Heifer health

Heifer health plans have five elements:

1. A biosecurity process
2. A vaccination programme.
3. A parasite management programme that limits drench resistance.
4. A trace element and mineral programme.
5. Address regional or farm relevant concerns (e.g. liver fluke, facial eczema, etc.)

Animal health plans need to be specific to the farm where the heifers are grazing as disease exposure, parasite presence, mineral deficiencies and biosecurity risk vary on each farm. The more stock movement between properties, the more comprehensive preventative measures should be.  A vet can help assess the appropriate animal health plan. 

Vaccinations

All animals that enter the farm should be appropriately vaccinated and disease tested. Protecting your animals and safeguarding your business against disease risks are for everyone’s benefit.

Diseases that must be managed by law are bovine tuberculosis (TB) and Leptosperosis (Lepto). All vaccines listed below are most effectively administered once animals are 12 weeks of age or older.

• Optional vaccinations

  Clostridia is the most common optional vaccine in heifers with farmers knowing it as 5-in-1, 6-in-1, or 10-in-1. Vaccination for Clostridia is very effective in preventing disease. Clostridia are a group of toxin-producing bacteria that are implicated in diseases such as: blackleg, pulpy kidney, malignant oedema, tetanus and black disease; which result in sudden death.

  Salmonella infections are a higher risk for heifers because of their developing immune system and changing farms. Risk factors like stress from transport and sudden diet changes while moving farms, as well as BVD infections means grazing managers should consider vaccinating. Salmonella bacteria colonise in the intestinal tract and can cause an infectious diarrhoea that, if untreated, may result in death. Salmonella are zoonotic organisms, so can cause disease in people as well. Whenever Salmonella is suspected extra hygiene precautions should be taken to prevent them from spreading. If cases of salmonellosis are infrequent, or never seen, then vaccination is unlikely to be warranted.  Vaccination is not completely protective but will lessen the frequency and severity of the disease when it is present. 

  Bovine viral diarrhoea (BVD) is a highly infectious viral disease which can spread via bodily fluids. It causes reduced growth rates, reproductive losses, an increase in disease in general, and lowers milk production. There is no treatment for BVD, prevention via vaccination is the only option. Find out more about BVD.

Parasite management

Parasites are farm specific and the farm owner/manager should select the drench types that are most effective at controlling the parasites on their farm. As part of the biosecurity process quarantine drenches should be administered on animal arrival and animals retained in a quarantine paddock, this prevents the transfer of parasites between farms.

There are three categories of cattle endoparasites: roundworms, tapeworms and flukes. Roundworms (nematodes) have the greatest economic impact and can cause reduced weight gain, weight loss, diarrhoea and death. Reduced weight gain is the first sign of parasites. Ninety percent of the parasite population is on pasture, not inside animals, so managing roundworms on pasture is as important as managing them in the animal.

There are three approaches to managing roundworms:

• reducing larval intake (preventing infection)
• helping the animal cope with roundworms (building resilience)
• killing the adult roundworms inside the animal (drenching).

Using drenches

When it comes to drenching, it is common for stock owners to select and administer drenches. This should be done in consultation with the grazing farm manager/operator so that drenches are relevant for the parasites present on their farm. 

Based on current information, it is clear that many New Zealand farmers are using drenches in a manner that will result in drench resistant parasites and drench failure. There are four ways to limit drench resistance, one method can be applied or a suitable combination of methods for your farm.

1. Grazing management
2. Good drench practice
3. Selective drenching or refugia
4. Fecal egg counting

If using parasite drenches, drenching should not occur more frequently than every 28 days and should be based on heifer growth and fecal egg counting. When conditions are cool and/or dry drenching should be spelled for longer. A heifer’s immune system will start to suppress roundworm egg production at about 8 months of age, which makes fecal egg counting less accurate, but the stronger immune system of the heifer should offset the measure.

Trace elements

The important trace element deficiencies of livestock in New Zealand are cobalt, selenium, copper and iodine. In heifers, the efficiency of uptake of trace elements from pasture changes as the rumen develops.

Trace minerals for dairy heifers

Find out more about trace elements.

Farm relevant concerns

Mob specific animal health plans should be agreed to by the grazing manager, even if the stock owner is the one implementing the animal health treatments.

When starting out in a grazing relationship all the key elements of animal health plans should be addressed. These questions can help develop a health plan:

• What are the stock movement levels on the property and potential disease exposure?
• What is the historical presence of Salmonella, theileria, facial eczema, etc.?
• What are the parasites present on farm? What is the farm management that will reduce parasite pressure (e.g. grazing management, cropping regimes, and stock classes)?
• What have been the historic trace element deficiencies? What pasture species, crop types, supplement, soil types, and fertiliser history will the heifers be grazing on that might impact the trace element presence and concentration in their diet?

Once a health plan has been discussed and implemented over the season, consider:

• How effective was last season’s health plan and are there any changes to be made?
• What has changed or are there any new risks to be aware of?

Other heifer mob level animal health issues to be aware of and incorporate into the health plan are in Table 1.