Keeping the Winter Diet Balanced for Pregnant Cows

Over the last 10 years farmer focus has been on improving cow condition over the winter period. This has been mainly facilitated by setting realistic figures on crop utilisation and ME requirements for condition gain, maintenance and pregnancy.

The winter diet for a pregnant cow, through until about the last 3 weeks of pregnancy, requires about 11-12% crude protein in the diet (or 1.2-1.4kg of crude protein). As well as cow’s normal base protein requirements, she has the demands of a rapidly growing calf, the development of new udder tissue and production of colostrum antibodies. Cows under protein stress for significant periods of time will break down their own body tissues to meet foetal demands, but the end result may be muscle loss (calving difficulty), poor udder development, poor colostrum quality and poor cow immunity (placing her at greater risk of mastitis or metritis).

Optimal crude protein requirements increase to 16-17% in the last 3 weeks before calving. Typically Fodder beet bulbs have crude protein levels less than 10%, whereas the leaf is in the 15-20% range. If the crop you are feeding is losing leaf yield in July, ensure that cows are receiving an additional supplement that has higher protein content.

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.