Research Review MINERAL SUPPLEMENTATION OF FEEDLOT CATTLE

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1 Research Review MINERAL SUPPLEMENTATION OF FEEDLOT CATTLE Simone Holt, Ph.D. and Joseph McMeniman, Ph.D. Mineral supplementation is typically divided into two categories; 1) macro minerals and 2: micro or trace minerals. Macro minerals (calcium, phosphorus, potassium, sulphur, magnesium, sodium and chloride) are required in large quantities and are generally fed at levels greater than 100ppm. Trace minerals (copper, zine, iodine, manganese, selenium, cobalt and iron) are required in small amounts and fed at levels less than 100ppm (Paterson and Engle, 2005). There is little doubt that trace minerals and vitamins are necessary for normal growth, health and performance of feedlot cattle (Underwood and Suttle, 2004). Trace minerals should not be underrated in a feeding program. Just because these components of the feeding program are provided in small quantities does not negate their larger role in entire production system. Macro and trace minerals required by cattle are presented in Table 1. Table 1. Mineral requirements of cattle. Macro Minerals Trace Minerals Calcium Copper Phosphorus Zinc Magnesium Manganese Salt Cobalt Potassium Iodine Sulfur Iron Selenium Mineral supplements can become complex as macro minerals play a large role in physiological function of cattle and as such are needed not only to be supplied in the correct amount but in balance with other minerals and nutrients. If not delivered in this manner, imbalances can lead to metabolic diseases and/or toxicities can be produced. Interestingly, most of the imbalances that occur in cattle are due to trace mineral imbalances. Years of intensive research has culminated in the establishment of standards for mineral requirements of beef cattle. The National Research Council in the United States last published standards in These recommended standards are utilised by nutritionists all over the world. Mineral requirements for feedlot cattle are listed below in Table 2. From perusal of the table below, it can be noted that requirements for stressed cattle are greater. This is due to the fact that in starting cattle or lightweight calves intake is depressed below normal levels and concentrations of nutrients need to be increased to compensate. High levels of potassium, zinc, manganese and copper have increased performance of stressed cattle. For this reason in some feedlots both a starter and finisher supplement is utilised.

2 Table 2. National Research Council Mineral Requirements of Feedlot Cattle (DM basis; NRC, 1996) Mineral Unit Growing/Finishing Stressed Cattle Cattle Calcium % NRC Equations Cobalt mg/kg Copper mg/kg Iodine mg/kg Iron mg/kg Magnesium % Manganese mg/kg Phosphorus % NRC Equations Potassium % Selenium mg/kg Sodium % Sulfur % Zinc mg/kg Macrominerals Calcium is the most abundant mineral in the body and is needed to promote proper bone and teeth growth. Without adequate dietary calcium, frame growth and ultimate feedlot performance is depressed. Calcium is also distributed in extracellular fluids and soft tissues, and is involved in such functions as blood clotting, membrane permeability, muscle contraction, transmission of nerve impulses, cardiac regulation, secretion of hormones and activity and stabilization of certain enzymes (NRC, 1996). For this reason most feedlot cattle are supplemented with > 0.70% (DM basis) calcium in their diets, usually via limestone. Phosphorus is often discussed in conjunction with calcium because the two minerals function together in bone growth, however the effect of calcium to phosphorus ratio has been overemphasised in the past. Dietary calcium to phosphorus ratios of 1:1 to 7:1 result in similar performance, provided that phosphorus intake is adequate to meet minimum requirements. Phosphorus deficiency results in reduced growth and feed efficiency, decreased appetite and weak, fragile bones. In feedlot cattle fed high concentrate diets, it has been shown that cattle do not require supplemental phosphorus as grain diets typically contain ample phosphorus (Erickson et al. 2002). These authors estimated phosphorus requirements of 265 kg feedlot calves fed for more than 200 d to be < 0.16% of the diet DM. Lighter weight feedlot calves may however require phosphorus supplementation to optimise growth. Potassium is the third most abundant mineral in the body. Potassium is important to maintain acid base balance, regulation of osmotic pressure, water balance, muscle contractions, nerve impulse transmission and certain enzymatic reactions. In diets supplemented with adequate molasses which is high in potassium, little supplemental potassium is needed. However in diets without molasses, supplemental potassium will improve performance, particularly in newly received cattle, and cattle subjected to heat stress. 2

