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DIETARY STRATEGIES TO PREVENT MILK FEVER IN DAIRY CATTLE

DIETARY STRATEGIES TO PREVENT MILK FEVER IN DAIRY CATTLE. MILK FEVER Parturient paresis syndrome in dairy cattle as caused by hypocalcemia. Intake. Absorption. Plasma Ca . Bone . Urine. Colostrum/milk/fetus. Feces. CALCIUM METABOLISM. CLASSICAL DIETARY STRATEGY TO PREVENT MILK FEVER.

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DIETARY STRATEGIES TO PREVENT MILK FEVER IN DAIRY CATTLE

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  1. DIETARY STRATEGIES TO PREVENT MILK FEVER IN DAIRY CATTLE

  2. MILK FEVER Parturient paresis syndrome in dairy cattle as caused by hypocalcemia

  3. Intake Absorption Plasma Ca Bone Urine Colostrum/milk/fetus Feces CALCIUM METABOLISM

  4. CLASSICAL DIETARY STRATEGY TO PREVENT MILK FEVER • Low calcium intake (20-25 g/day) during dry period • Normal calcium intake (80-100 g/day) around parturition and after that

  5. Calcium absorption in dry cows when fed either low or high Ca rations Low Ca High Ca Ca intake 47.5 83.7 Ca absorption g/day 2.2 2.3 % of intake 4.6 2.7

  6. MODERN DIETARY STRATEGY TO PREVENT MILK FEVER • Feeding of ration with negative DCAD (- 50 mEq/kg DM) during dry period • Change to ration with normal DCAD (> + 200 mEq/kg DM) around parturition

  7. ADVANTAGE OF MODERN VERSUS CLASSICAL STRATEGY : Ration with negative DCAD raises absolute calcium absorption

  8. DCAD = Dietary Cation-Anion Difference DCAD = m Eq (Na + + K +) - (Cl - + S 2-) / kg DM

  9. DCAD Incidence of milk fever Reference (mEq/kg ds) (%) Block, 1984 47.4 + 330 - 128 0 Oetzel et al, 1988 + 189 17.0 - 75 4.0 Goff en Horst, 1995 + 450 47.6 + 150 50.0 - 150 10.5 n = 19 – 24 / treatment Effect of a negative DCAD on the incidence of milk fever

  10. Influence of NH4Cl on urinary pH NH4+ + Cl- NH3 + H+ +Cl- H+ + Cl- ileum H+ + Cl- Rumen Urine Liver : urea

  11. Influence of CaCl2 on urinary pH Feces Ca2+ + 2 OH- Ca(OH)2 2 H20 2 OH- + 2 H+ Ca2+ + 2 Cl- GI-tract H+ Cl- (Urine)

  12. Urinary pH and Ca excretion in cows fed rations with either a positive or negative DCAD DCAD (mEq/kg DM) + 276 -170 8.7 7.9 pH 6.1 Ca (g/day) 0.4

  13. Hypothesis : Ration with a negative DCAD increases Ca-absorption (Schonewille et al, 1994)

  14. Cation-rich Anion-rich Grassilage (kg dm/day) 5.0 5.0 Cornsilage (kg dm/day) 1.9 1.9 Concentrate (kg dm/day) 1.0 1.1 Ca (g/day) 50 53 Na (g/day) 10 10 K (g/day) 175 175 Cl (g/day) 52 169 S (g/day) 20 24 DCAD (mEq/kg dm) +276 -170 COMPOSITION OF EXPERIMENTAL RATIONS

  15. CALCIUM BALANCE AND ABSORPTION Cation-rich Anion-rich (g/day) Intake 50.4 52.8 Feces 48.6 47.8 Absorption 1.8 5.0* Urine 0.4 6.1* Balance 1.4 -1.1 (% of intake) Absorption 3.6 9.5* *P<0.05 ( n = 6 in cross-over experiment)

  16. HYPOTHESIS : The extra flow of Ca through the body after feeding a ration with a negative DCAD, can be used to maintain the plasma Ca concentration at the onset of milk production

  17. Intake Absorption Plasma Ca Bone Urine Colostrum/milk/fetus Feces CALCIUM METABOLISM

  18. Experimental rations Cation-rich Anion-rich Grasshay (kg dm/day) 4.6 4.6 Cornsilage (kg dm/day) 1.5 1.5 Concentrate (kg dm/day) 1.1 1.0 Ca (g/day) 37 37 Na (g/day) 33 31 K (g/day) 160 160 Cl (g/day) 79 220 S (g/day) 15 15 DCAD (mEq/kg dm) +330 -230

  19. Experiment: • Induction of hypocalcemia by Na2EDTA (0.9 mmol/h) infusion. • Infusions were finished when plasma Ca not bound to EDTA was about 1.0 mmol/l. • Measurement of urinary Ca excretion during EDTA infusions (catheter in bladder). • Concentrations of Ca in plasma and urine were measured colorimetrically in order to obtain the concentration of Ca not bound to EDTA • (Schonewille et al, 1999)

  20. Urinary pH and Ca concentration before the infusion of EDTA DCAD (mEq / kg DM) +330 -230 pH 8.73 5.73* Ca (mM) 1.8 11.5* * P<0.05

  21. Plasma Ca DCAD (mEq / kg DM) +330 -230 Plasma Ca not bound to EDTA (mM) start of infusion 2.44 2.36 end of infusion 0.99 0.97 Amount of EDTA infused (mmol) 249 303* * P<0.05

  22. 5.0 4.0 3.0 Urinary Ca excretion (mmol/hour) 2.0 1.0 0.0 0 to 1.5 2.3 to 4.1 4.5 to 8.3 Time (hours) Urinary Ca excretion during EDTA infusion after feeding a ration with a negative DCAD

  23. Rations with a negative versus positive DCAD : - Increase Ca absorption and urinary Ca excretion. - Increase of the Ca flow through the body; the extra urinary Ca excretion can be reduced when plasma Ca is stressed.

  24. Practical relevance : - Assume production of colostrum is 10 L. (2 g Ca/L.) - Extra urinary Ca excretion after feeding ration with negative DCAD is about 6 g Ca /day - The amount of extra available Ca around parturition is sufficient to support the production of about 3 L. of colostrum.

  25. CONCLUSIONS : • The reduction of milk fever as induced by a negative DCAD, is explained by an increased absolute absorption of Ca and by immediate availability of the extra Ca flow through the body. • A negative DCAD can be achieved by the use of NH4Cl, CaCl2, MgCl2 an/or MgSO4.

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