Origins
Domestication of sheep started some11,000 years ago to produce an animal that was more docile and more flexible than the wild sheep to fit man's needs.
Sheep proved to be very adaptable to a wide range of environments.
After domestication, they spread across many continents and developed into a range of types.
They are found from cold continental areas, in dry deserts, and right through to the tropics.
Uses for sheep:
Meat
Wool - clothing
Skins - clothing, footwear, housing and saddles
Milk - cheese
Animal fat
Offal - wide range of products and pharmaceuticals
Companions - pets
Modern sheep problems
World sheep populations tend to be on the decrease for a number of reasons such as:
Wool garments and carpets have gone out of fashion.
The demand for wool is low, resulting in world surplus.
Sheep have too many predators that are protected by environmentalists.
Sheep meat is not eaten by many nations in the world.
NZ sheep population dropped from 70 million in the 1980s to 47 million today. It is not likely to increase rapidly in the near future.
Sheep senses
Sight
Sheep have generally very good vision.
The position of their eye allows for wide peripheral vision as they can span some 145 with each eye.
Binocular vision is much narrower - 40 wide. They have no vision 2-3cm immediately in front of the nose.
After locating a threat in their peripheral vision, they turn to examine it with binocular vision.
They have a blind spot at the rear around 70 which is wider than the cow and is useful when catching sheep.
Sheep tracks are never straight as sheep continually turn to watch behind them.
They have colour vision but it's not as well developed as in humans.
They often react in fear to novel colours that they're not used to, e.g. yellow raingear.
Sheep remember flock mates for very long periods (years) after separation.
Smell
Sheep have a good sense of smell and will not eat mouldy or musty feed.
Smell is a major factor in rams locating ewes in heat.
Smell is also vital in lamb identification by the dam associated with sight recognition.
Sheep are very sensitive to predator smells.
Hearing
Sheep have acute hearing and they can direct their ears to the direction of the sound.
Social order
Sheep are the classical social "flocking" animal and are a "follower species".
They use the flock for a defence against predators - running away a short distance to form a flock and then turning round to face the predator. On closer approach by the threat, they scatter and regroup.
Social ranking is not as obvious in sheep as in other species. Normally you'll see very few confrontations among ewes without young lambs to fight over.
Sheep work out a social order by head butting, nudging, poking with horns, shoulder pushing, blocking and mounting. This is seen most clearly in horned rams (American wild mountain sheep) that back off then charge, meeting head to head with a large bang.
Horned and polled rams should not be mixed as the horned rams will break the others' neck.
Submissive behaviours in sheep include lowering of the head and neck and moving away with a head shake.
In wild sheep a dominant ram leads a small flock followed by females, juveniles and lambs. He establishes this as a harem of about a dozen ewes.
Rams can form harems in farmed flocks in large hill country paddocks where they can easily get separated from main flock. Regular mustering is needed to prevent this.
In wild sheep, a lamb will stay with its dam till the next lamb is born. Both sexes will stay in their family groups till the adolescent males take off.
In farmed flocks you don't see much evidence of social order, as regular mustering and movement prevent much of it.
In groups of rams, especially Merinos in hot climates with no shade, they stand in a tight pack creating shade for each other.
The Merino packs especially tightly when being handled and once in a tight circular mob, you have to get a leader to spin off somewhere and act as leader to get some movement.
This leader sheep is not of high social rank - it's the first one who thinks they can escape. Pressure from barking dogs just makes the pack tighter, and if you are in the middle of this crush, you can feel the physical pressure that can lead to a smother.
Merinos need room to move and hate hassle. They have different behaviour to other farmed breeds.
Lambs are noted for their play behaviour - "follow the leader" and "king of the castle". It's said to be an indication of intelligence level and using this behaviour, sheep would rank higher than any other ungulate.
Feeding
Sheep are ruminants and they start nibbling pasture from about a week old. They are efficient ruminants by about a month old.
Sheep can graze more closely than cattle as they have a split upper lip.
They graze for about 8-9 hours/day, which can extend to 13 hours when feed is short.
Grazing bouts (when feed is plentiful) are about 20 -90 minutes, and they can have as many as 9 of them in 24 hours.
After a grazing bout they have spells of 45-90 minutes of rumination and rest.
In open range sheep have preferred areas and stick to these. This is seen in the UK "hefting" system in unfenced mountain grazings.
A major concern in the UK Foot and Mouth disaster was how to replace these sheep after slaughter as they would have to learn this behaviour all again.
