Recently, the Department of Agriculture, Food and the Marine (DAFM) released its Nematodirus forecast.
Nematodirus, along with coccidiosis, are two parasites of concern to young lambs and the signs of both are quite similar.
These parasites can affect lambs at a similar age and stage of the year and can have serious health implications in lambs.
Nematodirus
Nematodirus can cause problems for lambs that are between four and 12 weeks-of-age. Lambs can become infected when the eggs of this parasite overwinter on grass from the previous grazing season.
These eggs – when exposed to cold weather conditions followed by warm conditions (above 10°C) – will hatch. By the time these eggs hatch, it coincides at a stage where lambs are consuming large amounts of grass – which makes them very susceptible to picking up this parasite.
Once a lamb is exposed to the parasite, the larvae will damage the lining of the intestine, resulting in diarrhoea, dehydration, weight loss and, if left untreated, death.
The best way to prevent lambs from becoming infected is through the use of anthelmintic drenches. A white drench (Benzimadazole) should be used to treat against the parasite.
Faecal egg counts are not a good indicator of when to treat for Nematodirus as the larval stage of the parasite damages the gut, therefore damage may be done before eggs appear in the faeces, according to Teagasc.
Lambs will generally develop immunity once they reach approximately 12-weeks-of-age.
Coccidiosis
Coccidiosis occurs when lambs become infected orally from faecal contamination of bedding, water troughs or feed troughs. Coccidia can survive on pasture and in the environment from the previous grazing season.
In most cases, coccidia affects lambs from two weeks of age up to eight weeks of age, although it can occur in older lambs where immunity is suppressed or where naive lambs face a heavy burden.
Lambs are protected by antibodies in the colostrum for the first three weeks of life and they develop resistance to attack – from this parasite – at about 10 weeks of age.
Lambs become infected when they ingest coccidial oocysts, which penetrate the gut wall where it burst and causes damage – leading to the lambs becoming sick.
Lambs that are infected will develop a scour – which may contain blood or is black in colour. Furthermore, lambs may show signs of straining and appear empty and dehydrated.
It is best to talk to your local vet about what treatment should be used to treat any infected lambs. Treatment is based on the use of oral drenches with an in-feed medication also available.
Otherwise, a number of management practices can be carried out to limit the number of coccidial eggs present on pasture.
When outdoors, regularly moving feeders, particularly where poaching is occurring, will also help. Ideally keeping different ages of lambs separate at turnout i.e. later lambs grazing a different area than older lambs initially, however, this may not be practical on many farms.