Making $ense of Mineral Supplementation

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

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

3. 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

4. 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

5. 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

6. Assessing Mineral Status • Compare mineral supply to requirements • Consider intake • Feed and mineral

7. Requirements • Depend on • Age • Size • Sex • Physiological state • Level of performance • Breed • Presence of antagonists

8. 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

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

10. Western Wheatgrass Adapted from Grings et al. (1996) *Mineral concentrations in live and dead tissue differ P < .01

11. Western Wheatgrass Adapted from Grings et al. (1996) *Mineral concentrations in live and dead tissue differ P < .01

12. Sandhills Meadow Hay Adapted from Hickock et al. (1996) ≥ 75% of requirement for gestating cow

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

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

15. 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)

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

17. 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

18. Supplemental P Adapted from Paisley and Hill (2000)

19. Supplemental P Adapted from Paisley and Hill (2000)

20. Phosphorus in Feeds Gestating cows require .17 to .22 Lactating cows require .22 to .39

21. Formulating Supplements *Assumes 1200 lb cow consuming DM at 2% of body weight and mineral intake of 3 oz per day

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

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

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

25. 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)

26. Responses • Key to evaluating changes • Potential benefits • Health • Weaning weight • Growth performance • Reproductive efficiency

27. Responses  Immune Function  Growth or Fertility Clinical Signs Sub-Clinical Clinical

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

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

30. 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

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

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