Mixed grazing by cattle and sheep is ideal to maintain a good close pasture, and sheep adapt to this without any behavioural problems.
The condition of a sheep's teeth is critical, and can have a big effect on behaviour.
Sheep learn from their mothers which feed to eat. South Island sheep will eat grain and hay as they learn from their mothers in spring. North Island sheep will generally not eat grain or hay as they are never offered it, except in serious feed shortages such as droughts.
It often takes 2-3 weeks for sheep to learn as mature animals, and some may never accept supplementary feed and starve. Sheep also learn to eat different feeds from other adults or their peers.
Sheep store surplus energy as fat inside the body cavity (e.g. kidney fat and around the intestines) and under the skin. They use this up during late pregnancy and lactation for lamb growth and milk production.
About 3-4 weeks before mating ewes are given extra feed to encourage extra eggs to be shed from the ovary, ending in more lambs produced. This is called "flushing".
Sheep kept indoors show stress by eating the wood of their pens and they will also eat their wool, or the wool of the sheep in the next pen.
This wool eating is seen is sheep that have been buried in deep snow for up to three weeks.
Sheep need water - about 4litres/day/adult sheep and 1 litre/day for a lamb. But they can adapt to severe drought conditions and extract enough moisture to survive from herbage. The Australian outback Merino shows this important behavioural trait best.
The ewe
Sheep are seasonal breeders and ewes are stimulated to cycle by the declining daylight pattern in autumn.
Female sheep reach puberty at about 6 months old, depending on breed and live weight.
Only about 20% of farmers mate their ewe lambs and there is no problem getting these hoggets to come on heat if they have been well fed, and are a minimum of 35-40kg by 6-7 months old.
Ewes come on heat every 17 days (14-20 days range) and will be on heat for about 4-8 hours.
Pregnancy in the ewe is five months (154 days)
Signs of oestrus in the ewe
These are not very obvious compared to cattle. Here are some:
The ewe will seek out a ram.
She will sniff him and chase after him.
She will crouch and urinate when a ram sniffs her side or genital area.
She will fan her tail when the ram sniffs her.
When the ram is preparing to mount, she will turn her head to look at him.
Ewes do not mount other ewes as in cattle.
The ram
Rams reach puberty by about 6 months of age, but beware of younger ram lambs that miss docking as they could easily be fertile by autumn.
Rams are most active in the autumn and are stimulated by declining daylight. They show a kind of "rut", but nothing as well developed as seen in goats or deer.
They start to smell very strongly like a Billy goat approaching mating and the bare skin around their eyes and on their underside around front legs and crutch turns pink.
This smell comes from the grease in the wool and contains a pheromone that stimulates the ewes to ovulate.
Rams with high libido may not be fertile so fertility can be checked by a semen test using electro-ejaculation. This does not deliver the same quality of sperm as a good strong natural ejaculation but it is an indicator.
To avoid problems, farmers usually change rams after each cycle to lessen the risk of a ram being a dud.
Counting the number of mounts on a restrained ewe over time can also indicate libido, but seek veterinary advice on the ethics of this practice.
It's wise to use an older experienced ram on young ewes and a young ram on older experience ewes.
But some farmers argue the opposite and reckon the extra libido of young rams stimulated the young ewes better.
As rams are reared in homosexual groups, they may take time to learn how to mate females correctly.
Take time to watch new rams working to make sure they are serving correctly into the vagina and ejaculating. In a good ejaculation the ram will thrust forward with all four feet off the ground.
Courting behaviour is made up of a lot of "sniff hunting" ewes. Rams approach a ewe often from side, pawing her side with his head low, rattling his tongue and giving a low bleating.
Mating ratios of 1 ram to 40-50 ewes is normal but a good fit ram will easily mate 100 ewes. Ram lambs that are large enough (30-40kg) are given 30 ewes.
Having a surplus of rams in the flock may be a good insurance against infertility but they will spend more time fighting and establishing dominance and may miss ewes on heat. Fighting also leads to injuries which rarely recover before the end of mating, so an expensive ram is often a write off.
In large mobs where many rams are used, the dominant rams do most of the mating, chasing the less-dominant away. Practice makes perfect, so these dominant rams, getting more practice do the job quicker and so get more work.
The subordinate ram may get a service when the dominant one has moved away to find more fresh ewes, or with ewes that have come to him and are waiting. But it's just his luck if by the time it's his turn, the ewe is starting to go off heat and won't stand.
Rams can be racists - in mixed-breed groups they often show a preference to mate ewes of their own breed.
