Page 40

4—
Composition of Ingredients of Dog Foods

Specific nutrient content of some feed ingredients commonly used in dog foods have been extracted from United States-Canadian Tables of Feed Composition (NRC, 1982) and compiled by the International Feedstuffs Institute, Logan, Utah, as presented in Tables 6, 7, and 8. These may be used as an aid in compounding practical foods for dogs.

Alternately, for preparation of ''home cooked" formulas or for formulation of therapeutic diets or supplements, the user is directed to food composition tables published in the USDA Agriculture Handbook No. 456, Nutritive Value of American Foods (In Common Units), by Catherine F. Adams (USDA, 1975).

Nutrient concentrations are organized in Tables 6, 7, and 8 as follows: fat and fatty acid composition (Table 6), composition excluding amino acids (Table 7), and amino acid composition (Table 8). All data are expressed on a 100 percent dry matter basis.

International Nomenclature

In Tables 6, 7, and 8 and in the United States-Canadian Tables of Feed Composition, the Feed Name Descriptions are based on a scheme proposed by Harris et al. (1980, 1981). The names are designed to give a qualitative description of each product, where such information is available and pertinent. A complete name consists of as many as six facets, separated by commas and written in linear form. The facets are these:

Origin, consisting of scientific name (genus, species, variety); common name (generic name, breed or kind, strain or chemical formula)

Part fed to animals as affected by process(es)

Process(es) and treatment(s) to which the part has been subjected

Stage of maturity or development

Cutting (applicable to forages)

Grade (official grades with guarantees)

International Feed Classes

Feeds are grouped into eight classes on the basis of their composition and their use in formulating diets. (The first digit of each hyphenated set of numbers in the International Feed Number column of Tables 6, 7, and 8 is the feed class.) The numbers and the classes they designate are as follows:

Code

1.

Dry forages and roughages

2.

Pasture, range plants, and forages fed fresh

3.

Silages

4.

Energy feeds

5.

Protein supplements

6.

Mineral supplements

7.

Vitamin supplements

8.

Additives

Feeds on a dry basis that contain more than 18 percent crude fiber or 35 percent cell wall are classified as forages or roughages; feeds that contain less than 20 percent protein and less than 18 percent crude fiber or less than 35 percent cell wall are classified as energy feeds; and those that contain 20 percent or more protein are classified as protein supplements.

International Feed Number (IFN)

Each international feed name is assigned a five-digit international feed number (IFN) for identification and



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Page 40 4— Composition of Ingredients of Dog Foods Specific nutrient content of some feed ingredients commonly used in dog foods have been extracted from United States-Canadian Tables of Feed Composition (NRC, 1982) and compiled by the International Feedstuffs Institute, Logan, Utah, as presented in Tables 6, 7, and 8. These may be used as an aid in compounding practical foods for dogs. Alternately, for preparation of ''home cooked" formulas or for formulation of therapeutic diets or supplements, the user is directed to food composition tables published in the USDA Agriculture Handbook No. 456, Nutritive Value of American Foods (In Common Units), by Catherine F. Adams (USDA, 1975). Nutrient concentrations are organized in Tables 6, 7, and 8 as follows: fat and fatty acid composition (Table 6), composition excluding amino acids (Table 7), and amino acid composition (Table 8). All data are expressed on a 100 percent dry matter basis. International Nomenclature In Tables 6, 7, and 8 and in the United States-Canadian Tables of Feed Composition, the Feed Name Descriptions are based on a scheme proposed by Harris et al. (1980, 1981). The names are designed to give a qualitative description of each product, where such information is available and pertinent. A complete name consists of as many as six facets, separated by commas and written in linear form. The facets are these: • Origin, consisting of scientific name (genus, species, variety); common name (generic name, breed or kind, strain or chemical formula) • Part fed to animals as affected by process(es) • Process(es) and treatment(s) to which the part has been subjected • Stage of maturity or development • Cutting (applicable to forages) • Grade (official grades with guarantees) International Feed Classes Feeds are grouped into eight classes on the basis of their composition and their use in formulating diets. (The first digit of each hyphenated set of numbers in the International Feed Number column of Tables 6, 7, and 8 is the feed class.) The numbers and the classes they designate are as follows: Code 1. Dry forages and roughages 2. Pasture, range plants, and forages fed fresh 3. Silages 4. Energy feeds 5. Protein supplements 6. Mineral supplements 7. Vitamin supplements 8. Additives Feeds on a dry basis that contain more than 18 percent crude fiber or 35 percent cell wall are classified as forages or roughages; feeds that contain less than 20 percent protein and less than 18 percent crude fiber or less than 35 percent cell wall are classified as energy feeds; and those that contain 20 percent or more protein are classified as protein supplements. International Feed Number (IFN) Each international feed name is assigned a five-digit international feed number (IFN) for identification and

