Fermented corn can boost milk yield

Leaving corn to ferment for at least three months will improve metabolisable energy (ME) by 20%, improve throughput through the rumen and increase milk yields.

Irrespective of variety, using bioparametrics and rumen liquor on fresh corn had a much lower metabolisable energy than expected, irrespective of variety.

Fresh corn has a ME of about 10.4MJ/kg DM, and it takes about six-and-a-half hours for the rumen to process the material and extract ME, according to Jack Torrens, David Bright Seeds.

However, after two months in the clamp, ME had increased to 11.0MJ/kg DM and after five months ME was up to 11.4MJ/kg DM.

By the time corn had been ensiled for five months, there was good ME release and faster throughput through the rumen, said Torrens. After nine months of fermentation, the 'lag time' in the rumen had also improved, taking three-and-a-half hours for material to be processed.

Farmers will not get as much milk from feeding corn, and if forced to use it, rations must be balanced accordingly, he said, adding that cows could be sold short on energy if this is not taken into account.

The longer the crop is in the clamp, the more time there is for the acid from fermentation to act on the grain and improve starch degradability and digestibility, said consultant Robert Bull.

But digestibility is also in the farmers hands. High dry matter in mature fermented corn will increase NDF and reduce digestibility so it is important the crop is harvested on the correct date at 30-35% DM, said Torrens.