Sheep Farm Husbandry - Lamb mortality: Causes and Prevention

Sheep, husbandry, lambing, lamb mortality, identifying causes, feeding the dam, increasing fertility, multiple births, twins, triplet problems, actions on small & large farms, fostering methods, colostrum types, feeding with stomach tube.

By Dr Clive Dalton

Lamb mortality is the most frustrating part of keeping sheep. After planning and working all year to produce a lamb that dies soon after arrival is such a terrible waste and a killer of profit. You can get so depressed going around picking up dead lambs and worse still counting them. Your state of mind isn’t helped by the realisation that you’ll have to wait another year before you can make up for the loss.


Some farmers refuse to count lambs born dead, or that die in the first few days after birth (perinatal mortality), as it doesn’t help their morale at a busy and stressful time of year. In some areas dead lambs are collected as slinks so you can get an accurate figures of what died – if you want it! The amount earned from slinks is best not advertised in the district, and the children should also be sworn to secrecy if their bank accounts benefit. So the general feeling around sheep yards is that the subject is best not talked about, as it’s hard to know where to start to fix things.

What do we know about lamb mortality?
We know a lot, as there has been extensive research done in New Zealand on lamb mortality, and a lot of it is being (needlessly) repeated. Here’s what we know:

• We know that it’s bad! On average 20-25% of all lambs born never reach weaning but there is enormous variation around this average figure for a number of reasons.
• The lamb has low energy reserves - 3% of body weight compared to an adult at 10-15%.
• It needs energy in the first few hours to survive and it can only get this from its mother’s milk.
• The lamb has more surface area per unit of body weight than an adult.
• The birth coat has poor insulation in many breeds. The birth coat is wet and hence increases heat loss due to evaporation.
• Most of the deaths are described as “perinatal” – i.e. in the first three days after birth.
• After this killer period, deaths measured between birth and docking or birth and weaning are low – around 3-4%.
• Today because scanning is used extensively, we now know that 18-24% is a reasonable average for embryos that never become live lambs. Again there is a wide variation around this average with 28-30% in some very dry areas with poor feed.
• If you put a potential market value on all these lambs of $70 NZ from the national flock of 40 million ewes – then the waste of potential lambs from conception to market is astronomical. That’s why we don’t talk about it!
• In New Zealand the weather plays a big part in our outdoor farming systems, and severe storms over a few days at peak lambing will easily kill nearly all the lambs born while a storm lasts. This can easily put the average death rate for the flock up to 40% or more.
• Around 20% of all ewes fail to rear a lamb to weaning. This is a shock to most people who declare that it doesn’t happen on their farms – because they don’t count dead lambs.
• As fertility rises and more lambs are born – then lamb mortality increases.
• More multiples (twins, triplets and quads) die than singles. But twin survival has been often shown to be similar to singles.
• Triplets’ body temperature is 1°C lower than twins at birth, and shelter reduces thermal heat loss by 35%.
• The best birth weight for survival for both singles and twins is 3.6 – 5.6kg, but how you manipulate this is very difficult to achieve.
• Up to 80% of all lambs die (especially multiples) of a combination of starvation, mismothering and exposure referred to as SME.
  
• Starvation and mismothering are obviously strongly linked as these lambs at post-mortem have not fed (empty stomach).
  
• Exposure rapidly kills weak lambs and small multiples are certain targets for this. But even good lambs can die of exposure in storms going from 39°C inside the ewe to zero or lower on the wet ground.
• Dystocia causes birth injuries in lambs that are too big and get stuck in the birth canal. It’s the main killer of singles but birth injuries are also implicated in 60-80% of SME lambs.
• Hypothermia is the great killer of lambs in wet and cold conditions.
• Good maternal behaviour is a critical factor. Exceptional mothers don’t leave their lambs behind, and seem to be able to count them and shelter them from cold winds. Two-tooths with their first lamb can be a problem and may need extra care.
• Hoggets that have lambed and reared a lamb are good mothers at later lambings.
• Multiples are left behind to starve when ewes takes off with one lamb.
• Lambs suffocate as membranes around them have not broken at birth and the ewe has not licked them enough.
• Lambs follow other ewes away from their own mothers and are then rejected to die of starvation.
• Lambs slide down steep hillsides away from their birth site and mother. Anything steeper than 25 degrees where the sheep have made hillside tracks will cause major problems.
• Lambs die from haemorrhage when the ewe has chewed the navel or tail.
• Lambs with good thick birth coats (e.g. Drysdale or Romney) have a better chance of survival than those with thin outer birth coat (e.g. Merino).
• Birth fluids are only attractive to ewes around the period of birth.
• Skinny ewes produce small miserable lambs that are very keen to die! Ewes should have a condition score of 2.5 at mating and be 3.5 for lambing.
• Varying gestation length has little effect on lamb mortality.
  

