Animal nutrition: Difference between revisions

Browse history interactively ← Previous editContent deleted Content addedVisual WikitextInline

Revision as of 15:22, 6 September 2012 editJarble (talk \| contribs)Autopatrolled, Extended confirmed users149,691 edits →Other nutrients ← Previous edit		Latest revision as of 03:07, 15 September 2024 edit undoGreenC bot (talk \| contribs)Bots2,555,767 edits Move 1 url. Wayback Medic 2.5 per WP:URLREQ#pubmedcentral.nih.gov
(166 intermediate revisions by more than 100 users not shown)
Line 1:		Line 1:
			{{Short description\|Science of nutrition for animals}}
	{{Expert-subject\|Food and drink\|date=December 2009}}
			{{more citations needed\|date=March 2018}}
	{{duplication\|dupe = Nutrition#Animal nutrition}}
	] eating a ]]]

	Animal nutrition focuses on the dietary needs of ~~domesticated~~ animals, primarily those in agriculture and food production.		'''Animal nutrition''' focuses on the dietary nutrients needs of ], primarily those in ] and food production, but also in zoos, aquariums, and wildlife management.

			==Constituents of diet==
	==Introduction to animal nutrition==
			Macronutrients (excluding fiber and water) provide structural material (amino acids from which proteins are built, and lipids from which cell membranes and some signaling molecules are built) and ]. Some of the structural material can be used to generate energy internally,<ref name=Stryer>{{cite book \|vauthors=Berg J, Tymoczko JL, Stryer L \| title = Biochemistry \| publisher = W.H. Freeman \| edition = 5th \| location = San Francisco \| year = 2002 \| isbn = 0-7167-4684-0 \|page= 603 }}</ref> though the net energy depends on such factors as absorption and digestive effort, which vary substantially from instance to instance. Vitamins, minerals, fiber, and water do not provide energy, but are required for other reasons. A third class dietary material, fiber (i.e., non-digestible material such as cellulose), seems also to be required, for both ] and ] reasons, though the exact reasons remain unclear.
	There are seven major classes of ]s: ], ]s, ], ], ], ], and ].

			Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates range from simple ] (glucose, fructose, galactose) to complex ] (starch). Fats are ]s, made of assorted ] ] bound to ] backbone. Some fatty acids, but not all, are ] in the diet: they cannot be synthesized in the body. Protein molecules contain nitrogen atoms in addition to carbon, oxygen, and hydrogen. The fundamental components of protein are nitrogen-containing ]. ] cannot be made by the animal. Some of the amino acids are convertible (with the expenditure of energy) to glucose and can be used for energy production just as ordinary glucose. By breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. This occurs normally only during prolonged starvation.
	These nutrient classes can be categorized as either ] (needed in relatively large amounts) or ] (needed in smaller quantities). The macronutrients are carbohydrates, fats, fiber, proteins, and water. The micronutrients are minerals and vitamins.

			Other dietary substances found in plant foods (], ]s) are not identified as essential nutrients but appear to impact health in both positive and negative ways. Most foods contain a mix of some or all of the nutrient classes, together with other substances. Some nutrients can be stored internally (e.g., the fat soluble vitamins), while others are required more or less continuously. Poor health can be caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient. For example, both salt provides sodium and chloride, both essential nutrients, but will cause illness or even death in too large amounts.
	The macronutrients (excluding fiber and water) provide structural material (amino acids from which proteins are built, and lipids from which cell membranes and some signaling molecules are built) and ]. Some of the structural material can be used to generate energy internally, and in either case it is measured in ]s or ]s (sometimes called "kilocalories" and on other rare occasions written with a capital ''C'' to distinguish them from little 'c' calories). Carbohydrates and proteins provide 17 kJ approximately (4 kcal) of energy per gram, while fats provide 37 kJ (9 kcal) per gram.,<ref name=Stryer>{{cite book \| author = Berg J, Tymoczko JL, Stryer L \| title = Biochemistry \| publisher = W.H. Freeman \| edition = 5th \| location = San Francisco \| year = 2002 \| isbn = 0-7167-4684-0 \|page= 603 }}</ref> though the net energy from either depends on such factors as absorption and digestive effort, which vary substantially from instance to instance. Vitamins, minerals, fiber, and water do not provide energy, but are required for other reasons. A third class dietary material, fiber (i.e., non-digestible material such as cellulose), seems also to be required, for both mechanical and biochemical reasons, though the exact reasons remain unclear.

			Dietary fibre is a ] (polysaccharide or oligosaccharide) that is incompletely absorbed in some animals.
	Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates range from simple ] (glucose, fructose, galactose) to complex ] (starch). Fats are ]s, made of assorted ] ] bound to ] backbone. Some fatty acids, but not all, are ] in the diet: they cannot be synthesized in the body. Protein molecules contain nitrogen atoms in addition to carbon, oxygen, and hydrogen. The fundamental components of protein are nitrogen-containing ], some of which are ] in the sense that humans cannot make them internally. Some of the amino acids are convertible (with the expenditure of energy) to glucose and can be used for energy production just as ordinary glucose. By breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. This occurs normally only during prolonged starvation.

	Other micronutrients include ] and ] which are said to influence (or protect) some body systems. Their necessity is not as well established as in the case of, for instance, vitamins.

