Yeasts improve feed conversion efficiency

Yeasts could have an important role to play in boosting rumen health and improving feed use efficiency, as Dairy Update reports

Addressing feed conversion efficiency is one way producers can get more from their feed at a time when prices are at an all time high,

Many dairy farmers will be looking for new ways to reduce feed costs while maintaining output and there are plenty of obvious places to start. Are feeders and mixer wagons correctly calibrated? Are late lactation cows being overfed? Could better use be made of forage?

Yet one area that is sometimes ignored in dairy production is feed conversion efficiency – are cows actually making the best of the feed available to them?

Many factors can affect this, including feed quality, the energy and protein balance of the ration and the genetics of the cow. But probably the key factor is rumen health and this is where the addition of a live yeast to the ration can bring dividends.

The inclusion of protected live yeast in the diet, both at grazing and when housed, has been shown to deliver significant benefits, explains Keiron Forbes, technical director at Lesaffre Feed Additives (LFA).

“Yeast scavenges oxygen from the rumen, discouraging the growth of lactic acid-producing bacteria and helping to prevent acidosis. What’s more, live yeast increases the efficiency of fibre digestion, improves dry matter intakes and increases health and performance.”

With high feed prices it might seem counter-intuitive to spend even more money adding additional feed supplements such as live yeast. But the payback can be significant.

“Research conducted by LFA for EU registration shows that the inclusion of Actisaf Sc 47 live yeast in dairy diets resulted in milk yield increases of between 1.3 and 1.9kg of milk a cow a day,” Mr Forbes explains.

“Yeast can be added either through your compound feed or via a farm pack, which can be mixed into a TMR on farm. This costs about seven pence a cow a day and can deliver a payback of almost £1,250 a month for a 100-cow herd at current milk prices.”

One person who has seen the benefits of feeding live yeast is Devon dairy farmer, Jeremy Dennis.

Mr Dennis, who farms 700 acres at Fardel Barton near Ivybridge with his father Derek, feeds a protected live yeast to his 325-strong Dinnaton Herd of pedigree Holsteins, which average about 8,000 litres of milk a year.

“We first started including Actisaf Sc 47 in our dairy rations about 10 years ago,” explains Jeremy. “We had made particularly acidic maize silage that year and we had some trouble with acidosis. Feeding the yeast sorted it out and we have included it ever since, although now it is more to help fibre digestion and rumen function.”

Yeast is mixed on farm within a pre-mix, which is then fed with grass, maize and triticale whole crop silages as a TMR, with a small amount of compound feed being fed in the parlour.

Beyond the obvious role of yeast in improving feed conversion efficiency, it seems it might also offer some benefits in terms of methane and nitrous oxide emissions.

Due to the increased productivity that live yeast delivers, methane emissions for every litre of milk or kilogram of liveweight gain are reduced compared to an animal that is not being fed yeast. Research is also looking into whether feeding live yeast delivers absolute improvements in emissions, and while nothing of statistical significance has been found in respect of methane emissions as yet, things look more promising when it comes to nitrous oxide emissions.

There are some research findings which suggest that live yeast facilitates better nitrogen retention through increased microbial synthesis, reducing nitrous oxide output. Seeing as nitrous oxide is 298 times more polluting than CO2 this could be important and further research is already under way.

The general consensus is that improving technical efficiency will reduce carbon output when measured against production, says Mr Forbes.

“And live yeast certainly has a role to play here – delivering clear improvements in output from a given ration. Not only does it make financial sense to feed live yeast but it makes environmental sense too.”

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