Page 157 - Small Animal Clinical Nutrition 5th Edition

Commercial Pet Foods 159

The % DM difference = (22 – 18) ÷ 18 = 4 ÷ 18 x 100 =
VetBooks.ir 22% more nutrients in Food A than in Food B. Gums and
gelling agents are often used to solidify the food and imbibe
water in high-moisture foods to preclude “free” water in the
container. Many moist pet foods contain high levels of meat
and meat by-products. Higher levels of protein, phosphorus,
sodium and fat than semi-moist or dry forms also character-
ize these foods. Some moist foods are promoted as “meaty” or
having “meaty pieces” to fulfill the needs of “naturally carniv-
orous” pets. However, “meaty” is used as an adjective (“meat-
Figure 8-1. This cat food has a guaranteed analysis of 83% mois-
like”) and many meaty pieces are actually extruded soy or
ture. The food is shown after it has been removed from the pack-
wheat flour (textured vegetable protein), starches, gum and age (left). Another specimen of the same food (right) was dried to
meat meal combinations. constant weight in an oven. The dry matter portion of the food con-
The high palatability of moist foods is a primary reason for tains all the nonwater nutrients: protein, fat, carbohydrate, vitamins
the popularity of this form. The high preference that animals and minerals. Gums and other hydrocolloids are added to high-
express for moist foods requires portion-controlled feeding to moisture pet foods to imbibe water, which helps maintain the prod-
prevent over consumption. uct’s shape. The low percentage of dry matter in this pet food
Moist foods in North America are usually sold as “complete” means that feeding costs are high (Box 8-4).
with all nutrients present. A few moist foods are not complete
and are usually intended as either treats or palatability enhance-
ment modules for dry foods. In the United States, moist foods
are rarely fed as the sole food source (<10%). Rather, moist
foods are used to supplement the dry main meal as the pet
owners’ way to treat or pamper their pet. This behavior has
fueled the growth of the “gourmet” moist food category, which
is defined by its taste appeal and aesthetic attributes. The seg-
ment has seen a proliferation of flavor offerings as well as an
increasing number of textures (pâté, ground, flaked, chunks,
minced, stews, slices, etc.), and nontraditional packaging such
as single serving, plasticized foil pouches for moist foods and
other forms of single serving containers designed for consumer
ease of use.
In some international markets, moist foods serve as primary Figure 8-2. Moist pet foods are available in a variety of packages,
protein and fat modules in complementary feeding systems. In including multiple sizes of traditional steel cans, aluminum and
complementary feeding systems, pet owners mix the protein- plastic trays, chubs and compressed tubes.
fat source of the moist module with a “mixer,” which is a high-
carbohydrate dry food.When mixing the complementary com- Moist foods are packaged in a variety of containers including
ponents, pet owners have the latitude to modify the recom- paper trays, plastic pots and stuffed plastic tubes (“chubs”), in
mended quantity of moist and dry feeding components. addition to the more popular steel cans and aluminum trays
Whether mixing occurs for treatment purposes or as part of a (Figures 8-2 and 8-3). The food in chubs often is incomplete,
complementary feeding system, the variation in nutrient intake is unbalanced, contains excess mineral levels and does not have
may complicate obtaining an accurate dietary history. an extended shelf life (i.e., must be used within 48 hours after
Moist foods have a low caloric density as fed and typically opening the package). Chub contents are often added to dry
yield 0.7 to 1.4 kcal (2.93 to 5.86 kJ) metabolizable energy food or high-carbohydrate mixers, or are used as protein and fat
(ME)/g food.The lower caloric density and higher packaging modules in making homemade foods. In early 2006, in
and shipping costs translate to a higher cost per calorie. Australia where the chub form of food is commonly used, man-
Correspondingly, moist foods have the highest daily feeding ufacturers of this form of pet food encountered problems with
cost. excessive levels of sulfur dioxide preservatives, which con-
Moist foods are preserved with heat sterilization and vacuum tributed to thiamin deficiencies in a number of dogs (Central
preservation in an anaerobic environment. An enamel liner Western Daily, 5/30/06).
insulates moist pet foods from their container. Nutrient stabil-
ity is excellent. A shelf life of at least 18 months is anticipated, Dry Foods
provided the mechanical integrity of the seams and lid seals is Dry pet foods contain 3 to 11% water. The high DM content
maintained. All moist foods are seriously damaged by even a of these foods allows the expression of different formulation
single freeze-thaw cycle.Thus, care must be taken to store cans concepts. Dry food has been produced with a caloric density
at nonfreezing temperatures. of 2.7 to more than 7.1 kcal (11.3 to 29.7 kJ) ME/g food.