10 steps to starting selective dry cow therapy

Over the next two months, cows will be dried off and preparations will be under way for a new season.

There has been a lot of debate around the length of the dry period in recent years. With a good milk price, is it worth milking cows on and shortening the dry period? The dairy cow needs a dry period for recuperation and preparing her udder for another year’s lactation. The farmer needs a rest too from a long year. It is highly recommended the cow receives a 55- to 60-day dry period where she is not milked to allow her udder rejuvenate. It is well recognised that a very short dry period will lead to poorer milk production in the following lactation.

It also important for controlling mastitis and milk quality, giving time to control infections while the milk gland is in transition or on a break.

Most farms will treat every quarter with a dry cow antibiotic tube as part of a mastitis plan. This long-acting antibiotic preparation is designed to treat old infections and prevent new infections while the milk isn’t flushing the whole system out.

So how do I choose a dry cow tube?

The goal is to pick an antibiotic that is active against the bugs on your farm. This can be done by testing some high-cell-count cows to see what bugs are affecting them.

Sensitivity tests are useful also.

They look at what antibiotics work on what bugs, though recently the accuracy of this testing has been questioned.

For most this will seem over the top and they will pick a “good” tube that covers all bases.

However we can’t take the future availability of antibiotics we currently use for granted. Countries leading the way in reducing antibiotic usage are mostly restricted to penicillin-based dry cow tubes. This hasn’t led to any problem, so we may be about to see a mindset change around blanket dry cow therapy on our dairy farms over the next five years.

This is why we now talk about selective dry cow therapy, where we select the cow that receives antibiotics at drying off based on need for them. So, with selective dry cow therapy, a healthy udder with low SCC may not receive an antibiotic at drying off.

There are some challenges before we dive into this new way of thinking. Here is a step-by-step guide to dip your teat, I mean feet, in the water. There is huge value in carrying out this process with your vet; 150 vets have recently been trained with AHI to deliver selective dry cow therapy training with their clients.

Set the bar high the first year with a rolling herd SCC across the year below 150,000. The international recommendation is below 200,000. Anything above this, you must continue to use blanket therapy. You should aim to reduce your herd SCC if it is above 200,000.

Milk records of individual cows are key when deciding which animals to treat. The key times for milk recording are two in early lactation, two mid-lactation, and one towards or close to drying off. This also allows your vet to look at new infection rates in your herd after the dry period. This relates to cows with a low SCC before drying off, which then calve down with a high SCC, indicating that an infection was picked up during the dry period.

Set a limit of less than 100,000 SCC over the lactation for cows. Also, these cows should not have had a case of clinical mastitis in the last six months. They should have no damage to teat ends or swelling on the drying off day.

Testing four to five cows with high cell counts or freezing samples of mastitis from the last three months and sending them for testing allows us see what bugs are present. Strep agalactiae is rarely found, but if it is, no selective dry cow therapy should be started. This information can also feed into picking the correct tube for your farm.

The California mastitis test is a paddle test which picks up individual quarters with cell counts above 400,000. It is a useful last check to make sure no major infections have been missed. This can be done at the time of drying off.

The 4mm squared teat orifice must be kept surgically clean when drying off. When using antibiotics this is important and when using teat sealer on its own it is even more so. Have a routine – scrub, insert and move on. Start in front left and go clockwise, finishing on the back left teat. Mark cows only when drying off is complete.

Drying off cows is often a natural process where milk volume drops to 8-12 litres a day. Then it is important to make sure cows have stopped milking or are dried off correctly, the best method is abrupt dry off. Feeding has to wind down for seven days before this and on to the dry cow diet. Once cows are dried off, they must be removed from the milking routine – even the sound of the machine can cause leakage. If farmers have a large (>5%) milk leakage each year, they need to look at their drying off technique. Milk leakage must be avoided to avoid bacteria entering the quarters.

The milk flow rate in cows has doubled in 30 years, which means double the pressure on the teat muscle or teat end. This means at dry off the ability of the teat to form a plug (keratin) is a little slower. Because of this, we really need to use a teat sealer on these cows to help nature create that barrier for infection. Also, the location where cows spend the seven to 10 days after dry off must be clean.

Managing heifers is also really important, with some evidence suggesting their teats are open to infections from six to two weeks before calving. While some people use sealers in heifers, this should only be done after managing the environment and stress.

It can’t be stressed enough – where the cows go after drying off must be clean and dry to prevent new infections. Note, most selective dry cow therapy failures occur when bacteria enter the teat at drying off due to poor hygiene or in the days after drying off in dirty environments. You should see drying off cows like surgery – keep the environment clean.