The "ram effect"
It's an old practice to use the sight and smell of a ram to stimulate ewes to cycle. It's called "the ram effect".
To exploit it ewes are first isolated from sight, sound and smell of all rams for at least 2-3 weeks before joining.
Then both sexes are put in adjoining paddocks to view and smell each other through the fence.
After about 4 days the gate is opened between them and they are joined.
This practice is sometimes done using teaser (vasectomised) rams that are actually put in with the ewes for even close contact and serving.
Teasers lose their libido over time and young entire rams seem to have more stimulating power through the fence. The little bit of extra frustration seems to help.
Lambing
Ewe behaviour prior to lambing
A few hours before lambing, a ewe will move away from the main flock to find a quiet birth site.
Particular areas of lambing paddocks such as hollows or hill tops can be very popular spots and many lamb mix-ups and mismothering can happen here.
It may be necessary to fence these areas off after a while when they get muddy. This will avoid a great deal of extra work and frustration for the shepherd.
Ewes heavy in lamb become very quiet and near lambing are more vigilant and graze less. This restlessness lasts until the ewe finally selects a birth site.
On the birth site:
The ewe paws the ground.
She keeps turning round and round.
She lies down and gets up a lot.
Her waters burst and she gets up to smell the ground where it fell.
Then after labour contractions the lambs will be born.
The ewe then gets up and licks the lambs.
The lamb may be finally delivered with the ewe standing.
The ewe produces the afterbirth.
She will remain on the site till the lambs have suckled.
Ewes vary in the time they spend on the birth site.
Old experienced ewes will move off as soon as the lambs have suckled and can move with her.
These ewes with good maternal instincts and experience seem to be able to count and will not leave their lambs behind - going back to gather up stray twins or triplets. They stand with head down giving a low bleat and constantly nuzzling the lambs.
Younger ewes with no previous experience will stay longer on the birth site, as they have the novelty of a lamb to deal with. If disturbed then these sheep panic more easily leading to lamb neglect.
It's good practice to leave newly lambed ewes alone on their birth site, and only move them after a couple of days when they have clearly bonded and moved off to another area of the paddock themselves.
Shifting ewes or lambs in the middle of the birth process is a disaster and will lead to mismothering of lambs.
It's a good idea to spot mark multiples at birth and then leave them alone. This helps to ensure correct mothering later.
Burglar ewes
Often a ewe that has not lambed will steal a lamb from a newly-lambed ewe as her maternal instincts have got out of phase.
She can cause enormous disruption in a lambing paddock as you often don't know that she hasn't lambed until the day you find her with a lamb a few days old, and then a new one!
The only cure is when you discover the trick is to shut her out of the lambing paddock until she has lambed or if she is near lambing, lamb her.
Often you are tempted to put her in the killer's paddock when you discover what she's been up to and the trouble she has caused to your records!
Mothering and lamb survival
Sheep are classical "follower species" where the lamb follows the ewe most of the daylight hours and right up to weaning.
The lamb starts following movement immediately it is on its feet after birth. You'll see a very young lamb follow the shepherd, the dog or the bike, and this can lead to mismothering.
Lambs learn to recognise their mothers by sight by about 3 days of age.
Multiple births are common in sheep. Finnish Landrace sheep can even have litters up to 7-8. As the ewe has two teats, there is high mortality in these highly fertile breeds unless the lambs are artificially reared.
Breeders once started to select sheep with four functional teats but this has not got very far.
Good lamb survival depends on the ewe licking the lamb and the lamb finding the teat immediately after birth.
Teat seeking behaviour is important. The lamb has got to be determined to get on its feet, start nuzzling the ewe to find an area of bare skin and find a teat to suck on.
Some lambs find the skin under the front legs and waste time looking for a teat there before moving to the rear end of the ewe.
A good ewe will encourage the lamb to move to the rear by standing still and nuzzling its rump and anal area.
Inexperienced young ewes will not stand still and turn round to lick the lamb all the time. Lamb dies of starvation often through this overzealous mothering.
Once the lamb has found the teat it will stand with head down reaching below the ewe, pushing upwards and once on the teat, wagging its tail while suckling. But don't assume that a lamb wagging its tail has always found the teat - check that its under belly is rounded and full of milk.
Lambs in the first 3 days :
Dystocia of single lambs that get too big and stick in the birth canal.
Death of small multiple lambs that have not sucked.
Lambs that die from wet and cold - hypothermia.
Multiples left behind to starve when ewe takes off with one lamb.
Lambs that suffocate as membranes around lamb have not broken at birth.
Lambs that follow other ewes and are rejected. Not found again by own dam.
