All mixed rations are not the same, even when they have the same ingredients, according to recent research undertaken by the Centre for Dairy Research, at Reading University.

Speaking ahead of a press briefing at this week’s Dairy Event and Livestock Show, Stoneleigh, Tony Hall of Keenan USA told Farmers Weekly that ration mixing and presentation were crucial to cow intake and hence rumen function and yield.

“You have to pay attention to the physical side of the ration, how feed is presented to the cow is essential. Mixing identical rations in two different mixer wagons in the Reading trial gave markedly different results when they were fed to similar groups of mid-lactation cows.”

dairy feeding

Cows fed a ration mixed through a Keenan mixer gave an average of 1l a day more than those fed a ration containing the same ingredients mixed through a tub mixer

In the trial a ration containing straw, straights, grass silage and maize silage was mixed in a Keenan wagon and in the farm’s vertical tub mixer. Mixing in the Keenan machine was done to the company’s recommended protocol, while the vertical tub was used according to the farm staff’s own regime, he explained.

“With the Keenan mixer straw was added first, followed by straights, then grass silage and finally maize silage. Whereas for the tub mixer, straw was added first, followed by maize silage, then grass silage and finally straights so they didn’t settle to the bottom of the mixer.

“On paper these were identical 17% crude protein rations, but in practice cows gave an average of one litre a day more when fed the ration from the Keenan mixer.

“In addition, milk protein levels were higher in milk from cows fed the Keenan ration and rumen pH was above the critical point of six for 37% longer. When rumen pH drops below six there is a significantly higher chance of acidosis developing.”

Mr Hall believes the differences are due to two factors, firstly ration presentation to the cow, with cows able to sort the ration mixed in the tub mixer far more easily and hence pick out the grain content, leaving the fibre content.

“And secondly, it would seem that mixing in the tub mixer damages the fibre content of the ration, leaving it less able to provide the scratch factor so necessary to stimulate effective rumen function. Also it appears the fibre elements of the diet are less well incorporated into rations when mixed in a tub mixer.”

It appears there is a certain type of physical ration structure and fibre type produced in Keenan mixers which optimise rumen function and ensures the formulated ration will deliver the desired results, added Keenan international nutrition director David Beever.