Best Practice Parasite Management

A five year MPI / Beef and Lamb funded study was conducted to look at ways of helping farmers manage the impact of internal parasites and minimise selection for drench resistance – while helping them stay productive and profitable. In 2008 twenty farms, located from Northland to Otautau, were selected as case studies for this project.

An initial visit was made to each farm to understand the farm environment, livestock policies and management, grazing systems and current parasite control practices. The initial survey included consideration of soil type, soil fertility and trace element levels and fertiliser practice, and classes of livestock being run on the farm.

The purpose of the visit was to determine what was known about the farm and the issues that have impacted on livestock performance, and the quality and robustness of that information.

The research team, which included a consultant, vet and parasitologist, wanted to understand grazing management on each farm, and the extent to which animals of different ages and classes are integrated in grazing management. They also wanted to understand current parasite management practice and assess levels of animal productivity and farm production, and understand each farmer’s objectives.

Every farm was scored on the basis of a range of parameters including:

• effective parasite treatment

• how were they managing pasture contamination

• management of reinfection

• treatment of adult stock

• management of external risk

• management of risks of developing anthelmintic resistance

At the visit, gaps in knowledge were identified, strengths and risk factors in current practice were highlighted, and a parasite management plan for the next 12 months was developed.

A faecal egg count reduction test (FECRT), and a schedule of faecal sampling (FEC) to monitor all classes of stock pre-treatment was introduced on all the properties in the project.

The FECRT was undertaken by the veterinarian and the farmer. The FEC samples were couriered to a central laboratory for processing. Egg count results were emailed back to the farmer and veterinarian within a few days, and larval culture results were provided 5-6 weeks later.

The concept of refugia was also introduced, and throughout the grazing management system, opportunities to introduce, manage and enhance refugia were identified.

Between annual visits, there was an expectation that the veterinarian would be the initial contact point for the farmer for discussion around any issues and concerns.

Each year the farm was revisited for the purpose of reviewing performance. Risk factors were re-assessed, any gaps in knowledge were highlighted, and advice and recommendations refined as a result of the previous year’s growth in information.

PGG Wrightson consultant Tony Rhodes, says farmers varied in the rate at which they adopted recommendations and advice, and changed behaviour. He says the most important first step-change involved quantifying drench efficacy for each genus of worms, across both sheep and cattle on their farm.

Knowing what works and what doesn’t was important; but it was also important that treatments were administered effectively. Tony says the use of long-acting products, which are highly selective for resistance, was minimised, but not eliminated in all cases.

Overall, farmers were very smart in identifying how they could implement principles and practices in a way that best suited their management and farming system.

The opportunity to manage refugia on each farm generated the greatest level of innovation. Once they understood the principle, farmers found easy ways to achieve partial-mob treatment of adult sheep; made simple management changes that avoided “drench and shift” situations when grazing new grass, forage crop, silage and lucerne paddocks for the first time in the season and changed management of stock entering forage crops areas.

By running a monitoring programme, and taking monitor samples where there was concern, farmers ended up with a lot more information with which to make management decisions.

Over the course of the project the emphasis among farmers shifted away from attitudes, practices and behaviours that were based on “convenient”, “easy” and “just in case” to an approach that considered “effective”, “necessary” and “targeted” as the basis for management.

Other findings included a lack of awareness of what other factors might have an impact on stock performance other than parasites – such as mineral deficiencies. The trial highlighted the need to have systems in place to check for these issues.

Farms involved in this project were preferentially selected on the basis of multiple resistance to anthelmintics. One of the goals was to maintain drench efficacy at least at the level prevailing at the start of the programme.

Following the initial FECRT, eight sheep farms were determined to have multi drug resistant parasites.

On each of these farms use of combination anthelmintics was just one of the broad range of parasite management practices adopted by the farmer. In each case, these farmers actively implemented parasite management practices designed to reduce selection pressure for anthelmintic resistance, and to maintain effective sources of refugia across their farm.

Building the confidence to try and maintain new technology or behaviour is considered to be a critical success factor of the project. The routine monitoring programme of faecal samples and larval cultures collected from stock immediately prior to drenching .was important in building the farmers’ confidence around the management changes they were undertaking.

The second factor judged critical to underpinning farmer confidence and understanding was the annual review process – assessing what had been done and the timeliness of that, considering issues and difficulties that had arisen, and identifying opportunities to refine practices going forward.

Steve Wyn-Harris is a well-known rural commentator, a former Landcorp director and a highly impressive farmer. He and wife Jane run bull beef Fresians, a sheep stud and some forestry. They are former Hawkes Bay farmers of the year. From 2000 to 2004 they were Meat and Wool NZ monitor farmers.

Steve is a big fan of technology and science and uses a computerised system for feeding and breeding. He inputs data and the computer predicts what he will need in the future. The computer feed budget programme helps in key decision-making.

Steve believes a farm must be profitable before looking after the environment, but also acknowledges that farms need to be sustainable, and says his ongoing challenge is trying to find the balance between good stewardship and high productivity.