Milk quality

Dry Cow Therapy

Mastitis is a growing problem in New Zealand dairy herds. Mastitis reduces milk quality and it creates costs to farmers through decreased production, treatment costs, increased cull cows and increased risk of penalties due to high somatic cell counts or antibiotic residues. The dry period is a critical time in successfully managing mastitis and so it is crucial that you receive accurate, up to date and practical advice.

Why do we use dry cow therapy?

• Cure existing infections. Infection cure rates are higher when using dry cow therapy because of the longer contact time between mastitis bugs and antibiotic.

• Prevent new infections throughout the dry period. Many cases of mastitis in early lactation are due to bacteria that have been picked up over the dry period. Long-acting dry cow therapy can reduce cases of spring mastitis by up to 50%.

• Reduce new mastitis infections around calving.

• Reduce the somatic cell count and mastitis in the next milking season.

This coming dry period could either be a success where you make positive steps in controlling mastitis on your farm or it could be a missed opportunity. Come in and talk to the team at Tararua Veterinary Services to get accurate, up to date advice to make this dry period a success. We have a wide range of products available and can discuss the pros and cons of a range of dry cow strategies.

Minimising Dry Period Mastitis 

Most dairy farmers will be drying the bulk of their dairy cows off this month and will be trying to minimize the number of cases of udder infections over the dry period. The cow has a number of processes that help her to prevent infections while dry:

• There is an increase in the amount of the protein Lactoferrin in the udder which binds to and disables bacteria

• Cell count numbers rise making it more difficult for bacteria to establish

• Most importantly a plug forms in the teat canal. This acts as a physical barrier but also contains substances that inhibit bacterial growth

Unfortunately, even with all these defence mechanisms, the drying off phase is still a challenging time for high-producing dairy cows:

• Cessation of milking means any bacteria gaining entrance to the teat canal are no longer being flushed out by regular milking

• Teats are no longer protected with teatspray

• The teat sphincter is less able to seal the quarter off as the pressure of continued milk production builds up

• While the udder is in the process of involuting, the natural protective mechanisms described above are less effective

Once involution is complete the udder is very resistant to new infections. However as the cow nears calving and the udder is undergoing changes in preparation for the next lactation, it again becomes more susceptible to infection:

• The teat plug will often break down, allowing milk to leak out as well as bacteria to gain entry

• Protective substances such as lactoferrin become diluted by the increasing volume of colostrum

• White cells become less effective in fighting bacteria

• Standard DCT antibiotic levels have usually fallen to levels that are ineffective against new infections

Because the dry period is such a high risk for new intramammary infections it pays to plan a little ahead. All dairy farmers are aware of the benefits of Dry Cow antibiotics but a more holistic approach is vital:

• Watch the weather forecasts. Where possible try to avoid drying cows off when conditions are wet and muddy

• Dry cows off in mobs rather than the whole herd at once. Enthusiasm for inserting DCT wanes after a couple of hours. Avoid compromising the effectiveness of DCT with poor insertion technique

• Aim to reduce cow milk production leading to drying off and reduce feed levels to maintenance for the first 6 days after drying off. Any weight loss over this time will be rapidly replaced when feeding levels are increased. Cutting down on lush grass and feeding hay/straw will ensure low energy intakes while keeping cows full and content.

• Consider Teatsealing cows and heifers going onto a winter crop or that are likely to be spending much time on feed pads over winter