[Three lambings within two years following induction of oestrus (author's transl)].

The annual number of weaner lambs per ewe is a factor of major importance in the profitability of sheep farming. In the Netherlands, approximately 80 per cent of the incomes are derived from the returns for lambs sold. Induction of oestrus makes it possible for the ewes to lamb three times in two years. To achieve a high conception rate, tupping should take place under supervision. In the Experimental Livestock-Farming Station, Lelystad, studies on the possibilities of inducing oestrus were done in ewes in which tupping occurred for the first time at an age of approximately seven months during natural oestrus in the months of October and November. The results obtained by inducing oestrus in July and August were similar to those obtained with natural oestrus in October and November. The results obtained in February and March were slightly inferior, which probably was also due to the fact that the condition of the ewes was not very good immediately after weaning of the lambs at six weeks. The number of lambs born showed an average increase of 0.5 lamb per ewe mating with the ram per year. A further increase of the annual number of lambs per ewe is likely to be achieved.