Department of Animal Science, Texas A&M University, College Station, TX, 77843, USA.
Adv Exp Med Biol. 2024;1446:1-14. doi: 10.1007/978-3-031-54192-6_1.
Domestic dogs (facultative carnivores) and cats (obligate carnivores) have been human companions for at least 12,000 and 9000 years, respectively. These animal species have a relatively short digestive tract but a large stomach volume and share many common features of physiological processes, intestinal microbes, and nutrient metabolism. The taste buds of the canine and feline tongues can distinguish sour, umami, bitter, and salty substances. Dogs, but not cats, possess sweet receptors. α-Amylase activity is either absent or very low in canine and feline saliva, and is present at low or substantial levels in the pancreatic secretions of cats or dogs, respectively. Thus, unlike cats, dogs have adapted to high-starch rations while also consuming animal-sourced foods. At metabolic levels, both dogs and cats synthesize de novo vitamin C and many amino acids (AAs, such as Ala, Asn, Asp, Glu, Gln, Gly, Pro, and Ser) but have a very limited ability to form vitamin D. Compared with dogs, cats have higher requirements for AAs, some B-complex vitamins, and choline; greater rates of gluconeogenesis; a higher capacity to tolerate AA imbalances and antagonism; a more limited ability to synthesize arginine and taurine from glutamine/proline and cysteine, respectively; and a very limited ability to generate polyunsaturated fatty acids (PUFAs) from respective substrates. Unlike dogs, cats cannot convert either β-carotene into vitamin A or tryptophan into niacin. Dogs can thrive on one large meal daily and select high-fat over low-fat diets, whereas cats eat more frequently during light and dark periods and select high-protein over low-protein diets. There are increasing concerns over the health of skin, hair, bone, and joints (specialized connective tissues containing large amounts of collagen and/or keratin); sarcopenia (age-related losses of skeletal-muscle mass and function); and cognitive function in dogs and cats. Sufficient intakes of proteinogenic AAs and taurine along with vitamins, minerals, and PUFAs are crucial for the normal structures of the skin, hair, bone, and joints, while mitigating sarcopenia and cognitive dysfunction. Although pet owners may have different perceptions about the feeding and management practice of their dogs and cats, the health and well-being of the companion animals critically depend on safe, balanced, and nutritive foods. The new knowledge covered in this volume of Adv Exp Med Biol is essential to guide the formulation of pet foods to improve the growth, development, brain function, reproduction, lactation, and health of the companion animals.
家犬（兼性肉食动物）和猫（专性肉食动物）分别作为人类伴侣已超过 12000 年和 9000 年。这两种动物的消化道较短，但胃容量较大，在生理过程、肠道微生物和营养代谢方面有许多共同特征。犬和猫的舌头上的味蕾可以区分酸、鲜味、苦和咸物质。狗可以识别甜味，但猫不能。犬和猫的唾液中α-淀粉酶活性要么不存在，要么很低，而猫的胰腺分泌物中存在低水平或高水平的α-淀粉酶活性，狗的胰腺分泌物中则存在高水平的α-淀粉酶活性。因此，与猫不同，狗适应了高淀粉日粮，同时也食用动物源性食物。在代谢水平上，犬和猫都可以从头合成维生素 C 和许多氨基酸（如丙氨酸、天冬酰胺、天冬氨酸、谷氨酸、谷氨酰胺、甘氨酸、脯氨酸和丝氨酸），但形成维生素 D 的能力非常有限。与狗相比，猫对氨基酸、某些 B 族维生素和胆碱的需求更高，有更高的糖异生率，能更好地耐受氨基酸失衡和拮抗作用，从谷氨酰胺/脯氨酸和半胱氨酸分别合成精氨酸和牛磺酸的能力更有限，以及从各自的底物生成多不饱和脂肪酸（PUFAs）的能力非常有限。与狗不同，猫不能将β-胡萝卜素转化为维生素 A，也不能将色氨酸转化为烟酸。狗可以每天吃一顿大餐，并选择高脂肪食物而不是低脂肪食物，而猫在白天和黑夜进食更频繁，并选择高蛋白食物而不是低蛋白食物。人们越来越关注犬猫的皮肤、毛发、骨骼和关节（富含大量胶原蛋白和/或角蛋白的特殊结缔组织）、肌肉减少症（与年龄相关的骨骼肌质量和功能丧失）以及认知功能的健康问题。对于皮肤、毛发、骨骼和关节的正常结构，足够的蛋白质源氨基酸和牛磺酸以及维生素、矿物质和 PUFAs 的摄入至关重要，同时可以减轻肌肉减少症和认知功能障碍。尽管宠物主人对犬猫的喂养和管理实践可能有不同的看法，但伴侣动物的健康和幸福取决于安全、均衡和有营养的食物。本卷《高级实验医学与生物学进展》涵盖的新知识对于指导宠物食品的配方制定至关重要，有助于改善伴侣动物的生长、发育、大脑功能、繁殖、泌乳和健康。
