Researchers sampled 184 ewes from four maternal breeds before, at and after lambing.
Samples before and after lambing
A sheep study accepted for publication on 18 October 2026 measured blood glucose, non-esterified fatty acids, beta-hydroxybutyrate and four minerals in 184 ewes. Samples were taken about 14 and seven days before lambing, at lambing and seven days afterward. The four maternal breeds were Composite-IV, Polypay, Katahdin and Romanov.
Breed and litter differences
The USDA Agricultural Research Service summary reports evidence of metabolic stress in all four breeds. Nearly all ewes crossed the study threshold for fat mobilisation at least once. Romanov ewes showed the greatest stress at lambing, while younger Polypay ewes had longer elevations in ketones after lambing. Heavier total birth weight of a ewe’s litter was also associated with greater metabolic stress. The paper is listed as accepted, with no publication date yet.