Feeding and lamb mortality
Previous practice in New Zealand developed for old-fashioned Romney ewes was to flush them for the three weeks up to joining them with the ram, and then feed them on a level plane for a few weeks after mating until pregnancy was well established.

For the middle part of pregnancy you made them work by going out to the back of the farm to eat fern and scrub and do it hard for a while, and if they lost weight nobody worried. Then they were fed on a rising plane again, but for the three weeks before lambing they went back on to almost starvation rations to cut down the size of the lambs and prevent lambing problems. Fertility levels were so poor that most ewes had singles.

Today’s sheep have changed their complete genetic makeup and the above practice is certainly not recommended any more. But unfortunately what is recommended now is more confusing, because the results of research have been confusing. Current recommendations seem to be based on which research paper you believe. Here is a summary of the key points from all this:

• The majority of research shows that altering feeding levels has little effect on lamb birth weight or survival. This is after years of believing and preaching that it did.
  
• But most consultants still recommend that you feed today’s sheep well for the whole of pregnancy. In any case, manipulating feed levels is far too complicated and has animal health risks too. You need to keep thing simple, so:
• CONCLUSION – Feed sheep well during the whole of pregnancy.
  

• If you severely restrict feed in the first 60-100 days of pregnancy you’ll reduce the weight of the placenta and foetus, so:
  
• CONCLUSION – Don’t do this and feed them well all the time.
  

Computer modelling work in 2009 showed that providing good feed and shelter for the ewe two weeks before lambing was better at improving lamb survival than shelter at birth. I suggest you treat this conclusion with caution.

Pre-lamb shearing

• Shearing during mid-pregnancy can increase the birth weight of lambs provided the foetus is small. Initial University research results were positive but later on-farm trials have been very variable and of course have not been published in scientific journals. The subject seems to have gone off the radar!
  
• In any case shearing before lambing is too risky and has big animal welfare impacts that are not worth taking with the present value of ewes, and with international eyes on how we treat our sheep in New Zealand.
• The 2009 computer modelling work showed pre-lamb shearing to be very bad for lamb survival, and it was recommended that ewes should be shorn no later than mid pregnancy.
  
• CONCLUSION – Don’t risk it.
  

• The heritability of lamb survival is low (2-16%). Nevertheless breeders have made progress by selecting for easy-care sheep before they knew this.
• CONCLUSION – Breed for easy-care sheep with determination.
  

• Scanning allows you to identify and feed ewes carrying multiples well so feed them well all the time. Ewes carrying singles, especially if they lamb late, can have their feed restricted before lambing to prevent Dystocia.
• CONCLUSION – scan the flock and give the feed to the multiple-bearing ewes.
  

Increasing fertility and multiple births
As overall flock fertility goes up, this has important practical implications for managers as the number of singles, twins and triplets changes. Here’s a brief summary of what happens from resent research:

• In high-fertility ewes, deliberately not flushing before mating will only reduce lambs born/ewes lambing (LB/EL) by 1-2%.
• Up to 1.6-1.7 LB/EL, singles decrease and the number of twins increases. Twins substitute for singles.
• Around 1.7 LB/EL twins level off and triplets go up rapidly.
• Around 1.8 LB/EL twins decline and triplets show a rapid increase. Singles remain stable at low levels.
• At 2.2 LB/EL quads increase, twins decline and triplets level off at 30-40%.
• Above 2.3 LB/EL with so many quads, any extra lambs are not worth the bother as they have lower survival and lower growth to weaning, as a ewe cannot feed them all.
• Some farmers with 10-20% triplets or even up to 40% triplets leave them on the ewes. Above this you have to look at removing one lamb to mother on to another ewe, rearing it artificially or letting it die. The recent good prospects for lamb have changed attitudes considerably regarding putting more work into saving lambs.

