Farmers are being advised to get ewes in the correct condition ahead of tupping to avoid a second year of poor scanning rates.

Bryn Hughes, national sheep and beef adviser at Wynnstay, says following a drought in May and June, grass growth rates have returned to normal, however, a close eye still needs to be kept on ewe body condition score (BCS).

"It was widely reported that scanning rates were back 15-20% on some farms in 2022/23, which highlights the importance of getting ewes in the right condition ahead of tupping," he says.

Table 1: Targets for ewe BCS

Mr Hughes advises that if you have not already, BCS all ewes now so that any thin ones can be identified sooner rather than later.

"When identifying thin ewes, it's important to ask yourself why they are thin - is it down to late lambing, poor health, or grass availability. Once this has been agreed, take corrective action," he says.

"One BCS equates to 10-12% of body weight. For a 75kg ewe, this is 7.5kg. Ewes typically gain 300g/day, so it will take at least 25 days for her to regain condition.

"This requires very good grazing, so farmers will need to consider if they can achieve this or if ewes need supplementary feed.

"Depending on their BCS, good grazing with flusher buckets is often enough to put ewes in good condition for tupping," he explains.

Why is BCS important?

A large study of 2,516 ewes carried out over three consecutive years in four New Zealand flocks found that lamb growth rates were significantly impacted by ewe BCS.

Ewes with high BCS that lost condition during rearing were using energy reserves to feed lambs which led the researchers to conclude that "adequate feeding is required to achieve high BCS at lambing."

Triplets were at the highest risk of low lamb growth compared to singles and doubles, which indicated that increased energy demands during gestation and rearing were insufficient.

(Source: Ewe body condition score and the effect on lamb growth rate HC Mathias-Davis, GH Shackell, GJ Greer, AI Bryant and JM Everett-Hincks).