	Most foods contain a mix of some or all of the nutrient classes, together with other substances such as toxins or various sorts. Some nutrients can be stored internally (e.g., the fat soluble vitamins), while others are required more or less continuously. Poor health can be caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient. For example, both salt and water (both absolutely required) will cause illness or even death in too large amounts.

	==Carbohydrates==
	{{Main\|Carbohydrate}}

	Carbohydrates may be classified as monosaccharides, disaccharides, or polysaccharides depending on the number of monomer (sugar) units they contain. They constitute a large part of foods such as ], ], ], and other ]-based products.
	Monosaccharides contain one sugar unit, disaccharides two, and polysaccharides three or more. Polysaccharides are often referred to as ''complex'' carbohydrates because they are typically long multiple branched chains of sugar units. The difference is that complex carbohydrates take longer to digest and absorb since their sugar units must be separated from the chain before absorption. The spike in blood glucose levels after ingestion of simple sugars is thought to be related to some of the heart and vascular diseases which have become more frequent in recent times. Simple sugars form a greater part of modern diets than formerly, perhaps leading to more cardiovascular disease. The degree of causation is still not clear, however.

	==Fat==
	{{duplication\|dupe = Human nutrition#Fat}}
	{{Main\|Fat}}

	A molecule of dietary fat typically consists of several ]s (containing long chains of carbon and hydrogen atoms), bonded to a ]. They are typically found as ]s (three fatty acids attached to one glycerol backbone). Fats may be classified as ] or ] depending on the detailed structure of the fatty acids involved. Saturated fats have all of the carbon atoms in their fatty acid chains bonded to hydrogen atoms, whereas unsaturated fats have some of these carbon atoms ], so their molecules have relatively fewer hydrogen atoms than a saturated fatty acid of the same length. Unsaturated fats may be further classified as monounsaturated (one double-bond) or polyunsaturated (many double-bonds). Furthermore, depending on the location of the double-bond in the fatty acid chain, unsaturated fatty acids are classified as ] or ] fatty acids. ] are a type of unsaturated fat with ''trans''-isomer bonds; these are rare in nature and in foods from natural sources; they are typically created in an industrial process called (partial) ].

	Many studies have shown that unsaturated fats, particularly monounsaturated fats, are best in the human diet. Saturated fats, typically from animal sources, are next, while trans fats are to be avoided. Saturated and some trans fats are typically solid at room temperature (such as ] or ]), while unsaturated fats are typically liquids (such as ] or ]). Trans fats are very rare in nature, but have properties useful in the ] industry, such as rancid resistance.{{Citation needed\|date=July 2008}}

	===Essential fatty acids===

	{{Main\|Essential fatty acids}}

	Most fatty acids are non-essential, meaning the body can produce them as needed, generally from other fatty acids and always by expending energy to do so. However, in humans at least two fatty acids are ] and must be included in the diet. An appropriate balance of essential fatty acids -— ] and ] fatty acids -— seems also important for health, though definitive experimental demonstration has been elusive. Both of these "omega" long-chain ] are ] for a class of ] known as ], which have roles throughout the human body. They are ]s, in some respects. The omega-3 ] (EPA), which can be made in the human body from the omega-3 essential fatty acid ] (LNA), or taken in through marine food sources, serves as a building block for series 3 prostaglandins (e.g. weakly ] PGE3). The omega-6 dihomo-gamma-linolenic acid (DGLA) serves as a building block for series 1 prostaglandins (e.g. anti-inflammatory PGE1), whereas arachidonic acid (AA) serves as a building block for series 2 prostaglandins (e.g. pro-inflammatory PGE 2). Both DGLA and AA can be made from the omega-6 ] (LA) in the human body, or can be taken in directly through food. An appropriately balanced intake of omega-3 and omega-6 partly determines the relative production of different prostaglandins: one reason a balance between omega-3 and omega-6 is believed important for cardiovascular health. In industrialized societies, people typically consume large amounts of processed vegetable oils, which have reduced amounts of the essential fatty acids along with too much of omega-6 fatty acids relative to ]s.

	The conversion rate of omega-6 DGLA to AA largely determines the production of the prostaglandins PGE1 and PGE2. Omega-3 EPA prevents AA from being released from membranes, thereby skewing prostaglandin balance away from pro-inflammatory PGE2 (made from AA) toward anti-inflammatory PGE1 (made from DGLA). Moreover, the conversion (desaturation) of DGLA to AA is controlled by the enzyme ], which in turn is controlled by hormones such as ] (up-regulation) and ] (down-regulation). The amount and type of carbohydrates consumed, along with some types of amino acid, can influence processes involving insulin, glucagon, and other hormones; therefore the ratio of omega-3 versus omega-6 has wide effects on general health, and specific effects on immune function and ], and ] (i.e. cell division).

	Good sources of essential fatty acids include most vegetables, ]s, seeds, and marine oils,<ref name=Barker2002>{{Cite book \| last = Barker \| first = Helen M. \| year = 2002 \| title = Nutrition and dietetics for health care \| page = 17 \| isbn = 0-443-07021-0 \| publisher = Churchill Livingstone \| location = Edinburgh \| oclc = 48917971 \| postscript = <!-- Bot inserted parameter. Either remove it; or change its value to "." for the cite to end in a ".", as necessary. -->{{inconsistent citations}} }}</ref> Some of the best sources are ], ] oils, ]s, ]s, ]s, and ]s.

