Making $ense of Mineral Supplementation Cody Wright, PhD Extension Beef Specialist South Dakota State University

Introduction Animals require numerous minerals (macro and trace) for maintenance, growth, and reproduction Mineral nutrition is complex and not well understood

Assessing Mineral Status Objectively analyze production –Rule out other factors Determine mineral supply –Forage, supplement, and water –SAMPLE, SAMPLE, SAMPLE!! Directly sample the animal –Blood or liver

Sampling Feeds Trace minerals in clipped and selected samples are similar Selected samples generally contain greater levels of Ca and P than clipped samples Sample the forages that cattle are grazing

Sampling Feeds Sample silages or delivered feeds periodically to monitor changes Minerals in feeds and forages are not 100% available –50% is a reasonable guideline Don’t forget the water

Assessing Mineral Status Compare mineral supply to requirements Consider intake –Feed and mineral

Requirements Depend on –Age –Size –Sex –Physiological state –Level of performance –Breed –Presence of antagonists

Antagonists Sulfur –> 500 ppm in water can  Cu absorption –Alone or in combination with Mo Molybdenum –Cu:Mo ratio of 4.5:1 and dietary S >.25% Iron –> 50 ppm

Meeting Requirements Primary sources of minerals –Forage (grazed or harvested) –Supplemental feed ingredients –Supplemental minerals Fed Bolus Injected

Western Wheatgrass MineralLiveDead % of DM Ca.25*.22 P.16*.07 Mg K1.6*.3 Adapted from Grings et al. (1996) *Mineral concentrations in live and dead tissue differ P <.01

Western Wheatgrass MineralLiveDead ppm Zn20*15 Cu22 Mn4749 Mo11 Adapted from Grings et al. (1996) *Mineral concentrations in live and dead tissue differ P <.01

Sandhills Meadow Hay MineralCherryRockHolt Cu (ppm) Zn (ppm) Mn (ppm) P (%) Mg (%) K (%) Adapted from Hickock et al. (1996) ≥ 75% of requirement for gestating cow

Formulating Supplements Considerations –Animal requirements –Minerals in feeds and forages –Potential antagonists –Sources and levels –Expected responses

Formulating Supplements Phosphorus is generally the most expensive mineral to supplement So, why do we feed so much?

Phosphorus Late 1930’s –King Ranch –  % calf crop by 40% and 41% –  weaning wt by 69 lb and 49 lb –  lb weaned per cow exposed by 156 lb and 165 lb –Return per $1 invested = $3.95 and $12.35 Adapted from Herd (1997)

Phosphorus Karn (1995 and 1997) –Less dramatic responses –Heifers -  conception rates and weight gain –Cows -  weight gain and weaning weights –Small and inconsistent

Formulating Supplements General guideline –Each 1% P costs adds ~$11 per ton Reducing from 12% to 8% P –  mineral cost by ~$44 per ton –Savings of $1.50 per cow –$750 per year for a 500 hd operation

Supplemental P Body weight, lb Total diet P, % % P needed in supplement Adapted from Paisley and Hill (2000)

Supplemental P Stage of production Total diet P, % % P needed in supplement Late gestation 1666 Lactation 10 lb/d lb/d lb/d16126 Adapted from Paisley and Hill (2000)

Phosphorus in Feeds Feed % P in feed lb fed per day % P added to diet CGF DDG SFM WM Gestating cows require.17 to.22 Lactating cows require.22 to.39

Formulating Supplements Mineral % of NRC requirement* Cobalt Copper Iodine Manganese Selenium Zinc *Assumes 1200 lb cow consuming DM at 2% of body weight and mineral intake of 3 oz per day

Maximum Levels Selenium –3 mg/hd/d or.3 ppm in diet Iodine –10 mg/hd/d –Well below level claimed to prevent footrot

Mineral Sources Critical to formulating cost- effective programs Cost per unit of mineral –Consider mineral concentration and bioavailability

Bioavailability Most bioavailable Organic Sulfate and chloride Carbonates Oxides Least bioavailable IN GENERAL, BUT NOT ALWAYS!!

Organic Minerals? Two supplements –100% of 3 oz per day –100% inorganic = $580/ton –50/50 blend = $680/ton –17.2%  in cost ($3.42 per cow)

Responses Key to evaluating changes Potential benefits –Health –Weaning weight –Growth performance –Reproductive efficiency

Responses Sub-ClinicalClinical  Immune Function  Growth or Fertility Clinical Signs

Responses Cost / benefit analysis Must be able to pay for any increase in cost Can we reduce cost without sacrificing production?

Strategic Supplementation Supplement only when needed Begin ~45 days before calving Continue through breeding season

Strategic Supplementation Year round –$400 per 2 oz per day –$9.13 per cow Strategic (Feb 1 to July 1) –$400 per 3 oz per day –$5.63 per cow (38% less) –$1750 savings on 500 hd operation

Summary Objectively evaluate current herd mineral status Rule out other factors Sample forages, supplements, and water to determine mineral intake and level of antagonists

Summary Formulate or purchase mineral supplements to correct imbalances Develop strategic mineral program to reduce expenses Estimate and objectively evaluate production responses