Sheep Welfare: Nutrition in Late Pregnancy
The last six weeks of pregnancy represent the most nutritionally critical period for ewes. The rapid growth of foetuses (60-70% of birth weight is gained in this period) combined with decreasing rumen capacity creates intense nutritional demands that, if unmet, cause severe welfare problems for both ewe and lambs.
Twin Lamb Disease (Pregnancy Toxaemia)
Pregnancy toxaemia results from negative energy balance in late pregnancy, particularly in ewes carrying multiple foetuses. The ewe cannot meet glucose demands from feed intake alone, mobilises body fat, and accumulates ketone bodies, leading to hepatic lipidosis. Clinical signs include lethargy, star-gazing, teeth-grinding, recumbency, and death. This is an extremely painful and distressing condition.
Prevention relies on scanning ewes (6-8 weeks before lambing) to identify singles, twins, and triplets, then grouping by litter size and feeding accordingly. Triplet-bearing ewes have twice the energy requirement of singles and must be fed substantially more.
Energy Requirements and Practical Feeding
Energy requirements increase by approximately 75% for twin-bearing ewes in the final six weeks of pregnancy. Grass alone is insufficient — concentrates (0.5-1.0 kg/day depending on body condition and litter size) are essential. Root vegetables, high-energy blocks, and sugar beet pulp can supplement forage. Condition scoring at scanning allows identification of thin ewes requiring additional support.
Ad libitum good-quality hay or silage alongside appropriate concentrate feeding maintains both energy balance and rumen function. Sudden dietary changes should be avoided to prevent digestive upset and off-feed periods that trigger toxaemia.
Mineral and Vitamin Supplementation
Calcium demand increases dramatically at lambing. Hypocalcaemia (milk fever) causes muscle weakness, recumbency, and can result in death without treatment. Vitamin E and selenium deficiencies cause white muscle disease in lambs and can impair ewe immunity. Cobalt deficiency affects vitamin B12 production and impairs metabolism. Pre-lambing mineral supplementation (boluses, injectable preparations, dietary inclusion) prevents these conditions.
Iodine deficiency causes goitre in newborn lambs and reduced lamb viability. Copper status requires careful monitoring — both deficiency and toxicity cause significant welfare problems in sheep.
Welfare Indicators of Nutritional Status
Body condition scoring (BCS) at scanning and at lambing allows objective assessment of nutritional status. Target BCS for lowland ewes at lambing is 3.0-3.5 (scale 1-5). Ewes below BCS 2.5 are at high risk of pregnancy toxaemia and poor lamb survival. BCS below 2.0 indicates severe welfare compromise requiring urgent intervention.
Feeding Space and Group Dynamics
Inadequate trough space causes competition, subordinate ewes being displaced from feed, and uneven body condition within groups. Minimum 450-500 mm trough space per ewe for unrestricted access, or 200 mm for restricted feeding periods, is recommended. Grouped by litter size, ewes should have sufficient space to feed without stress.