	===Fiber===
	{{Main\|Dietary fiber}}

	Dietary fiber is a ] (or a polysaccharide) that is incompletely absorbed in humans and in some animals. Like all carbohydrates, when it is metabolized it can produce four calories (kilocalories) of energy per gram. But in most circumstances it accounts for less than that because of its limited absorption and digestibility. Dietary fiber consists mainly of ], a large carbohydrate polymer that is indigestible because humans do not have the required enzymes to disassemble it. There are two subcategories: soluble and insoluble fiber. Whole grains, fruits (especially ]s, ]s, and ]s), and vegetables are good sources of dietary fiber. Fiber is important to digestive health and is thought to reduce the risk of colon cancer.{{Citation needed\|date=April 2009}} For mechanical reasons it can help in alleviating both ] and ]. Fiber provides bulk to the intestinal contents, and insoluble fiber especially stimulates ] -- the rhythmic muscular contractions of the intestines which move digesta along the digestive tract. Some soluble fibers produce a solution of high ]; this is essentially a gel, which slows the movement of food through the intestines. Additionally, fiber, perhaps especially that from whole grains, may help lessen insulin spikes and reduce the risk of type 2 diabetes.

	===Protein===		===Protein===
			Proteins are the basis of many animal body structures (e.g. muscles, skin, and hair). They also form the enzymes which control chemical reactions throughout the body. Each molecule is composed of ] which are characterized by the inclusion of nitrogen and sometimes sulfur. The body requires amino acids to produce new proteins (protein retention) and to replace damaged proteins (maintenance). As there is no protein or amino acid storage provision, amino acids must be present in the diet. Excess amino acids are discarded, typically in the urine. For all animals, some amino acids are '']'' (an animal cannot produce them internally) and some are '']'' (the animal can produce them from other nitrogen-containing compounds). A diet that contains adequate amounts of amino acids (especially those that are essential) is particularly important in some situations: during early development and maturation, pregnancy, lactation, or injury (a burn, for instance).
	{{duplication\|dupe = Human nutrition#Protein}}
	] such as ] contain all the ] needed for humans]]

	{{Main\|Protein in nutrition}}

	Proteins are the basis of many animal body structures (e.g. muscles, skin, and hair). They also form the enyzmes which control chemical reactions throughout the body. Each molecule is composed of ] which are characterized by inclusion of nitrogen and sometimes sulphur (these components are responsible for the distinctive smell of burning protein, such as the keratin in hair). The body requires amino acids to produce new proteins (protein retention) and to replace damaged proteins (maintenance). As there is no protein or amino acid storage provision, amino acids must be present in the diet. Excess amino acids are discarded, typically in the urine. For all animals, some amino acids are '']'' (an animal cannot produce them internally) and some are '']'' (the animal can produce them from other nitrogen-containing compounds). About twenty amino acids are found in the human body, and about ten of these are essential, and therefore must be included in the diet. A diet that contains adequate amounts of amino acids (especially those that are essential) is particularly important in some situations: during early development and maturation, pregnancy, lactation, or injury (a burn, for instance). A ''complete'' protein source contains all the essential amino acids; an ''incomplete'' protein source lacks one or more of the essential amino acids.

	It is possible to combine two incomplete protein sources (e.g. rice and beans) to make a complete protein source, and characteristic combinations are the basis of distinct cultural cooking traditions. Sources of dietary protein include ]s, ] and other ]-products, ], ]s, ]s, and ]s such as ] and ]. A few amino acids from protein can be converted into glucose and used for fuel through a process called ]; this is done in quantity only during starvation~~. The amino acids remaining after such conversion are discarded~~.		A few amino acids from protein can be converted into glucose and used for fuel through a process called ]; this is done in quantity only during starvation.

	===Minerals===		===Minerals===
			Dietary ]s are the ]s required by living organisms, other than the four elements ], ], ], and ] that are present in nearly all ]. The term "mineral" is archaic, since the intent is to describe simply the less common elements in the diet.
	{{Main\|Dietary mineral}}

			Many elements are essential in relative quantity; they are usually called "bulk minerals". Some are structural, but many play a role as ]s.<ref>{{cite book \| author1=Nelson, D. L. \| author2=Cox, M. M. \| title=Lehninger Principles of Biochemistry \| edition=3rd \| publisher=Worth Publishing \| location=New York \| year=2000 \| isbn=1-57259-153-6 \| url-access=registration \| url=https://archive.org/details/lehningerprincip01lehn }}</ref> These include:
	Dietary minerals are the ]s required by living organisms, other than the four elements ], ], ], and ] that are present in nearly all ]. The term "mineral" is archaic, since the intent is to describe simply the less common elements in the diet. Some are heavier than the four just mentioned—including several ], which often occur as ions in the body. Some dietitians recommend that these be supplied from foods in which they occur naturally, or at least as complex compounds, or sometimes even from natural inorganic sources (such as ] from ground ] shells). Some are absorbed much more readily in the ionic forms found in such sources. On the other hand, minerals are often artificially added to the diet as supplements; the most famous is likely iodine in ] which prevents ].
			* ], a common electrolyte, but also needed structurally (for muscle and digestive system health, bones, some forms neutralizes acidity, may help clear toxins, and provide signaling ions for nerve and membrane functions)

