Assessing whether a dairy cow’s diet is being used as efficiently as possible is essential as they transition from a grass-fed diet to a winter ration.
Evaluating manure provides a good insight to the interaction between the cow and her ration, detailing how the rumen is functioning and where and how well feed is being digested.
Not only is it important to make sure a diet is optimising production, but also to make sure it is not causing health problems, such as sub-acute rumen acidosis (SARA).
SARA occurs when the rumen pH drops below 5.5 and can be a result of an increasing amount of concentrates being fed. However, by observing cow behaviour and assessing their manure, issues such as this can be detected and rectified.
Agri-Lloyd dairy product manager James Ireland says conducting a rumen status audit, which is done over a 12-week period as cows transition onto a winter diet, is a good way to make sure the diet is feeding as efficiently as possible.
He says: “The best time to have a rumen status audit is the autumn when the diet has been changed.
“Last winter, when I was conducting rumen status audits, I saw a lot of cows which were not performing as they should. Often herds were averaging two to three litres down in milk production across the country.
“When you are spending money on feed to push performance you want to make sure it is being used efficiently and not being wasted.”
Here Mr MnNAMEFACE outlines his key steps to take when conducting rumen audits.
The first thing is to get background information about what is happening on-farm – the number of cows in milk, average milk yield, peak milk yield, number of cubicle spaces, milk fat and protein percentage and ketosis levels.
Observing cows in the shed can tell you a lot about how well animals are and how their diets are performing.
Ideally, 66 per cent of cows should be ruminating at any one time in a shed.
The presence of cud balls at the front of cubicles is a telltale sign of acidosis in the herd. The more severe the acidosis, then the more cud balls you will see, which are caused when the cud becomes excessively acidic and unpalatable.
Look for evidence of feed sorting. If sorting is happening then cows are not consuming the planned diet.
The cleanliness of water is something which can often be forgotten about and this can affect the amount of water being consumed, which in turn will impact on milk yield.
Other things to look out for include general cow condition, lameness and how contented the cows are.
When collecting manure samples, look at its consistency and score it on a scale of one to five; one being like soup/water and five being dry and high in undigested fibre. A score of two to three is ideal depending on stage of lactation.
Look at the manure and see if there are any gas bubbles – bubbling is a sign of acidosis.
Gas bubbles are often seen in loose manure and these are associated with irritation to the hindgut, due to excess production of acid where it cannot be well buffered.
All samples should be weighed individually before they are washed through a manure sieve.
Transfer each sample into a manure sieve. Gently wash the manure through 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 the acid load.
Assess the washed manure and look out for small clay-like balls as these are 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 hindgut. Too much acid loading damages the gut lining. Mucin casts are produced to cover the damage and are then shed out.
Ideally, when assessing manure you should find no grain in the washed sample. If wholegrain is found, then it shows it is not being digested.
This could be because the rumen is not working efficiently enough to digest all the grain, due to the rumen pH being too low, which affects the ability of rumen microbes to breakdown the feed. Or it could be it has not been cracked properly, enabling digestion.
You also need to look for other undigested material in each sample. You should be looking for a cup 20-25 per cent full of undigested material after washing, with no clear signs of unaltered feed particles still present in the washed sample.
Anything more than 25 per cent means the rumen is not using what is being fed to the cows as efficiently as it could.
Once all this is done you can weigh the manure again to get a pre-and post washing percentage.
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 herd, then it may be the diet needs tweaking and a stabilised yeast product fed to help 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 rumen microbes.
Cows 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. A final audit should then take place six to eight weeks later.