3 Over 300 enzymes are known to be activated by Magnesium. It is therefore essential to provide adequate levels to optimise performance. Increased levels of magnesium have also been linked to increased marbling in cattle in some research. Magnesium deficiency in calves results in excitability, anorexia, convulsions, frothing at the mouth, profuse salivation and calcification of soft tissue. A common disorder of grazing cattle is grass tetany, which can be fatal. This disorder results from a magnesium deficiency induced when lactating cattle graze lush early season pastures, which are often rich in potassium. Sodium and chlorine are essential in maintaining osmotic pressure, water balance, ion channelling, muscle contractions, nerve impulse transmission and glucose and amino acid transport. Signs of sodium deficiency include a rough coat, reduced feed intake and growth. Cereal grains and feedstuffs typically contain adequate sodium to maintain performance. Cattle desire salt, and it is typically including at low levels in the diet to keep cattle drinking and prevent urinary calculi, especially in Bos indicus breeds. Several recent trials, however, have demonstrated that salt supplementation is not necessary in typical feedlot diets and has no effect on animal performance (Wilson et al. 2004; Colgan et al. 2006). Sulfur is an important mineral, as a component of amino acids and B-vitamins. Sulfur is also required by rumen micro-organisms for microbial protein synthesis. Severe sulphur deficiency results in weight loss, emaciation, excessive salivation and death. Marginal sulphur deficiency may reduce microbial protein synthesis, decreasing protein deposition and carcass weight gain. Although not a major problem in Australia, care must be taken to ensure that sulphur in water and diet does not exceed 0.40% (DM basis), as excess sulphur can depress feed intake and induce metabolic deaths in feedlot cattle. This is a common problem in the United States in areas with high sulphate water, or feedlots feeding high levels of wet-distillers grains. Trace Minerals Trace minerals need to be maintained within narrow concentrations (Underwood and Suttle, 1999) to promote normal tissue growth, homeostasis, enzyme function, cell regulation and immune function. Furthermore, trace mineral imbalances and/or deficiencies require the animal to metabolically compensate for the nutritional deviation. Small or marginal deficiencies can be a greater problem than large or acute deficiencies because clinical symptoms are not evident and most of these imbalances are not identified. However, at the same time the animal continues to grow and perform but at a reduce rate. This reduced performance is often overlooked and more often than not poor genetics and or poor weather conditions during the feeding period are blamed. The impact of marginal deficiencies on feedlot performance was well illustrated by a study conducted at Colorado State University (Engle et al., 1997) where Zinc was reduced to marginal deficient levels for 21 days and then re-supplied. Average daily gain and feed efficiency (Figure 1.) decreased within 21 days of removing supplemental zinc. This decline in performance occurred without a change in zinc plasma or liver concentration which suggests performance was more sensitive to the marginal deficiency status of the animal. Upon repletion of zinc with an organic zinc complex (eg. Availa 4 Zinpro Corp.), average daily gain and feed efficiency improved within 3 days. 3

4 Figure 1. Effect of zinc depletion on feed efficiency in beef calves In general, as trace mineral status begins to decline immunity and enzyme functions are compromised first (Figure 2.). This is followed by reductions in maximum growth and fertility and once clinical signs appear normal growth and fertility are greatly impaired (Wikse, 1992). Immunity & Enzyme Function Adequate Maximum Growth/Fertility Normal Growth/Fertility Clinical Signs Subclinical Clinical Figure 2. Effect of decreasing trace mineral status on animal performance. Underwood and Suttle, 1999 describe the function of trace minerals as being: Structural Physiological Catalytic Regulatory Structural refers to minerals forming structural components of body organs and tissue. An example of this is zinc s contribution to molecular and membrane stability. This is why zinc is recommended to improve hoof integrity and reduce the incidence of foot rot cases. Zinc helps to make the hoof 4

