2025 Results from an Outdoor lambing trial.
James (father) and Sandy Storrar‘s Arable & Livestock Rossie Farms is by Auchtermuchty in Fife. Lambing started on the 13th April 2025 and they were weaned on the 27th July 2025. Lambing was outdoors, and lambs were weighed as clips, or rings fitted. Twins and triplets only, and EID tagged at the same time. 82 lambs were clipped (43 ewes, 39 rams) and 89 rung (39 ewe lambs and 50 rams).
This is the analysis we did ourselves from the data supplied.
Professor Cathy Dwyer describes the results far more succinctly and with greater gravitas of course !
“Only a preliminary look so far, and I have assumed that the lambs are all the same breed because there was no data to suggest otherwise but would be good to know if that was the case or not. Data on sire identity would be useful as well – just we know quite a lot about what influences lamb growth so the more of these factors we can include in a model the better the accuracy of any effect of using clips or rings.
So at the moment I have included everything in a big model with ewe status (hogg or ewe), lamb birth litter size, lamb rearing litter size, lamb sex and treatment (clipped, rung, a few ewe lambs were left intact but hard to include these fully in the model, I did keep them in but they might just be increasing variability). So maternal status, lamb sex and rearing litter size are the most important (birth litter size also important but confounded with rearing litter size so only kept one in the model), in ways we would expect. BUT there is significant tendency for clip/rung to have an effect on both weaning weight and average daily gain (ADG) to weaning (for Brian’s info: we usually consider something to be significant at 5% probability, ie would arise by chance only 1/20 times. The data did not reach that but probability of the observed effect occurring by chance was 9.1% for ADG and 9.8% for weaning weight) – and this was in the direction we might have predicted so mean values were:
Ewe lambs clipped = 0.281 kg/d, ewe lambs RR = 0.268 kg/d
Ram lambs clipped = 0.295 kg/d, ram lambs RR = 0.290 kg/d
So not huge effects and I would not be looking to publish this in a peer-reviewed journal for example but there is some evidence of a small effect on growth, obviously good to have more data to see if this is a robust effect. I do have some other data that Brian sent me but it is not quite so easy to work with as this dataset (please thank Sandy, his data were very easy to sort for the stats!) – ideally we would combine all the farm data if we could and see if that helps improve the confidence we might have in an outcome.
So encouragingly in the right direction, but not yet a result we might be hugely confident in.