A good grass growing autumn is to be welcomed, but has left some breeders concerned about their flocks being in too good condition in the lead up to lambing. In general, ewes being too thin is the bigger problem, but over-fat ewes bring their own issues with a risk of twin-lamb disease and lambing difficulty.
So what can be done?
The first step is to get to grips with the key times in the ewes pregnancy. From the date the rams went in, and out, until predicted start of lambing the different stages of pregnancy should be ‘blocked’ into early, mid and late pregnancy. Months one and two are classed as early pregnancy and it’s all about successfully get the ewe in lamb and maintaining the pregnancy with good placental development. Generally maintenance feeding over this period should be the priority, unless ewes are too thin.
In over-fat ewes some loss of condition can be allowed, but the time to allow this is actually the third month of pregnancy where ewes at condition score 3.5 or higher can be allowed to lose about half a condition score. This should be done slowly and depending on the time of year and weather often occurs naturally as grass quality declines and wet weather sets in. Leading up to the last six weeks of pregnancy ewes should already be at the target condition score of 3 for lambing.
Now the targets are in place the next step is to actually condition score the ewes. Every ewe should be handled as visual assessment is misleading when it comes to the condition of the ewe. What we see is conformation rather than condition so regularly placing a hand on all ewes is vital. Once the actual situation is known and when it is practical to do so (e.g. after the rams have come out) then ewes should be split according to condition. Ideally the grouping should be: on target (3 to 3.5), over-target (4 or more) and below target (2.5 or less). Regular checking will allow small changes to be made to the diet without sudden swings in feeding levels.
What happens when ewes are still too fat at lambing?
The problem is that in the last six weeks of pregnancy the placenta is fully developed and lambs are rapidly increasing in size and taking up much of the nutrients which are made available to the ewe. Underfeeding fat ewes can lead to poor sized lambs while over-feeding thin ewes can lead to big lambs and ewes that are still too thin. In both cases colostrum production can also be compromised.
To try and avoid these problems there are, however, some steps that can be taken. Any forage fed should be analysed to get a handle on feeding levels required in the run up to lambing and whether a focus needs to be put in supplying additional energy and/or protein. Where ewes are in exceedingly good condition some of their energy requirements can be derived from body reserves and a greater focus can be placed on protein supplementation. Specialist nutritional advice can help to ensure all requirements are met and a well-balanced diet formulated.
Blood tests can also be carried out about four weeks before lambing to provide an indicator as to whether sufficient energy and protein are being supplied to the ewe. This is a cost-effective exercise and at this stage it is a great opportunity to get your vet involved in the lambing process as well as giving some time to tweak the diet.
Other management options also exist to help manage ewes in too good condition before lambing. Keeping them out as long as possible and when housed allow plenty of space for movement. Splitting any supplementary feeds can help ewes maintain their appetite and always make sure they have plenty of forage available – the rumen is an engine that needs to be kept working.