VET’S DIARY: Importance of finding the key to successful flock performance

THE value of ewes, and the lambs they produce, has improved dramatically over the last couple of years, writes Dominic Plumley. In good years as in bad, the key to successful flock performance is to achieve a good crop of lambs and to minimise losses. Working with your vet at a pre-lambing visit can help avoid the most common pitfalls.

Managing the condition of ewes correctly during pregnancy will have a major impact on losses around lambing time both in ewes and their lambs.

Poor nutrition prior to lambing will lead to weak lambs, poor colostrum and milk production and losses due to twin lamb and other ewe diseases.

Regular body condition scoring throughout pregnancy is vital to assess how well the ewes are having their nutritional requirements met. If you are unsure how to condition score, ask your vet to teach you!

In sheep, the lamb becomes attached to the womb at about 35 days and from there up until about the 12th week of pregnancy the lambs are relatively small and ewes can obtain enough energy from reasonable grazing to maintain pregnancy.

Beyond this, additional feed will be required for thin ewes and ewes carrying multiples.

It is important therefore to scan and body-condition score ewes around the 70-90 day mark to identify barrens, singles and multiples for later management.

Scanning may also pick up ewes that are going to lamb at the end of the lambing period which, depending on numbers, can either be managed separately or kept with the singles for longer.

In later pregnancy, ewes carrying multiples may be unable to eat enough to maintain their lambs and themselves and will draw on body reserves.

If these reserves are not available then twin lamb disease and other metabolic conditions may follow.

In severe winters such as this, where little grazed grass is available, ewes in mid pregnancy will require good quality silage or hay to maintain body condition.

Silage and hay can vary hugely in quality so ideally it should be analysed to avoid over or underfeeding.

Knowing what the forage contains allows correct concentrate feeding.

Ideally, concentrates should be formulated to complement the forage.

For home mixing, a good quality protein source should be used, preferably rolled rather than whole grains to avoid grain being passed undigested.

For pre-formulated bought-in compounds ingredients should be checked before ordering.

Two apparently similar rations may have completely different energy values. Compounds containing a lot of feed by products such as cocoa and citrus pulp should be avoided; unrecognised ingredients are probably of low quality!

Ingredients are listed in order of percentage inclusion, giving an indication of how the compound is likely to perform.

On reasonable quality big bale silage, twin bearers should start on concentrates four to six weeks prior to lambing, the quantity gradually increasing weekly. Triples will need to be fed two weeks sooner; singles in good condition can start two weeks later. Adequate trough space (at least 18 inches per head) is very important to avoid bullying.

Once lambing has begun it is important to remember that the ewe’s milk production doesn’t peak for three to six weeks and ewes should continue to be fed for this time or until grass growth produces pasture of at least four inches of grass cover.

Northumbrian deficiencies of vitamin E and selenium can cause lambs to have poor vigour so adequate levels of trace elements are important. It mustn’t be assumed that ewes will take what they need from mineral licks, as consumption of these can vary massively.

Blood sampling can be used to assess the energy status of ewes in the run up to lambing. High levels of butyrate can indicate weight loss and risk of twin lamb disease.

Trace element levels can also be checked to avoid deficiencies or unnecessary supplements.

Samples should be taken early enough to spot problems before they happen rather than to find out why things went wrong.

It won’t be long before the fields are full of gambolling lambs and proper preparation now will identify problems before it is too late to fix them.