Staph aureus is in 85% of herds – often causing minimal issues

The latest DairyNZ mastitis fact sheet states that about 85% of herds will have some cows that are infected with Staph aureus. It goes on to say that Staph aureus accounts for about 10% of clinical mastitis cases but can be significantly more in an out-break situation.

There are options for screening your herd to find the Staph aureus cows, and either cull them or manage them in such a way as they don’t spread the infection.

Remember though, there are many herds out there where there is Staph aureus found in the Bulk Milk (we find it regularly in the Antibiogram tests, even in low BMSCC herds). Staph aureus in the Bulk Milk is not causing a significant issue, so before you decide to test and cull your way to being “Staph free” decide … do you have an issue and, what are the herds that have Staph but not an issue doing that you aren’t.

What is happening with infected herds that don’t have an issue, knowingly or unknowingly, is the cows are managed and that infection is not being spread from cow to cow, so the percentage of infected cows is low.

The main source of Staph aureus is infected milk from infected quarters, being transferred on liners or milker’s hands to uninfected cows. Effective practices to slow or prevent the spread of Staph aureus are:

• Having clean hands – this really means wearing gloves, wet gloves are cleaner than wet hands.

• Using teat-spray on every teat at every milking will reduce the spread by 50%.

• Have teats that are not cracked or have teat end lesions – these teats are harder to disinfect, and teat end lesion suggests there is over milking occurring or the vacuum is excessive, or the pulsation is incorrect, or the liners are well past their life expectancy.

• These farms usually have good records so when they have a cow that gets a repeat mastitis case, before treating for the 3rd or 4th time, they consider drying the quarter off, drying off the cow early, or even culling.

If your farm set up allows it, consider running the 3 titters, high SCC cows and cows that have been treated for mastitis in a mob that gets milked last – or at least not in the first herd – so any contaminated liners end up on less cows. If you are considering testing the whole herd for Staph please phone your prime vet at the Veterinary Centre. There are numerous options out there, each with their pros and cons.

Yersinosis in Calves

Yersiniosis frequently rears its head in the months of December through to May in calves of 4-10 months of age. Calves with the disease suffer a chronic scour, elevated temperature, loss of appetite and weight loss. It is caused by the bacteria Yersinia pseudotuberculosis, which can be found in the gut in over 85% of herds of yearling heifers around the country and up to 60% of individuals. Although it is commonly found in the gut of healthy calves, an overgrowth of the bacteria and invasion of the gut lining results in millions of micro-abscesses throughout the length of the intestines.

Conditions which may precipitate an overgrowth in the gut are low levels of the trace elements copper and selenium, parasitism, BVD, long transport, poor feed quality or feed stress.

Once an outbreak starts, an insidious spread through a mob of calves occurs via the faecal-oral route.

Control and treatment comprise the removal of affected animals and use of appropriate antibiotic. Further prevention should focus on the underlying risk factors – correction of trace mineral status, drenching and increasing feed allocation. We have seen a lot of success with the use of Multimin injection.

There is a registered Yersinia vaccine available for deer. This has been used off-label in cattle but can result in anaphylactic reaction. We have a limited number of clients that have used a single dose of this vaccine with apparent protection inferred. You would need to talk with your prime vet about the pros and cons of using this product off-label.

Correctly Identifying the Lame Claw

Over the years I have witnessed multiple occasions where farm staff have attacked hooves with knives, grinders and hoof trimmers before correctly determining the site of lameness. This will have frequently resulted in an exacerbation of the overall lameness in the cow.

Before putting any lame cows into the crush, it is important to determine which leg is affected. Our vets tend to record these on a recording sheet. Look for:

• obvious swelling (and hoof shape)

• weight bearing while standing still (the lame foot will be positioned so not to carry as much load)

• a head nod while walking in the case of front leg lameness

• the stride length and speed (the lame leg will have a short stride before taking weight, then the sound leg swings through with a longer stride and is weight loaded for longer.

Once you have determined the lame leg, have tied it up, washed it down and checked for footrot, use hoof testers to confirm where the lameness is located. This simple tool works by squeezing and putting pressure on the claw. Watch for a repeatable pain response which is easy to recognise in the hind legs by a tensing of the ‘hamstring’ muscles and the front legs by a tensing of the shoulders. Cows with sole bruising will often have very soft hooves and you will see that the testers easily depress the sole. If there is no response to either claw to hoof testers, then chances are you either have the wrong foot or the cause of lameness is located further up the leg.

Fonterra on Farm Efficiency & Emissions

Many of you will be getting your heads around Fonterra’s recent emission target of a 30% reduction in on farm emissions intensity by 2030 compared to 2018. This target has been put in place for several reasons.

1. Fonterra’s customers are requiring this. They all have green house gas targets and require it from their suppliers. To be able to access these high value markets targets must be set and met.

2. Finance: Sources of capital want to see a reduction in emissions over time.

3. Regulatory; Fonterra must meet disclosure requirements about their greenhouse gases.

While NZ dairy farmers start in a good position with them having the lowest baseline emissions intensity, the international competition is moving quickly. If Fonterra did nothing the overseas competition would overtake them. This would mean Fonterra’s high value customers would potentially move to other suppliers.

The 30% reduction is a collective target across the whole Co-op. To reach this there are four areas that will be addressed, with individual farmers probably most interested in the adoption of best farming practices. Think of it as an opportunity to use all the metrics you are being provided with, to improve efficiency on farm by addressing areas such as:

• Animal health: e.g. mastitis, Johne’s or lameness.

• Improving reproductive performance

• Genetics

• Nutrition

• Minimising environmental stress.

As the season progresses, we can have discussions about what this all means and talk through your Farm Insights Report.

Effect of Lameness on Reproduction

Lame cows continue to be among the three main problems we are seeing on our clients farms together with mastitis and infertility. Lame cows are clearly visible but often not treated promptly.

At this time of year with peak milk production and AB well under way, the economic effect of lame cows can be huge due to lost milk production, lost body weight and the fact that lame cows are less likely to cycle on time.

Lame cows are half as likely to conceive and take on average 40 days longer to conception, compared to their healthy herd mates.

If you need help with lameness contact Andrew, Luke or Ryan at The Veterinary Centre.