Mastitis, as reflected in both clinical cases and a rise in somatic cell count (SCC), usually increases when cows are housed at this time of year.

Some of the increases in SCC are due to the stage in lactation of spring-calving cows – as milk yield drops the concentration of somatic cells in the milk increases. It’s like putting a spoon of salt in a shot glass of water versus a pint glass of water, the concentration will be much higher where the volume is lower.

Faeces are everywhere and this presents an ideal breeding ground for bugs and bacteria

That aside, the risk of mastitis also increases when cows are housed. A shed is a much more unhygienic environment compared to a field. Cows are kept in close quarters and the lying area is right next to the feeding and walking areas. Faeces are everywhere and this presents an ideal breeding ground for bugs and bacteria.

Cubicle beds

Cubicle beds are particularly attractive for bugs and bacteria. Firstly, there is a ready food source with little bits of faeces, urine and organic matter and sometimes milk as some cows will secrete milk while lying down. The second thing is that the cubicle bed is warm because the cow is transmitting her heat on to the cubicle mat or cubicle surface. So there’s lots of food and lots of heat – therefore an ideal breeding ground for bacteria.

Hygiene in cubicle sheds for milking cows is critically important

Cows that are housed in late lactation or indeed early lactation are at much more risk of infection than say dry cows, two or three weeks after drying off. This is because the cows’ teats are still open as they are being milked twice a day whereas a dry cow that has soaked up and has a plug formed in her teats has got a defence against bugs entering.

This is not the case with a milking cow, who is really exposed to an infection. Therefore, hygiene in cubicle sheds for milking cows is critically important, much more so than for dry cows. Suitable bedding material is one that provides comfort to the cow and reduces bacterial loading in the cubicle.

Cubicle mats and lime

For most farmers, cubicle mats provide the comfort and cubicle lime provides the disinfectant. The purpose of liming cubicles is to increase the pH on the cubicle bed which inhibits the growth of bacteria.

It also helps to soak up moisture, which helps to prevent the growth of bacteria also. Hydrated lime has a higher pH than ground limestone. It increases the pH of the bed to 12.4, which kills all bacteria. For this reason it is a registered disinfectant.

Using too much hydrated lime could cause sores or teat end damage

Ordinary ground limestone raises the pH to 8.4 which is not high enough to kill staph and strep bacteria. Hydrated lime is generally more expensive than ordinary cubicle lime because it goes through extra processing. The recommendation is to use no more than 170g per bed, which is equivalent to a fistful of lime per cubicle. Using too much hydrated lime could cause sores or teat end damage.

Other types of cubicle disinfectants are available also. Stalosan F is a product that works in the opposite way to lime in that it reduces the pH.

While significantly more expensive than ordinary lime, less of it is used and farmers who use it tend to find it effective. Sawdust, while comfortable for cows, is not a disinfectant and it can actually harbour mastitis-causing bacteria.

The use of harvested peat for bedding is not encouraged from a greenhouse gas point of view

Peat is another option that is both comfortable and effective in that it reduces the pH of the cubicle, making it acidic. However, the use of harvested peat for bedding is not encouraged from a greenhouse gas point of view.

Scraping

Regardless of what bedding material is used, scraping down cubicle beds twice a day, keeping passageways clean and applying a suitable bedding material to reduce bacterial loading will help to minimise the risk of mastitis for cows being milked in sheds this winter.

The big advantage of lime is that it increases the pH of the lying area up to around a pH of 12.4. Once the pH of the lying area goes above 12, most bacteria should not be able to survive. Many farmers who use sawdust or peat will add lime to this to increase the pH.

Hydrated lime is very alkaline

However, you need to be sure about what type of lime to use. There are three types of lime on the market – ground limestone, hydrated lime and a mix of hydrated and ground limestone. Hydrated lime is very alkaline.

However, in an experiment conducted at Moorepark in 2013, no adverse reaction was found from using hydrated lime over and above ground limestone or a combination of ground limestone and hydrated lime.

The experiment involved teat spraying with iodine and chlorohexidine-based teat sprays. There was no significant difference in SCC between the quarters in the various treatments six weeks after calving and there were no lesions observed in the legs or udders and only very slight changes to teat condition over time. The conclusion was that hydrated lime is safe to use for animal bedding.