A Northern Irish dairy and beef farmer has seen an increase in milk yield and improved killing out percentage of his cattle as a result of tackling acidosis in his herd. 
Robin McCloy, who milks 150 Friesian cows and finishes more than 300 cattle a year near Ballymena, first identified he had an acidosis problem in his herd when he had a rumen audit conducted on his cattle more than a year ago.  
The audit, conducted by Agri-Lloyd, evaluated the animal’s general appearance and behaviour and also analysed manure to give an indication of rumen health. 
“I thought the cows weren’t quite performing as they should and they seemed a bit agitated, but I couldn’t quite understand what was wrong with them,” said Mr McCloy, who farms with his wife, Heather and son, Jonathan. 
The herd is fed a TMR of silage, brewers grains and dairy blend and is housed all-year-round. 
Manure samples were collected and when washed through in a manure sieve, he was shocked at how much meal and fibre was passing through the cows undigested. 
It was identified that the cows had a problem with rumen acidosis, which occurs when the rumen pH drops to less than 5.5. As a result, this can depress appetite and production and also affect the rumen bacteria, due to the excessive acid conditions. Feeding increased concentrates compared to forage can be a risk factor. 

Stablilised yeasts 
As a result of the finding, Mr McCloy started feeding Lactaid, a stabilised yeast product to his cows as well as a rumen buffer. The buffer was the removed after three weeks.
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. 
The problem with feeding live yeast is they have to be alive in order for them to work in the rumen to produce the metabolites. 
Performance benefits – dairy cows 
Stablilised yeast is fed in the TMR at a rate of 50g per cow a day and after a month of feeding it to his milking herd, saw an increase in milk yield of 2.5-3l per cow per  day. 
“The cows are now more settled and are still performing and less undigested meal is passing though the cows now,” added Mr McCloy. 
Cows are yielding on average 27 litres per day and with the increase in yield, he reckoned it is earning him an extra 75p per cow each day at a milk price of 25p per litre, or £112.5 per day across the herd. 
“This made a big difference to our bottom line particularly at a time when milk prices weren’t very good,” he added. 

Performance benefits – beef herd 
Mr McCloy also conducted the same rumen audit on his beef herd. 
Most of his heifers and bullocks, which are finished for WD Meats, in Coleraine, are Friesian cross Angus, with some Friesian crosses also bought in as stores.
“I just couldn’t believe the amount of undigested meal that was passing through the cattle – you could see lots of cracked whole grains. It was an awful shock to me,” he said. 
Beef cattle are fed a TMR of silage and meal and since adding in 40g of the stabilised yeast, he has seen cattle perform a lot better. 
“Although I thought my cattle were doing quite well prior to feeding yeast, their performance has increased,” he says. 
Since then, cattle have gone up a grade too, which Mr McCloy equates to about £25 per animal. 
He also reckons they are finishing about a month earlier, with most cattle finished by two-years-old at a weight of 330-350kgs. 

Feeding the rumen 
Agri-Lloyd’s Adam Robinson, who conducted the rumen audit on the farm, says it’s important farmers remember they are feeding the rumen not the cow. 
“When you feed the microbes in the rumen with the right feed, they reproduce and the more microbes you have then the more food they digest and the more efficient the rumen becomes. This translates into better milk yield, growth and health of the animals. 
“Conducting a rumen audit is really useful as it highlights how well the food is being digested, all of which is potential energy to the animal,” says Mr Robinson. 
Mr Robinson says six weeks after Mr McCloy introduced the stabilised yeast into the cow’s diets, he revisited and performed another rumen audit. 
“In both the beef and dairy herd the amount of undigested grain had gone down and the fibre was perfect. This indicates the animals were using the feed more efficiently,” he adds.