Dry Matter Intake
Dry matter intake is probably the most important aspect of dairy cow management through the transition and early lactation period and beyond. Often metabolic disease ‘outbreaks’ can be helped by simply increasing dry matter intake and thereby the intake of energy, calcium and magnesium. For this reason it is important to know accurately how much you are feeding to high risk groups such as transition/springer cows and colostrum cows. Target intakes in the springer mob are intended to offset the energy drain from the rapidly growing calf. We should aim for an intake of 2% of body weight in the last few weeks before calving which equates to about 11kg for a Friesian and 9-10kg for a Crossbred/Jersey. This should increase as rapidly as possible post calving to 3.5-4% of bodyweight as a lactating cow. Failure to do this may result in energy deficit and subclinical and clinical ketosis 2-3 weeks post calving.
Body Condition Score
It is widely accepted that having cows in the correct condition score at calving is an important part of metabolic disease prevention. The target condition score is 5. Management of this begins in late lactation.
Cows that are too fat or too thin are at increased risk of metabolic disease and should be managed as higher risk cows (see below).
Dietary cation anion balance (DCAD)
Preventing metabolic disease on pasture based systems can present a few problems. The main reason for this is that the potassium level in NZ pastures is generally very high and this drives up the DCAD (dietary cation/anion deficit) of the ration and increases metabolic disease risk. This is particularly true of effluent paddocks where potassium levels will be the highest. Avoid having springers/calving cows on these paddocks. Also winter saved grass is generally lower in potassium than spring grass. Where possible we should look to drop the DCAD pre calving to prevent metabolic disease. Feeds with lower DCAD levels that are well suited to feeding springers include;
Cereals e.g. whole crop
Other products that reduce DCAD significantly include:
Please contact us to discuss the feeding of these products as part of a milk fever prevention plan.
Transition Rations (3 weeks pre calving)
Another challenge of pasture based dairy farming is providing a transition ration to the springers. The aim of a transition ration is to prepare the rumen for the post calving diet and is also an opportunity to prevent metabolic disease. In the last 4 weeks of pregnancy the unborn calf grows by over 1kg/day. This has a significant energy drain on the cow and it is vital she does not enter an energy deficit pre calving. Higher energy feeds in the transition period will help develop rumen papillae and the correct bug population so cows are able to efficiently digest the higher energy post calving ration. Feeding supplements such as those listed above in the transition period are useful for this purpose and also as a vehicle for magnesium supplementation. Other products such as ‘Biochlor’ are also available to feed in the transition period to reduce DCAD and provide some energy.
A source of fibre is also very important in pre calving rations to maintain rumen size and muscle tone.
Palm Kernel is less valuable as a precalving feed as the high oil content can prevent calcium absorption.
On farms with a high incidence of metabolic disease analysis of pasture and supplement will enable a DCAD calculation to be done and some prevention options can then be implemented.
Supplementation of magnesium:
Magnesium status pre and post calving is very important. Cows are not able to store magnesium so a constant daily intake is required. Cows failing to get this intake will get metabolic disease.
Causmag .Dusting of breaks for springers. Assume at least 50% wastage and use 60-70g of good quality causmag per cow/day. Also a drench at 30g/cow/day. Causmag is very alkaline so take care not to overdose particularly if drenching. The result would be a severe increase in rumen ph.
Magnesium chloride. This form of magnesium is soluble in water and can be effectively fed through dosatrons and Pieter dispensers. Use 70-90g/cow/day.
Magnesium Sulphate. This is least palatable form of magnesium but like magnesium chloride can be useful for reducing the DCAD status of the diet. Use 40g/cow/day on supplement.
Bullets are available for magnesium supplementation usually pre calving. These are an effective way of getting good levels of magnesium into high risk cows e.g. fat carryovers.
More Mag is a drenchable form of magnesium that has a 2 week length of action that can be a useful extra source of magnesium in severe outbreaks of metabolic disease.
Calcium levels pre calving must be kept low. Ideally 0.5% of the total ration. Post calving the cows’ calcium requirement increases massively and cows that are not able to switch their metabolism towards preserving calcium will get milk fever. Ensuring cows have adequate dietary calcium post calving is vital, it need to increase to 1% of total ration. Lime flour can be a useful way to feed supplementary calcium at a rate of about 150g/cow/day, preferably on supplement. Alternatively feeding products such as calcium enriched molasses (which has calcium as calcium chloride) is a good option for calved cows (e.g. the colostrums mob) as it will provide a good source of energy too.
Strategic products for high risk cows
Starter plus and calol are high energy and calcium drenches designed to be given to freshly calved cows to offset the risk of metabolic disease in high risk cows. These cows may be overfat (over BCS 5.5)/over thin (under BCS 4.5)/carryovers/older cows (over 7) .In particular, cows with a history of facial eczema are high risk. Given that many cows this year will have had subclinical eczema, widespread use of these products this year is recommended. These drenches have also been shown to benefit production in all cows drenched. They are intended to be used as a bolus drench.
Treatment of cases of metabolic disease
It is useful to have a standard approach to the treatment of cows with metabolic type disease on your farm. As most cases of wobbly or downer cows at or around calving will probably involve energy, calcium and magnesium deficiency a suggested protocol for all cases is:
1 bag Magnesium Sulphate (yellow) under skin
1 bag Calpro 375 (purple) intravenous or under skin
Drench with starter plus or Calol (if swallowing well)
If the cow is not up within 1-2 hours then give another Caplro 375 and check if there is another cause for the cow to be down or call the vet!
Other causes of down cows include:
Hip clamps can then be used if no other cause is obvious. If a cow remains down after that then she should be managed as a ‘downer’. Turn her regularly to prevent muscle damage and provide food and water. Call the vet for an assessment of her chances of a full recovery.
Please remember we are here to help and we look forward to working with you through a successful spring.