Optimum nutrition in ewes will reduce mortality rate
Many of the causes of lamb mortality can be avoided with appropriate nutrition of the ewe. Scanning and penning according to litter size, a good estimation of lambing date, forage analysis, adequate trough space and appropriate concentrate formulation and feeding are all important considerations.
Forage analysis will dictate how much meals are required. In general ewes will consume 1kg of grass silage DM in late pregnancy (average across last seven weeks), but this level will drop in the final two weeks of pregnancy. Issues such as low DM percentage, high ammonical nitrogen content, low DM digestibility, long chop length and low crude protein content will all reduce silage DM intake.
Any factor reducing the intake of silage or any forage offered will necessitate the earlier introduction of concentrate feeding and feeding of higher levels of concentrates.
Another issue with low forage quality is the time it spends in the rumen. Low dry matter digestibility leads to forage spending a long time in the rumen and produces a physical fill effect. This leads to pressure within the abdomen increase and is often implicated as a predisposing factor in prolapse. The risk is increased with small ewes, large litter size and excessive body condition score (BCS).
Inappropriate formulation of concentrates (ie a lot of rapidly fermentable starch) and feeding large quantities of concentrates in a single feed (greater than 500gr per feed) can cause the pH in the rumen to fall. In mild cases this slows down the rate of forage digestion, increasing the filling effect of the forage. In severe cases acidosis develops which greatly reduces intake, predisposing conditions such as twin lamb disease and milk fever.
At high levels of cereal grain in the diet, inclusion of whole grains should be considered. These will not pass through the digestive system as is often feared. Rather they will slow down the rate of starch digestion in the rumen and help to maintain a healthy rumen. Other options include the inclusion of fibrous concentrate ingredients such as soya hulls or citrus pulp. However, overall energy content of the ration should not be compromised.
Other simple things to consider include ensuring all ewes are accessing the feed (trough space of 450-600mm per head), and no persistent underlying health conditions such as lameness or internal parasites.