Triplet problems

Two lambs feeding, the third lamb waiting. When will it get a turn?

• 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 cannot be reared by the ewe.
• 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.
  

Selecting only for twins
To avoid the problems mentioned above, geneticists are now working on the genetic variation they have found in ewes that twin regularly. This they say will allow improved twinning without producing triplets and quads. It’s clearly a complex trait with low heritability with many environmental factors involved to confuse things. It cannot be done by just selecting rams and ewes that were born as twins. We want ewes that consistently produce two eggs every time and they all survive. It will take a long time to achieve this in a flock unless aided by gene technology.

What can be done about lamb mortality?
Researchers have been telling farmers about the statistics of death for at least three decades, but both have failed to come up with good cost effective practical solutions to cut down the waste.

Admittedly from the national flock we dock and wean more lambs now than ever before, but this is because more lambs are born through introduced higher fertility breeds like the Finn which have been crossed into other breeds. But the problem of perinatal lamb mortality remains.

All we’ve been good at over the years is talking about it, doing more endless post mortems and reporting what’s already been done! We hoped that more practical answers would come out of all this but they haven’t. So what can be done? The truthful answer is “not a lot” but here are a few thoughts:

The more lambs there are, the greater is the risk of mismothering

On big commercial sheep farms

• Don’t plan to have the first lambs in the district – lamb when the feed is going to be there.
• Pay special attention to feeding. Feed high producing ewes on a good plane of nutrition for the whole of pregnancy. They should be going into 1200kg DM/ha (4cm high) in the four weeks before lambing.
• Condition score is important. At mating they should be CS 4 and lamb at a minimum of CS 3-3.5.
• Scan the ewes at 80-90 days of pregnancy, and lamb all those carrying multiples separately in good level paddocks and with shelter if available.
  
• Accept the fact that a lot of good lambs will die, and don’t wait for research to come up with any solutions to do anything practical about saving them.
• Select ewes intensively for “easy-care” (non-assisted) lambing. The trait has low heritability (0-15%) but if you put enough emphasis on it, then progress although slow will bring results. Many farmers who have made spectacular improvements have certainly backed the theory.
• Buying rams from breeders recording on SIL who can show genetic gains in lamb survival is a high priority, and if you cannot find any that meet your needs, start and breed your own rams.
• Remember this easy-care approach has welfare implications and you’ll need to meet the requirements of the sheep code of welfare, where any ewes in need must be helped to lamb. These ewes and their offspring should be marked for subsequent culling.
• Give ewes plenty of undisturbed space to lamb and leave them on their birth sites till they want to move away.
• Get them used to you moving through the paddock on foot, by bike and with a dog before lambing or keep right away from them.
• Any shelter must be at ewe and lamb level. You may have to fence off popular areas where ewes camp and lamb when they get dirty.
• Watch out for ewes with multiple lambs needing assistance, and lambs that seem motherless and are not getting a feed. At current prices it’s worth mothering them on to other ewes if you can streamline the process – normally it is not.
• Put covers on weak lambs in cold wet spells or if one is forecast. Don’t rely on the general weather forecast – get regular reports on the one for you local area.
• Give ewes carrying singles different care with controlled feeding to prevent oversize lambs.
  
• Give ewes a good pre-lamb crutch taking plenty of belly wool off in front of the udder if it’s long so newly-born lambs can easily find the udder and teats.
• If time permits, check for cast ewes and lambs with stuck-down tails.
• Euthanase ewes with bearings that are too difficult to treat and make them for culling.
• Before lambing, check with your vet about the mineral status of the flock incase any extra supplementation is needed.
• Lamb on the flattest paddocks you have, and try to avoid steep country above 25-30°.
  

On small farms

• Provide intensive care for the flock and try to save every lamb. It will be a lot of work so don’t count your hours and charge them at business rates! Take the view that you are saving lives and costs are not the main issue.
• Scan the ewes at 80-90 days of pregnancy and lamb all those carrying multiples separately in a level paddocks and with good feed and shelter.
• Get the sheep used to disturbance by shepherd, farm bike and dog and the children before lambing.
• Give them plenty of undisturbed space to lamb and leave them on their birth sites till they want to move away.
• Provide plenty of shelter with hay or straw bales in the paddock. Any shelter must be at ewe and lamb level.
  
