October 2017 | News
For beef finishers, winter is often a time when a high level of starch is being fed to get animals finished as efficiently and profitable as possible, which can be a risk factor for acidosis.
Acidosis occurs when the rumen pH drops below 5.5 and can be as a result of an increasing amount of concentrates being fed.
When cattle have acidosis, appetites can be depressed and the rumen bacteria affected due to excessive acid conditions. This not only reduces daily live weight gains, but can also lead to extended finishing times and reduced grading results.
James Ireland, product manager with Agri-Lloyd, says when he conducts rumen audits on beef units across the UK, to assess how well the rumen is functioning, he often finds high levels of acidosis and high amounts of undigested grain in the manure samples.
“This often explains why some cattle outperform others on the same diet, it’s all down to how well the rumen is performing,” says Mr Ireland.
He adds: “On several occasions when doing a rumen status audit, I’ve seen manure samples from beef units with over 40 pieces of grain in the sample.
“This meant the famer was paying good money for the grain, only for it to pass through the digestive system undigested and spread on the field as a very expensive fertiliser,” he says.
A rumen status audit, which is conducted over a 12-weeks period, can help assess whether a diet is working efficiently in order to maximise production and also to avoid health issues, such as acidosis.
Mr Ireland talks through the key steps he takes when out on farm conducting rumen status audits.
Step 1 - Gather Farm Data
The first thing is to get background information about what is happening on the farm. Information such as; stock numbers, daily liveweight gain, weight of animals, average grades (if selling deadweight) and housing area etc.
Step 2 - Observe The Cows
Observing cattle in the shed can tell you a lot about how well animals are and how their diets are performing.
Ideally, you should be looking for 66% of cows ruminating at any one time in a shed.
Beef housing can make it harder to find tell-tale signs of acidosis, such as cud balls compared to dairy cows housed in cubicles. However, if you see cud balls in the shed, then it’s likely acidosis is a problem.
Look for evidence of feed sorting. If sorting is going on then it means the cattle aren’t actually consuming the diet that is on paper.
The cleanliness of water is something that can often be forgotten about on a farm and can affect the amount of water being consumed, which in turn will impact on growth rates.
Other things to look out for include general cow condition, lameness and how contented the animals are. Is there a lot of groaning coming from the cattle, then it could be a sign there is an acidosis problem.
Step 3 - Taking Manure Samples
Take 10 representative samples of fresh manure. Each sample should be collected in plastic cups that are labelled 1-10.
Step 4 - Assess Manure Consistency
When collecting the samples of manure record the consistency of the manure and score it on a scale of 1-5; 1 being like soup/water and 5 being dry and high in undigested fibre. The ideal is a score of 2-3.
Step 5 - Look For Gas Bubbles
Look at the manure and see if there are any gas bubbles. If there is any bubbling, then it is a sign of acidosis, which is a result of gas production from too much hind gut fermentation.
Step 6 - Weigh and Wash Manure
All samples should be weighed individually before they are washed through in a manure sieve.
Completely transfer each sample into a manure sieve, gently wash through the manure until the water coming out the bottom of the sieve runs clear.
During washing, you are looking for any foaming, which is a sign of a high acid load.
Step 7 - Assess Washed Manure
You are then looking to assess the washed manure. Look out for small clay like balls of manure. If you find any, then this is a sign of poor rumen function.
You are also looking for mucin casts, which look like sausage casings, they are shed out of the large intestine if too much acid is formed in the hind gut. Mucin casts are produced to cover the damage and are then shed out. In beef cattle fed high starch diets, you are more likely to see mucin casts, compared to dairy cows.
Ideally, when assessing manure, you should find no grain in the washed sample. If there is grain found, then it shows it’s not being digested. This could be because the rumen is not working efficiently enough to digest all the grain due to the rumen pH been too low which affects the ability of the rumen microbes to breakdown the feed. Or it could be that it hasn’t been cracked properly.
You also need to look for other undigested material in each sample. You should be looking for a cup 20-25% full of undigested material after washing, with no clear signs of any unaltered feed particles still present in the post washed sample.
Anything more than 25% means the rumen is not using what is being fed to the cattle, which is lost growth rate potential.
Once all that is done then you can weigh the manure again to get a pre-and post-washing percentage.
Step 8 - Next Steps
Only once all this information is gathered can a report be generated and advice given to rectify any problems.
If acidosis is a problem in the cattle, then it may be that the diet needs tweaking and a stabilised yeast product fed to help the rumen microbes digest feed.
Unlike live yeast, stabilised yeasts are produced in a factory under controlled conditions, where they undergo fermentation and produce metabolites. The stabilised yeast product is made up of these metabolites, which are a food source for the rumen microbes.
Cattle should then be reassessed six weeks later to evaluate the impact on the rumen function corrective measures, such as a change of diet or introduction of a stabilised yeast product has had. A final audit should then take place six to eight weeks later.