Page 94 - Small Animal Clinical Nutrition 5th Edition

94 Small Animal Clinical Nutrition

folic acid cofactors.The carboxyl group of glutamate is replaced mine has been reclassified as a conditionally essential amino
VetBooks.ir by an amide nitrogen in glutamine. The two amino acids are acid (Neu et al, 1996; Lacy and Yost, 1990).
Supplementation of pet foods or any food product with L-
interconverted by the enzymes glutaminase (glutamine to gluta-
mate + ammonia) and glutamine synthetase (glutamate +
glutamine is difficult because the amino acid is unstable
ammonia to glutamine). through heating and cooking processes. Glutamine breaks
For many years, glutamine and glutamate were considered down into glutamate and ammonia. The latter can be toxic
nonessential amino acids; however, numerous studies have when ingested. L-glutamine can be added safely to powdered
demonstrated that endogenous glutamine storage and synthe- amino acid mixtures that are reconstituted with water and
sis may not be adequate to meet the body’s needs in certain sit- administered immediately to the animal. In complete pet foods,
uations, such as critical illness, infection, cancer chemotherapy, glutamine is best supplied by a high-quality, high-protein food.
low birth weight infants, diarrhea, human immunodeficiency
virus infection, bone marrow transplantation and cardiac sur- Protein Deficiency
gery (Neu et al, 1996; Souba et al, 1990; Klimberg et al, 1990; Clinical signs of protein deficiency include reduced growth
Furst et al, 1989; Lacy and Yost, 1990). Glutamine is also the rate, anorexia, anemia, infertility, reduced milk production,
preferred fuel of the small intestinal mucosa. Therefore, gluta- alopecia, brittle hair and a poor coat (Harper et al, 1970) (Case

Table 5-17. Summary of protein quality of common pet food ingredients.
Protein Amino acid Other
Ingredient (%)* (protein) quality** comments
Egg (dried) 45-49 Good Also contains lecithin
High quality, the standard to which many
other sources are compared
CS = 100, BV = 94, NPU = 94, PER = 3.92
Casein 80 Good
High tryptophan, lysine
CS = 58, BV = 80, NPU = 72, PER = 2.86
Whey 12 Good
High lysine, isoleucine, threonine, tryptophan
Beef, lamb, pork, chicken 29 Good May be variable in fat and connective
Low tryptophan tissue content
CS = 69, BV = 74, NPU = 67, PER = 2.30
Liver 20 Good Also a good source of vitamin A
Fish meal 59 Good
High tryptophan, lysine, methionine Highly variable
Meat and bone meal 45-50 Good Highly variable, may contain high levels of
bone that contribute to excess calcium,
phosphorus and magnesium in food
Lamb meal 55 Good Highly variable, may contain high levels of
bone that contribute to excess calcium,
phosphorus and magnesium in food
Chicken/poultry 58 Good
by-product meal High lysine, methionine Mineral levels can be variable
Soybean meal 48 Good
High tryptophan, lysine
CS = 47, BV = 73, NPU = 61, PER = 2.32 Good complementary protein source for
meats, fish meal and corn
Corn gluten meal 60 Good Good complementary protein source for
meats and fish meal
Corn (whole) 8 Adequate
Low tryptophan, lysine, methionine
CS = 41, BV = 59, NPU = 51, PER = 1.12 Also good source of linoleic acid
Rice (white) 7 Adequate
CS = 56, BV = 64, NPU = 57, PER = 2.18 Low-mineral levels
Wheat 14 Adequate
Low tryptophan, lysine
CS = 43, BV = 65, NPU = 40, PER = 1.53 Contains gliadin
Barley 12 Adequate
Low tryptophan, methionine Contains gliadin
Collagen (gelatin) 88 Poor
Totally deficient in tryptophan
CS = 0, BV = 0, NPU = 0, PER = 0
Key: CS = chemical score, BV = biological value, NPU = net protein utilization, PER = protein efficiency ratio.
*Feedstuffs Ingredient Analysis Table: 1996 Edition. (As is basis.)
**Adapted from Brody T. Protein. In: Nutritional Biochemistry. San Diego, CA: Academic Press Inc, 1994; 295-352. Jurgens MH, Animal
Feeding and Nutrition, 6th ed. Dubuque, IA: Kendall/Hunt Co, 1988; 172. National Research Council. Improvement of Protein Nutrition.
Committee on Amino Acids, Food and Nutrition Board. National Academy of Sciences, Washington, DC, 1974; 70. Robinson DS. The
nutritional value of food proteins. In: Food Biochemistry and Nutritional Value. New York, NY: Wiley & Sons Inc, 1987; 117-151.