Managing ewes through winter
The management of ewes through pregnancy is important to maximise lambs’ survival rates and the ewes’ ability to produce large volumes of good quality colostrum and milk. Both these factors are the key to profitable lamb production on breeding farms.
Knowing whether ewes are carrying singles or multiples by scanning, enables accurate feed allocation and informed prioritisation of feed and supplement. This task on the farm calendar will be particularly relevant this year with many districts facing tight feed availability due to prolonged summer/autumn drought.
As the foetus grows it demands more energy and protein from the ewe. Ewes that maintain a Body Condition Score (BCS) give birth to heavier and more vigorous lambs. Lambs that are more vigorous at birth have a significantly higher survival rate. Ewes that lose significant BCS through winter often have poor placental development, which compromises foetus development and birth weight, which results in lower lamb survival.
Internal parasites can in some cases build to levels which impact ewes through pregnancy and into early lactation. Mob monitoring of worm burdens through faecal egg counts, taken at or around scanning time, enables targeted anthelmintic treatments in different mobs. A general reduction in ewe drenching is recommended by WormWise to manage drench resistance, so identifying the need to drench is a better approach than implementing blanket treatments.
Iodine is a trace element required to help the lamb maintain body heat when it’s born. Iodine is depleted in ewes grazing winter brassica crops, supplementation by injection, oral dosing or in the feed should be considered. Iodine deficiency is also seen in some areas when grazing grass. Autopsies of newborn lambs help determine if there is an issue you can manage in the future.
If hoggets have been mated, then they need to keep growing throughout pregnancy at a rate of 150 g per day to ensure good lamb birthweight, as well as the hogget reaching liveweight targets as a two tooth. If a hogget was mated at 40 kg then she should weigh 50 kg immediately after giving birth. Poor growth of the hogget through pregnancy results in the birth of lighter and less vigorous lambs and a hogget less able to support the lamb.
A sudden change of diet pre-lamb can result in metabolic disease in ewes, especially older, multiple carrying individuals. It is important to transition ewes off winter crops to spring grass at least two weeks before lambing to minimise this occurring. If ewe deaths are high, pasture and blood sampling can help identify metabolic issues that can be remedied through an alteration of the diet.
Any pre-lamb animal health should be given ideally three to four weeks before the lambing date to help reduce inducing metabolic diseases. Try not to have ewes off feed for any longer than necessary during yarding. This may mean taking several smaller mobs to the yards on larger farms.
For further advice on managing ewes through pregnancy and their pre-lamb animal health and nutrition requirements contact your local PGG Wrightson Technical Field Representative.