Mineral Supplements for Beef Cattle
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Mineral Supplements for Beef Cattle Lawton Stewart Extension Animal Scientist - Beef Cattle Introduction Beef cattle require a number of minerals for optimal growth and reproduction. Se- lecting the correct mineral supplement is important for maintaining healthy animals, and optimal growth and reproduction. Since high-quality forages and/or grains can furnish a large portion of the required minerals, producers should select supplements that will meet animal requirements and avoid excesses that reduce profits and lead to unnecessary mineral excretion. Minerals not provided by feed can be easily and inexpensively supplied with a simple mineral supplement. A good mineral program for brood cows should cost about $10 to $20 per year. This bulletin provides information on basic mineral nutrition for most forage and feeding programs in Georgia. Minerals essential to cattle nutrition are classified as either macrominerals or mi- crominerals, depending on whether they are found at levels greater than or less than 100 parts per million (ppm) in the animal’s body. Mineral Supplements for Beef Cattle 2 UGA Cooperative Extension Bulletin 895 Macrominerals The macrominerals beef cattle require include Concentrates contain moderate to high concentra- calcium, magnesium, phosphorus, potassium, so- tions of phosphorus. Protein supplements such as dium, chlorine and sulfur. Macromineral require- cottonseed meal and soybean meal contain mod- ments and maximum tolerable levels for beef erate concentrations, whereas many by-product cattle are shown in Table 1. feeds such as distillers grains, corn gluten feed and wheat middlings, have high phosphorus Calcium and Phosphorus concentrations. Calcium and phosphorus are the major min- eral components of the skeleton. Ninety-nine Sodium and Chlorine percent of total body calcium and 80 percent of Sodium and chlorine (salt) provide for the total body phosphorus are stored in the bones. proper function of the nervous and muscular The skeletal stores of calcium and phosphorus systems. They help regulate body pH and the are used to meet short-term dietary inadequacies. amount of water retained in the body. A defi- Long-term deficiencies of either can cause bones ciency of these elements causes loss of appetite to weaken and even break. and inefficient weight gains or body weight loss. Calcium and phosphorus also play impor- Sodium is commonly deficient in diets, but chlo- tant roles in other bodily functions. A decrease rine levels are usually adequate. Both minerals in either or both can cause a decrease in weight are present in soft tissues and fluids and there is gain and/or a decrease in efficiency of gain. Dur- very little storage of these elements, so a constant, ing lactation, low amounts of either will reduce daily source of sodium and chlorine must be pro- milk production. A superior milking cow requires vided. Cattle will voluntarily consume more salt three times more calcium than a non-lactating when forage is young and succulent than when it cow. A phosphorus deficiency can delay puberty matures. Silage-fed cattle will consume more salt in heifers and can delay mature beef cows from than those fed hay, and consumption is higher in returning to heat following parturition. Cattle cattle fed high-roughage diets than in those on also need correct amounts of calcium for the ner- high-concentrate diets. As a rule of thumb, cattle vous and muscular systems to function properly. consume 0.005 to 0.010 percent of their body Proper utilization of calcium and phosphorus weight as salt daily. For example, a mature cow is affected not only by the amount of each mineral weighing 1,200 pounds would consume 0.06 to fed, but also by their ratio. The optimum Ca:P 0.12 pounds (1,200 x 0.00005 = 0.6), or 1.0 to 1.9 ratio is about 1.5:1, with a range of 1:1 to 4:1 being ounces of salt daily. satisfactory. In some high-concentrate rations, ratios higher than 2:1 have been successful. Magnesium Most grasses are adequate in calcium. Le- Magnesium is essential for proper enzyme gumes such as alfalfa, peanut, clover and soybean and nervous system function and for efficient hay are good sources of calcium, but corn silage carbohydrate metabolism. A magnesium defi- and sorghum silage are poor sources of calcium. ciency is uncommon except for cows grazing In general, most concentrates are relatively poor lush-growth fescue or small grain pastures dur- calcium sources. One exception is citrus pulp, ing the late winter and early spring, which may which is relatively high in calcium concentration cause grass tetany, a serious and sometimes fatal (1.9 percent). Corn, corn by-product feeds and metabolic disorder. A high rate of nitrogen and sorghum grain are particularly low in calcium potassium fertilization contributes to grass tetany. content, and cattle fed grain or corn silage-based Excess potassium