The birth and fate of 818 lambs born to 571 ewes on a low-ground farm in the Scottish Borders with a history of substantial perinatal mortality were monitored with a range of physiological, biochemical and pathological measurements. In lambs which survived, the rectal temperature, birthweight and plasma concentrations of fructose, insulin, thyroxine and the third component of complement at birth, and the weight at four months of age, decreased with litter size. One hundred and thirty-seven lambs were stillborn or died within four days and seven others died later. The mothers of 77 per cent of these lambs had low condition scores, but the lamb deaths did not correlate significantly with the condition scores. From data relating to birthweight, temperature, packed cell volume and plasma composition it was deduced that placental insufficiency was involved in 24 per cent of these deaths; acute hypoxaemia at birth accounted for 35 per cent, inadequate thermogenesis for 12 per cent and starvation for 13 per cent. The remaining 16 per cent of dead lambs could not be assigned to any of these categories. Using only clinicopathological criteria, 37 per cent of the lamb deaths were attributed to antenatal influences which included immaturity, developmental anomalies, and degenerative or inflammatory changes. Thirty-three per cent of the deaths were due to post natal factors which included, in declining order of frequency, starvation, enteritis, misadventure, pneumonia, navel infections and septicaemia. No conclusions could be drawn from the pathological examinations alone in the remaining 30 per cent, although almost half of these had low rectal temperatures after birth, death being attributed to hypothermia.(ABSTRACT TRUNCATED AT 250 WORDS)
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