TotalDairy Seminar Management crucial to benefit from feeding risky high starch rations

Dairy farmers could make big gains in performance by feeding high starch rations with good starch degradability, but they need to ensure top notch management "to avoid walking off the edge of a cliff."

That was the message from both Professor Sergio Calsagmiglia from The University of Barcelona and Australian consultant, Professor Ian Lean of Scibus, at this year's TotalDairy Seminar at Tortworth Court, Gloucestershire.

Professor Calsagmiglia said boosting starch degradability in the ration could drive milk production, maintain milk fat and increase milk protein yields and believed many dairy farmers could benefit from considering processing maize.

"The higher the processing, the better and the limitation is going to be the risk of acidosis. The risk of acidosis can be controlled in one part in the diet…but it is also highly dependent, not only on ration calculations, but also management. How accurate are you in guaranteeing a 28% (starch) ration?" he asked. At high levels of starch variation from day to day by as little as 2% additional starch could put cows at serious risk of rumen acidosis.

Processing had the potential to increase maize energy levels by 5%, which could lead to about a two litre a cow increase in production. However, Professor Calsagmiglia said it was important to weigh up the costs of processing and it was likely the benefits would be higher for maize harvested at over 35% dry matter.

He explained that processing became more important when feeding rations with lower total starch levels. When feeding high starch levels, processing became more "risky" and good management was essential to avoid acidosis. In fact, going down a high starch route in general, required close attention to detail.

Professor Calsagmiglia added: "The first thing I'd like to find out on farm - before formulating the ration - is to meet the farmer. Is he reliable enough. Do you trust the management capacity to actually prepare and make the animals eat what you have formulated?"

In a lecture and small group, interactive workshop on acidosis, Professor Lean also highlighted that although high fermentable carbohydrate diets could work, management was a must.

"The more you push to the edge, the more precise you have to be….If you're not managing with high attention to detail, back off or you'll end up with a crash," he stressed.

High risk feeds included high lactic silages, very digestible, rapidly fermentable grains and sugars. To avoid hiccups with rumen health, Professor Lean said the critical components to success were ensuring cows couldn't sort the ration and providing adequate bunk space.

He also suggested that there was a need to re think how acidosis was identified and reduce the emphasis on rumen pH as an indicator of rumen upset.

Research carried out by Scibus and the University of Sydney, which looked at parameters for defining acidosis, found that pH alone was a poor predictor of acidosis in individual cattle, partly due to the fact readings differed in different parts of the rumen. Instead, levels of the volatile fatty acid (VFA) valerate were potentially a more useful indicator.

Professor Lean said: "Moving forward we need to start think differently. In the future we may have different monitors which may include rumination scoring and monitoring (rumen) volatile fatty acids such as valerate." he said. These tools will help farmers more effectively manage the risk associated with higher starch or sugar containing diets. For the moment the practical observational methods of looking at clinical signs of acidosis, such as is scouring, lameness and poor fibre digestion and low milk fat, as well as rumen pH were important and could be combined to create an overall acidosis score in the field.

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