NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare.

Farmers are advised to discuss their individual farm circumstances with their veterinary surgeon.

Ram Management

The achievement of a satisfactory pregnancy rate is dependant on good ram management and breeding soundness. The average barren rate for UK flocks is about 5 per cent and barren rates exceeding 7 per cent generally merit investigation.

Rams often lose about 0.5 of a unit of body condition per week during the mating period, so should have been be in body condition score 3.5 to 4 (on a scale of 1 to 5) at joining.

The ideal ratio of sound rams to ewes is between 1 and 2 rams per 100 ewes, depending on –

- paddock size and topography

- sheep breed

- stage in the breeding season

- age of both the ewes and the rams

Whenever possible, sheep should be mated in small flat fields to avoid dispersion of the flock and ensure that all oestrus ewes can be found by the rams. When such mating paddocks are unavailable, a higher than average ratio of rams to ewes should be employed. The pasture cover in the mating paddocks should be good, to ensure that ewes can display oestrus rather than foraging behaviour.

In lowground flocks, mated in small flat fields, a ratio of one sound adult ram to up to 80 adult ewes can be used without any reduction in the fertilisation rate, although one ram per 50 ewes is more commonplace. Higher numbers of rams are required for groups of gimmers or ewe lambs. When ram lambs are used, the ratio should not generally exceed one ram per 30 ewes. Mating inexperienced ewe lambs or gimmers with ram lambs should be avoided.

Whenever possible, a minimum of three rams should be run with any group of ewes. It can be useful to remove and rest rams after about 20 days and replace them with fresh chaser rams.

Most flocks adopt a 50 day joining period, although more than 95 percent of the ewes should be pregnant after 2 cycles (34 days). Provided that ewes are cycling and rams working, there are few advantages to be gained by leaving rams with the ewes for more than 36 days. The management of the small number of ewes that conceive over a prolonged period after 34 days is often uneconomical.

Ram harnesses or keel can be used to provide reassurance that the rams are working. The crayon or keel should be changed to progressively darker colours at intervals of about 14 days. Alternatively, harnesses or keel can be used from about 16 days after joining to monitor the number of ewes returning to oestrus. Hard or soft crayons should be used during warm or cold weather respectively. Ram harnesses should be a comfortable fit and regularly checked and adjusted to avoid brisket sores. Infected brisket sores often involve the cartilage of the sternum and respond poorly to antibiotic and supportive treatment. However, stressful gathering to adjust harnesses should also be avoided.

The management of the small number of ewes that conceive over a prolonged period after 36 days is often uneconomical.

Keel or crayon marks can be used to aid future feeding management by enabling pregnant ewes to be separated into different groups on the basis of their predicted lambing dates. The recording of keel or crayon marks should be an important part of the investigation of poor breeding performance, providing information about the mating pattern, submission and return rates.