• You may have to fence off popular areas where ewes camp and lamb when they get dirty.
• Try a zigzag temporary fence across the lambing paddock for both shelter and to restrict the mobility of ewes and lambs in the first day after lambing – especially if they have multiples.
• In storm conditions get newly-lambed ewes into cover, especially if they have multiples. Use a shed or an old-fashioned lambing pen made of hay bales and a sheet of corrugated iron for a roof – with a large rock on it to stop it taking off in the wind! It’s a handy place for the shepherd to have a snooze after lunch!
• Put covers on all lambs at birth unless it’s brilliant weather. You can buy plastic or wool ones or use old bread and supermarket bags. But buy some decent covers as remember what each lamb is worth, and you can use them again.
• Code mark multiple lambs at birth with raddle to remind you which they are and which ewe they belong to. Check they are correctly mothered up during the day and particularly at night.
• Be prepared to foster all spare lambs or rear them artificially.
• Check for cast ewes and lambs with stuck-down tails.
• Get the vet to deal with any ewes with bearings.
• Select replacement ewes and rams for high survival (See breeding).
• If you have lambing problems that you can’t fix, don’t delay in getting experienced help.
• Before lambing, check with your vet about the mineral status of the flock incase any extra supplementation is needed.

Where's this lamb's mother? Be wary of single lambs on their own that don't have full belly. They could be dead next morning

Temperature of a 'starving"

• 39-40 degrees C - normal healthy lamb
  
• 37-39 degrees C - lamb is at risk and needs feed and shelter
• Below 37 degrees C - Lamb is in grave danger and needs urgent emergency treatment.
  

Glucose injection for starving lamb
For a lamb that has not fed, is starving and cold, it's important to get some energy into it before you warm it up as warming it up will increase the demand for nutrients. If they are not available, then the lamb may die faster. An injection of glucose is worth a try.

Method

• Use 30ml of 40% dextrose and mix it with 30ml of boiled (and cooled) water. You can buy ready-to-use product.
• Disinfect the injection site.
  
• Use a 3/8 inch needle (sterilised by boiling and then storing in meths).
• Hold the lamb up by the front legs and insert the needle in front of the navel.
• You will hear a 'pop' sound if the needle goes through the body wall, and to confirm this the syringe will empty easily. If you get a lump appearing at the end of the needle, then the needle has not gone through.
• Some folk find this better than 'tubing' a lamb with less risk of lung damage.
• After treatment, warm the lamb in an old electric blanket and feed colostrum to keep it going. Feeding rate is 50ml of colostrum/kg of body weight, for at least three days.
  

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 another 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.
• For guaranteed success, you really need to confine the ewe so she has little room to move away from the lamb, and the lamb is in constant physical contact with the ewe. Special mothering-up pens are commercially available.
• Tying a ewe to a fence or to a peg in the ground by her front leg, and expecting the fostered lamb to mother itself on is a waste of time.
• 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 suck. It’s best to stomach tube 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 the lamb and up the ewe’s nostrils. This is not always effective.
• Put the ewe in a headbail in a pen and leave the lamb with her till she accepts it. This may take a few days and some ewes will still win the battle.
  
• Some people recommend washing the fostered lamb to remove all the smell and then rub it on the dead lamb or the ewe’s own lamb. Ewes are not that stupid and can still smell an alien lamb.
  

Colostrum

• This is the first milk produced by the ewe and is thicker and more yellow than normal milk. It’s often more like glue.
• Colostrum is full of antibodies that help protect the lamb from infections, and also has a laxative effect to remove the meconium (foetal faeces).
• It helps keep the lamb warm because it is rich in energy.
• It is easy to digest and it helps the lamb strengthen and grow. It can work miracles on weak newborn lambs.
• If lambs don’t get enough colostrum in the first hours of life, they will be very susceptible to infections for months afterwards.
• Be aware that many orphan lambs haven’t had sufficient colostrum in their first few hours of life and are prone to die. They are very susceptible to infections like diarrhoea and pneumonia.
  

