Whether to breed from your ewe lambs or keep them until they are shearlings depends on your farm type, availability of housing and land, but also type of system, says Dr Liz Genever, AHDB livestock specialist.
Puberty in ewe lambs is influenced by breed, cross, age, body weight and time of year. It is crucial if you are mating ewe lambs they are at least 60 per cent of their mature weight at mating.
Ewe lambs should be run as a separate group so their nutritional needs can be met throughout the pregnancy.
AHDB’s Dr Liz Genever says: “Ewe lambs tend to have lower fertility and prolificacy rates than those of adult ewes. This is because they have lower ovulation rates and higher embryo mortality.
“However, ewes bred as lambs have a higher lifetime production rate compared with those bred as yearlings.”
In systems breeding their own ewe lambs, it is advisable to keep 25 per cent more than required as it is likely even in well-grown ewe lambs, up to 20 per cent exposed to the ram will not become pregnant.
This increases scope for selection and lambs which are not pregnant can be sold. This can be used as a tool to select lambs to retain in the longer term as lambs which hold to first service are likely to be naturally more fertile than those which become pregnant in subsequent cycles.
Culling the latter after the first lambing can lead to a gradual improvement in fecundity within the flock.
Dr Genever says: “Replacement ewe lambs should not be selected solely on body weight. Choose ewe lamb replacements from well-grown twins to put selection pressure on twinning, growth rate and milk yield.
“Do not choose replacements from ewes which are persistently lame, need excessive dagging, have prolapsed, or are poor mothers.
Effective record keeping and the quick retrieval of data is essential for matching up breeding ewes with their offspring.
“If buying ewe lambs, try to buy from one place and if possible the same source every year. This reduces the risk of introducing disease onto the farm. If possible, ewe lambs should be by rams which have good estimated breeding values for liveweight gain, muscle depth and fat depth. Information on maternal ability and litter size should also be scrutinised if available.”
Mating ewe lambs to rams of breeds with a smaller mature size should reduce the incidence of difficult births. However, whatever the choice of ram, it is important to have some knowledge of the likelihood of lambing difficulties from a breed.
Dr Genever says: “Ewe lambs should be mated separately from mature ewes as their oestrus behaviour is less aggressive. Vasectomised [teaser] rams running with ewe lambs for 15 or 30 days immediately before introducing fertile rams can successfully synchronise their heat.
“Mixing fertile rams with the ewe lambs for just three weeks should result in most females being served at least once. Lambing is focused within this defined period and can be easier to manage. This technique could be used to select for the most fertile sheep.
“Ewe lambs have a shorter ‘standing heat’ period than ewes, and this, coupled with their reluctance to seek out and court a ram, means more ram power is required.”
Lambs born to ewe lambs should be fed creep pellets to appetite from one week of age, says Dr Genever. This will help dam performance as the lamb will partly satisfy its appetite from dry food.
Ewe body condition is therefore likely to be maintained and she is more likely to be in optimum body condition when served again at 18 months old.
The high nutrient demand for growth (6-7 MJ for a daily gain of 200g) in lactating ewe lambs, means their offspring should be weaned at a relatively young age, certainly before they are 14 weeks old.
Early weaning at eight to nine weeks old may be the best option if ewe lambs are in poor condition or are smaller than expected to allow them time to recover before the next breeding season.
During early and mid-pregnancy, ewe lambs need about 20 per cent more feed than mature ewes to sustain their growth. They should be at an optimum body condition score of three, six weeks before lambing starts.
Most foetal growth occurs at this time and feeding too much then can lead to oversized lambs and difficult births. It is best to feed only for maintenance and the growth of the lamb in utero during this time.
Aim for 250g/day growth for the first two months after the rams are introduced. From then on and until six weeks before lambing, a growth rate of at least 150g/day is desirable.
It is likely there will be a higher percentage of empty ewes within a group of ewe lambs than within a group of mature ewes. Pregnancy scanning ewe lambs is important for identifying non-pregnant animals so these can be managed differently, for example, sell for slaughter, sell for breeding or keep for breeding in a subsequent year.
Ideally, it is better for ewe lambs to rear one lamb and multiple births are best avoided. This is especially the case where ewe lambs give birth later than the rest of the flock, as there are no newly lambed mature ewes with single lambs available for fostering on to.
Ben Carter, 23, is tenant on a 61-hectare (150-acre) grassland farm near Gloucester. He runs 200 North of England Mules as well as a small British Blue cross suckler herd, 300 free-range hens and rears game birds, turkey and ducks hatched from eggs.
In addition, a key part of his business is buying-in ewe lambs to put to the ram.
He says:“Between the end of August and the beginning of October every year, I buy 100-200 North of England Mule Sheep Association-registered ewe lambs privately from a producer in Swaledale, North Yorkshire, who I have bought from for a number of years.
“I no longer go to see lambs before I buy them as I have developed a good relationship with him and rely on photos and information about their breeding. I did do a lot of investigating before I started buying from him though, as it is important to start with good quality, well-bred lambs which are well grown.”
In recent years, lambs have averaged a delivered price of £120/head. They are started on a vaccination programme against pasteurella and clostridial diseases and are put to rams on November 5 to lamb start lambing on April 1.
Mr Carter uses Texel, Suffolk and Charollais rams bought either privately or from Cirencester and Hereford markets. He says: “I look for easy lambing type rams with high estimated breeding values for growth rates. I do not want anything too extreme or overly shapey. I buy rams without figures from people I know have been monitoring growth rates.”
At tupping, ewe lambs are kept on good grazing and given access to a basic molasses lick. Mr Carter says: “Ideally, I would like them all to have one lamb each, but they never usually scan below 150 per cent.”
In spite of it being generally accepted ewe lambs have a lower conception rate than mature ewes, Mr Carter says his lambs have, on average, scanned at 95 per cent in lamb.
Sheep are fed a very small amount of concentrate for six weeks before and after lambing, with those rearing twins separated out and fed a little more for longer.
“They all lamb outside and this year we lambed 100 and only had to pull two lambs out. Ewes mothered their lambs with no problems, which I put down to the mothering ability of the Mule. It is the only breed I would want to do this with. I did have Suffolk cross Mules, but would not want to go back to them.”
Mr Carter believes in shearing them as late as possible. He says: “Our land is quite high up and if you clip too early and get some bad weather, it causes milk to dry up.”
Lambs are not creep fed and are finished off grass. This year, Mr Carter sold eight-week-old lambs weighing 32kg liveweight for £75/head in Cirencester market. All lambs are sold by the end of September with any which are left put through the store ring.
Mr Carter says: “I need to have lambs away as I need grass for the next batch of Mule ewe lambs as it is important they have plenty of grass well into winter.”
Early weaning is key to the success of the system, says Mr Carter.
“I wean everything by mid-July, which gives the ewe time to recover and grow on ready to be tupped again. If you wean too late, it stunts the growth of the ewe and they do not realise their potential size. I believe Mules continue growing until they are three years old.”
Most Mules are kept on as shearlings and join the main flock to build up numbers, but when maximum numbers are reached, Mr Carter says he will then be in a position to sell some younger ewes.
Mr Carter believes ewe lambs make a valuable contribution to the flock. He says: “By tupping ewe lambs, it gives us an extra crop from the ewe for a relatively low input.”