With the dry and hot weather last year, many grass-based grazing systems had a distinct reduction in grass growth. This has meant that in order to keep lambs growing well and ewes in good condition, many farms have needed to supplement with forage and fodder far earlier than expected.
With an increased reliance on supplemented feed, we’ve seen an overall picture of leaner ewes going to the tup and in general, leaner across the board.
We can quantify this by using body condition scoring to allocate a numerical value to the body reserves of an adult animal. The scale consists of 1 (thin) to 5 (fat) and assesses the amount of fat cover and muscle mass. By assigning a numerical value, you can track changes in the condition of the flock throughout the year.
The main points to be checking condition of the flock are tupping, scanning and lambing.
Listed below are ideal scores for each broad category of sheep breed at each time point:
As we are coming in to lambing time, I want to highlight why condition scoring at lambing is important.
During the last 6 weeks of gestation, 70% of the foetal growth occurs. This has large impacts on the energy requirements of the ewe as well as the amount of feed she can ingest. If the ewe is unable to meet her energy requirements, she will use her own body reserves to make up the deficit. This results in fat mobilization in the blood stream which is metabolized to ketones in the liver. This in itself is a vicious circle as the presence of ketones often suppresses an animal’s appetite which worsens the problem.
If a ewe is already in poor condition when these requirements suddenly increase, she has no stores of energy available and will deteriorate; We see this as twin lamb. With low blood sugar and no fat reserves to mobilise, she is at risk of losing her lambs or even dying herself. If we can pre-empt this condition, our prognosis is much better. The same can occur with over-fat ewes as they have readily available stores of fat and will end up using fat as her energy source instead which is not ideal either. Other impacts of low energy in late gestation can be low colostrum production, poor quality colostrum and small birth weights of lambs.
A way of checking that our ewes have enough energy to see them through lambing is to measure NEFAs (Non-esterified fatty acids), butyrates and urea in the blood between 4 and 6 weeks pre-lambing. These are markers of energy in the ewe. By finding out individual accurate levels, we can adjust the diet for the flock early enough pre-lambing in order to prevent any problems occurring at and around lambing. Talk to your vet about whether they could benefit you.
There are several things we can to both prevent and treat the problem.
Treatment revolves around correcting the lack of available energy; the earlier this is identified, the better the prognosis.