1- By Maintaining Negative Dietary Cation-Anion Difference (DCAD)
Concept:
- By reducing cations and increasing anions in the diet in transition period, blood pH drops slightly. Physiological effects of negative metabolic acidosis (low blood pH),
- This shift increases the sensitivity and responsiveness of bone and kidney tissues to Parathyroid Hormone (PTH). PTH increases the blood calcium by mobilization of calcium from bone.
- Kidney more efficiently converts Vitamin D to 1,25-dihydroxy Vitamin D. Activated vitamin D, leads to increased intestinal Ca absorption.
- Reduced urinary calcium loss and more calcium retained in circulation
During and after calving, calcium demand increases multiple times for milk and colostrum production and requirement cannot be full filled by dietary sources only. Metabolic acidosis induced by anionic diet (negative DCAD) in transition period can quickly mobilize calcium from her bones and absorb it more efficiently from her intestines.
Remarks:
- Highly recommendable, most successful approach specially, when combined with low calcium and important pre-mixes in diet.
- Commercial products are available or negative DCAD can be achieved by anionic salts also.
- Palatability may be an issue with anionic salts
- Urine pH act as indicator for metabolic acidosis
2- By Formulating Low Calcium Diet (Calcium Restriction/Chelation)
Concept:
Feed a diet with minimal calcium to create a temporary deficiency. The parathyroid gland detects low blood calcium and responds by releasing Parathyroid Hormone (PTH). PTH mobilizes calcium from bones and activates Vitamin D to enhance intestinal absorption.
Traditionally, we can achieve it with diet having minimal calcium level but practically difficult to reduce the diet calcium up to the level that induce PTH. There is a alternative strategy to functionally reduce the calcium in diet that is by use of calcium binders like Zeolite (sodium aluminosilicate).
Remarks:
- Less frequently recommended and used
- Zeolite can also bind with Phosphorus, trace minerals and vitamins
- No palatability issue like anionic salts
- No need to check urine pH, regularly
3- By Using Regular Transition Diet (without DCAD balance)
Concept:
Pre-calving regular transition diet contains all the necessary nutrients and feed additives (without negative DCAD balancing). It formulated by considering on following points,
- Necessary nutrients like trace minerals like Cu, Zn, Mn, Se, Co, Fe etc.
- Macro minerals specially Magnesium.
- Proper balance of energy, protein and fiber.
- Vitamins like Vit A, E, D, Choline, Biotin, Niacin etc.
- Protected amino acids like Lysine, Methionine etc.
- Feed additive like Toxin Binder, Glucogenic Precursor, Monensin, Yeast powder, Betaine, Essential oils, Antioxidants etc.
Remarks:
Small dairy farmers often trying to manage pre-calving transition period by using supplements or premixes containing these nutrients and feed additives.
- This is also very effective but not alternative of DCAD concept.
- No palatability issue, easy to use, no extra labour required
- If negative DCAD balance is not possible, you can go with regular transition diet.
Conclusion:
It is always good to go with negative DCAD balance in pre-calving transition diet, along with low calcium, optimum magnesium and adequate use of all necessary pre-mixes like trace minerals, feed additive etc. Transition diet must be balanced for protein, energy and fiber for better performance in lactation.