Late-pregnancy feeding in a twin-bearing ewe flock
A flock of 90 mature ewes is six weeks from lambing. Scanning shows 150% lambing: 45 singles and 45 twins. Average body condition score is 2.0, with 20 ewes at 1.5. The ewes are grazing wet permanent pasture with limited grass and are offered pit silage analysed at 11% crude protein and 64 DMD. No concentrate is fed. The farmer has 500 kg of a 19% crude protein ewe ration and a hay store. Two ewes have become weak and separated from the flock. The vet has ruled out acute disease but advises that the flock is at risk. The farmer wants to avoid buying more feed and asks if the silage is sufficient until lambing.
1. Assess the risk to the flock. Explain why the silage alone is unlikely to be sufficient and which ewes are most at risk.
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The silage is moderate in digestibility and low in crude protein for late pregnancy. At 64 DMD and 11% crude protein, it will not supply enough energy and protein for ewes carrying twins, especially when grass is limited. Body condition score 2.0 is below the target for late pregnancy, and the 20 ewes at 1.5 are thin. Twins increase the demand for glucose in the last six weeks, and thin ewes are at high risk of pregnancy toxaemia, also called twin lamb disease. The two weak, separated ewes may already be showing early signs. The 500 kg of 19% ration is only about 5.5 kg per ewe, which is far too little to correct the deficit across the flock. Hay is lower quality than silage and will not fill the energy gap. The risk is not only metabolic: thin ewes may produce weak lambs, have poor colostrum and suffer higher lamb mortality.
2. Produce a feeding plan for the next six weeks, including how you would prioritise the limited concentrate.
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Separate the ewes into at least two groups: thin ewes and twins in one group, and singles in another. Give the thin and twin-bearing ewes the best silage and begin concentrates gradually, split into two feeds per day to avoid digestive upset. A practical starting point is about 0.3–0.5 kg per ewe per day, increasing towards lambing according to silage intake and condition, but the exact amount depends on ewe size and silage quality. Use the 500 kg to start the thin ewes and buy additional concentrate; it cannot cover the flock. Provide clean water, minerals and adequate trough space so that timid ewes are not bullied. Keep the 20 thin ewes under close observation and ask the vet about monitoring for ketones. The singles should not be overfed, or they may become overfat and suffer lambing difficulty. Continue to offer silage but do not rely on it as the sole feed.
3. What welfare and management checks should be put in place before and during lambing?
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Check body condition score again in two weeks and adjust feed for any ewe losing condition. Provide dry lying areas, good ventilation and enough space; wet pasture and crowding increase stress and disease. Clean and disinfect lambing pens, and have colostrum, bottles, stomach tubes and a heat source ready. Inspect the flock at least twice daily, looking for ewes that separate, stop eating, appear dull or have a swollen abdomen. Handle weak ewes gently and call the vet for a full examination. Ensure lambs receive colostrum within the first hours and that ewes have adequate teats and udder health. Keep records of lambing, lameness and mortality so that problems can be traced. The farmer should also plan for extra feed and bedding, because the current store is not adequate for a twin-bearing flock.