Many farmers who closed up paddocks in good time last autumn are in a good position with a favourable supply of grass.

This is putting farmers who generally lamb outdoors in a great position after a few difficult years and possibly enticing those who generally lamb indoors or ceased the practice in recent years to reconsider the practice.

Big attraction

The big attraction is lower labour and reduced feed costs, while rising straw supplies have also led some people to consider lambing a portion of ewes outdoors.

However, this statement should be taken with an air of caution, as outdoor lambing still requires high levels of management.

Similar to indoor lambing, its success is highly dependent on advance preparations.

Research carried out by AFBI* a few years ago highlighted a number of factors that should be taken into account.

Value of grass

Good-quality grass (grown from tightly grazed paddocks) is potentially five to 10 units higher in nutritive value than high-quality grass silage, with a nutritive value listed as similar to a high-energy 18% protein ewe concentrate.

As well as being potentially 30% cheaper than grass silage, the fact that ewes will consume up to 50% more dry matter compared with grass silage makes grass the ideal feed to meet the elevated nutritional demands of single- and twin-bearing ewes in late pregnancy without the need for concentrate supplementation.

This is reflected in Table 1, which shows the performance of twin-bearing ewes fed a diet of grass or grass silage in late pregnancy.

The ewes on the grass diet gave rise to heavier lambs than the ewes on the high-quality grass silage and concentrate diet, while producing a slightly lower colostrum yield but still sufficient to meet the demand of suckling lambs.

Surplus grass

It may seem strange to be saying after the recent difficult spring, but strong grass supplies also bring risks in the form of ewes consuming too much grass giving rise to the birth of oversized lambs, lambing difficulty and higher levels of labour and mortality.

This is reflected in Table 2, which shows the effect of increasing the volume of grass on offer to ewes on lamb birth weight, assistance required and subsequent performance.

When ewes were offered high volumes of grass, the number of ewes requiring assistance spiked to 18% as a result of heavier lambs and ewes in excessive body condition at lambing.

As such, it is crucial that grass intake is controlled.

It is unlikely in most flocks that sufficient grass will be available to lamb all animals outdoors.

Or, if it is available to lamb ewes outdoors, there may not often be a supply of grass for early lactation if it is not budgeted carefully.

Therefore, the best approach is to focus on offering grass to the ewes that will benefit most.

This includes twin- and triplet-bearing ewes and particularly those that may be below optimum body condition, as these will benefit most from the nutritional boost.

The area selected for lambing should have good shelter.

Many steer clear of actually lambing too many triplets outdoors due to the higher possibility of ewes needing handling.

Most farmers practicing outdoor lambing successfully often retain single- and triplet-bearing ewes in close proximity indoors to better supervise triplet-bearing ewes, restrict intake in single-bearing ewes and give the best opportunity to cross-foster.

Twin-bearing ewes are also housed until two to three weeks pre-lambing or supplemented outdoors in a confined area to help conserve and build grass supplies.

Stocking rate

The general stocking rate recommended is about five ewes per acre for a mid-March lambing flock that has sufficient grass reserves available or coming on stream to carry ewes post-lambing.

This is also a vital aspect to consider, as there is little point lambing outdoors if it overcomes lambing, but then requires supplementation in early lactation.

This recommendation is based on a grass height of about 5cm and may need to be increased if heavier covers are present.

Weather and levels of grass utilisation will also have a role to play.

Irrespective of the system, ewe body condition should be monitored regularly and only suitable sheep should be selected for the practice.

Where lambing outdoors is not a runner but there is scope to take advantage of a surplus supply of grass, then target this to ewes that will deliver the best return.

Triplet-bearing ewes will, in general, still require a small level of concentrate supplementation in the final weeks of pregnancy even if offered access to grass.

Other important factors

There are also a number of other important factors that should be taken into account if considering outdoor lambing. Some of these are listed below.

  • Ewe breed: hill breeds, such as Scottish Blackface, Cheviot and Swaledale, and crosses, such as the Mule, Greyface and Hiltex or Lleyn breed, are most suited due to their natural maternal instincts.
  • Facilities available: while outdoor lambing has the potential to lower labour, it will not eliminate supervision or handling of some animals. A handling pen or shed should be available to flock sheep, while back-up facilities are advised to guard against inclement weather.
  • Grass supplies: do not leave yourself short of grass. Spreading 20 to 25 units of nitrogen when ground conditions allow will help boost supplies.
  • Mis-mothering: sufficient grass supplies are essential in avoiding supplementation and, in turn, lambs getting mis-mothered from their dams. It is also important to either remove ewes and lambs from the group or ewes still to lamb regularly to cut down on the number of lambs in close quarters with ewes still to lamb and mis-mothering. Most farmers leave freshly lambed ewes for 12 to 24 hours to develop a bond before moving.
  • Sheltered paddocks: settled weather will greatly influence mortality and the risk can be minimised by selecting sheltered paddocks.