Incorrect liner size could be reducing milk let-down

Preventing heifer mastitis and choosing the correct bedding were just some of the topics up for discussion at last week’s British Mastitis Conference in Worcester. Aly Balsom reports

Incorrect liner size and stress around milking could be compromising milk let down and mastitis rates in freshly calved heifers.

Ian Ohnstad, of the Dairy Group, said producers needed to look critically at the teats of heifers post-milking to see whether liners were creating unnecessary trauma.

“When a heifer comes into the herd it’s a hugely stressful time. You want her to be as relaxed as possible at milking to maximise milk let down, so why have a milking liner that adds trauma,” he asked.

Discoloured teats, teat ringing and heifers kicking off the clusters were all signs that things needed to be addressed. However, Mr Ohnstad explained that the issue of incorrect liner size was not just limited to heifers.

“A significant number of farms have the incorrect liner size for their cows. I’d urge everyone to be proactive in establishing the average size, diameter and length of teats in their herd,” he said.

Milking would always be a compromise between milking quickly and gently while ensuring cows were milked out. But to ensure teat health was maintained, there was a fine balance between liner open and close times.

“If we’re to start looking at the correct liners, we need to understand how they impact on the teat,” Mr Ohnstad said.

He reminded delegates that milk was actually released when the liner opened around the teat. However, the role of liner compression was essential to ensure maximal milk let-down.

“Compression removes the fluids from around the teat end, promoting faster milk flow and keratin growth. But too much liner compression will cause hyperkeratosis,” he said.

“Compression is needed on the lower 25mm of the teat. However, remember many heifer’s teats are not much more than 30mm in length at the start of lactation.” This could lead to very red, almost blue teats, a very uncomfortable animal and severe teat oedema if liners were the wrong size.

Speaking to Farmers Weekly, Mr Ohnstad said he knew of one producer who had invested in a separate cluster for heifers to ensure teat health was not compromised.

“This cluster, with shorter, narrower liners will support the narrower teat, and is swapped over when a heifer comes into the parlour,” he said.

Mr Ohnstad believed at a cost of about £200 for a cluster and shells, it would be worth investing in a separate unit when issues were identified.

Vet Roger Blowey from the Wood Vet Group said on average a heifer received 10 aggressive interactions every hour for the first one to two days when she was introduced into the herd, which all affected the chance of her developing mastitis.

“In those first few milkings you need to bring her into the parlour gently and not after she’s been waiting two hours at the back of the collecting yard.” He also said good stimulation for good milk let-down was crucial.

Choice of bedding material

Paper ash mixed with sand is the best bedding material to help reduce mastitis rates, according to new research findings.

Vet Roger Blowey said an ideal bedding would have no initial bacterial loading and would also mop up any added bacteria from milk or faeces.

“By acting as a desiccant, paper ash leads to a marked reduction in the bacterial load both in the environment and on the teat end,” he said.

“However, I wouldn’t use ash on its own, as its high pH could lead to teat burn.”

Consequently, he said ash and sand mixed 25:75 would provide the best bedding at a cost of about 10p a cow a day.

“Eight farms using ash in bedding have seen a 34% decrease in mastitis rates, where as four farms not using ash have recorded a 12% increase,” he said.

In trials, a 50:50 sand/ash mix had an initial Strep uberis load of less than 50cfu/ml and after 48 hours this had dropped to less than 20cfu/ml. This compared with straw with an initial load of 25,800cfu/ml, increasing to 74,000cfu/ml in 48 hours.

Sawdust, gypsum, sand and a 50:50 straw/ash mix also saw a rise in Strep uberis bacteria. Gypsum also had a high initial total bacteria loading of 7.8m bacteria/g, begging the question why farmers would use it, said Mr Blowey.

Aly Balsom on G+

More on this topic

Read more from the mastitis conference, including how politics rather the science is driving antibiotic use limitations