When should colostrum be fed and how much?

• It is very important that every lamb gets colostrum during the first 24 hours of life.
• Ideally they should get a good colostrum feed between 1 hour and 6 hours of birth. After this time, the ability of the gut to absorb the antibodies decreases rapidly.
• It’s best to let the lamb suckle naturally from its mother. And if you can supervise without causing distress, make sure the lamb has found the teat and is sucking properly, and not just wasting time pretending and wagging its tail.
• Colostrum varies in quality. The quality decreases quite rapidly after birth, and some ewes produce better quality colostrum than others.
  
• The following recommendations apply when colostrum is given by bottle or stomach tube.
• Depending on their size, lambs should get about 100-200 ml colostrum per feed (600ml in total in the first 12 hours of life), and larger newborn lambs need up to 1500 ml daily. Only the really heavy-milking breeds of ewe would produce this much milk if well fed – so you may need to supplement their feed if they are not milking well.
• Colostrum feeding should continue for at least 4 days if at all possible.
• Then get the lamb on to a good quality powder lamb milk replacer and follow the instructions on the bag to the letter! If in doubt make it weaker rather than richer and watch for sticky tails and constipation.
• Generations of orphan lambs have been fed on cows’ milk after getting minimal colostrum, and sometimes it was even diluted with water to cut costs! Lambs will not die on this but don’t grow very well.
  

What type of colostrum is best?

• Without doubt, the lamb is best left on its mother to suckle colostrum naturally.
• However if the lamb is too weak to suck naturally, colostrum can be milked from its mother or from other newly-lambed ewes and fed by stomach tube. If it’s weak it won’t be able to suck fast enough if at all.
• f you have stored sheep colostrum in the freezer, don’t thaw it in the microwave oven as this will destroy the antibodies.
• If colostrum from ewes is not available, newly calved cow colostrum can be used.
• Try to get some sheep colostrum into the lamb before you try the cow colostrum.
• Good quality colostrum substitutes can be purchased, but it is important to use only the type of colostrum that contains antibodies.
• Beware of old home-made colostrum substitutes that use egg yolks and cod liver oil. These don’t contain protective antibodies.
  

Feeding by stomach tube

• Colostrum can be given to newborn lambs by stomach tube when they are too weak to suck.
  
• A rubber stomach tube made especially for lambs should be used (obtainable from rural suppliers or your vet). Tubes that are too large can cause damage.
• Extend the head so the mouth, throat and gullet (oesophagus) are in a straight line.
• Gently thread the tube through the mouth into the throat, then down into the gullet, taking care to ensure it hasn’t gone into the lungs.
• If the tube is correctly inserted, you will see it distend the gullet a little on the left of the windpipe as it goes down into the stomach.
• Warm the colostrum to body temperature before pouring it down the stomach tube.
• Never warm or thaw colostrum in the microwave because the important antibody proteins will be damaged and will congeal.
• If colostrum is not immediately available for the first feed after birth, give electrolyte solution with no protein added (see your vet). Feeding non-colostrum proteins to newborn lambs results in subsequent impairment of their ability to absorb colostrum proteins.
  

Ewe milk

• A ewe’s lactation peaks at about 3-4 weeks after lambing.
• How much milk she gives depends greatly on the number of lambs she is suckling.
  
• If her udder is emptied often, then the milk producing cells (alveoli) in the udder are stimulated to produce more milk.
• Ewes suckling multiple lambs will have a later lactation peak in production.
• Grazing ewes suckling singles will produce about 2 L/day and 3L/day suckling twins.
• Ewe milk is especially high in fat and protein compared to the goat and cow.
  

Disclaimer
This material is provided in good faith for information purposes only, and the author does not accept any liability to any person for actions taken as a result of the information or advice (or the use of such information or advice) provided in these pages.

Animal behaviour and welfare: Sheep Part 2

SHEEP BEHAVIOUR BASICS: PART 2

Reproduction: Lambing: Lamb survival: Fostering

By Dr Clive Dalton

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.

Ram has found ewe on heat. She stands still, looking around at the ram, tail fanning, ears pricked. She is waiting to be mounted.

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.