			* ] as ] ions; very common electrolyte
	====Macrominerals====

	Many elements are essential in relative quantity; they are usually called "bulk minerals". Some are structural, but many play a role as ]s.<ref>{{cite book \| author=Nelson, D. L.; Cox, M. M. \| title=Lehninger Principles of Biochemistry \| edition=3rd \| publisher=Worth Publishing \| location=New York \| year=2000 \| isbn=1-57259-153-6}}</ref> Elements with recommended dietary allowance (]) greater than 200 mg/day are, in alphabetical order (with informal or folk-medicine perspectives in parentheses):
	* ], a common electrolyte, but also needed structurally structural (for muscle and digestive system health, bones, some forms neutralizes acidity, may help clear toxins, and provide signaling ions for nerve and membrane functions)
	* ] as ] ions; very common electrolyte; see sodium, below
	* ], required for processing ] and related reactions (builds bone, causes strong peristalsis, increases flexibility, increases alkalinity)		* ], required for processing ] and related reactions (builds bone, causes strong peristalsis, increases flexibility, increases alkalinity)
	* ], required component of bones; essential for energy processing<ref>{{cite book \| author=D. E. C. Corbridge \| title=Phosphorus: An Outline of its Chemistry, Biochemistry, and Technology \| edition=5th \| publisher=Elsevier \| location=Amsterdam \| year=1995 \| isbn=0-444-89307-5}}</ref>		* ], required component of bones; essential for energy processing<ref>{{cite book \| author=D. E. C. Corbridge \| title=Phosphorus: An Outline of its Chemistry, Biochemistry, and Technology \| edition=5th \| publisher=Elsevier \| location=Amsterdam \| year=1995 \| isbn=0-444-89307-5}}</ref>
	* ], a very common electrolyte (heart and nerve health)		* ], a very common electrolyte (heart and nerve health)
			* ], a very common electrolyte
	* ], a very common electrolyte; not generally found in dietary supplements, despite being needed in large quantities, because the ion is very common in food: typically as ], or common salt
	* ] for three ~~essential~~ amino acids and therefore many proteins (skin, hair, nails, liver, and pancreas)		* ] for three amino acids and therefore many proteins (skin, hair, nails, liver, and pancreas)

			Many elements are required in trace amounts, usually because they play a ] role in ].<ref name=lipp>{{cite book \|author1=Lippard, S. J. \|author2=Berg, J. M. \| title=Principles of Bioinorganic Chemistry \| publisher=University Science Books \| location=Mill Valley, CA \| year=1994 \| isbn=0-935702-73-3}}</ref>
	====Trace minerals====

	Many elements are required in trace amounts, usually because they play a ] role in ].<ref name=lipp>{{cite book \| author=Lippard, S. J. and Berg, J. M. \| title=Principles of Bioinorganic Chemistry \| publisher=University Science Books \| location=Mill Valley, CA \| year=1994 \| isbn=0-935702-73-3}}</ref> Some trace mineral elements (RDA < 200 mg/day) are, in alphabetical order:

	* ] required for biosynthesis of ] family of ]s
	* ] required component of many redox enzymes, including ]
	* ] required for sugar metabolism
	* ] required not only for the biosynthesis of ], but probably, for other important organs as breast, stomach, salivary glands, thymus etc. (see Extrathyroidal ]); for this reason iodine is needed in larger quantities than others in this list, and sometimes classified with the macrominerals
	* ] required for many enzymes, and for ] and some other proteins
	* ] (processing of oxygen)
	* ] required for ] and related oxidases
	* ] present in ]
	* ] required for ] (antioxidant proteins)
	* ] (Speculative: there is no established RDA for vanadium. No specific biochemical function has been identified for it in humans, although vanadium is required for some lower organisms.)
	* ] required for several enzymes such as ], ], ]

	===Vitamins===		===Vitamins===
			] deficiencies may result in disease conditions. Excess of some vitamins is also dangerous to health (notably ]), and animal nutrition researchers have managed to establish safe levels for some common companion animals.<ref>Morris PJ, Salt C, Raila J, Brenten T, Kohn B, Schweigert FJ, Zentek J. Safety evaluation of vitamin A in growing dogs. British Journal of Nutrition. 2012; 108(10):1800-1809.</ref> Deficiency or excess of minerals can also have serious health consequences.
	{{Main\|Vitamin}}

			ASH
	As with the minerals discussed above, some vitamins are recognized as essential nutrients, necessary in the diet for good health. (] is the exception: it can alternatively be synthesized in the skin, in the presence of ].) Certain vitamin-like compounds that are recommended in the diet, such as ], are thought useful for survival and health, but these are not "essential" dietary nutrients because the human body has some capacity to produce them from other compounds. Moreover, thousands of different ] have recently been discovered in food (particularly in fresh vegetables), which may have desirable properties including ] activity (see below); experimental demonstration has been suggestive but inconclusive. Other essential nutrients not classed as vitamins include ]s (see ]), ], ]s (see ]), and the minerals discussed in the preceding section.
			Though not a nutrient as such, an entry for ''ash'' is sometimes found on nutrition labels, especially for ]. This entry measures the weight of inorganic material left over after the food is burned for two hours at 600 °C. Thus, it does not include water, fibre, and nutrients that provide calories, but it does include some nutrients, such as minerals <ref>Purina; {{webarchive \|url=https://web.archive.org/web/20110721050811/http://www.purinaone.com/CoolTools/Nutrition101.aspx?ArticleId=CE5F9A76-C480-496F-A0B1-9BDAA4675A4F \|date=July 21, 2011 }}; last checked 2009-07-22</ref>

