November 24, 2008

Animal behaviour and welfare: Sheep Part 1


Origins: Senses: Social behaviour: Feeding

By Dr Clive Dalton

  • 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

Sheep using all their senses to check out a threat - man and dog


  • 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.
  • 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.
  • Sheep have acute hearing and they can direct their ears to the direction of the sound.

Social order

'Flocking and follower' behaviour used in mustering sheep
Note the heading dog behind the mob allowing them to move quietly along the tracks
  • 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.

A wonderful example of sheep as a 'follower species'. It's easy in a round sale ring to keep sheep circling following each other to show them to buyers. Notice the shepherds are going against the flow of the sheep, so the sheep think they are escaping away from danger.
(Photo by kind permission of Helen Brown)
  • 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.

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