Yeast boosts yields by 1.5 litres a day

Adding yeast to dairy rations could be the answer to balancing poor quality silages this year

Coping with poor-quality second-cut silage and its adverse impact on rumen function is certainly going to be one of the big challenges facing milk producers this winter. But a Yorkshire herd that had silage “verging on butyric” last year, took measures that not only improved herd health, but lifted yields by 1000 litres a cow.

Andrew Reilly, new herd manager at Askham Bryan College, York, had his rationing skills put to the test last year when, like many other milk producers, he had to formulate a complete diet to compensate for poor-quality silage.

“We operate a simple system using a TMR diet. Cows were milking reasonably well, but we’d big problems with a lot of dry cows going down with milk fever and conception rates slipping. We knew we needed to make changes to the diet to get things back on track,” Mr Reilly told a briefing this week.

Vet nutritionist Richard Vecqueray, of EBV consultants, Penrith, became involved with the 170-cow Holstein herd and introduced a farm health plan that has successfully reduced the incidence of milk fever to almost nil within 12 months.

The dietary-based health plan – which included the use of a stabilised yeast culture for the milkers – has also improved overall cow health and overcome low conception rates, and contributed to an increase in average cow yield of 1000 litres lifting income by almost £14,000.

Tackling the dry cow problems meant getting them all in one group and on a stable ration right up to calving, says Mr Vequeray. “We reformulated the diet to remove the background potassium that was being generated by silage and interfering with magnesium absorption in the rumen.

“We created a ‘cardboard’-style diet based on maize silage, straw and grass silage, and including soya and rape as a protein source that could also carry essential minerals. We needed cows to eat more of this lower-energy-density diet.”

Making bigger loads of the mix to improve accuracy of ingredient inclusion and achieve a more consistent length of chopped straw were also recommended. The mix also included a specific range of minerals to counter the adverse impact of the potassium.

Cows are still split into two groups, one run as a demonstration herd that’s milked robotically and the other milked through a parlour. The herd is strip grazed in summer and brought inside for a mid-day TMR feed prior to milking milkers have access to a loafing area and the TMR mix overnight.

Last winter the TMR diet for the milking herd included maize silage, grass silage, soya and a 21% protein blend and provided high yielders with M+40 litres. Cows were eating 50-60kg of fresh weight a day.

“We’d some outstanding first cut – but not enough of it – and too much dreadful second cut that was verging on butyric. It was a wet ration, with maize silage at 25% dry matter. We started to use sodium bicarbonate to counter acidosis, added straw and introduced molasses to lift the energy, but it wasn’t working,” said Mr Reilly.

But he agreed to undertake a trial using a stabilised yeast culture that was fed over a 64-day period. The aim was to stabilise rumen pH, reduce acidosis, improve palatability of the feed and increase feed conversion rate.

Introduced in powder form to the TMR mix at the rate of 50g a cow a day at a daily cost of 9p, the stabilised yeast inclusion quickly lifted yields and milk quality as well as changing dung consistency.

Andrew Clark of Agri-Lloyd, manufacturers of the stabilised yeast product Lactaid, said the fermentation of live yeast produced metabolites essential for feeding rumen bacteria and stabilising the pH. But the environment within the rumen is unfavourable for this to happen.

“The fermentation of stabilised yeasts – now widely used in the USA – is carried out during the manufacturing process rather than in the rumen to ensure a high level of metabolites is produced and is available to the cow,” said Mr Clark.

The 64-day trial lifted daily yields by 1.5 litres a cow worth 36p (based on 24p/litre) giving a daily milk income rise of 27p a cow.

Using the stabilised yeast and taking advice on rationing and the dry cow management has been like putting all the pieces of the jigsaw together, added Andrew Reilly. “But after this wet summer it looks as though a lot of us face another winter of feeding silages of very mixed quality.”

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