Fit for the mating season
Mary Castell prepares for next year’s lambs
A stranger in the countryside, who has seen young lambs in the fields in the spring and had his attention drawn to rams running with the ewes in the autumn, may assume that farmers choose the season in which the ewes are mated, so that their lambs will be born in the spring. This is not untrue, but it’s only a very partial explanation. The breeding season of sheep is controlled by melatonin, a hormone that is only produced during the hours of darkness. In man, this is the hormone which controls our sleeping rhythms. During the summer, the short nights mean that sheep produce very little melatonin. As autumn approaches, the days shorten and the nights lengthen, allowing the sheep to produce increasing amounts of this hormone. Therefore, the majority of British sheep breeds become sexually active from October through to December. They ovulate for one to two days and come into season every 16 days.In most parts of Britain, it’s usual to introduce the rams in November, so that lambing takes place in the warmer weather of spring, and the freshly growing grass can provide excellent grazing for the lactating ewes and encourage the young lambs to nibble at these succulent plants. In the southern counties and the lowlands of the south west, where spring arrives earlier, rams are often introduced to the ewes in late October, resulting in a March lambing, while in the north, the rams may be kept back till December. Even so, in the north, it’s wise to lamb inside, and keep the lambs in sheltered paddocks close to the farm until they’re starting to graze, and are sufficiently large to withstand the wet, windy climate of the exposed hills.Sheep breeds originating in other latitudes, have their melatonin clock still set to the conditions of their native land. For this reason Dorset Horn/Polled Dorset sheep are able to take the ram at any time of the year, because they’re related to the Merino breed of Spain, where the difference between the length of the daylight hours of winter and summer isn’t as significant as further north. The Dorsets can be put to the ram three times in the course of two years, but must be well fed to support this strain. The ability of these sheep to breed frequently, and their exceptionally creamy milk, makes them a favourite with sheep dairy farmers, who produce sheep’s milk, sheep’s ice cream and yoghurt.Rams produce some sperm throughout the year but only become sexually active as daylight decreases. They also become more aggressive, so should be approached with care, especially when they’re running with the ewes. They can accept the presence of their shepherd, but feel it’s their duty to be rid of strangers.Preparing the ewes for matingA period of at least two months must pass between weaning and mating. All ewes lose condition after the strain of pregnancy and lactation, but ewes with twins or triplets are more seriously affected. Weaning usually takes place between 12 and 16 weeks following birth, but may have to be delayed for multiples. The ewes and lambs must be kept out of sight, and preferably out of sound, of one another. Where a field with poor grazing, out of sight of the lambs, is available, the ewes can be removed there, or they can be housed on a diet of straw and water. It’s unwise to move the lambs from their accustomed field when they have been separated from their mothers. Cases of mastitis occur less frequently when the ewes are dried off as quickly as possible. Culling of ewes also takes place at this time. The main reasons are lumps in the udder, a prolapse at lambing, barrenness for two seasons, and very bad feet. Ewes that are unlikely to be able to lamb in the coming autumn, due to age or disease, may be culled, and also those with bad teeth. Condition scoring At tupping, the ewes should have a condition score of 3.0-3.5, or 2.5-3.0 for hill sheep. Ewes unlikely to achieve this can be fed 0.25kg - 0.5kg for six weeks before and during tupping. Overweight ewes can be put on poor grazing until they reach a score of 3.0-3.5. Ewe lambs are put to the ram if they’ve reached two thirds of their body weight by the time the ram is introduced. They must receive sufficient feed throughout the winter for them to continue their growth as well as support the pregnancy. Flushing Two or three weeks before the rams are introduced, the ewes are put on the best grazing available to encourage them to shed as many eggs as possible. When the grazing isn’t top quality, it can be supplemented with feed blocks. This regime should be continued throughout tupping. Hill ewes aren’t flushed unless sufficient grazing is available for them to support twins.Preparing the rams for mating
Rams are easy to forget during the busy summer months, since they’re usually kept in a small paddock well away from the ewes and lambs, with perhaps a wether for company. They should be treated when the rest of the flock are vaccinated, wormed or treated for flystrike. Special attention must be paid to their feet. Not only is a ram less enthusiastic when his feet are killing him, but a foot rot infection can lower his sperm count for up to eight weeks! At eight weeks pre-tupping, the following checks are made:
Condition: thin tups should be fed 450g (1lb) of 18% CP (crude protein) pelleted feed nuts per day to enable them to reach a condition score of 3.5-4.0 by mating. If they don’t improve sufficiently rapidly, the ration is increased gradually up to 900g (2lb) per day.
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Teeth: inspect the incisors and feel along the outside of the jaw to check there are no swellings under the molars. A ram with poor teeth may need to be replaced, or be given supplementary feeding. Feet: care of the feet is of primary importance. A ram whose feet are painful may be deterred from mounting a ewe, so his feet should be clipped and medicated if necessary. The ram should be observed regularly before he’s turned in with the ewes, to make sure he isn’t showing any sign of limping. Foot infections spread rapidly, and every care must be taken to prevent the ram infecting the ewes. Worms: if the ram shows any sign of scouring he should be wormed immediately, otherwise you can wait to worm him until two weeks before tupping. General health: check that the testicles are even and firm, with no lumps, and observe the ram to see if he is passing water normally. When there are problems, the vet should be contacted. Orf may attack the sheath and sometimes the penis, which makes it impossible to use the animal.Inspect the eyes for inflammation and if necessary, treat for conjunctivitis.The body and legs are checked for lumps and abrasions.Some smallholders have flocks that include ewes of several breeds, and may wish to use one ram to cover the whole flock. They should be aware that rams prefer ewes that resemble their mother, or foster mother, and that these animals will be covered first when the ram has a choice of several ewes on heat.TuppingIf the ewes are all to be served within the first 17 days, the number of ewes per ram must be limited to 40, or no more than 20 for a ram lamb. Two rams should not be put in together, as they will fight rather than cover the ewes, and this will continue until one is injured or killed. Three rams tend to ignore one another. Presumably, they’re aware that if two fight, the third will be enjoying all the fun. The use of raddleRaddle is a colouring agent smeared on the ram’s lower chest between his front legs. It’s usually sold as a powder, which can be mixed with a little vegetable oil and smeared on the lower chest of the ram to indicate which ewes have been covered. This mixture will have to be replenished regularly, the frequency depending on the activity of the ram. With a small flock, it’s possible to bring the sheep into a yard or a building for the evening feed, and the ear tag numbers of the ewes covered that day are easy to record. A small colour spot can be sprayed onto the ewe’s ear to indicate that this has been done, and the likely lambing date calculated. When the same number is recorded twice, it’s clear that the ewe has returned to service. Alternatively, the colour of the raddle can be changed after the first 17 days, which will also indicate ewes that have not held to the first service, and have returned to the ram.Commercial flocks usually use a ram harness fitted with a colour block. The activity of the ram may cause the harness to loosen, and he has to be induced to enter a pen while the necessary adjustments are made. Feeding the flock during tuppingWhere it’s not possible to bring the flock into a building during tupping, jostling for nuts etc can be avoided by offering feed blocks or liquid feeders, placed well apart over the pasture. Hay in a hayrack out in the field is unlikely to cause much trouble as long as it’s regularly filled. Jostling is only likely to occur when little hay remains in the rack.
This article is from the September 2006 issue of Country Smallholding magazine. << To order back issues click the link to the left.