Making $ense of Mineral Supplementation

Cody Wright, PhDExtension 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 WheatgrassMineral Live Dead

------------------ % of DM ------------------

Ca .25* .22P .16* .07Mg .12 .07K 1.6* .3Adapted from Grings et al. (1996)*Mineral concentrations in live and dead tissue differ P < .01

Western WheatgrassMineral Live Dead

--------------------- ppm ---------------------

Zn 20* 15Cu 2 2Mn 47 49Mo 1 1Adapted from Grings et al. (1996)*Mineral concentrations in live and dead tissue differ P < .01

Sandhills Meadow HayMineral Cherry Rock HoltCu (ppm) 9.4 6.7 6.5Zn (ppm) 26.1 25.5 27.5Mn (ppm) 85.9 111.9 131.5P (%) .25 .29 .15Mg (%) .17 .19 .16K (%) 1.1 1.6 1.3Adapted 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, %.05 .15 .25

------ % P needed in supplement ------1000 8 6 61100 10 6 61200 10 6 61300 12 6 61400 12 6 6Adapted from Paisley and Hill (2000)

Supplemental P

Stage of production

Total diet P, %.05 .15 .25

------ % P needed in supplement ------Late

gestation 16 6 6Lactation10 lb/d 16 6 620 lb/d 16 10 630 lb/d 16 12 6Adapted from Paisley and Hill (2000)

Phosphorus in Feeds

Feed % P in feed

lb fed per day2 4 6

------- % P added to diet -------CGF .95 .07 .14 .21DDG .83 .06 .12 .19SFM 1.02 .08 .15 .23WM 1.00 .08 .15 .23

Gestating cows require .17 to .22Lactating cows require .22 to .39

Formulating Supplements

Mineral % of NRC requirement*75 100 125

Cobalt 9.6 12.8 16Copper 960 1280 1600Iodine 48 64 80Manganese 384 5120 6400Selenium 9.6 12.8 16Zinc 2880 3840 4800*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

BioavailabilityMost bioavailable

OrganicSulfate and chlorideCarbonatesOxides

Least bioavailableIN GENERAL, BUT NOT ALWAYS!!

Organic Minerals?• Two supplements

– 100% of NRC @ 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-Clinical Clinical

Immune Function

Growth or Fertility

Clinical Signs

Time

Min

eral

Sta

tus

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 ton @ 2 oz per day– $9.13 per cow

• Strategic (Feb 1 to July 1)– $400 per ton @ 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