Ram 'sniff hunting' ewes.

• 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.

A good ewe will stand still while the lamb is seeking the teat

• 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 :

A nice sunny sheltered spot to aid survival but where's its mother?

• 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

A good ewe will recognise she has more than one lamb and mother them all

• 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 quads, at least one lamb has to be removed

• 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

A lamb on its own calling out and not full. Find its mother or else it could mean fostering or artificially rearing it with all the work involved

• 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.
  

Animal behaviour and welfare: Cattle Part 4

CATTLE BEHAVIOUR BASICS: PART 4

Calf rearing: Fostering: Housing: Bobby calf; Premature calves

By Dr Clive Dalton


The young calf

• Calves are very delicate animals; they are not robust small cows.
• Their rearing system can have a big effect on subsequent behaviour.
• It's vital that calf gets 2 Litres of colostrum (from dam or other newly-calved cow) before 6 hours old). Keep some colostrum in the freezer for emergencies.
• There is a wide range of calf rearing systems where the main aim is to give the calf a good start and encourage it to become a ruminant.
• A calf is born with a large abomasum (gastric stomach) and offering fibrous feed from birth (hay and meal) will encourage its rumen to grow and develop. This reduces the need for milk and lowers feeding costs.

The large gastric stomach (abomasum) of a milk-fed calf. Note the very small rumen on the left of the picture.

When do calves become ruminants?
Calves start to chew hay and straw if provided in their pen a few days after birth, and if offered concentrates and good quality pasture they will be fully-functional ruminants by 3-4 weeks of age.

Four-week-old calves offered good leafy pasture

Getting calves to drink

• Most calves are now reared using communal systems with a "calfeteria" allowing them individual feeding but run in a group environment.
• Initially a calf wants to push upwards when sucking and bunts to stimulate milk flow from the udder.
• To get the calf to suck on a “calfeteria”, let it suck your fingers and then lead it to teat to suck. Hold its head gently on the teat for a few seconds once on the teat.

Calf rearer using a single-teat feeder (standing on rail) to teach calf to suck from a rubber teat, then taking it to the Calfeteria to suck from one of its teats.

• If you use a bucket, let the calf suck your fingers and then press its head down into the bucket while sucking. Withdraw your fingers and keep its head in bucket. Initially it will gulp milk and choke - let it up for air!

Feeding calves from buckets once they have been taught to change from sucking (with head up) to drinking (with head down). This can take time and be frustrating for the calf rearer.

• Calves often want to continue suckling after their milk supply is finished. This "suckling reflex" encourages them to suck the ears, navels and teats of other calves. It can lead to problems so this vice must be discouraged.
• Calves that suck other's teats may continue into adulthood and it can cause problems. How to stop it?
• Make the calves work harder for their feed so the sucking urge runs out.
• Tie them up after sucking till their mouths are dry.
• Separate out the culprits as they will teach others.
• Fit irritant device in the nose of sucker so others won't let them suck.
  
• Provide dry palatable feed immediately after sucking.
  
• A combination of wet and cold is the biggest killer of young calves or can be the reason for poor performance. Calves at pasture need shelter, either natural or artificial.
  

Fostering new calves on to nurse cows

• Cows vary in their maternal instinct. If a cow is too determined not to take strange calves, don't bother with her as it will cost you too much time. She'll associate you with the calf and will soon learn not let it suck unless you are there or she is bailed up.
• The easiest way is to have the strange calf to be fostered ready at birth, and cover it with the birth fluids from the cow. Make sure she licks and mothers both calves.
• You can try the same trick using odours such as neatsfoot oil or perfume. They don't work as well, and certainly not as well as birth fluid. The oil will get the cow to at least lick the calf, and this may trigger maternal acceptance. The perfume may put her off. Cows' preferences in perfume are not known!
• Remove her own calf at birth before she has smelled and licked it, and introduce the fostered calf (or calves) after rubbing them in birth fluids (collected in a bucket) or with the afterbirth.
• Blindfold the cow while the alien calves are introduced to her but she may not like this idea.
• Remove the cow's own calf after 2-3 days, and bail her up tight with some good strong alien hungry calves. Make sure she cannot get round to bunt them (dehorn the cow) and that she cannot kick them too violently.
• While letting her suckle her own calf, introduce the alien calf and teach it to suck through her back legs (the cow's blind spot). It will end up with a dung cap but at least it will be well fed!
• Put leather dog collars on the cow's own calf and the alien one, and tie them together with a short length of chain containing a swivel. When the cow lets her own calf suck, the foster one will be close too, and the cow will hopefully get used to having both suckling at the same time.
• If her own calf has died, skin the dead calf and tie it over the new calf until she lets it suckle. This will vary from a day or so up to a week or more, when the skin starts to stink! This is mainly used in a beef herd where getting a cow in daily to suckle a calf is not practical.
• A vaginal douche with iodine solution (5ml of veterinary iodine in 250ml water) used to be practiced and was sufficient to treat three cows. It seems to cause irritation of the vagina and stimulates straining and maternal instincts. It is not a welfare-friendly method so consult a veterinarian before use.
  