5 and areas around the hoof more pliable so that the skin is not easily broken reducing the ability of bacteria to invade. Physiological refers to minerals in body fluids and tissues that act as electrolytes. Catalytic is probably the biggest function as trace minerals are structural components involved in enzyme activity that it required for energy production, protein digestion and wound healing to name a few. Lack of adequate trace minerals would cause a large reduction in enzyme activity. Trace minerals also have a role in regulating thyroid function and energy metabolism. Inorganic vs. Organic Trace Minerals Traditionally, trace minerals have been supplied to cattle in the form of inorganic salts; sulphates, oxides and chlorides such as copper sulphate or copper chloride. More recently, the use of organic trace minerals has proven to improve performance and immune response, although in some cases no difference with inorganic mineral sources is observed. Organic trace minerals are hooked chemically to a carrier, most likely an amino acid/protein complex so that it is more bioavailable to the animal. Quite often one mineral can affect the intake and absorption of another mineral (antagonistic mineral). In these cases by changing the source of trace mineral (inorganic to organic) and binding the trace mineral to a proteinate will decrease the opportunity for antagonist minerals to attack and increase the availability of the trace mineral. Some of the most common antagonists include high levels of molybdenum and sulphur reducing the absorption of copper (Suttle, 1991). Another common interaction is caused by high iron levels. High iron levels can interfere with zinc, copper and manganese absorption by the animal (Gengelbach et al., 1994). It is important to note that water can provide these additive levels of trace minerals that have the potential to cause problems. Water should be sampled to examine if any potential problems exist. Health & Immune Response Profitability of a cattle feeding operation can be rapidly reduced through medication costs, lost performance in individual sick animals and death. Trace minerals are key in maintaining normal immune function and disease resistance. The first level of defence in fighting an immune challenge is the skin. Zinc and manganese are key elements for maintaining epithelial tissue integrity. Keep in mind that the lining of the respiratory tract, lungs and gastrointestinal trace are also epithelial tissue. This makes the role of zinc and manganese all the more critical as these trace minerals can help to reduce the infiltration of pathogens. Copper has also been shown to play an important role in immune function. Evidence suggests that copper metabolism affects the function of several classes of immune system cells, particularly those involved in producing antibodies (Ahola and Engle, 2005). Many feedstuffs contain low levels of copper. In addition, the presence of copper antagonists (previously mentioned), such as molybdenum (Mo), sulphur (S) and/or iron (Fe) can substantially lower absorption and metabolism of copper inducing deficiencies. Macro and trace-minerals are necessary for many metabolic functions in cattle. To maintain optimal performance not only is adequate intake required but these additives need to be supplied in the correct balance. Research has shown that small and marginal deficiencies can compromise health and performance. 5

6 References Ahola, J.K. and Engle, T.E Trace minerals and the immune system in cattle. Cattle producer s library. Wester Beef Resource Committee Nutrition Section Colgan, S.L., and T.L. Mader Sodium chloride and soybeans in feedlot diets. Nebraska Beef Cattle Report 88-A: Engle, T.E., Nockels, C.F., Kimberling, C.V., Weaber, D.L., and Johnson, A.B Zinc repletion with organic or inorganic forms of zince and protein turnover in marginally zinc-deficient calves. J. Anim. Sci. 75: Erickson, G.E., T.J. Klopfenstein, C.T. Milton, D. Brink, M.W. Orth and K.M. Whittet Phosphorus requirements of finishing feedlot calves. J. Anim. Sci. 80: Gengelbach, G.P., Ward, J.D. and Spears, J.W Effect of dietary copper, iron, and molybdenum on growth and copper status of beef cows and calves. J. Anim. Sci. 72: Larson, C.L Role of trace minerals in animal production. University of Tennessee Nutrition Conference Proceedings. NRC Nutrient Requirements of Beef Cattle, 7 th Edition. National Academy Press, Washington, DC. Paterson, J.A. and Engle, T.E Trace mineral nutrition in beef cattle. University of Tennessee Nutrtion Conference Proceedings. Sanders, S.K., Morgan, J.B., Wulf, D.M., Tatum, J.D., Williams, S.N. and Smith, G.C Vitamin E supplementation of cattle and shelf-life of beef for the Japanese market. J. Anim. Sci. 75: Suttle, N.F The interactions between copper, molybdenum, and sulphur in ruminant nutrition. Annu. Rev. Nutr. 11: Underwood, E.J. and Suttle, N.F The Mineral Nutrition of Livestock. CABI Publishing, New York, NY. Wikse, S.E The relationship of trace element deficiencies to infectious diseases of beef calves. Texas A & M University Beef Shortcourse Proceedings. Wilson, C.B., G.E. Erickson, C.N. Macken, and T.J. Klopfenstein Sodium chloride levels for finishing feedlot heifers. Nebraska Beef Cattle Report MP 80-A: Last Updated: November,

7 Simone Holt, Ph.D. Joseph McMeniman, Ph.D. Consulting Nutritionist Consulting Nutritionist Mobile: Mobile: Nutrition Service Associates 18/18 Brookfield Road PO BOX 388 Kenmore QLD 4069 Ph: Fax: