lower levels in patients with ulcer- evaluation of 19 canine and feline products claiming to contain
ative colitis (Macfarlane et al, 2005). In young puppies, bacter- probiotics, no product contained all the listed organisms, 11
ial populations in the GI tract establish gradually, and can be products contained additional organisms and five products did
influenced by diet and environment. Changes in the types and not have any relevant growth when tested.
proportions of bacteria in puppies can influence their resistance
to diseases. Total bacterial numbers in older dogs were lower Synbiotics
than in younger dogs, whereas numbers of putative pathogens Feeding synbiotics is a third approach to modifying gut flora. A
such as C. perfringens were higher (Benno et al, 1992). synbiotic is “a mixture of probiotics and prebiotics that benefi-
Furthermore, widespread use of antibiotics can lead to addi- cially affects the host by improving the survival and implanta-
tional perturbations of the gut flora, especially in the compro- tion of live microbial dietary supplements in the GI tract”
mised GI tracts of young and older animals. Therefore, prebi- (Gibson and Roberfroid, 1995). The simplest approach
otic fibers, which support the growth of bifidobacteria, should includes feeding a probiotic and a prebiotic together in a food,
confer benefits to the health of the host. Feeding probiotics is preferably a prebiotic that can be metabolized by the probiotic,
another approach to modulating gut flora. with the objective of obtaining synergistic effects. A study using
this approach failed to yield significant synergistic effects
Probiotics (Swanson et al, 2002a). Another more targeted approach is to
Probiotics are live or viable bacterial cell preparations that have design a synbiotic using a probiotic and a prebiotic specifically
beneficial effects on the health of the host when administered used by the probiotic, preferably to produce an antimicrobial
in adequate amounts. Levels of 1 x 10 to 1 x 10 colony form- substance (Rabiu et al, 2001).This concept is still in its infancy
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ing units (cfu)/day have been tested and determined to be a and will require more research.
desirable inclusion range although more research needs to be
done. Probiotics should be nonpathogenic and resist stomach
acid and bile. Some probiotics adhere to intestinal epithelial tis- FIBER INTERACTIONS WITH
sue and colonize the intestinal tract; adherence but not colo- NUTRIENT DIGESTIBILITY AND
nization may be necessary for some beneficial effects.The abil- AVAILABILITY
ity to adhere to the intestine depends on the bacterial strain The amount and type of fiber in a pet food have the greatest
rather than the host species. When administered in adequate overall effect on digestibility of all nutrients. In general, foods
amounts various strains of lactobacilli of human and canine ori- containing slowly fermentable fiber sources have lower overall
gin were able to adhere to human, canine, emu, ostrich and DM digestibility than foods without fiber or those containing
rainbow trout intestinal or fecal mucus with no host species rapidly fermentable fiber sources. Also, as the level of fiber in
specific adhesion (Rinkinen et al, 2003).There was a clear trend the food increases, the DM digestibility of the food decreases.