Let’s make the most of the moment of truth
Words: Mary Bowron, Wormwise
With the economic forecast for the red meat sector predicting ongoing record prices for the 2025/2026 season, every lamb born this spring is an opportunity to make money.
Mary Bowron, Wormwise.
Tailing time is the first chance your farmers get to see how well lambing has gone, and to get an indication of how many lambs there will be at weaning time. A farmer can’t sell a scanning percentage, yet that is a statistic that is often quoted! What is more important is the total weight of lamb sold and the timing of those sales. Early-finished lambs are the gold mine – they are generally worth more, and their departure frees up feed for the rest of the farm’s enterprises.
To maximise this potential, it is important your farmers ensure lambs continue to grow well through to weaning. Energy and protein requirements for lambs increase after tailing. Offering high quality, legume-dominant pasture is important, as milk production is dropping off and lambs are eating more grass. Rotational grazing of mobs as soon as possible after tailing is a great way to ensure lambs are getting a fresh pick, and teaching them about moving around the farm.
A lamb drench at tailing time is typically not necessary. Lambs aren’t old enough to mount an immune response to the important gut worms, so they don’t tend to suffer production losses at this point. Any scouring seen is likely to be due to lambs fighting off Strongyloides parasite, which they will conquer without a drench anyway. The rise in egg counts that some mixed age ewes experience around lambing will be decreasing at tailing as immunity kicks back in. Whole-flock drenching of ewes at tailing is unlikely to be worthwhile. However, younger ewes and fine wool breeds can take longer to regain immunity to parasites at this time. Monitoring of these ewes with faecal egg counts keeps an eye on potential worm issues, especially if long acting drench products were given pre-lamb. Tailing is a good time to test for any leakage of that product and to determine if an exit drench is needed.
Whether or not a lamb pre-weaning drench is needed depends on several factors. If ewes have lambed in good condition, milked well and there’s plenty of legume-dominant feed on offer, a response to drenching is less likely. With quality feed and high grazing residuals, lambs will have lower worm burdens, so a pre-weaning drench may be of little benefit. If it has been a tight season for feed, then a pre-weaning drench may help maintain lamb growth prior to the stressful weaning period. Faecal egg counting of lambs pre-weaning can help with this decision. The more information available regarding worm burden, the more confident your farmers can be around that drenching decision.
Regional variation with parasite species can influence pre-weaning drench decisions, such as Nematodirus in Southland and in the top half of the country Haemonchus. However, seasonality of parasites is shifting. A recent survey completed by Waghorn et al, found some interesting differences from previous seasonality work. With respect to egg outputs from ewes, the dominant species were Cooperia curticei, Haemonchus contortus and Oesophagostomum venulosum. Of the three parasites H. contortus is the most pathogenic and was present year-round in all stock classes (predominantly North Island farms in the survey), providing evidence of anecdotal reports of barbers pole shifting south. C. curticei (generally not considered as pathogenic for sheep) was higher from May through to August often being the predominant parasite in ewe larval cultures in the winter. In the spring/summer Teladorsagia circumcincta and Trichostrongylus vitrinus were prevalent in lambs and ewes. In the autumn, dominating in lambs was Trichostronglus colubriformis peaking in May-July.
The mixed aged ewes showed consistently low levels of this parasite throughout the year. Considering lambs are drenched more often than other age groups of sheep, this finding may explain why there is such high triple drench resistance in T. colubriformis (51 per cent of farms, Awanui FECRT survey 2023/2024). For those farmers finishing lambs this is a significant detail to consider when planning sustainable parasite management.