Chapter 3 Energy Nutrients Livestock Nutrition Chapter 3 Energy Nutrients

Objectives Define terms of associated with energy. Describe the energy nutrients. List sources of energy nutrients. Describe the functions of energy nutrients. Describe symptoms of deficiencies of energy in the ration.

Terminology Calorie, (cal)- the amount of heat energy required to raise the temperature of one gram of water form one degree C3. Kilocalorie, 1,000 calories. Mega calorie, 1,000,000 calories.

Terminology Gross Energy (GE)- the total amount of heat released when a substance is completely oxidized in a bomb calorimeter. Digestible Energy (DE)- The gross energy of feed consumed minus the gross energy excreted in the feces. Metabolizable Energy (ME)- The gross energy of the feed minus the energy in the feces, urine, and gaseous product of digestion.

Terminology Heat Increment (HI)- that portion of the ME which is used for digestion or metabolism of absorbed nutrients into body tissue. Net Energy, (NE)- the metabolizable energy minus the heat increment. Used for growth, maintenance, production, work, fetal development and heat production.

Energy Nutrients Carbohydrates and lipids ( fats and oils) are the major sources of energy in livestock rations. Carbohydrates are the most important because they are readily available, easily digested & lower in cost. Proteins are seldom fed for their energy content because of the higher cost of this source.

Carbohydrates Organic compounds made of carbon,( C ), Hydrogen (H), & Oxygen (O). Each C2H2O molecule is made up of 40% C, 7% H and 53% O2. Carbohydrates found in plants include starch, sugars, hemicellulose, cellulose, pectin's, gums, & lignin.Sugars are the most easily digested while cellulose and lignin are more difficult. Carbohydrates in the feed are changed to simpler forms.

Carbohydrates 75% of all the dry matter in plants is carbohydrates. More easily digested forms of carbohydrates are generally found stored in the seeds, roots and tubers of the plant. Hemicellulose and cellulose are converted to glucose. Because hemicellulose and cellulose require more energy, they are less efficient sources of energy for the animal.

Carbohydrates Carbohydrates are divided into two groups, FIBER & NITROGEN-FREE EXTRACT. Fiber because of the lignin, cellulose and hemicellulose it is less of an efficient feed than NFE. The NFE group includes sugar, starch and some hemicelluloses.

Carbohydrates Starch is made up of many molecules of glucose. Grains have a high feeding value because the starch is easily digested. Ruminant animals because of bacterial action in the Rumen can utilize large portions of coarse roughage. Non-ruminants have less ability to utilize energy from fiber. The young of all species require more easily digested feeds.

Lipids (fats & oils) Lipids are 77% C, 12% H & 11% O. Because there is more carbon and hydrogen and less oxygen in the molecule, lipids supply approximately 2.25 times as much energy as an equal weight of carbohydrates. Lipids are classified as simple, compound and derived. Simple lipids are true fat and waxes.

Lipids Compound lipids are esters, which contain groups in addition to an alcohol and fatty acid. Derived lipids are from simple or compound lipids, separated by hydrolysis. Fatty acids are either saturated or unsaturated. Fats are used to raise the energy level of the diet and/or improve the flavor, texture and palatability of the feed. Rations for adult ruminant animals should contain no more than 3-5% fat and 15-20% fat for nonruminants.

Sources of Energy Concentrates A major source of energy nutrients is the grains and grain byproduct. These feeds are called energy concentrates or basal feeds when their crude protein is less than 18% in the air-dry state.

Shelled Corn One of the highest energy feeds available. The most widely grown and used feed grain crop. Corn produces more #’s of TDN/acre than any other. It is an economical and superior source of energy. Consideration must be given to amount to feed, frequency and combinations with other feeds, in order to get the most efficient use of this high energy feed source without causing digestive problems.

Corn & Cob Meal Contains about 10% less energy than shelled corn because of the fiber content in the cob. All species can utilize it, however, when feed to growing-fattening hogs because they do not have the ability to digest and use much of the cob content.

Ground Snapped Corn Made up of the grain, cob and shucks and is considerably higher in fiber and lower in TDN than shelled corn. Comparable to oats. Very seldom used because of the high labor requirement in harvesting it.

Corn Starch and Corn Oil Fairly pure forms of starch and oil. Generally not used in commercial enterprises however, they are sometimes used in the purified diets of experimental animals.

Oats About 85% of the energy of shelled corn. Higher in crude protein than shelled corn and add fiber and bulk to the ration. Help the rumen maintain bacterial and protozoa function. Not a good fattening feed but are used extensively in rations for horses, young growing stock, show stock and breeding animals. Usually fed rolled, crimped or ground.

Barley Almost equal to corn in energy value, but lies between corn and oats in fiber content. Used in a ration in a manner similar to oats. Barley may replace up to 50 % of the corn in rations for fattening animals. The grain content of the ration may be decreased by 10 % if barley replaces all of the corn. To improve palatability it is usually steam rolled, crimped or coarsely ground.

