UK - Adding yeast to cow diets can help improve milk yields and increase liveweights through improved feed digestibility.
Active live yeast feed additives lifted average daily milk yields by 2.1 litres/cow and increased cow liveweight by up to 20kg in just five weeks, in a New Zealand farm trial.
The active live yeast improved rumen function in grazing cows and improved dry matter digestibility by 30 per cent.
The results come from a herd of 300 robotically-milked cows with a mix of autumn and spring calvers. All cows also had access to a mixed ration of grass silage, maize silage, straw and concentrates, plus an extra 3-6 kg/day of concentrates fed during milking depending on yield.
“This is the first time we’ve had access to individual cow data on such a large scale, and the results are relevant to any herd where grazing accounts for a significant portion of the daily feed intake,” stated Dr Nicola Walker, Ruminant Product Development Manager at product trialists AB Vista.
“In fact, this particular setup was very similar to the majority of feeding systems in the UK and Ireland.
"When supplemented with additional feeding, grazed grass is now known to pose a significant risk of inducing low rumen pH and sub-acute ruminal acidosis (SARA), both of which can significantly compromise fibre digestion and feed conversion efficiency.”
The impact of the yeast was confirmed when removed after an initial five week period.
Milk yields dropped 1-2 litres/cow over the following two weeks, with cows losing an average of 5-10 kg LW as they attempted to maintain production by drawing on body reserves.
Dr Walker said that the increased fibre digestibility, shown by manure sieving tests, led to increased availability of nutrients for growth and milk production, which would otherwise be lost in manure.
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