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Page 41 computer manipulation. The IFN is particularly useful as a tag to recall nutrient data for calculating diets. As indicated above, the feed class number has been entered in front of the international feed number (see Tables 6, 7, and 8). The following table shows how three feeds are described: Components of Name Feed No. 1 Feed No. 2 Feed No. 3 Origin (or parent material) Soybean Alfalfa Wheat Species variety or kind — — soft white winter Part eaten seeds — grain Process(es) and treatment(s) to which product has been subjected meal solvent extracted meal dehydrated — Stage of maturity — — — Grade or quality designations — 17% protein — Classification; first digit in International feed number (IFN) (5) protein supplements (1) forages and roughages (4) energy feeds IFN 5-04-604 1-00-023 4-05-337 Thus, the names of the three feeds are written as follows: No. 1: Soybean, seeds, meal solvent extracted No. 2: Alfalfa, meal dehydrated, 17% protein No. 3: Wheat, soft white winter, grain Carotene Conversion International standards for vitamin A activity as related to vitamin A and b-carotene are as follows: 1 IU vitamin A  =  1 USP unit =  vitamin A activity of 0.300 µg crystalline all-trans retinol (vitamin A alcohol), which corresponds to 0.344 µg all-trans retinyl acetate (vitamin A  acetate) or 0.550 µg all-trans retinyl palmitate (vitamin A palmitate). b-carotene is the standard for provitamin A. 1 IU vitamin A  =  0.6 µg all-trans b-carotene. 1 mg -carotene  =  1,667 IU vitamin A. International standards for vitamin A are based on the utilization of vitamin A and b-carotene by the rat. Since it is not well established that dogs convert carotene to vitamin A in the same ratio as rats, it is suggested that consideration be given to reducing carotene conversion to vitamin A in Table 7 as follows: 1 mg provitamin A (carotene)  =  833 IU vitamin A activity for the dog. Data The analytical data are expressed in the metric system and are shown on a dry basis. See Table 9 (p. 62) for weight-unit conversion factors. Analytical data may differ in the various NRC reports because the data are updated for each report. The feed names may also differ as feeds are more precisely described or as official definitions change. However, if the feed is the same, the international feed number will remain the same. Metabolizable Energy (ME) Since ME content of food ingredients listed in Table 7 have not been determined by studies in dogs, no values were included; instead approximated values have to be calculated. For this purpose, the Atwater factors of 4-9-4 for crude protein (CP), ether extract (EE), and nitrogen-free extract (NFE), respectively, commonly used, are inappropriate. These were developed for and are more applicable to foods consumed by humans and not to combinations of ingredients used in dog foods. Their use here would overestimate the ME values of dog foods, since their derivation was based on assumed digestibility coefficients of 91, 96, and 96 percent, respectively. The studies of Kendall et al. (1982) strongly support this conclusion. Their study included data from 106 digestibility trials of commercial foods including 42 canned, 24 intermediate moisture, and 40 dry-type dog foods. The overall mean apparent digestibility reported for CP, acid ether extract (AEE), and NFE was 81, 85, and 79 percent, respectively. Energy losses in urine were not measured, nor was there a separation of fiber from the NFE term. However, acid ether extraction was used, assuring maximal measurement of fat content. The above were both positive and negative factors contributing to average coefficients suggested in the NRC (1974) report for calculation of ME values for commercial dog foods and/or their individual constituents. For this revision the Subcommittee on Dog Nutrition suggests average coefficients of 80, 90, and 85 percent, respectively, for CP, AEE, and NFE, and 0.0 for fiber. Users are cautioned that these average values may result in underestimating ME content of low-fiber, low-connective-tissue-containing meat and animal by-product foods and in overestimating foods primarily from plant and cereal sources that contain elevated fiber contents.