IT IS a well-known problem that as milk yield increases, so does the risk of rumen health issues. This can have a knock-on effect on the fitness and health of the cow if not resolved quickly enough.
This was precisely the case on Tredinney Farm, at St Buryan, near Land's End, where the Warren family's pedigree herds of Guernsey and Jersey cattle were delivering large quantities of milk under a relatively high-input system.
With average production exceeding 7,000 litres – with 600kg combined fat and protein for the Guernsey portion and one cow even breaking breed records by exceeding 1,000kg combined fat and protein – a lot was being asked of this high-performing herd.
But owner James Warren, who runs the farm with his parents, Dennis and Rosemary, was not entirely happy.
"The cows were performing well, but not quite as well as they should be," he said. "I originally had a suspicion that they might have Sub-Acute Ruminal Acidosis, as yields were not quite as high as I would have liked considering their ration, and they were not cudding as they should be. It was difficult to pinpoint, but something was not right."
It was at this point that Matthew Jenkin, a trainee nutritionist with Cornwall Farmers Ltd, suggested the idea of rumen taps.
"I was starting to see quite a bit of rumen tap work being done by vets in the area and it was proving to be a useful tool to indicate whether there actually were acidosis issues," he said.
Matthew Berriman, from the Rosevean Veterinary Practice, who undertook the task, said: "The rumen tap involves withdrawing fluid from the cow's rumen using a needle through the body wall. A local anaesthetic makes it a painless procedure. A variety of observations and measurements can then be made from the rumen fluid, including, most importantly, pH and microflora motility."
Mr Warren was keen to give the procedure a go, and decided to use the opportunity to undertake a small farm trial. Taking his first readings from a small group of early lactation cows, he found their initial pH to average 5.34.
"This is too acidic for healthy digestion," said Mr Jenkin. "The optimum pH is over 5.8, which will give significantly better digestion and more efficient production of milk from forage."
As part of the trial, the team at Cornwall Farmers suggested the use of a yeast product, which was known to reduce acidity in similar situations. "We tried a Rumenco product called XP yeast, which is a pre-fermented yeast culture," said Mr Jenkin. "He opted for the pre-fermented product as it's easy to store and handle, there are no issues with stability and it's been shown to produce consistent results."
On March 1, almost two months after the first rumen taps were undertaken, Mr Berriman returned to repeat the rumen taps. Randomly choosing six cows, at the same stage of lactation as the previous group, the average pH was found to have increased to 5.87, with a high of 6.37 in one of the Jersey cows.
"This was very good news," said Mr Warren. "But the improved rumen health came through to me even more clearly when we looked at the bugs under the microscope, which we'd set up on the farm.
"The change was really pronounced. When we looked at the rumen flora at the beginning of the trial, the bugs were slow and lethargic, hardly moving at all. But at the end of the trial, they seemed to be flying around on the slide. I was amazed to see the difference."
The bugs he saw were protozoa and their previous inactivity was a clear sign that they were not working well in the rumen. Once the rumen pH was optimised, they were highly active, giving a clear indication of improved rumen health. He also noticed that the dung was of a far better consistency.
Now opting to retain XP yeast as part of the regular ration, Mr Warren said other lines of inquiry also yielded worthwhile results.
As the herd now increases in size to 230 head and adjusts to the recently introduced complete diet feeding, Mr Warren intends to closely monitor water and feed before it goes to his cows.