Lambs that have slipped down steep hillsides away from their birth site.
Lambs that die from haemorrhage as ewe has chewed the navel or tail
Bonding
First sound then sight soon reinforce the ewe/lamb bond that was built initially on smell. The ewe recognises the lamb's bleat, and the lamb learns the ewe's call.
This is important as lambs get older and spend time away from the ewe for short periods, e.g. with other lambs.
Lambs show great play behaviour especially approaching dusk when they race along fences and play "king of the castle". They can often fall down holes and drown in water troughs during this activity.
When danger is seen, the ewe first calls the lamb then checks its approaching identity by sight.
Triplet problems
The increasing fertility in modern sheep breeds has led to higher numbers of triplets and quads in commercial flocks.
As a ewe only has two teats, inevitably there are higher death rates in these multiples and if they are reared, either on the ewe or artificially, it leads to many smaller lambs at weaning.
Some farms now get up to 40% triplets and once litter size (number of lambs born/100 ewes lambing) gets over 2.2, an increasing number of quads are born which the ewe cannot rear.
With triplets, observant farmers have noticed that between 10-15 days after birth, the ewe decides that she cannot feed all her lambs so she starts to leave one behind.
The two that get to the udder first can soon drink all the milk so when it's the turn of the third lamb, there is no milk left. The neglected third lamb is found motherless in the paddock and will die if not removed and fed which may not be economic.
Advisors recommend that ewes with twins and triplets are run together and ewes with singles grazed on their own.
This is because there’s a better chance of multiples moving between dams than a ewe with a single accepting a stray multiple lamb.
Reviving starved lambs
If a lamb is badly chilled and not had any colostrum, chances of survival are poor.
Colostrum is vital – and it will have to be tube fed.
Wrapping the lamb in an old electric blanket works best. It stays at constant heat.
Bathing a starved lamb in a blood-heat water may work followed by placing them under a heat lamp.
In the batch as the water cools, this effectively finishes the lamb off.
Make sure you don’t overheat the lamb under the heat lamp.
Vigorous rubbing with an old towel helps circulation followed by the heat lamp.
Whisky or brandy was a traditional lamb “saviour” but it’s more effective if the shepherd takes it!
Fostering
Bonding of the ewe and lamb is very rapid at birth - it only takes a few minutes. Once the ewe has smelled the lamb she will not take a lamb that smells differently.
To foster lambs on to ewes, there are a few tricks but realise that some ewes are more determined than others not to be fooled.
To add a lamb to a ewe that already has a single, have the lamb ready and cover it in the ewe's birth fluids so both lambs smell the same. The fostered lamb will be more active so make sure the ewe licks her own lamb well and it gets a drink. It's best to artificially feed it to make sure it gets enough colostrum.
For a ewe with a dead lamb, skin the dead lamb and make it into a suit with holes for legs to fit on the fostered lamb.
Use strong smelling oil or commercial product to put on lamb and up the ewe's nostrils. This is not always effective.
Put the ewe in close confinement or in a headbail and leave the lamb with her till she accepts it. This may take a few days and some ewes will win the battle with you and never take the lamb.
Are sheep intelligent?
You have to be careful not to define "intelligence" in human terms.
Sheep are not the stupid animals many people take them for.
Sheep are certainly capable of learning simple routines like coming when called, finding holes in fences, opening gates and they can learn these tricks from each other.
Food rewards are the way to teach sheep routines and tricks, if you think it's a wise move. You may live to regret it!
Lambs quickly learn from their dams - e.g. eating new feed like concentrate meal, grain, hay, silage, cracking open chestnuts with their feet, selecting garden flowers, and so on.Sheep handling tips
To keep sheep moving, make sure there's always a clear way ahead.
Sheep don't like visual dead ends - they don't move freely towards them.
Arrange things so that they think they're about to escape back to their home territory - the paddock they came from!
For a dead end in a woolshed, put a mirror on the wall so the sheep see a sheep to move to for security.
If you have to put sheep along a handling race, pen a decoy sheep at the far end to help attract them along.
Make races narrow enough to prevent sheep turning round and blocking the flow. This is not easy, as you have to handle sheep ranging in size from large pregnant ewes to small lambs in the same facilities.
Having tapered sides to the race (slightly wider at the top than at the bottom) can help.
Make sure the sides of pens and races where you do most of the handling are closely boarded, so the sheep cannot see through and get distracted.
Advancing sheep should not be able to see those following them, as they'll stop then reverse, or try to turn round and block the flow.
