1. Forage Macro-Minerals (Ca, P, K, Mg, Na, Cl, S) and Dairy Cow Requirements Jim Linn, PhD Professor Emeritus – University of Minnesota Milk Specialties Global Waconia Farm Supply

2. Importance of Minerals Animal Health Production/Reproduction Ration cost Lactating Cow 8 to 10% of total $/cow/day 0.75 - 1.00 Close-Up Dry Cow 18 – 22% of total $/cow/day 0.75 - 1.00

3. Nutrient Composition (% DM) of Dairy Rations

4. Forage Minerals Forage minerals Contribute to animal requirement Variability – species, maturity, soils, fertilization Animal – Plant Imbalances

5. Forage Mineral Analysis NIRS or Wet Chemistry? – NIRS doesn’t measure minerals only C,N,O bonds – Are the minerals reported on NIRS forage tests accurate? – At the end of the day, when nutritionists have several rations to formulate, can NIRS predicted forage minerals be used?

6. NIR Prediction of Minerals Haylage Calibration Data MineralMeanSECRSQSECV Ca1.12.15.86.16 P.34.04.61.04 Mg.32.05.69.05 K2.66.32.81.32 S.26.04.75.04 Source – Dairyland Labs, Arcadia WI SEC – Std Error Calibration – lower better (±1 SEC – 67% of values) RSQ – R 2 1 = perfect prediction SECV – Prediction validation – lower the better NIR mineral validity depends on good reference wet chemistry methods and equation(s) development

7. NIRS Analysis – Forage Minerals Macro Minerals – – Lactation rations Acceptable estimator – Ca, P, K, Mg and S Rationale – Most rations over formulated and supplemented – Small range in P, Mg and S within species – Salt meets Na and Cl req’t – Dry cow NIRS not recommended for mineral analysis Forages are large proportion of diet Accuracy needed for DCAD and requirements Trace minerals – NIRS not recommended

8. Forage Macro Minerals SGS Forage Summary - 2012 MineralLegume Haylage Grass Haylage Grass 2+ Haylage Mixed Haylage Mix-Leg Haylage Corn Silage ------------------------------- Mean / SD --------------------------------------------- Ca1.130.670.751.051.330.22 SD0.370.260.250.390.340.07 P0.290.310.320.290.300.21 SD0.070.080.07.070.060.03 K2.462.572.652.452.410.88 SD0.540.780.580.630.540.24 Mg0.270.250.300.260.310.18 SD0.08 0.060.080.070.06

9. Mineral Mineral bioavailability (%) estimate of forages NRC 2001 Ca30 – 35 P60 – 65 K>85 Mg15 – 20 S85 – 90 Na>85 Cl>85

12. Minerals in Rations of Lactating Dairy Cows

13. Feed DM (lb) – 85 lb Milk LbFeedDMLbFeedDM 52 lb DM 17% CP 1.18 Mcal ME/lb 32% NDF 25.5% Starch 61 % Forage DM

14. Macro Minerals for Lactating Cows Requirements vs. Ration Formulation Mineral2001 NRCUpdated NRC Weiss 1 Formulated ------------------------------- % of DM ---------------------------------- Calcium0.6 – 0.750.70 - 0.860.9 – 1.0 Phosphorus0.32 – 0.400.38 – 0.48>0.42 Magnesium0.200.280.32 – 0.38 Potassium1.01.15>1.5 Sodium0.220.250.4 – 0.6 a Chloride0.260.30>0.4 b Sulfur0.20 0.25 1 Weiss – Hoards Dairyman Feb 10, 2013 a Sodium Buffers b Higher forage concentrations - legume

15. Calcium Contribution From Feeds Lactating cow diet – 0.90% Ca lb or %

16. Phosphorus Contribution From Feeds Lactating cow diet – 0.40% P lb or % lb Feed DM % P contribution

19. Magnesium Contribution From Feeds Lactating cow diet – 0.35% Mg lb Feed DM % Mg contribution lb or %

20. Potassium Mineral required in the highest amounts in lactating dairy cows K balance studies indicate 1.6% K needed in early lactation for positive balance Heat stress increases requirement Forage K >85% available

21. Potassium Contribution From Feeds Lactating cow diet – 1.5% K % K contribution lb or %

23. Sulfur Contribution From Feeds Lactating cow diet – 0.28% S % S contribution lb or %

24. Sodium and Chloride Contribution From Feeds Lactating cow diet – 0.5% Salt lb or % Ration – 0.5% Na and 0.62% Cl

26. Minerals in Rations of Close-up Dry Dairy Cows

27. Close-up Dry Cow Diet 28 lb DM/day lb/cow/day Grass hay8.3 Corn silage 13.7 Corn0.8 Protein3.8 Macro minerals1.04 TM/Additives0.64

28. Close-up Dry Cow Diet % Macro Mineral from Forage 77% Forage diet – 13.7 lb Corn sil + 8.3 lb Grass Hay DM %

29. Minerals from Forages in Dry Cow Diets Forages can supply 20 to 70% a mineral Accuracy on mineral concentration in forages more important – less error tolerance  Cation – Anion balance  Metabolic problems – greater risk with mineral imbalance Wet chemistry analysis recommended for minerals in dry cow forages

30. DCAD, mEq/100g = [(%Na  43.5 + %K  25.6)  (%Cl  28.2 + %S  62.5)]

31. LACTATING COWSCLOSE-UP DRY COWS DCAD, mEq/100g = [(%Na  43.5 + %K  25.6)  (%Cl  28.2 + %S  62.5)]

32. Macro Minerals in Forage Summary Forages are an important source of most macro minerals in lactating and dry cow rations. Ration formulation needs to consider – Requirements – Sources – Amounts fed – excess as well as deficiencies – Interactions amongst minerals fed in excess

33. Macro Minerals in Forage Summary NIRS acceptable estimator of Ca, P, K, Mg and S in lactating rations. – Formulations usually exceed minimum requirements Forages are a greater proportion of dry cow ration and mineral formulation requires accuracy – Wet Chemistry mineral analysis recommended. Precision feeding lactation and/or dry cow diets require wet chemistry analysis of minerals.

34. THANK YOU!