Calf housing

Good calf housing with clean dry bedding, sunshine in the shed, plenty
of feed and water points, and a quiet stress-free environment.

• In New Zealand calves are only housed for a very short time, as we want them to get outside and start grazing as early as possible to reduce costs.
• Housed calves often suck the sides of the building and woodwork so it's important to make sure they cannot reach treated timber, old doors or the sides of the shed painted with old lead paint, and they cannot eat treated (arsenic) shavings used for bedding.
• Veal calves are kept in narrow crates in Europe but these are banned in UK and not used in NZ.
• The bobby calf pen is the main concern in NZ, but there are clear size specifications for this in the Welfare Code for Bobby Calves.
  

The “bobby“ calf

• The bobby calf trade is a very important source of export income for dairy farmers.
• Bobby calves go for high quality veal to the US.
• The calf's stomach (vel) is used for the enzyme rennet used in the cheese industry.
• The MAF Bobby Calf Code of Welfare states that a "bobby calf" must:
• Be at least four days old.
• Have a dry withered navel.
• Have worn feet pads proving it has stood up and walked.
• Be healthy and free of disease and injury.
• Have been fed only on milk.
• Calf pens have now been removed from the roadside to inside the farm gate to prevent welfare concerns of those who pass by, especially tourists.
• Bruising, skin damage and navel infection are the main causes of wastage.
• Calves must be electrically stunned and then stuck (bled) immediately after stunning.
• The main concern is transport. The code says they must reach destination within 8 hours of collection. This is often not achieved as meat works move them around to keep killing chains in business.
  

Premature calves for blood harvesting

• These are calves born before time or induced (aborted).
• Their blood is used for the special pharmaceutical export market.
• They have not had colostrum and so have not ingested any antibodies.
• There are very tight regulations on their transport, welfare and slaughter.

Weaning

• Weaning is usually defined as the time when you stop feeding milk and this is best determined by weight rather than by age.
  
• Dairy calves are generally weaned when they are eating at least 1kg of meal/head/day.
• Single-suckled beef calves are weaned in autumn when they are generally about 6 months old. Here they do wean more on age than weight as it's a seasonal practice.
• Weaning is a gradual process in dairy calves as they move from milk to meal, then from indoor pens to outside an on to pasture.
• In suckling beef calves, weaning is much more of a shock as it all happens on one day. It's usually accompanied by a few days of roaring by both calf and cow trying to get back together.
• It's a good idea to separate them by 2-3 well-fenced paddocks away from the house, as the stress and noise can go on for up to a week.
  

Animal behaviour and welfare: Pigs Part 2

PIG BEHAVIOUR BASICS: PART 2

Reproduction: Birth behaviour: Fostering

By Dr Clive Dalton


The female

• Puberty can be affected by breed, season of the year, and social environment (e.g. crowding) but especially by live weight.
• Mixing during transport sometimes triggers puberty where the transport stress is thought to trigger reproductive hormones.
• Contact with males will also stimulate first oestrus. However if exposure is too early or for too long, the gilts may become accustomed to the boar's presence and not react.
• To exploit this male effect, expose the gilt to the boar at about 160-175 days of age, and 60-90% of then should show oestrus within 10 days after exposure.
• Most breeds of gilts today come into oestrus between 170-220 days of age, when they have been moved from their finishing pens at around 90kg live weight.
• Weaning a litter will trigger the sow to come in oestrus. She usually cycles 4-5 days after removal of her litter.
• For best results, make sure the gilts are kept totally from within sight, smell or sound of the boar.
• Rearing gilts with contemporary male pen mates does not seem to advance their age of puberty.
• In general practice, gilts are mated and their third heat, when weighing about 118kg. However mating them at their second heat has economic advantages.
  

