Specialist diets help limit post-calving problems

The method of managing dry cow diets has changed drastically over the years, as Bruce Jobson reports.

A newly-calved cow needs up to 10 times more calcium in her bloodstream for colostrum and milk production, so ensuring she is set up to deal with these post-calving challenges is crucial.

Traditionally, dry cows are “steamed-up” but the process tends to produce overweight animals at calving, often resulting in calving difficulties, milk fever, retained placentas and displaced abomasums.

However, the concept of a specialist diet has changed the way many farmers manage their dry cows.

And meeting the cows’ needs is where the DCAB concept (dietary cation anion balance) has worked – helping animals produce more acidic conditions within the body. The acidity level helps maintain calcium balance and cows are therefore better prepared prior, during and post partum, according to Almins consultant Archie Leach.

“The increased levels of calcium are considered beneficial in order to help prevent milk fever and other metabolic disorders. A partial DCAB diet has a smaller quantity of anionic salts included in the ration. Partial DCAB diets are becoming more popular due to the inclusion of up to 200g a head a day of magnesium chloride and the reduction of feeds which tend to be high in potassium and sodium.

“Urine monitoring is important in order to observe calcium, magnesium, sodium, potassium and chloride levels as well as the amount of dissolved carbon dioxide, which is linked to the amount of bicarbonate in the blood. When blood levels are excessively alkaline, cows are more susceptible to milk fever and other related conditions. An individual case of milk fever with all costs and loss in production involved can cost a farmer over £250,” says Mr Leach.

Case study: Michael Howie, Morwick, Northumberland

The Howie family milk 200 red and white Holsteins, Ayrshire x Holsteins and a small herd of Jerseys at Morwick, Northumberland.

And having a high herd health status is crucial, with the farm attracting thousands of visitors a year to their ice-cream parlour. Feeding a partial DCAB diet is an important part of producing healthy cows, according to Michael Howie. “We want our animals healthy and trouble-free all year round and all three breeds receive the same dry cow diet six to eight weeks prior to calving.

“The partial DCAB diet has been a proven success and we haven’t encountered any milk fever-related problems, displaced abomasums or retained placentas,” he says.

Dry cows at Morwick are housed indoors and receive a mix of rape meal, premix, soya bean, maize dark grains, wheat and minerals. Cows receive the daily mix plus 15kg of grass silage and 4kg straw through a TMR feeder.

Case study: Ian and Mark Mallinson, Cumbria

Father and son, Ian and Mark Mallinson, Carhall Holsteins, Cumbria, milk 100 cows and encountered an increasing number of retained placentas two years ago. After consulting with their vet, the Mallinson’s decided to switch to a DCAB diet in order to help resolve their concerns. Today, the herd health dry cow programme has proven a resounding success, according to Mark Mallinson.

“Our feed is sampled and analysed on a monthly basis. A special mineral ration including DCAB is subsequently formulated to the specific needs of the herd and incorporated into the diet. The improvements were immediate and we’ve only had four incidences of milk fever, three retained cleansings and not had any displaced abomasums in the past two years,” he says.

The Mallinsons feed a blend of rape seed meal and high-pro soya with pre-calving minerals mixed into the ratio. Grass silage, maize silage and straw is mixed into the TMR feeder and fed ad-lib once a day. Cows are housed in straw yards and receive the diet three to four weeks prior to calving.

The most important cows on a farm are the pre-calving animals, according to Agri-King consultant, David Donaldson. “We’ve been working with DCAB diets for many years and know a cow having a healthy start in lactation is critical to achieving good production and fertility. Mineral analysis cannot always explain on-farm results as we know other dietary parameters affect the acid base status of the blood.”

After monitoring detailed blood results from a sample of 7,988 US cows fed on different forage diets, Agri-King was able to introduce a new measure know as a pre-calving index (PCI).

“Accurate forage analysis allows more precise adjustment in the diets to prevent milk fever and other metabolic disorders,” explains Mr Donaldson.

Using the PCI to adjust diets in the 7,988-cow sample resulted in a reduction in milk fever incidences down to 1%, displaced abomasums to 3% and retained placenta to 5%. This compares to average US national figures of 5.8%, 5.9% and 11%, respectively.