CARLA could soon help combat goat parasites
June 27, 2014
A saliva test successfully used for selecting sheep with enhanced protective immunity to internal parasites may soon be also helping to increase the productivity and profitability of goat farming.
AgResearch Senior scientist Richard Shaw, who’s based at the Hopkirk Research Institute in Palmerston North, has developed a test – based on the CARLA test – that has the potential to help the goat farming industry.
The CARLA saliva test was originally developed for use in sheep, but has positive applications for goats.
Farmed goats are vulnerable to parasites, which can impact their growth, health and productivity. Although goats evolved as browsers (nibbling on shrubs and small trees), intensification of farming has meant goats are forced to graze pasture where parasite infections are more likely to occur.
Parasites can quickly develop resistance to anthelmintic drenches, and this resistance seems more prevalent in goats than in cattle and sheep. Additionally, ongoing reliance on chemical control of parasites is not sustainable. In the New Zealand dairy goat industry most flocks are housed indoors and grass is cut and carried to the animals to minimise parasite infections, but this kind of management is costly and time-consuming to the farmer.
Mr Shaw, who has years of experience in dealing with parasite infections in livestock, says he saw a need to investigate the test as an alternative approach to controlling internal parasites in goats.
“The CARLA saliva test involves taking a sample of a goat’s saliva and testing it in the lab, to detect an antibody response to parasite infection in the animal’s gut,” he says.
“CARLA is a carbohydrate molecule found on the surface of third-stage internal parasite larvae in livestock. The presence of antibodies interferes with the parasite’s ability to take hold in the animal’s gut, which leads to resistance to infection, a desirable trait to breed.
“For the past three decades the standard method for identifying animals with enhanced protective immunity to parasites has involved counting eggs in animal faeces.
While this has been used in sheep successfully, faecal egg counting is not as reliable in goats, particularly when it comes to being used as a variable for selection and breeding.”
The first trial in 2012, funded by Beef and Lamb NZ residue goat levy, tested 48 Angora goats; while the next round of research, funded by the Ministry for Primary Industries’ Sustainable Farming Fund, began in July 2013 and is ongoing for three years – mainly testing 400 Angora does and their progeny.
“So far it looks like the CARLA results are more reliable than the faecal egg counting results,” says Mr Shaw.
In the future his research may help goat breeders to select animals with naturally higher levels of immunity to parasites – a long-term and sustainable way of limiting the impact of parasitic infection on the industry.
Breeding programmes may take eight to 10 years to have an impact, but are likely to improve immunity to parasites such as roundworm. It may also mitigate time-consuming and costly animal management practices for goat farmers.
That has great implications for our export industry, and for increasing the production in the goat dairy, fleece and meat sectors.
Goat farming is a growing area, worth millions to New Zealand: approximately $110 million a year in dairy (milk), $600,000 a year in mohair (Angora fleece) and $10 million a year in meat trade. There are approximately 210 mohair goat producers in New Zealand and more than 50 suppliers to Dairy Group Co-operative Ltd (DGC). Goat milk is a highly desirable dairy product, with goat milk solids worth more than cow milk solids.