inhibits magnesium absorption diets require calcium supplementation. in both forage and animals. Grass tetany usu- Most forages are low in phosphorus, particu- ally occurs following an extended period of cold larly late in the growing season. Cattle are more weather combined with high levels of nitrogen likely to be phosphorus-deficient during the and potassium fertilization. Mature lactating winter, when they often subsist on dry forages. cows are particularly susceptible to grass tetany. UGA Cooperative Extension Bulletin 895 3 Mineral Supplements for Beef Cattle Grass tetany can usually be prevented by potassium for grazing cattle and supplementation feeding cattle a mineral mixture containing mag- is rarely needed. However, potassium may occa- nesium oxide. A mineral mixture containing 10 to sionally be low in stockpiled forages or hay that 14 percent magnesium consumed at 4 ounces per was rained on prior to baling because potassium day should provide adequate magnesium. Ad- is soluble and will leach from the forage. equate salt intake is also important for preventing grass tetany. Avoid using hard blocks to supple- Sulfur ment salt when cattle are at risk for grass tetany; Sulfur is a part of the essential amino acids supply salt in a loose form to allow for adequate methionine and cystine, which make up protein. salt consumption. When grass tetany is not a risk, A sulfur deficiency in beef cattle diets is not likely blocks can be used to supplement minerals, pro- to occur under normal feeding conditions. Sulfur vided trace minerals are elevated to account for is more likely to be in excess, which can interfere lower intake of block versus loose salt minerals. with the metabolism of copper, resulting in a Animals with grass tetany respond almost im- copper deficiency. Also, excess sulfur can reduce mediately to an intravenous infusion of calcium- feed intake and cause a brain lesion condition magnesium gluconate. known as polioencephalomalacia (PEM). Certain by-products such as distillers grains and corn glu- Potassium ten feed contain higher concentrations of sulfur, Potassium functions in acid-base balance, os- which should be taken into account in ration motic pressure and the amount of water retained balancing. Sulfur is often added indirectly to the in the body. Grasses, particularly early lush mineral mix through sulfate forms of the microm- spring growth, contains adequate amounts of inerals. Table 1. Macro mineral requirements and maximum tolerable levels for beef cattle. Mineral Lactating Cows Dry Cows Growing Calves Maximum Tolerable Level Calcium, % 0.31 0.18 0.58 — Magnesium, % 0.10 0.12 0.20 0.40 Phosphorus, % 0.21 0.16 0.26 — Potassium, % 0.60 0.60 0.70 3.0 Sodium, % 0.07 0.07 0.10 — Sulfur, % 0.15 0.15 0.15 0.40 NRC, 1996. Adapted from NRC. Nutrient Requirements of Beef Cattle, Sixth Edition. Mineral Supplements for Beef Cattle 4 UGA Cooperative Extension Bulletin 895 Microminerals Beef cattle require 10 microminerals. Seven of supplemented as ethylenediamine dihydroidide the 10 microminerals have established require- (EDDI). The maximum legal supplementation of ments, including iron, manganese, copper, zinc, EDDI is 50 mg per head per day. In some instanc- selenium, cobalt and iodine. The microminerals es, EDDI has been included in diets to prevent chromium, molybdenum and nickel do not have foot rot; however, the amount of EDDI required an established requirement and are not normally to prevent foot rot is much higher than require- added to mineral mixes fed to beef cattle. Only ments and most likely will not prevent foot rot three of the microminerals (copper, zinc and when included at the legal maximum. selenium) are likely to be deficient in grazing beef cattle diets. Micromineral requirements and maxi- Iron mum tolerable levels for beef cattle are shown in Iron is primarily required for the formation of Table 2. hemoglobin. Deficiency symptoms include ane- mia, depressed immunity and decreased weight Cobalt gains. Iron deficiency is rarely observed in graz- Cobalt functions as a component of vitamin ing cattle. Iron oxide is often included in mineral B-12, which is synthesized in the rumen by bac- mixtures, but is unavailable to the animal and teria. The primary deficiency symptom is loss of serves only as a coloring agent to give the mineral appetite and poor growth. Most forages in the a dark red color. Iron sulfate is available to the Southeast have adequate levels of cobalt; how- animal and should be used if iron supplementa- ever, it is usually added in the mineral mix at tion is needed. approximately 10 ppm to ensure no deficiencies. High-grain diets require more cobalt than forage- Manganese based diets, and cobalt should always be included Manganese is required for normal reproduc- in the mineral mix when feeding grain-based tion, and fetal and udder development. Manga- diets. nese deficiency is rare and unlikely to be a prob- lem in grazing cattle in Georgia.