			Too much ash may contribute to ] in ]s.<ref>R. Glenn Brown; ; Canadian Veterinary Journal 1989 January 30(1): 73–79; last checked 2009-07-22</ref>
	Vitamin deficiencies may result in disease conditions: ], ], ], impaired ], disorders of cell ], certain forms of cancer, symptoms of premature ], and poor ] (including ]), among many others.<ref>{{cite book \| author=Shils et al. \| year=2005 \| title=Modern Nutrition in Health and Disease \| publisher=Lippincott Williams and Wilkins \| isbn=0-7817-4133-5}}</ref> Excess of some vitamins is also dangerous to health (notably ]), and for at least one vitamin, B6, toxicity begins at levels not far above the required amount.
	Deficiency or excess of minerals can also have serious health consequences.

			==Intestinal bacterial flora==
	===Water===
			Animal ]s contain a large population of ] which are essential to ], and are also affected by the food eaten.
	{{duplication\|dupe = Human nutrition#Water}}
	{{Main\|Drinking water}}
	] ] in ]]]
	About 70% of the non-fat mass of the ] body is made of water.<ref>{{cite web\|last=Goldwater\|first=William\|title=Analysis of Adipose Tissue in relation to Body Weight Loss in Man\|url=http://jap.physiology.org/search?author1=William+H.+Goldwater&sortspec=date&submit=Submit\|publisher=Journal of Applied Physiology\|accessdate=June, 28, 2011}}</ref> Analysis of Adipose Tissue in Relation to Body Weight Loss in Man. Retrieved from Journal of Applied To function properly, the body requires between one and seven ]s of water per ] to avoid ]; the precise amount depends on the level of activity, temperature, humidity, and other factors.{{Citation needed\|date=April 2008}} With physical exertion and heat exposure, water loss increases and daily fluid needs will eventually increase as well.

	It is not fully clear how much water intake is needed by healthy people, although some experts assert that 8–10 glasses of water (approximately 2 liters) daily is the minimum to maintain proper hydration.<ref>{{cite web \|url=http://www.bbc.co.uk/health/healthy_living/nutrition/drinks_water.shtml \|title=Healthy Water Living\|publisher=BBC\|accessdate=2007-02-01\| archiveurl= http://web.archive.org/web/20070203112214/http://www.bbc.co.uk/health/healthy_living/nutrition/drinks_water.shtml\| archivedate= 3 February 2007 <!--DASHBot-->\| deadurl= no}}</ref> The notion that a person should consume eight glasses of water per day cannot be traced to a credible scientific source.<ref> by Heinz Valdin, Department of Physiology, Dartmouth Medical School, Lebanon, ]</ref> The effect of, greater or lesser, water intake on weight loss and on constipation is also still unclear.<ref>, Factsmart.org web site and references within</ref> The original water intake recommendation in 1945 by the ] of the ] read: "An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods."<ref>Food and Nutrition Board, National Academy of Sciences. Recommended Dietary Allowances, revised 1945. National Research Council, Reprint and Circular Series, No. 122, 1945 (Aug), p. 3-18.</ref> The latest dietary reference intake report by the ] recommended, generally, (including food sources): 2.7 liters of water total for women and 3.7 liters for men.<ref>, Food and Nutrition Board</ref> Specifically, ] and ] women need additional fluids to stay hydrated. According to the ]—who recommend that, on average, women consume 2.2 litres and men 3.0 litres—this is recommended to be 2.4 litres (approx. 9 cups) for pregnant women and 3 litres (approx. 12.5 cups) for breastfeeding women since an especially large amount of fluid is lost during nursing.<ref>{{cite web\|url=http://www.mayoclinic.com/health/water/NU00283 \|title=Water: How much should you drink every day? - MayoClinic.com \|publisher=MayoClinic.com<! \|date= \|accessdate=2009-05-21}}</ref>

	For those who have healthy kidneys, it is somewhat difficult to drink too much water,{{Citation needed\|date=July 2008}} but (especially in warm humid weather and while exercising) it is dangerous to drink too little. People can drink far more water than necessary while exercising, however, putting them at risk of ], which can be fatal. In particular large amounts of de-ionized water are dangerous.

	Normally, about 20 percent of water intake comes in food, while the rest comes from drinking water and assorted beverages (] included). Water is excreted from the body in multiple forms; including ] and ], ]ing, and by ] in the exhaled breath.

	===Other nutrients===
	{{duplication\|dupe = Animal nutrition#Other compounds}}
	Other micronutrients include antioxidants and phytochemicals. These substances are generally more recent discoveries which have not yet been recognized as vitamins or as required. Phytochemicals may act as antioxidants, but not all phytochemicals are antioxidants.{{Citation needed\|date=December 2009}}

	====Antioxidants====
	{{Main\|Antioxidant}}

	Antioxidants are a recent discovery. As cellular ]/energy production requires oxygen, potentially damaging (e.g. ] causing) compounds known as ] can form. Most of these are oxidizers (i.e. acceptors of electrons) and some react very strongly. For normal cellular maintenance, growth, and division, these free radicals must be sufficiently neutralized by antioxidant compounds. Some are produced by the human body with adequate ] (], ]) and those the body cannot produce may only be obtained in the diet via direct sources (Vitamin C in humans, ], ]) or produced by the body from other compounds (] converted to Vitamin A by the body, ] synthesized from ] by ]). Phytochemicals (''Section Below'') and their subgroup polyphenols are the majority of antioxidants; about 4,000 are known. Different antioxidants are now known to function in a cooperative network, e.g. vitamin C can reactivate free radical-containing ] or vitamin E by accepting the free radical itself, and so on. Some antioxidants are more effective than others at neutralizing different free radicals. Some cannot neutralize certain free radicals. Some cannot be present in certain areas of free radical development (Vitamin A is ] and protects fat areas, Vitamin C is ] soluble and protects those areas). When interacting with a free radical, some antioxidants produce a different free radical compound that is less dangerous or more dangerous than the previous compound. Having a variety of antioxidants allows any byproducts to be safely dealt with by more efficient antioxidants in neutralizing a free radical's ].

	====Phytochemicals====
	] are a source of ]]]

	{{Main\|Phytochemical}}

	A growing area of interest is the effect upon human health of trace chemicals, collectively called ]. These nutrients are typically found in edible plants, especially colorful fruits and vegetables, but also other organisms including seafood, algae, and fungi. The effects of phytochemicals increasingly survive rigorous testing by prominent health organizations. One of the principal classes of phytochemicals are ]s, chemicals which are known to provide certain health benefits to the ] and ]. These chemicals are known to down-regulate the formation of ], key chemicals in ].

	Perhaps the most rigorously tested phytochemical is ], a yellow-pigmented carotenoid present in many yellow and orange fruits and vegetables. Repeated studies have shown a strong correlation between ingestion of zeaxanthin and the prevention and treatment of ] (AMD).<ref>{{cite journal \|doi=10.1001/jama.272.18.1413 \|author=Seddon JM, Ajani UA, Sperduto RD, ''et al.'' \|title=Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group \|journal=JAMA \|volume=272 \|issue=18 \|pages=1413–20 \|year=1994 \|month=November \|pmid=7933422 }} See http://www.mdsupport.org/library/zeaxanthin.html.</ref> Less rigorous studies have proposed a correlation between zeaxanthin intake and ].<ref>{{cite journal \|author=Lyle BJ, Mares-Perlman JA, Klein BE, Klein R, Greger JL \|title=Antioxidant intake and risk of incident age-related nuclear cataracts in the Beaver Dam Eye Study \|journal=Am. J. Epidemiol. \|volume=149 \|issue=9 \|pages=801–9 \|year=1999 \|month=May \|pmid=10221316 }}<br/>{{cite journal \|author=Yeum KJ, Taylor A, Tang G, Russell RM \|title=Measurement of carotenoids, retinoids, and tocopherols in human lenses \|journal=Invest. Ophthalmol. Vis. Sci. \|volume=36 \|issue=13 \|pages=2756–61 \|year=1995 \|month=December \|pmid=7499098 }}<br/>{{cite journal \|author=Chasan-Taber L, Willett WC, Seddon JM, ''et al.'' \|title=A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women \|journal=Am. J. Clin. Nutr. \|volume=70 \|issue=4 \|pages=509–16 \|year=1999 \|month=October \|pmid=10500020 }}<br/>{{cite journal \|author=Brown L, Rimm EB, Seddon JM, ''et al.'' \|title=A prospective study of carotenoid intake and risk of cataract extraction in US men \|journal=Am. J. Clin. Nutr. \|volume=70 \|issue=4 \|pages=517–24 \|year=1999 \|month=October \|pmid=10500021 }}</ref> A second carotenoid, lutein, has also been shown to lower the risk of contracting AMD. Both compounds have been observed to collect in the retina when ingested orally, and they serve to protect the rods and cones against the destructive effects of light.

	Another carotenoid, beta-], appears to protect against chronic joint inflammatory diseases, such as ]. While the association between serum blood levels of beta-cryptoxanthin and substantially decreased joint disease has been established, neither a convincing mechanism for such protection nor a cause-and-effect have been rigorously studied.<ref>{{cite journal \|author=Pattison DJ, Symmons DP, Lunt M, ''et al.'' \|title=Dietary beta-cryptoxanthin and inflammatory polyarthritis: results from a population-based prospective study \|journal=Am. J. Clin. Nutr. \|volume=82 \|issue=2 \|pages=451–5 \|year=2005 \|month=August \|pmid=16087992 }}<br/>Am J Epidemiology 2006 163(1).</ref> Similarly, a red phytochemical, ], has substantial credible evidence of negative association with development of prostate cancer.

	The correlations between the ingestion of some phytochemicals and the prevention of disease are, in some cases, enormous in magnitude.

	Even when the evidence is obtained, translating it to practical dietary advice can be difficult and counter-intuitive. Lutein, for example, occurs in many yellow and orange fruits and vegetables and protects the eyes against various diseases. However, it does not protect the eye nearly as well as zeaxanthin, and the presence of lutein in the retina will prevent zeaxanthin uptake. Additionally, evidence has shown that the lutein present in egg yolk is more readily absorbed than the lutein from vegetable sources, possibly because of fat solubility.<ref>{{cite journal \|author=Handelman GJ, Nightingale ZD, Lichtenstein AH, Schaefer EJ, Blumberg JB \|title=Lutein and zeaxanthin concentrations in plasma after dietary supplementation with egg yolk \|journal=Am. J. Clin. Nutr. \|volume=70 \|issue=2 \|pages=247–51 \|year=1999 \|month=August \|pmid=10426702 }}</ref> At the most basic level, the question "should you eat eggs?" is complex to the point of dismay, including misperceptions about the health effects of cholesterol in egg yolk, and its saturated fat content.

	As another example, lycopene is prevalent in tomatoes (and actually is the chemical that gives tomatoes their red color). It is more highly concentrated, however, in processed tomato products such as commercial pasta sauce, or ], than in fresh "healthy" tomatoes. Yet, such sauces tend to have high amounts of salt, sugar, other substances a person may wish or even need to avoid.

	The following table presents phytochemical groups and common sources, arranged by family: {{-}}
	{\| class="wikitable" border="1"
	\|-
	! Family !! Sources !! Possible Benefits
	\|-
	\| ]s\|\|], ], ], ], ], ]\|\|general ], oxidation of ]s, prevention of ] and ]
	\|-
	\| ]s (])\|\|], ], ]\|\|general ], prevention of ] and ], easing symptoms of ], ]<ref>Note that some isoflavone studies have linked isoflavones to increased cancer risk.</ref>
	\|-
	\| ]s\|\|]\|\|]
	\|-
	\| ]s\|\|] peels, ]s, ], ], ], ]<ref>Monoterpenes are enormously widespread among green plant life (including ]). Many plants, notably coniferous trees, emit beneficial monoterpenes into the atmosphere.</ref>\|\|], treating ]
	\|-
	\| ]\|\|], ], ]s\|\|], lowered ]s, assistance to the ]
	\|-
	\| ]s\|\|]s, ]s, ]\|\|], ], ], ],
	]
	\|-
	\| ]s\|\|]\|\|topical ], ], cancer cell ]
	\|}

	===Ash===
	Though not really a nutrient as such, an entry for ''ash'' is sometimes found on nutrition labels, especially for ]. This entry measures the weight of inorganic material left over after the food is burned for two hours at 600°C. Thus, it does not include water, fibre, and nutrients that provide calories, but it does include some nutrients, such as minerals <ref>Purina; ; last checked 2009-07-22</ref>

	There have been some concerns that too much ash may contribute to ] in ]s.<ref>R. Glenn Brown; ; Canadian Veterinary Journal 1989 January 30(1): 73–79; last checked 2009-07-22</ref>

	===Intestinal bacterial flora===
	{{Main\|Gut flora}}
	It is now also known that animal ]s contain a large population of ]. In humans, these include species such as '']'', '']'' and '']'', among many others. They are essential to ], and are also affected by the food we eat. Bacteria in the gut perform many important functions for humans, including breaking down and aiding in the absorption of otherwise indigestible food; stimulating cell growth; repressing the growth of harmful bacteria, training the immune system to respond only to pathogens; producing ], and defending against some infectious diseases.

	==See also==		==See also==
	*]		*]
			*]

	==References==		==References==
	{{reflist\|2}}		{{reflist\|30em}}

	==External links==		==External links==
	===Bovine nutrition===
	*
	*		*
	*		*

	===Poultry nutrition===
	*		*

			{{Veterinary medicine}}
	===Swine nutrition===
	===Fish nutrition===

	===Dog nutrition===

	{{DEFAULTSORT:Animal Nutrition}}		{{DEFAULTSORT:Animal Nutrition}}
	]		]
	]		]
			]


	]

Latest revision as of 03:07, 15 September 2024

Science of nutrition for animals

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.
Find sources: "Animal nutrition" – news · newspapers · books · scholar · JSTOR (March 2018) (Learn how and when to remove this message)

Animal nutrition focuses on the dietary nutrients needs of animals, primarily those in agriculture and food production, but also in zoos, aquariums, and wildlife management.

Constituents of diet

Macronutrients (excluding fiber and water) provide structural material (amino acids from which proteins are built, and lipids from which cell membranes and some signaling molecules are built) and energy. Some of the structural material can be used to generate energy internally, though the net energy depends on such factors as absorption and digestive effort, which vary substantially from instance to instance. Vitamins, minerals, fiber, and water do not provide energy, but are required for other reasons. A third class dietary material, fiber (i.e., non-digestible material such as cellulose), seems also to be required, for both mechanical and biochemical reasons, though the exact reasons remain unclear.

Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates range from simple monosaccharides (glucose, fructose, galactose) to complex polysaccharides (starch). Fats are triglycerides, made of assorted fatty acid monomers bound to glycerol backbone. Some fatty acids, but not all, are essential in the diet: they cannot be synthesized in the body. Protein molecules contain nitrogen atoms in addition to carbon, oxygen, and hydrogen. The fundamental components of protein are nitrogen-containing amino acids. Essential amino acids cannot be made by the animal. Some of the amino acids are convertible (with the expenditure of energy) to glucose and can be used for energy production just as ordinary glucose. By breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. This occurs normally only during prolonged starvation.

Other dietary substances found in plant foods (phytochemicals, polyphenols) are not identified as essential nutrients but appear to impact health in both positive and negative ways. Most foods contain a mix of some or all of the nutrient classes, together with other substances. Some nutrients can be stored internally (e.g., the fat soluble vitamins), while others are required more or less continuously. Poor health can be caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient. For example, both salt provides sodium and chloride, both essential nutrients, but will cause illness or even death in too large amounts.

Dietary fibre is a carbohydrate (polysaccharide or oligosaccharide) that is incompletely absorbed in some animals.

Protein

Proteins are the basis of many animal body structures (e.g. muscles, skin, and hair). They also form the enzymes which control chemical reactions throughout the body. Each molecule is composed of amino acids which are characterized by the inclusion of nitrogen and sometimes sulfur. The body requires amino acids to produce new proteins (protein retention) and to replace damaged proteins (maintenance). As there is no protein or amino acid storage provision, amino acids must be present in the diet. Excess amino acids are discarded, typically in the urine. For all animals, some amino acids are essential (an animal cannot produce them internally) and some are non-essential (the animal can produce them from other nitrogen-containing compounds). A diet that contains adequate amounts of amino acids (especially those that are essential) is particularly important in some situations: during early development and maturation, pregnancy, lactation, or injury (a burn, for instance).

A few amino acids from protein can be converted into glucose and used for fuel through a process called gluconeogenesis; this is done in quantity only during starvation.

Minerals

Dietary minerals are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen that are present in nearly all organic molecules. The term "mineral" is archaic, since the intent is to describe simply the less common elements in the diet.

Many elements are essential in relative quantity; they are usually called "bulk minerals". Some are structural, but many play a role as electrolytes. These include:

Calcium, a common electrolyte, but also needed structurally (for muscle and digestive system health, bones, some forms neutralizes acidity, may help clear toxins, and provide signaling ions for nerve and membrane functions)
Chlorine as chloride ions; very common electrolyte
Magnesium, required for processing ATP and related reactions (builds bone, causes strong peristalsis, increases flexibility, increases alkalinity)
Phosphorus, required component of bones; essential for energy processing
Potassium, a very common electrolyte (heart and nerve health)
Sodium, a very common electrolyte
Sulfur for three amino acids and therefore many proteins (skin, hair, nails, liver, and pancreas)

Many elements are required in trace amounts, usually because they play a catalytic role in enzymes.

Vitamins

Vitamin deficiencies may result in disease conditions. Excess of some vitamins is also dangerous to health (notably vitamin A), and animal nutrition researchers have managed to establish safe levels for some common companion animals. Deficiency or excess of minerals can also have serious health consequences.

ASH Though not a nutrient as such, an entry for ash is sometimes found on nutrition labels, especially for pet food. This entry measures the weight of inorganic material left over after the food is burned for two hours at 600 °C. Thus, it does not include water, fibre, and nutrients that provide calories, but it does include some nutrients, such as minerals

Too much ash may contribute to feline urological syndrome in domestic cats.

Intestinal bacterial flora

Animal intestines contain a large population of gut flora which are essential to digestion, and are also affected by the food eaten.

References

Berg J, Tymoczko JL, Stryer L (2002). Biochemistry (5th ed.). San Francisco: W.H. Freeman. p. 603. ISBN 0-7167-4684-0.
Nelson, D. L.; Cox, M. M. (2000). Lehninger Principles of Biochemistry (3rd ed.). New York: Worth Publishing. ISBN 1-57259-153-6.
D. E. C. Corbridge (1995). Phosphorus: An Outline of its Chemistry, Biochemistry, and Technology (5th ed.). Amsterdam: Elsevier. ISBN 0-444-89307-5.
Lippard, S. J.; Berg, J. M. (1994). Principles of Bioinorganic Chemistry. Mill Valley, CA: University Science Books. ISBN 0-935702-73-3.
Morris PJ, Salt C, Raila J, Brenten T, Kohn B, Schweigert FJ, Zentek J. Safety evaluation of vitamin A in growing dogs. British Journal of Nutrition. 2012; 108(10):1800-1809.
Purina; The Facts About Dietary Ash Archived July 21, 2011, at the Wayback Machine; last checked 2009-07-22
R. Glenn Brown; Low ash cat foods: The role of magnesium in feline nutrition; Canadian Veterinary Journal 1989 January 30(1): 73–79; last checked 2009-07-22

External links

v t e Veterinary medicine
Practitioners	Veterinarian Paraveterinary worker Veterinary pharmacist List of veterinarians
Education	List of schools Veterinary education in France Veterinarian's Oath Veterinary Medical College Application Service
Associations	American Veterinary Medical Association Royal College of Veterinary Surgeons College of Veterinarians of Ontario Evidence-Based Veterinary Medicine Association
Specialties	Alternative medicine Anesthesia Birds Behavior Dentistry Ethics Exotic animals Fish Nutrition Obstetrics Oncology Parasitology Pathology Preventive medicine Surgery Theriogenology Virology Veterinary Corps
Places	Indonesia United States United Kingdom Philippines

Categories: