Maximise lamb survival this spring
Late pregnancy nutrition of the ewe has the greatest influence on lamb survival, impacting lamb vitality at birth and ewe milk.
To maximise ewe Body Condition Score (BCS) at lambing, separate ewes below BCS 3 at scanning for preferential feeding. Due to limited rumen space, this needs to be energy-dense and high-protein feed.
Supplementary feeding with sheep nuts or dehydrated molasses blocks containing bypass protein are good options for providing extra nutrients.
Foetal growth in the last 50 days of pregnancy is rapid and coincides with significant udder development. Feed restriction at this stage of pregnancy results in poor colostrum production, and lower milk quality and quantity for lactation.
The metabolic diseases, including ketosis (sleepy sickness) or hypocalcaemia (milk fever) in late pregnancy result in higher rates of lamb and ewe deaths. These problems are all preventable through identifying at-risk ewes early and feeding optimally highly nutritious feeds.
For those starting to lamb, dystocia (difficult birth), starvation or exposure are the main causes of lamb deaths. Lamb birthweight which is already set by this stage is the main influence in the starvation or exposure complex especially in multiples.
Lambs born to low BCS ewes are smaller, have less brown fat and are more prone to the effects of hypothermia. If on a lambing beat and coming across weak, cold lambs, immediate energy is required before they can be warmed up. Intra-abdominal glucose administration is vital to increasing the survival of these lambs. Once glucose is on board and lambs are responsive, warm and feed them with milk.
Cow colostrum from the first milking only, not transition milk, is adequate or mixed-up freeze-dried product. Thaw frozen colostrum slowly, do not use a microwave to heat as it destroys the antibodies in the milk. In the first week, a lamb requires around 700 mL of milk per day, split into five feeds, starting with 50 mLand no more than 150 mL per feed. This is time-consuming but rewarding as the lambs grow faster with fewer gut upsets.
Whey powders anecdotally result in fewer cases of abomasal bloat in older lambs, but a New Zealand study¹ found that lambs on whey powders were more susceptible to infections and higher death rates, something also seen in calves. Lambs may begin on a casein-based product and then transfer onto a whey-based one. Keep the lamb rearing area and equipment as clean as possible. Also, consider the volume and frequency of feeding and note feed volumes of greater than 350 mL per feed seem to increase the risk of abomasal bloating in lambs.
Maximise the number of live lambs this spring by having ewes well-fed throughout pregnancy.
For help maximising lamb survival, contact your local PGG Wrightson Technical Field Representative.
¹ McCoard, S.A., Knol, F.W., & Stevens, D.R. (2020). Lamb Rearing Technical Manual. Retrieved from agresearch-lamb-rearing-manual-aug-2020r.pdf
