The rumen is a competitive place these days and optimising dry matter intake is an essential part of the nutritional management of any dairy herd and underpins all aspects of production – health, fertility and milk yield.

Unfortunately, the rumen does not have an infinite capacity and a typical 650kg Holstein Friesian cow, yielding 30 litres, will consume 20 kg of dry matter per day. Therefore, each kg of any ration should serve a distinct purpose in meeting the cows’ nutritional requirements.

Feedstuffs that pack a big punch relative to the amount consumed, ie have a high energy density, are an important part of the herd manager’s toolbox.

Fats have the highest energy density of any feedstuff available for use in ruminant diets and are a prime example of being able to pack a big ‘punch’. Their general use in dairy cow diets is well established and they have typically been used to boost milk production, minimise body condition loss, improve fertility or improve milk fat.

However, just like sources of starch and protein, not all fat sources are created equal. It is essential to identify what it is that you hope to achieve by including a fat supplement in rations, so that the correct fatty acids (component parts of fat) can be used.

The five key fatty acids are palmitic, stearic, oleic, linoleic and linolenic and each has a primary function within the cow:

C16:0 Palmitic – milk fat

C18:0 Stearic – dry matter intake and milk yield

C18:1 Oleic – body condition management

C18:2 Linoleic – immune function and embryo development

C18:3 Linolenic – immune function and embryo survival

Work at Michigan State University has looked at the effects of feeding different combinations of these fatty acids on dairy cow performance. In all cases, fat supplementation increased energy corrected milk yield.

However, interestingly, cows supplemented with a palmitic/oleic acid blend also had an increase in body weight, meaning that the extra milk yield was not coming at the expense of cows gaining body weight. The ideal is to minimise body condition loss post-calving, whilst maintaining milk yield, which should help the cow throughout the remainder of her lactation.

Global ‘fats expert’, Dr Adam Lock, of Michigan State University, will be challenging perceptions surrounding feeding fats to dairy cows as part of a Mole Valley Farmers mini-roadshow in August. On August 7, Dr Lock will be heading up two events under the theme of: ‘Get your fa(c)ts right.’

He’ll be presenting the latest research surrounding dietary fats at a day-time meeting hosted by the Templeton family,at Pocknave Farm, Kilmarnock, the home of the renowned Carnell Ayrshire herd. Dr Lock will then head to Castle Douglas for an evening event. For more information call 01260 279539.