Springer Mix Support Data
Magnesium
This is important for the calcium metabolism because it influences the ability to reabsorb calcium from the bone as well as help activate Vitamin D in the kidney. Vitamin D helps with calcium absorption.
Magnesium availability is influenced by season and fertiliser application. Pasture uptake of magnesium depends on the relative concentration and activity of magnesium in the soil solution relative to potassium and other ions. Where potassium is high then less magnesium is absorbed. Therefore if potash is applied then relatively more magnesium will be required - and in wet years when potassium is leached from the soil, the relative magnesium demand will be less.
It is important to have low calcium content in the springer diet. If the levels are too high then the active absorption mechanisms become lazy and are switched off. This means that when the cow calves and its calcium demand suddenly increases then the absorption mechanisms will not crank up quick enough to prevent problems like milk fever occurring.
DCAD
Anionic salts like chloride and sulphate help create a systemic acidosis that increases bone mobilisation of calcium.
The body's normal balancing mechanisms will adapt to return blood pH to normal in a few weeks. Therefore the timing of the use of anionic salts is critical. DCAD should not be lowered more than 3 weeks before planned start of calving (PSC); thus accurate prediction of calving dates is critical.
When ionic salts are removed at calving the pH rebounds. This will reduce the affective availability of calcium to the cow, but fortunately this usually takes about five days, by which time feed intake is usually back to normal.
New Zealand pastures have a DCAD value between 400 and 800 mEq/kgDM. If we reduce the CDAD from +600 to + 400 we have changed the daily cation-anion load and will disrupt pH.
Practically, decreasing the amount of cations and increasing the amount of anions in the diet can lower the DCAD. Cations can be decreased by using feeds low in potassium e.g. maize, silage or straw.
The anionic component can be increased by use of the Springer Mix containing magnesium chloride and magnesium sulphate. Because these two salts are fairly unpalatable, molasses has been added to the Springer Mix. This is important for maintaining feed intake when these anionic salts are used on silage and hay. Remember though, maintaining feed intake is always more important than maintaining DCAD.
When anionic salts are used before calving, cows have been found to reach their peak milk yield 10 to 14 days earlier, have easier calving and healthier calves, and greater protein and fat percentage in their first 2 months because these cows end up eating more.
After Calving
At calving there is a decrease in feed intake, which takes several weeks to reach maximum intake again. During this time there is a dramatic increase in the demand for calcium and energy. The first few days after calving are critical. Products like Starter Plus help to get the cows through this period by providing calcium, magnesium and energy.
Starter Plus contains mono-propylene glycol, bypass fat, molasses, calcium and magnesium. It can be applied to feed or be given as a drench 1 to 2 litres as a single drench or 500ml daily for 3-4 days.
ByPass fat
This has value in cows that have a low intake by increasing the ME intake while avoiding degradation in the rumen. The extra energy this can provide when intake is low gives the cow a boost and may reduce the incidence of ketosis.
Propylene glycol
This is a readily available source of energy. It is rapidly absorbed from the rumen then metabolised in the liver (therefore it requires a functional liver) to glucose, which is used by the body for energy for its metabolic processes. Propylene glycol is a cheaper source of energy than molasses.
Conclusion
With a combination o f careful observation and management of cows during their transition from dry to milking cows we should be able to minimise any problems with disease, and maximise their production for the season.
6 July 1999
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