Clostridial Deaths

Having recently dealt with a case of ‘sudden death’ in R1 dairy heifers (7-8 months old) due to clostridial disease, it came as a timely reminder of the importance and effectiveness of a vaccination programme against this group of diseases.

• 16 heifers out of 360 were lost sporadically over a period of 5-6 weeks whilst grazing a high clover content sward.

• Post-mortems were performed - a diagnosis of clostridial deaths was made.

• Although they had been vaccinated with a 10 in 1 as calves (Covexin-10) it is believed that they had not received their booster vaccination.

• They have since had a sensitiser followed up by a booster vaccination 4 weeks later.

• One week on since booster and we have had no further deaths.

Clostridial diseases are a group of infections that cause sudden death. Death is very rapid and usually occurs before the animals are even noticed. There are dozens of Clostridial species whose spores survive in the soil indefinitely. Control therefore relies on vaccination.

Calves usually receive their first vaccination at the time of disbudding. This should be followed up with a booster vaccination four weeks later. Full protection is not achieved until 10 days after the booster vaccination. It is now also advised that stock grazing crops – particularly Fodder Beet – get a booster against clostridial diseases two weeks before going onto the crop, regardless of their previous vaccination history.

The risk of clostridial deaths is higher for stock grazing crop due to a combination of factors but largely due the high ‘sugar’ level in the crop and high soil intake. When grazing fodder beet, once fully transitioned the main risk of disease comes from clostridial infections.

Covexin 10 in 1 vaccine is considered the ‘Rolls Royce’ of clostridial protection covering 10 different strains of the disease. Cost = $1.44 excl. per 2ml dose.

Vaccination is extremely effective at preventing and minimising losses associated with this group of diseases. It is also cost effective and losses of even small numbers of stock will cover the cost of vaccination. Because the bacteria form spores that are resistant in the environment, every animal is likely to experience a challenge in their lifetime.

Copper Complacency in Replacement Dairy Stock

Unfortunately many of you will know that feeling of absolute despair when a healthy two year old heifer who has just come into the herd spontaneously fractures its humerus and has to be destroyed. There is often a difficult conversation with staff about stock handling and welfare regarding the possible cause of the fractured leg.

Although two-year-olds are more commonly affected, three-year-olds can also be affected and the condition is usually encountered up to two months after calving. The onset is sudden and there is no humane treatment available other than immediate slaughter.

Extensive research at Massey University has failed to pinpoint an exact cause, however it did uncover some closely associated risk factors.

• Copper deficiency.

• Under nutrition.

Replacement dairy cattle spend a lot of time away from the milking platform where they are managed extensively and fed a mostly pasture/winter crop diet. Replacements, therefore, are at higher risk of developing Cu deficiency than a herd being fed PKE if there is no trace mineral monitoring and supplementation.

How do we boost young stock copper levels in April/May to ensure adequate levels over the winter/early spring period?

• Copacap bullets. Bolus’s are the most long acting copper product and generally effective for 6-9 months.

• Coppermax. Copper injection. Dosing needs to be repeated every 3 months.

• Multimin. A combination injectable product which provides: Copper, Selenium, Zinc and Manganese. Dosing needs to be repeated every 3 months.

Footrot as a Component of Lameness

Footrot accounts for approximately 10% of lameness in the dairy herd. It is caused by bacterial invasion of the soft tissue between the claws after injury to the interdigital skin. The initial injury is often caused by stones lodging between the claws. These are most often picked up at gateways and at water troughs, or along the edges of tracks – especially later in the season as track deterioration can become an issue.

Treatment of footrot is straightforward and normally very successful. Remove the stone if it is still there, clean between the claws with iodine or antiseptic and inject with procaine penicillin. Anti-inflammatories will speed up recovery too.

Prevention is a more important aspect of footrot management. Foot baths are the easiest way to keep things under control.

The whole herd should be treated twice a week during risk periods with either 5% Copper Sulphate or 5-10% Zinc Sulphate. Construction of the footbath is important to ensure a successful outcome. It should allow for good cow flow and be a permanent feature of the shed exit. It should be no less than 2.5m long and no longer than 3m to ensure the cow places all 4 feet in the bath and to reduce contamination. With these dimensions, on average, 3-4 cows per 100 defecate in the bath, so it stays relatively clean. The easiest way to construct the footbath, is with concrete blocks on top of the exit race, with a drain in the lowest corner for easy emptying. The volume of the bath should be one litre per cow and should be at least 8-10cm deep.

With good footbath design and targeted prevention, footrot numbers and the concurrent antibiotic use will be kept to a minimum. Should you have any further queries about footbath design or footrot control, please get in touch with one of our Healthy Hoof Advisers.

Horns - Unwanted in Dairy Cattle

Primitive cattle needed horns to fight off predators and to sort out the social ranking within the herd. But in modern dairy farming these duties are redundant so there is no reason to persist in running cattle with horns.

I’ve been surprised how many dairy cows still have horns, particularly when our vet techs are pushing down the front of a herringbone shed reading ear tags and recording aged pregnancy testing data.

What can you do?

• Check calves that have been disbudded carefully when they are being run through the runoff yards for drenching or Lepto vaccination. If the disbudding was botched, the scurs will grow into nasty small horns that can still do damage and should be removed.

• If you have horned cattle on your farm now be aware that from 1 October 2019, it was prohibited to dehorn cattle without the use of local anaesthetic. Talk to one of The Veterinary Centre vets about getting these cows dehorned. There are ways to minimise the pain and distress and other potential negative health consequences (such as infection) that can be caused

  through this procedure.

• Ingrown horns are painful. If you allow horns to become ingrown, or transport an animal with an ingrown horn, you can be fined and risk an animal welfare prosecution. So get them sorted out now.

Lameness

The summer period is often a time when lame cow numbers increase, this can be a result of how cows have been managed in the season so far, wet weather, thin soles and stressors that have occurred during the calving period.

The numbers can be made worse with people having time off .

• If we get a bout of wet weather it is worth taking the time to improve drainage off the edge of tracks. Take a spade and open up the grass, a spades width wide at regular intervals to allow water to drain off the track. The grey box shows a good spot to cut away the grass.

• If you have an underpass, keep it free of water and slurry. Make sure that sump pumps are working properly, sumps are cleaned out and pumps are turned on when it rains.

• If you have a section of lane that is chronically wet, especially just prior to the yard, consider scrapping the surface. Wet areas slow cow flow which means that more pressure has to be put on cows to get them on the yard and the moisture increases the foot problems. Scrapping lanes can damage the top surface of the lane, but these are often damaged when you get to this stage anyway, however it can allow them to dry out faster and improve cow flow. Look at a more permanent fi x over the dry period.

• Have someone who can do lame cows every day or every other day. It becomes much harder to start treating doing them when there are heaps in the mob. They also get a lot worse.