Lambing special 2010: blood-test ewes for pre-lambing insight - farmers weekly

BODY CONDITION SCORE IS A GOOD GENERAL GUIDE TO SHEEP NUTRITION, BUT FOR A MORE ACCURATE VIEW OF NUTRITIONAL STATE, SHEEP PRODUCERS SHOULD GIVE EWES A BLOOD SAMPLE THREE TO FOUR WEEKS AHEAD

OF LAMBING, SAYS EBLEX BEEF AND SHEEP SCIENTIST, LIZ GENEVER. “Although body condition scoring is vital, it can be too insensitive to pick-up inadequacies in energy and protein levels ahead

of lambing. This makes a simple, vet-organised blood test to indicate the actual nutritional state of ewes invaluable.” Body condition scoring is retrospective, so although a ewe may be in

good condition, her current energy state could be poor, explains Kat Bazeley, Kingfisher Vets. “Assessing body condition is essential, but a short metabolic profile adds valuable

information.” And with 70% of foetal growth and the bulk of udder development occurring in the final six weeks of pregnancy, ensuring the right nutrition in the run-up to lambing is

essential, says Dr Genever. “Failure to fine-tune energy and protein intakes can easily compromise lamb vigour and survival and ewe health and seriously undermine flock performance.” As a

result, a group of 10-12 ewes representing a cross section of breed, diets, litter size and body condition should be given blood tests four hours after the last supplementary feed. “Bloods

samples should be tested for beta-hydroxybutyrate (BOHB) – a ketone produced when ewes mobilise body reserves in the absence of sufficient dietary energy, and urea and serum albumin –

indicators of protein levels.” ENERGY Testing for BOHB is cheap and gives something to play with straight away, says Ms Bazeley. “When BOHB is high, you are on a knife edge for pregnancy

toxaemia, weak lambs and poor colostrum quality. “Identifying raised levels of BOHB will send alarm bells ringing – the next step is to interpret why.” Because BOHB levels are linked to

energy deficiencies, it is possible to work out the extra MJ of energy needed to bring levels back into balance, says Matt Colston, Frame Swift and Partners. “This may involve changing the

balance of concentrate in the ration or adding a liquid feed such as treacle.” However, although high BOHB levels are an indicator of low-energy levels, do not assume it is just because

energy is lacking in the diet, says Ms Bazeley. “A ration may be well balanced, but if trough space is insufficient, or ewes are lame, they may not be able to access feed.” Although bloods

should be taken in advance, ewes should not be tested too far ahead, she says. “When testing too far in advance, you could be lulled into a false sense of security, as it is only in the last

few weeks before lambing where energy demand increases dramatically.” PROTEIN Ideally, protein levels should be assessed three to four weeks from lambing, but you can make a difference a

couple of weeks before, says Mr Colston. “Bloods will identify whether ewes are short of rumen degradable protein and/or rumen bypass protein (UDP). The ration can then be assessed

accordingly. “For colostrum production, ewes need a good source of UDP, such as soya, but, for rumen function, rumen degradable protein is essential – the key is getting the balance right.”

And for ewes carrying triplets or twins, the demand for UDP will be even higher. “Good UDP levels also influence worm egg outputs, potentially reducing pasture contamination,” he says.

-------------------------