Heifer health

Heifer health plan

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.

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.

Once a health plan has been discussed and implemented over the season, it’s important to assess how effective the health plan was and if there are any changes to be made. Consider what has changed or any new risks to be aware of.

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. A focus on addressing farm-specific or regional issues (e.g. liver fluke, facial eczema, etc.)

Consider risk factors and management for facial eczema, liver fluke, pneumonia and theileria.

Vaccinations

As part of your biosecurity process, all animals that enter the farm should be appropriately vaccinated and disease tested. Protecting your animals and safeguarding your business against disease risks benefits everyone involved. Diseases that must be managed are bovine tuberculosis (TB) and Leptosperosis (Lepto). All vaccines listed below are optional, and are most effectively administered once animals are 12 weeks of age or older.

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. Clostridia is very effective in preventing disease.

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 you should select the drench types that are most effective at controlling the parasites on your farm. As part of the biosecurity process, quarantine drenches should be administered on animal arrival and the animals then 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).

Find out more about managing internal parasites on the Wormwise website.

Drenching

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.

'Drench resistance' is present on a farm when there are a measurable number of worms surviving in the animals after treatment with anthelmintics. You can test for it with simple 'drench checks' or a more detailed faecal egg count reduction test.

Management practices that improve nutrition to all animals and reduce larval intake by young stock, can reduce our dependence on drench – making resistance less of a threat.

There are four ways to limit drench resistance, one method can be applied or a suitable combination of methods for your farm.

• Grazing management
• Good drench practice
• Selective drenching or refugia
• Faecal egg counting

If using parasite drenches, drenching should not occur more frequently than every 28 days and should be based on heifer growth and faecal 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 faecal egg counting less accurate, but the stronger immune system of the heifer should offset the measure.

Abamectin withholding periods

Milk withholding (WH) periods for abamectin-only pour-on products changed from nil WH to 35 days in September 2022 to comply with the lower maximum residue level (MRL) for abamectin in milk. Always check WH periods on products before using them.

China and the EU both expect exported dairy products to contain no detectable levels of abamectin residues, with international limits of detection as low as 0.002 mg/kg. A previous detection of abamectin residues in dairy products in 2020 resulted in a negative impact on trade, leading to New Zealand Food Safety taking this action to prevent any issues or stoppages in the future.

Trace elements

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.

Copper deficiency impacts weight gain, mating results, coat colour (often lighter), and increases the risk of broken bones and scouring. Copper deficiency can be caused by low copper content in feed sources, grazing heifers on heavy soils with Molybdenum, or ingesting soil during grazing (particularly on crops), and from treating facial eczema with zinc.

Selenium deficiency impacts weight gain and mating results. This can be caused by low Selenium levels in the soil and grazing in the Central Plateau of the North Island or on peat soils in the Waikato.

Cobalt/Vit B12 deficiency impacts ill-thrift and can be caused by grazing in the Central Plateau of the North Island.

Idoine deficiency causes Goitre (swelling in the neck due to the enlargement of the thyroid gland) and can cause calf deaths at calving. This deficiency can be caused by low iodine levels in feed, like a brassica-based diet.