At our farm we have always used the traditional method of lamb production, which is seasonal. The natural time for sheep to be mated (tupped) is in the autumn as the nights get darker around November, this brings the females (ewes) into cycle, which occurs every 17 days until Christmas. Thus hopefully producing a crop of lambs in early April as the weather gets warmer, the days become longer and the grass starts to grow. The ewes produce lots of milk from the young grass and the lambs grow rapidly and naturally over the summer.
This is the traditional time for lambing in Northumberland but, as you can understand, lambing time varies throughout the country depending on the arrival of spring.
There are artificial ways to change the lambing time, which produce lambs as early as Christmas in pedigree flocks and for the Easter sales. To do this, the ewes have to be 'sponged' and can be artificially inseminated or even embryo transplanted but this is very high tech, normally tups are used. The ewes and lambs are usually housed in the wet, cold winter months and fed concentrates ad-lib, which we think produces a different flavour and colour to the meat, which is more akin to veal.