Page 71 - Small Animal Clinical Nutrition 5th Edition

Macronutrients 71

improved weight gain, increased nitrogen digestion and reten-
Table 5-5. Nutritional classification of starch.*
VetBooks.ir odor (Grieshop et al, 2004; Flickinger et al, 2003, 2000; Bunce Example of Probable
tion, reduced body fat, improved stool quality and reduced fecal
digestion in
et al, 1995; Willard et al, 1994; Delzenne et al, 1993; Morissee
Type of starch occurrence the small intestine
et al, 1992).
Rapidly digestible Freshly cooked Rapid and complete
starch starchy food
Analyses Slowly digestible
starch Most raw cereals Slow and complete
The total carbohydrate content of pet foods and ingredients is
Resistant starch
not typically determined directly by analysis but indirectly by Physically
difference. NFE is the carbohydrate fraction of a proximate inaccessible starch Partly milled grain
and seeds Resistant
analysis. NFE is determined by adding the percentages of
Resistant starch
water,crude protein,crude fat,ash and crude fiber and subtract- granules Raw potato and
ing from 100%. NFE is primarily made up of readily digestible banana Resistant
Recrystallized
carbohydrates (e.g., sugars and starches) (Figure 5-3).
starch Cooled, cooked
Techniques such as gas-liquid chromatography and high- potato, bread and
performance liquid chromatography can be used to separate cornflakes Resistant
*Adapted from the British Nutrition Foundation. Complex
and analyze different monosaccharides. In addition, colori-
Carbohydrates in Foods. New York, NY: Von Nostrand Reinhold,
metric enzymatic assays specific for each sugar are available. 1990.
The starch content of foods can be determined by heating the
sample to gelatinize the starch followed by incubation with
starch-digesting enzymes (amyloglucosidase and pancreatin). and had reduced plasma concentrations of lactate and alanine,
The amount of glucose liberated by enzymatic hydrolysis is a reduced number of live births, lethargy and reduced mother-
analyzed and converted to starch content (Herrera-Saldana ing ability compared with bitches fed a food containing 44% of
and Huber, 1989). ME as starch (Romsos et al, 1981). In another study using 51%
of ME as protein, pregnant bitches fed either a starch-free or
Requirements, Deficiencies and Excesses starch-containing diet performed similarly (Blaza et al, 1989).
Dogs and cats do not have an absolute dietary requirement for Extensive research in dogs indicates that a starch-free food
carbohydrates in the same way that essential amino acids or containing at least 33% of ME from protein is necessary to
fatty acids must be provided.They do, however, have a require- supply needed glucose precursors (Kienzle et al, 1985). Fetal
ment for adequate glucose or glucose precursors to provide abnormalities, embryo resorption, ketosis and reduced milk
essential fuel for the central nervous system. When energy production are other possible adverse effects of providing
needs are high and anabolic processes are proceeding at an inadequate carbohydrate during gestation and lactation
active rate (e.g., during growth, gestation and lactation), it is (NRC, 2006).
best to supply a food containing readily digestible carbohy- Overall,a minimum of 23% carbohydrate is recommended in
drates and starches. Without dietary carbohydrates, there is foods for gestating and lactating bitches. Excess starch in the
added strain on lipid and protein metabolic pathways to supply food typically does not cause health problems in dogs. Dry
glucose precursors (NRC, 2006). Lipolysis must be increased to extruded dog foods typically contain 30 to 60% carbohydrate,
provide energy and glycerol units for gluconeogenesis. mostly starch, and cause no adverse effects. Excesses of simple
Similarly, glucogenic amino acids from dietary protein must be sugars in commercial pet foods are also not a practical concern
used for glucose formation; therefore, these amino acids are not because sugar levels are usually low. On the other hand, carbo-
available to meet body protein synthesis requirements. hydrate intolerances may occur in some animals as a result of
From a practical standpoint, whether carbohydrate is essen- primary or secondary disaccharidase deficiencies. For animals
tial in the food or not is of little importance because most com- with obesity or diabetes mellitus, foods with low glycemic
mercially prepared pet foods contain carbohydrates well in indices are indicated for controlling the postprandial increase in
excess of glucose requirements. Grains such as corn, rice, wheat, blood glucose.
barley and oats provide the bulk of starch in commercial pet
foods and are well digested and absorbed due to the cooking FELINE CARBOHYDRATE
and extrusion processes used to make pet foods. REQUIREMENTS
Normal cats can maintain adequate blood glucose levels
CANINE CARBOHYDRATE when fed low-carbohydrate, high-protein foods (Kittlehut et al,
REQUIREMENTS 1978). Cats have some unique metabolic differences that limit
Gestation and lactation increase the need for glucose to sup- their ability to efficiently use large amounts of absorbed dietary
port fetal growth and lactose synthesis in milk. In one study, carbohydrate. For example, cats have low activities of the intes-
pregnant bitches were fed a high-fat but carbohydrate-free (0% tinal disaccharidases sucrase and lactase (Kienzle, 1993b); fur-
of energy from carbohydrate) food with 26% of ME from pro- thermore, the sugar transportation system in the feline intestine
tein. They developed hypoglycemia the week before whelping does not adapt to various levels of dietary carbohydrates. Cats