Feeding fats could help boost energy in dairy herd

Fats have up to three times the energy levels of typical cereals so they improve dietary energy density, an important factor for high-yielding cows that are unable to consume enough energy to meet their maintenance and production needs.

Due to poor growing and harvesting conditions, silage rumen fermentable energy (FME) levels are generally low. Maize silage energy levels may also be relatively poor because crops had little sunshine and the generally late growing season limited starch production.

The net result is that a winter ration for high-yielding cows could have an energy density of only 11.7MJ ME/kg DM, making it harder for the cow to milk to her genetic potential, says Trident’s Daniel Chilvers.

“It will be extremely valuable to be able to boost energy content safely by adding relatively small quantities of protected fat – typically 0.20-0.50kg a cow a day – with minimal substitution effect,” he says.

Provided the other nutrients are suitably balanced, adding 0.5kg of protected fat into the ration could raise overall energy intake enough to support an extra 2.0-2.5 litres of milk. “To increase energy intakes by the same amount by adding starch to the diet would require significant quantities of cereal to be included,” adds Mr Chilvers.

Rumen protected fats are not fermented in the rumen, therefore they help to reduce the build-up of acid in the rumen and the risk of acidosis. Volac nutritionist Richard Kirkland sees this as a key aspect of feeding fats to dairy cows. “Reducing acid load helps rumen function and improves feed efficiency and animal performance,” he says.

Research suggests there are a number of benefits in adding proven fats to herd diets. Trial work at the University of Edinburgh showed an 18.2% improvement in conception rate to first service and a 23.6% increase in 100-day in-calf rate in cows fed a rumen-protected fat supplement.

And recent data from the University of Reading recorded an improvement in milk yield of 4.3kg a cow a day when cows were offered a rumen-protected fat supplement at 500g/day from calving to 120 days in milk.

But farmers are advised to ensure the benefits outweigh any additional cost. “This is currently helped by the fact that most protected fat products have come back in price significantly in recent weeks due to falling palm oil prices,” says Mr Chilvers.

With a large range of fat supplements available, it is vital to look at the “type” being offered to the cow (see left). It is not only the level of fat in a supplement that is important, but also the fatty acid profile of the fat, as this largely determines how the animal will respond.

Fat supplements can be incorporated into concentrate pellets and blends or added to TMRs, says Dr Kirkland. “Ideally fat supplements should be introduced gradually, over a number of days, to allow the animal to acclimatise to the increased fat supply,” he advises.