Battle is on to lower dairy saturated fats

Monitoring milk saturated fat levels in a similar way to bulk somatic cell counts, bactoscan and butterfats could become the norm in the not-so-distant future.

In October 2011, Marks and Spencer became the first UK supermarket to stipulate specific saturated fat levels from its liquid milk pool, potentially paving the way for other buyers to follow suit.

Since the initiative was introduced, the 50 Marks & Spencer suppliers have reduced overall saturated fat levels by 6% against winter milk production. To receive a premium of 0.7p/litre they are required to have a two-month rolling saturated fat level of below 69%.

Chair of the Marks & Spencer milk pool Mark Robins says the supermarket’s approach is unique in its stipulations to farmers.

“Marks & Spencer are not saying what producers need to feed their cows, but they are saying they have to get a certain set of results. It’s about outcome measures.”

The move by the supermarket follows concerns over the negative implication of saturated fats on human health and the fact a large proportion comes from dairy.

“Rather than get consumers to reduce their intake of dairy, the aim is to make dairy products healthier,” says Mr Robins.

Both Mr Robins and Marks & Spencer milk pool nutritional adviser Diana Allen admit the nutritional aspect of achieving these standards have been challenging and are a continuous learning process.

Although many Marks & Spencer dairy farmers run high-yielding herds, there are a range of different systems, with varying periods at grass and varying complexities and types of ration.

The spring grass effect

Milk saturated fat levels naturally drop when cows go out to grass and increase at housing. This natural fluctuation is due to oil levels in the grass, and specifically Omega 3 fatty acids. Omega 3 fatty acids in grass are anti-carcinogenic, anti-inflammatory and also reduces saturated fats in milk.

The main aim is to mimic spring grass growth in the ration

The roll of oilseed products

A number of research papers say oilseed-type products will reduce milk saturated fat levels.

Overall, extruded linseed is currently seen as the quickest and most effective way to reduce saturated fats by most Marks & Spencer suppliers, but whole rapeseed and extruded rapeseed could have a similar effect.

Due to the high cost of extruded linseed, many producers will introduce linseed to the ration when saturated fat levels start to rise and remove it once they have reduced

All Marks & Spencer farmers have access to computer software that will generate an omega 3 fatty acid index (IT3 index) for a ration. The aim is for an index of 50-100, as a low level will cause problems

Further research is needed to gain an understanding of other routes to reducing saturated fat levels. There is a need for a more sustainable, long-term strategy that is more reliant on a consistent ration.

Health considerations

Initial trial work was carried out by Marks & Spencer to assess the effects of feeding linseed and what the optimum levels of inclusion were.

At an inclusion rate of 1.5kg a head, gut condition was compromised. The target of a saturated fat level lower than 69% was based on what levels were achievable on farm, without compromising cow health.

Linseed products have been claimed to improve cow fertility and general health.

Main ration considerations

Saturated fat levels will depend on total ration oil levels, the type of oil and straights fed.

Generally, in some herds, when palm oil products are removed from a ration, saturated fat levels will drop (Marks & Spencer farmers are not allowed to feed palm oil).

There’s no set oil level to ensure low saturated fat levels, but when the oil level is 8% or less, scouring can be a problem. The key is to have a quality, consistent and well-balanced ration and use common sense when it comes to the type of ingredients.

Future research

To help understand what other factors influence milk saturated fat levels, the Scottish Rural University College (SRUC), NMR and Marks & Spencer are currently undertaking a four-year UK-wide trial on 210 herds.

Initial findings show a huge range in saturated fat levels on individual farms, from 58% up to more than 70%. The aim is to understand how fatty acid profiles can be used to predict animal health and welfare, latitude effects on fatty acid profile and how body condition score correlates to fatty acid data.

Simple ration and reliance on grass 

The block-calving herd at South Lynch Dairy is fed 1kg a head of extruded linseed during the whole housing period to maintain ration consistency, cow fertility and saturated fats.

Because the winter housing period coincides with breeding, herd manager Nils Kurkutakis says limiting ration change is crucial.

“Any slight change could hit fertility,” he says. “With the cost of semen and staff time, we don’t want to compromise fertility.”

When housed, the herd of 290 Holstein Friesians, which are being crossed to Swedish Red, are fed a simple TMR of grass silage, straw, extruded linseed and an 18% cake and topped up in the parlour with up to 8kg a cow a day.

The aim is to have cows out as much as possible and Mr Kurkutakis explains it is only necessary to feed linseed when cows are housed, because as soon as cows are out, saturated fat levels drop.

“At housing, it is a struggle to keep saturated fat below 70%, but at grass, this can drop to 64%.”

In the middle of March, 100 of the low yielders were out at grass and being buffer fed silage and cake because of limited grass growth. This helped bring down the overall average milk saturated fat levels.

“Linseed is very expensive, but the costs are spread out,” explains Mr Kurkutakis. “All cows are housed for 150 days and fed 1kg a head, so that’s about £104 a cow over the housing period.

“It is a lot of money, but linseed is a high-energy feed and meant to help fertility. To keep saturated fat levels down, you have to feed some kind of omega 3, and linseed is one way to do this. One kilogramme a head is the benchmark we have set ourselves from experience.” 

A complex dairy ration 

john-trottOne of the first tasks of the morning for herd manager John Trott is checking the milk saturated fats graph and assessing whether ration changes are needed.

Due to the fact extruded linseed can add 1p/litre to costs at high inclusion rates, the product is only fed when saturated fat levels start to rise.

The herd of 210 Holsteins yield 9,000-10,000 litres a cow a year and consequently are fed a high-performing ration, including 18kg maize silage, 12kg grass silage, 1.5kg baled haylage, 6kg caustic wheat, 3kg Trafford Gold, 1.5kg high-protein soya, 1.5kg rape meal, 100g minerals and 100g urea. They are also topped up in the parlour with up to 6kg of cake. Linseed is added when necessary.

Nutritionist Diana Allen explains how care is needed when incorporating linseed against this background ration: “Cows are on a knife edge, so if you have to push linseed up while on this finely-tuned ration, you need to be careful,” she says.

Mr Trott says linseed is the easiest way to manipulate the ration to control saturated fat levels, but he admits the process has been “a steep learning curve”.

“We have struggled a bit. We find when we try to push down saturated fats quickly it can bring cows to the brink of acidosis. We’ve used a lot of linseed to a maximum inclusion of 0.8kg a cow.”

The farm saw little decrease in saturated fats when linseed was included at 0.2-0.4kg and Mrs Allen says it is necessary to go in hard when saturated fat levels start to rise.

Mr Trott explains that saturated fat levels drop as soon as cows are at grass, so the added costs of linseed are diluted throughout the year. “We aren’t feeding it all year round, so it balances out with the milk premium we receive,” he says.

Mr Trott is also interested in establishing if there is a link between daylight hours and saturated fat levels and whether silage additives have a role to play in helping silages mimic grazed grass. 

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