Mineral Nutrition of Grazing Cattle Oklahoma State University

Mineral Nutrition of Grazing Cattle Oklahoma State University

Lesson Outline and Objectives n Discuss typical mineral composition of common Oklahoma forages n Consider mineral needs of cattle n Determinerals that are most likely needed in a supplement

Importance? Proper mineral and vitamin nutrition contributes to: q A strong immune system q Reproductive efficiency q Weight gain

Why All the Fuss? n Producers have endless options n Annual mineral costs vary from $2 to $40 per cow: Cattle Fax n Requirements vary considerably

Why All the Fuss? …cont. n Forage mineral concentration changes over time (within a year) n Mineral interactions add to the uncertainty n Identifying site specific mineral needs and(or) deficiencies is costly and time consuming

“In matters of style, swim with the current; In matters of principle, stand like a rock” Will Rogers

Why Do We Supplement Salt and Minerals? n Forage diet may not meet the animals requirement n Offset imbalance of an antagonistic mineral that is too high in forage n Deliver vitamins, antibiotics, ionophores

Macro or Major n Ca n. P n Magnesium n Sulfur n K - potassium n Sodium Micro or Trace n Selenium n Zinc n Manganese n Iron n Copper n Cobalt

Factors That Influence Forage Mineral Concentration n Forage species n Plant maturity n Grazing pressure (leaf vs stem) n Weathering n Soil mineral concentration and/or fertilizer applications

Forage Species n Composition data: n Oklahoma, Lusby and Selk, 1994 n National, Greene et al. , 1998

Sodium Requirement

Phosphorus Requirement

Copper Requirement

Zinc Requirement

Manganese Requirement

Selenium Requirement

Iron Requirement

Species Summary n Legumes are an excellent source of minerals n Almost all forages (except legumes) are low in Native warm season grasses are moderate to low in P while other grasses are moderate n All grasses contain low Cu and Zn n Fescue tends to be low in Se, while other forages are moderate to adequate

Plant Maturity

Influence of Plant Maturity on Mineral Composition Source: Greene et al. , 1987

Carotene in Native Pasture NRC Req. Waller et al. , 1972

Grazing Pressure

Influence of Grazing Pressure on Forage Minerals n Leaf has 2 X to 3 X of most minerals compared to stem n Limited forage availability (<1, 200 lb per acre) reduces dry matter intake

Nitrogen Fertilization

Effects of Late-summer N Fertilization Rate on Minerals in Bermudagrass Did not change concentrations of: Mineral Ca, % Cu, ppm Mo, ppm Mean 0. 42 3. 86 0. 43 Source: Lalman et al. , 2002 SE 0. 02 0. 14 0. 02 P>F 0. 9 0. 8 0. 6

Effects of Late-summer N Fertilization Rate on Minerals in Bermudagrass Increased concentrations of: Mineral P, % Mg, % K, % S, % Mean 0. 16 0. 10 0. 36 0. 22 *P <. 01 Source: Lalman et al. , 2002 Contrast* Lin Lin Percent 0 vs 135 17 33 36 19

Effects of Late-summer N Fertilization Rate on Minerals in Bermudagrass Decreased concentrations of: Mineral FE, ppm Zn, ppm Mean 318 21. 7 114 *P <. 01 Source: Lalman et al. , 2002 Contrast* Lin Lin Percent 0 vs 135 27 16 18

Weathering

Harvest Date: Calcium NRC Nov vs March = 24% Linear P <. 01 Quad P <. 01 Source: Lalman et al. , 2002

Harvest Date: Phosphorus NRC Linear P <. 01 Quad P <. 01 Nov vs March = 39% Source: Lalman et al. , 2002

Harvest Date: Magnesium NRC Nov vs March = 50% Linear P <. 01 Quad P <. 01 Source: Lalman et al. , 2002

Harvest Date: Potassium NRC Nov vs March = 76% Linear P <. 01 Quad P <. 01 Source: Lalman et al. , 2002

Summary: Forage Mineral Composition n Many factors influence forage mineral composition n A general idea of species differences, maturity, and weathering (standing forage) can lead to a logical supplementation plan

Mineral Supplementation

Consider the Form n Sulfates are more available than oxides: 80 to 100 VS 0 to 70 q Cu q Zn n Organic forms have higher availability compared to inorganic: 100 to 130

If It Isn’t Broke, Don’t Fix It! n Are you satisfied with fertility? q Pregnancy = 90% or more? q Weaning rate = 86% or more? n Are you satisfied with weaning weights? q Weaning weight = 525 lb or more? n Do you have evidence that your calves remain healthy (don’t get sick) after they are weaned?

Take Care of the BIG Things First n Cows calve in good body condition (nutrition) n Well planned and executed herd health program (disease control) n Maintain a fertile cow herd and bull battery (culling and selection)

Strategic Mineral Supplementation Assuming forage mineral deficiencies have been identified, the most critical times to insure adequate mineral status are: n Last trimester = new-born calf health and vigor n Early lactation = cow rebreeding performance n Pre-weaning = calf health during the stressful weaning period and beyond

Composition of OSU Range Research Center Mineral Cost per ton = $550 Mineral Concentration Ca, % 14 P, % 5 Mg, % 1 Cu, ppm 1000 Zn, ppm 3000 Se, ppm 15 Cows consume both native and bermudagrass forage

Other Additives?

Home Mixing?

Protect Your Investment

Summary n Production history and forage/feed mineral concentration are a good place to begin n Na, P, Cu, Zn are frequently deficient in Oklahoma. Se, Mn ? n Mineral supplements do not need to be extremely complicated or expensive