Wheat High in both energy and protein it is generally not used in livestock rations because of the high value as a small grain crop on the cash market. Wheat is similar to corn in composition and feeding value. If and when it is used in a ration it is included at low levels in a mix with other grains because it is rapidly digested and may cause digestive disturbances.

Grain Sorghum There are many varieties, milo, kafir and various hybrids. Smaller than shelled corn and may replace up to 100% of the corn in a feedlot ration. Generally rolled or ground when included in a ration.

Rye Rye is usually used for bread for human consumption and has limited use as a livestock feed. It is not as valuable as corn, whet or grain sorghum. Ergot contaminated rye can be toxic to livestock. The use of rye in livestock rations should be limited to no more than one-third of the ration. It should be coarsely ground or rolled to increase palatability.

Sources of Energy Forages (roughages) can supply some of the energy needs in the livestock ration, although they are not as concentrated a source of energy as the grains. Value of forages for livestock feed is highly dependent on time of harvesting. As forage plants mature, the crude fiber content (cellulose and lignin) increases, which lowers the digestibility of the feed. When forages are harvested as silage, more of the nutritional value of the plant is preserved.

Corn Silage Corn silage, which contains almost 50% grain on a dry matter basis, is an excellent energy source for certain classes of livestock. Sorghum and small grain silages are lower in energy content than corn silage.

Straws Oat, barley and wheat are low in energy value and are not used as a major source of energy. It may be used if additional fiber is needed in the ration.

Pastures Properly managed pastures can be a good source of nutrients. Rotating and fertilizing pastures to get the best yield and nutritional value. Quality of pasture must be closely watched and supplemented with good quality stored forages when necessary.

Sources of Energy Byproducts These include the following: Dried citrus pulp. Dried beet pulp. Potato meal. Dried sweet potatoes. Cotton seed hulls. Beet tops.

Dried Citrus Pulp The remaining pulp, after the fruit is removed, can also come from cull fruit. Can be fed dried or wet. High in fiber content but it is considered an energy feed. It usually limited to not more than 20-25% of the ration.

Dried Beet Pulp Primarily used in dairy cattle rations but is occasionally used in rations for horse, beef and sheep. Adds bulk to rations. Makes rations more palatable, mild laxative. Should not replace more than 20% of the grain in a ration.

Sources of Energy---Fats A byproduct of packing plants, and poultry processing plants. Commercial feed mixes will contain 1-7% animal fat. Animal fat in the feed reduces the dustiness of the feed. Often treated with antioxidants to prevent the feed from becoming rancid in storage. Beef and dairy rations can contain up to 5% while swine rations may have up to 20%.

Sources of Energy---Molasses Common types of molasses are cane or blackstrap, beet, citrus and wood. Molasses is used in rations for cattle, sheep and horses but is seldom used in swine rations, because it causes scouring. Improves palatability, aids rumen microbial activity, reduces dust and serves as a binder when feeds are pelleted. Molasses is usually limited to not more than 10-15% of the ration.

Functions of Energy Energy nutrients are needed for the maintenance of life in the animal. Maintains basal metabolism. Basal metabolism is defined as the heat production of the animal while it is at rest and not digesting food. Beating of the heart, maintenance of blood pressure, transmission of nerve impulses, breathing and work of other internal organs.

Functions of Energy When animals are on full feed they seldom reach lower critical temperature unless the weather is extremely cold. It is only after all the maintenance needs of the animals are met that energy nutrients can be used for growth or production. Fattening livestock requires a large amount of energy nutrients. Energy not used for other needs is deposited as fats within the body tissues. The deposition of fats makes the meat tender,juicy and gives it a better flavor.

Functions of Energy When feeding horses, the amount of energy needed for no body weight change and the normal activities of the nonworking horse is called the maintenance requirement. A number of factors affect the amount of energy needed, intensity and duration of work, condition and training of the horse, the ability and weight of the rider, degree of fatigue of the horse and environmental conditions in which he is performing.

Effects of Energy Deficiency Slow growth of young. A delay in the onset of puberty. A decrease in milk yield in lactating females. A shortened lactation period. A Los in body weight. Several kinds of reproductive problems including reduced fertility and delayed estrus.

Effects of Energy Deficiency In sheep, a reduction in wool quantity and quality. A higher mortality rate. A lowered resistance to disease. Weakness, generally poor condition, and unthrifty appearance. Hypoglycemia. A loss of subcutaneous fat. A reduction in levels of blood glucose, calcium, and sodium.

Do the Following Review Questions Numbers 1, 2, 3, 5, 6, 8, 9, 10, 11, 12, 14, 18, 19, 20, 22, 23, 24, 25, 27, 28, 29, 30.