Nematodirus caution

There have been some queries in recent days regarding the risk of nematodirus given the higher than normal temperatures in recent months.

Last year’s weather followed a similar pattern, leading to the Department releasing their Nematodirus Forecast on 6 April 2023.

The warning in 2023 listed the peak hatching period in the final days of March in a number of coastal locations and generally from 6 to 12 April elsewhere.

This year’s forecast is not expected to differ majorly. The advice is to be on guard for the characteristic signs of nematodirus and to treat accordingly.

The general guidance is treatment of lambs aged six to 12 weeks two weeks after peak egg hatching, or on seeing clinical signs. If lambs are suffering from diarrhoea at present it is important to establish the cause, with many ailments giving rise to lambs scouring.

Reports indicate there is a higher incidence of coccidiosis prevalent this spring, which is not surprising given the challenging conditions.

Lambs suffering from coccidiosis exhibit a dark grey/black or blood stained scour, while the characteristic scour with nematodirus is green.

With both ailments, performance will be greatly curtailed and mortality can be significant where not addressed.

It is also important to note that both ailments can be present at the same time, but this is generally more common after the general timeframe for peak hatching of nematodirus eggs. Department veterinary advice for reducing the risk of coccidiosis includes rotation of pasture and frequent movement of feeding troughs to drier areas, citing that localised poaching creates moist conditions suitable for the spread of coccidia.

It adds that raising feeding troughs will also help to reduce the contamination of feed with faeces, and hence transmission of coccidiosis. Where coccidiosis is present then administration of a coccidiostat will be required.

There is no product with a residual activity against nematodirus, therefore treatment in advance is of no use.

Conserving grass

Grass supplies on farms operating an early and mid-season lambing spread are diminishing rapidly. One option to reduce demand on such farms is to consider early weaning.

Grass intake in lambs increases significantly from six weeks of age onwards, rising from 0.3kg DM/head daily to 0.5kg DM/ha daily in weeks seven and eight, followed by another significant increase to 0.7kg DM daily at nine to 10 weeks of age.

This coincides with ewe milk yield declining significantly, and presents an opportunity for some to consider early weaning to conserve supplies by targeting the best-quality grass to lambs and transferring ewes on to silage/hay.

Lambs can be weaned where they are consuming at least 250g/day concentrates on three consecutive days. Early weaning also opens up the opportunity of feeding lambs a restricted level of concentrates.

Another option to reduce grass supplies is to temporarily house dry yearling hoggets where forage supplies are adequate.

There are also some questions regarding the merit of offering creep to aged lambs, as opposed to continuing to offer concentrates to ewes. Once lambs are aged upwards of four to five weeks of age there is more merit in offering creep to lambs versus offering meal to ewes.

Where grass supplies are depleted, then ewes will need some supplementation, but there is a greater financial and animal performance return from supplementing lambs.