A NEW UK-based trial undertaken at Reading University indicates that using an inoculant on grass silage can improve clamp stability, increase feedable dry matter by 29%, and improve fat-corrected milk yields by 1.9kg/day.

Lee Gresham, UK and Ireland country manager at Lallemand Animal Nutrition, says the trial shows how the use of a crop and condition specific inoculant on UK grass silage can offer benefits on farm.

The trial used 28% DM grass harvested in April, with half the crop treated with Magniva Platinum Grass Dry and the other half left untreated. It looked at how inoculant impacted the grass’s fermentation, locking in nutrients, and how this translated into cow performance when feeding the silage.

The Scottish Farmer: FCM milk yields increased 1.9kg/day when cows were fed the inoculant treated silageFCM milk yields increased 1.9kg/day when cows were fed the inoculant treated silage

“There were significantly higher dry matter losses in the control clamp than the treated clamp, which means there was less silage available for the cows,” he said. “Due to the dry matter losses, the untreated clamp shrunk considerably more than the treated clamp, equating to 29% more feedable dry matter,” explained Mr Gresham.

The fermentation results from the two clamps showed that the treated silage had superior lactic, acetic and propane diol acid profiles and it had 10 times less butyric acid.

“The lower butyric acid in the treated silage indicates that clostridia, the bacteria that break down protein and cause foul-smelling silage, were effectively inhibited. This resulted in a more palatable silage, which was evident in the increased dry matter intake seen in the group of cows receiving treated silage in their ration.”

Aerobic stability was also improved in the treated silage. This resulted in less heating in the clamp, reducing the energy lost to the environment as heat instead of being turned into milk by the cows. This energy loss is caused by aerobic spoilage that occurs when air gets into the clamp and activates spoilage microbes, including yeasts and moulds. “The control clamp temperatures peaked at 34.6oC, whereas the treated silage reached only 26.7oC – a significant difference in energy terms,” he said. “This extra 8oC of heating in the control group is the equivalent of losing 28MJ of energy for every tonne of silage fresh weight that is unstable. This equates to 5.4kg of milk lost.”

He added that significant improvements were also seen in cow performance when cows were fed the treated silage. “The well-preserved and stable treated silage resulted in a significant increase in dry matter intake by 1.5 kg/day compared to the control. This correlated with an increase in fat-corrected milk of 1.9kg/day. A 0.1% improvement in protein and 0.19% increase in fat was seen in the milk constituents when comparing treatment and control group cows.”

The trial shows that with the increased feedable dry matter and energy available in the treated forage, as well as improved dry matter intakes and milk yields, producers will see a good return on investment if they use an inoculant when making grass silage.