Milk Fever Case Study: Robert Mallett, Wiltshire
At Northleaze Farm, regularly monitoring transition cow diets, urine pH and fresh cow blood calcium levels is part of routine for the farm team.
Having experienced ‘major issues' with milk fever, Robert Mallet started working with vet consultant, James Husband from EBVC to identify a control strategy. Ration analysis showed the version of the milker's ration then being fed to transition cows was delivering more than the recommended level of potassium thanks to its grass silage base.
As a result, a dedicated ration was formulated and grass silage was replaced with wholecrop which is low in potassium. The background calcium content of the diet was also higher than expected, making a low DCAB route appropriate. Cows were put on a low DCAB ration which works by making the cow metabolically acidotic, primarily by using anionic salts. This helps mobilise calcium from the gut and bones after calving to prevent milk fever. Robert says the results were almost instant.
"It's horrible when every cow calving falls over with milk fever, but the diet changes more or less fixed the problem over night" he says.
The 220 cow herd yields 10,500 litres/cow/year and calves outside from August to March. To avoid milk fever issues due to high potassium levels in grass, grazed grass intakes are limited. Whilst at grass, cows less than 21 days from calving are also provided with access to a TMR in the shed.
This transition diet includes 15kg forage rye wholecrop, which helps achieve high intakes, 6kg maize, 1kg soya hulls, 1.25kg rape meal, 0.75kg hypro soya, 120g minerals, 120g magnesium chloride, 90g ammonium chloride.
Having been involved in the EBVC trial, at the start of the calving period, forages and the TMR will be tested for macro-minerals, which will influence how the ration is balanced. Robert has also been vet trained to take blood sample which he does on a batch of cows at the start of calving to assess how the ration is working. Last year, nine samples averaged 2.1mmol/litre of calcium.
Due to the fact the farm is managing a DCAB system, herdswoman Sophie Malt, will also take four urine samples once a week from transition cows. On a conventional system, urine testing may only be required as part of troubleshooting.
"We do a pH urine dipstick there and then and if they're all under pH6, we're confident they'll be no milk fever problems. If they're all over pH7, we'll ring James and ask him to acidify the ration further. It's about prevention and being one step ahead," explains Robert who farms with his wife Maria and son David.
The benefits have been marked with just two cases of clinical milk fever last year. "Cows also get eating quicker after calving and fertility is better thanks to better health," comments Robert.