The issue of acidosis prevention and the use of technology to accurately predict disease onset were just some of the topics discussed at this year’s TotalDairy seminar held in Gloucestershire. Ann Hardy reports.
Adding protein to a total mixed ration can reduce the risk of acidosis, according to Ian Lean of the University of Sydney and managing director of Australian research and cattle consultancy company, Scibus.
Prof Lean suggested the condition of acidosis was far more complex than traditionally thought and the existing model for the disease should be ‘strongly reviewed’.
Techniques being developed in Australia were also uncovering vastly different and unexpected acidosis risks from apparently similar feeds, with wheat tending to be the worst culprit for causing the condition, but some different varieties of barley described as ‘spectacularly different’.
This information had been uncovered by cattle studies which analysed the acidosis risk of a variety of feeds, including different cultivars of the same grains. From this study, he said an acidosis index had been developed which could be used to predict the acidosis risk of different feeds, and was likely to be introduced for commercial use in the UK.
Prof Lean also suggested rumen pH – traditionally thought of as the barometer for acidosis – was not always a reliable indicator for the disease as some cows were apparently normal (or at worst sub-clinical) when their rumen pH was as low as 4.5, a level at which they would traditionally be thought of as suffering with acidosis.
“We need to think very hard before we start hanging our hat on a single measure,” he said.
On-farm, he said it was important to look for signs of acidosis including scouring, lameness and milk fat depression, which were well known to producers. If these conditions existed, he said there could be a place for measuring rumen pH to confirm the diagnosis.
However, he said the rumen’s ability to ‘hide’ or sequester hydrogen ions (responsible for acidity or a low pH) in other compounds meant some of these compounds were proving to be more reliable indicators of acidosis than pH itself. These included some volatile fatty acids and ammonia.
The relationship between acidosis and level of protein in a ration was partly related to this.
He said microbial protein increased as feed protein was raised, and provided a safe place for the hydrogen ions to hide, thereby reducing acidosis.
“Increasing protein too far will not be sensible but where you have a high risk of acidosis you should not run a low protein diet,” he said.
“I would not doubt acidosis cases will start being obvious due to low protein diets in America.”
Recommending producers should not chase lower protein diets without an understanding of ration fermentation, he said good sources of added protein were rape seed meal and some proprietary products such as slow release urea, amino acids and peptides.
Other practical, on-farm recommendations revolved around limiting high acidosis-risk feeds which included turnips and some ‘problematic silages’.
“If farmers make a change to the grain in the diet and see sudden acidosis or a drop in milk production, it could be due to the change in grain,” he added.
He suggested developing a relationship with a grain supplier and aiming to stick with a variety which had been safe and productive in the past.