Anaemia in housed newborn lambs.

The mean (+/- sd) packed cell volume (PCV) of the lambs in a flock mated by 'out-of-season' breeding methods and housed throughout the last six weeks of pregnancy and the whole of the suckling period declined to 23.3 +/- 3.34 per cent when the lambs were a month old, but recovered spontaneously to reach values within the normal range (30 to 35 per cent) before they were weaned at two months. Clinical signs of anaemia were observed in only a few lambs at three weeks old but the PCV values of all the lambs were significantly lower at this time than at weaning. There was no relationship between the PCV values during the two to four weeks after birth and the growth rate of the lambs. The administration of 200 mg iron, as iron dextran, by intramuscular injection to the newborn lambs prevented the decrease in PCV, but had no measurable effect on the health or growth rate of the lambs throughout the suckling period.