Maize silage could kickstart diets

Initial analysis of maize silage indicates the crop could be a welcome addition to dairy rations this winter, helping offset some of the challenges presented by this year’s grass silage.

“Having analysed over 1300 forages we have a good picture of how maize silages will feed and it is encouraging,” comments Trouw Nutrition GB Ruminant Manager Adam Clay, who adds that anecdotal evidence indicates that many farmers have seen a positive yield response since introducing maize into the diet.

Mr Clay says that high energy content and dry matter coupled with reduced NDF levels suggest that maize silages will support increased performance. He points out that ME levels are slightly lower this year at 11.3MJ compared to 11.4. Although only a small difference it means that rations will still need careful balancing to ensure that the cows’ total energy requirements are met.

Maize silage is a vital source of starch in diets and Mr Clay explains that total starch levels are lower than last year but are still good at 30.6% compared to 31.6%. However, the starch is more degradable and this is significant.

“Higher starch degradability means that more of the starch is used in the rumen. This increases the available rumen energy which supports microbial growth. A more active rumen with higher microbial growth is important as this drives dry matter intakes and yields. Promoting high intakes has been an issue with many grass silages this year so this will be an added benefit from getting maize into diets.

“Conversely, there is an 8% reduction in by-pass starch. Including by-pass starch is the diet is an effective method of increasing the total starch fed and therefore glucogenic energy in a rumen friendly manner. Farmers will need to ensure they feed sufficient by-pass starch in the total diet to avoid pushing cows towards sub clinical acidosis.”

Mr Clay says reduced NDF and increased starch degradability could mean maize silage could cause acidosis problems unless diets are carefully balanced and cows closely monitored.

“It is also important to remember that starch degradability increases with time in the clamp so the risk of disrupted rumen health could rise during the winter. For this reason we would recommend that maize is sampled monthly throughout the winter and diets fine tuned for rumen available starch levels, and that nutritionists use a formulation package capable of identifying the speed at which carbohydrates are degraded in the rumen.”

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