Sheep following each other should see sheep moving ahead, preferably around a bend. Moving sheep will generally "pull" the followers with them - once you've got a flow going.
Sheep move best from dark into light, and generally dislike changes in light contrast.
Sheep don't like bright lights e.g. reflections from windows.
They don't like light coming up from under gratings. Gratings at woolshed doors should to be laid so the floor looks solid on entry to the sheep.
Sheep really panic on slippy floors so provide some grip.
Sheep soon get adjusted to any noise used to move them - so keep changing the noise for effect.
Changing it (or stopping it) will also help prevent the workers going silly!
Sheep remember past experiences. Run them through new facilities a few times and let them think they can escape before you subject them to any unpleasant procedures like ear tagging or shearing.
If you have badly designed handling facilities that cannot be fixed - keep a "Judas" sheep to lead the doubters through.
To lead other sheep into the truck, you can train a Judas sheep with some pellets, and pet lambs are useful for this job. Make sure the Judas sheep isn't accidentally loaded into the truck though! Cover it with coloured marker raddle.
Catching and holding sheep
Don't catch or hang on to sheep by their wool. It will cause pain.
To catch a sheep, move up quietly behind it. This is the 'blind zone' but in practice the sheep will always see you coming so it's best to have it in a crush pen blocked in with other sheep.
The aim is to end up with it sitting on its rear end for jobs like feet trimming.
Hold it still by putting one hand under its chin and lift its head slightly to stop it lurching forward. If it gets its head down you will lose control.
Start by placing one hand under its chin, and turn its head round to face its rear on the side away from you. Grab its rear end with your other hand, or down where the back leg joins the body. See picture below.
Hang on tight and move backwards pulling the sheep towards you. Keep pressure on its head.
The sheep's legs should buckle and its body will fall back towards you. Don't let it fall to the ground or you'll lose it.
If you are strong and the sheep small, a lift along with the twist will stop the sheep's legs contacting the ground and reducing the chances of it getting a foothold and fighting to escape.
Then quickly grab its front legs and pull it up on its rear end at an angle of about 60 degrees from upright. If it is too far forward it will jump back on to its feet - be prepared for this. If it is too far back it will struggle and kick with both back legs in unison.
Practice finding the right angle to sit the sheep, and keep your legs close in behind its body.
When you find the right angle, the sheep will relax and you can take your hands off and hold it only with your legs and especially your knees. It's the position a shearer uses before starting to shear.
Sheep-human problems
Declining profits on sheep farms has lead to:
Reduced farm maintenance seen in poor fences /yards/woolshed.
Reduced fertiliser so less quality feed.
Increased flock size so more sheep/person and overwork brings less care about the individual animal.
An aging farmer and family wanting less work.
Shortage of skilled labour - shepherds, shearers, wool handlers.
All these points have animal behaviour and welfare implications.
What are the solutions? Farmers must devise and use more technology without compromising the welfare of the sheep. Start to use the sheep's innate behaviour to make handling easier.
Sheep welfare issues
The many people and organisations interested in sheep welfare list the following topics for concern:
Lameness. The pain caused by sore feet, so sheep graze walking on their knees.
Flystrike. The agony of being eaten alive by maggots.
Shearing. Stress caused by catching the sheep and then having a machine run all over its body with the risk of being cut.
Shearing. Cold stress caused by losing its fleece, especially in unseasonal storms.
Stress from not shearing. Having to carry many years of wool in summer heat. And often not being able to see (wool blind) into the bargain.
Dystocia. Problems caused by difficult births.
Lamb mortality. Lambs lost through hypothermia.
Castration. The pain of having rubber rings put on testicles or having them cot out with a knife and no anaesthetic.
Docking. Having the tail removed with a rubber ring or a cut off with a hot cauterizing iron and no anaesthetic.
Transport. The stress of long journeys in land vehicles and even longer journeys by ship to hot countries.
Dipping. Making sheep run through or stand in showers or swim through dip baths.
Swim washing at works. Sheep don't like having to be made to swim.
Dog worrying. The panic and pain that stray dogs cause.
Mulesing. Removal of the loose skin around crutch by hand shears with no anaesthetic.
Parasites. The stress and poor health caused by both internal and external parasites.
Untreated diseases. Sheep left to suffer the disease without any treatment.
Underfeeding. This happens when farms have too many stock and in droughts.
Easy-care or minimal-shepherding systems. This is where shepherds keep away from their sheep and rely on "the survival of the fittest" principle. Animals may be left to suffer in this system.
Dr Clive Dalton
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