Cutting cost of parasites
INTERNAL PARASITES are costing British sheep producers 84m a year, but a single round of genetic selection of resistant animals would save £21m of those costs.
MLC geneticist Gert Nieuwhof told the BSAS conference this high cost of internal parasites compared with other major disease costs made it worth breeding for resistance.
He calculates that footrot costs producers £24m a year, scab £8m, chlamydial abortion £20m and toxoplasmosis £12m. “And all animals have internal parasites, so we want to reduce their effect as well.”
Gail Davies of the Roslin Institute added that the £84m cost equated to £4.79 a lamb on average. “We have traditionally treated internal parasites with anthelmintics, but anthelmintic resistance is becoming a major problem.
“We need alternative control strategies.” These could include grazing management, vaccines – although development is slow and none are available yet – protein supplementation or through selecting animals with better resistance to intestinal worm effects, she said.
Dr Nieuwhof reckons breeding animals with resistance would prove economically beneficial. In a single round of selection for resistance in terminal sires, internal parasites in lambs would reduce by 17%. “If there were 100% uptake by breeders it would reduce parasite costs by £21m a year. At 20% update, £4m would be saved.”
But to realise these benefits would require identification of animals with resistance. Genetic markers offer considerable scope to achieve this, without having to infect animals with internal parasites for selection to take place, said Ms Davies.
Her work, funded by DEFRA, the EU and BBSCR, has identified several quantitative trait loci (QTL) associated with two specific parasites across four chromosomes. “These results so far are promising.”