Digestibility of maize vital to avoid fall in milk output

The degradability of early season maize is lower than in late season maize silage, and the bypass starch is higher. Digestibility increases with storage time and the bypass starch decreases.

“Low starch degradability will have an impact on cow health and performance and if we understand this we can put solutions in place that will allow us to maintain health and performance and adapt as maize silage changes across the season.

Mr Berni says the starch in maize silage early in the season is not broken down as readily in the rumen as later in the season and more makes its way to the intestine. Some of this will be broken down into glucose and absorbed and some of it will pass straight through the cow and end up in the manure.

Nutrients

“This leads to an increased level of faecal starch, which is effectively poor utilisation and a waste of nutrients but it can also cause some hind gut fermentation in extreme circumstances.”

He says it also has the potential to reduce cow performance, not seeing the expected jump in production associated with feeding maize silage.

“For every 1 per cent increase in faecal starch over 3 per cent, there is the potential to lose 0.5kg milk.

“In certain circumstances where high levels of maize are being fed it would not be uncommon to see faecal starch levels at 5 per cent which could potentially be up to 1.5kg lost milk,” he adds.

However there are several ways to determine the impact of feeding particular silages, including kernel processing scoring, ration sieving, manure sieving, or using near-infrared analysis to look at the manure.

Clamp management

“For many people it may be difficult to avoid feeding maize early in the season because of forage stocks or clamp management. But if you do have the option to keep maize for later in the year and are able to replace with grass silage or wholecrop that would be beneficial to save the maize silage for when it is more accessible in terms of starch and energy for the cow.

If this is not an option, he says farmers should look at increasing the energy feeds which are more rumen degradable or provide higher levels of rapidly fermentable energy such as barley or wheat, or by-products such as biscuit meal or confectionary products.

Mr Berni says there are also strategies from a micronutrient perspective which can be adjusted to help with feeding early season maize silage.

He says: “You could look to include a yeast fermentation concentrate to help increase rumen degradability and improve intestinal digestibility.”

These products work to increase rumen microorganisms such as fibre digesting bacteria and lactate utilising bacteria as well as fungi. They also increase starch degradability, increase microbial protein and increase starch utilisation and can also help to increase dry matter intake.