Signs of oestrus
Sows and gilts in oestrus show any combination of the following signs:

• Swollen and reddened vulva about 2-6 days beforehand.
• Mucous discharge from the vagina.
• Restlessness and a poor appetite.
• Females coming into heat may sniff the genital area of their pen mates.
• They may ride others and stand to be ridden.
• They will show a feature unique to pigs - the "stance reflex" where they arch their backs , stand rigidly when pushed from behind, and allow a person to sit astride them.
• Prick-eared breeds carry their ears erect and held back.
• Oestrus pigs make a characteristic grunt and seek other pigs while go around searching for a boar.
  

Mating

• The female pig assumes a major role in mating by searching for the male and converting social contact into sexual behaviour.
• "Standing heat" when the female will stand for copulation lasts around 48 hours (range of 38-60 hours). Some sows can stay on heat for up to 120 hours.
• The first heat is usually shorter and sows have longer receptive periods than gilts.
• Length of oestrus is also affected by breed, season and management system such as if sows are group our individual housed.
• Ovulation occurs during the second half of the oestrus period, so it's best for the boar to serve the sow twice - at the start and end of the standing heat period.
• Females not mated will cycle every 21 days (range of 19-24 days).
• Gestation in the modern hybrid pig kept intensively averages 115 days (range 108-122 days).
• The "standing reflex" of the sow where she will not move when weight is applied to her back increases as the oestrus period advances.
• The sow is stimulated by the boar and his pheromones from his body, especially his frothing mouth and the gelatinous exudates from his prepuce.
• The order of priority of these stimuli seems to be smell, sound, sight with physical contact last.
• Some sows show a preference for a particular boar and this can cause inconvenience in breeding programmes.
• When the boar is too large and heavy and risk damaging the sow (as mating can take a very long time), the female is best held in a crate where the boar's front legs rest on the sides of the crate to take some of his weight.
• Gilts may often only stand for a boar in the presence of another female in the mating pen, or with a familiar pig in an adjoining area. However, if these support pigs are nearing oestrus, they'll only distract the boar from the job in hand.
• It's a good idea to mate gilts to an old experienced boar and mate old sows with a young boar.
  

Female behaviour before birth

• Sows show great variation in their behaviour approaching birth. This depends mainly on age, previous experience, breed, strain and the husbandry system.
• Sows carrying a litter of more than 11 pigs will have a 5-day shorter gestation than those carrying average litters of 9-10 piglets.
• To avoid stressing the sow, she should be transferred to her farrowing quarters about a week before birth. This will allow them to settle in and reduce stress levels.
• Stressed sows (especially inexperienced ones) will have higher piglet mortality through overlaying and even attacking piglets.
• Heavily pregnant sows spend most of their time resting, sleeping and feeding.
• As gestation length varies widely, recognising the signs of approaching birth is very important, to ensure the welfare needs of the sow are met.
• Sows are nest builders - and they need to express this desire in intensive farming. A sow starts to nest build 3-7 hours before farrowing, and after giving birth she stays in the nest for 24 hours, nursing every 45 minutes.
  

Signs of birth

• The vulva swells and becomes redder, especially obvious in white skinned pigs about 4 days before birth (range 1-7 days). In black pigs you will only see the vulva starting to look like a swollen prune.
• The udder swells, becomes firm and colostrum can be obtained by gentle massage up to 24 hours before farrowing. Rubbing the front teats usually stimulates the sow to lie down.
• Increased restlessness. The sow gets up and lies down or changes side more frequently, twitches the tail, and chews the pen railings.
• She also urinates, defaecates and drinks more.
• The sow chews up the bedding (when provided) and makes the nest. She paws the ground, especially where no bedding is provided. This is a key sign.
• There will be a discharge of blood, birth fluid from the sow and green-brown faecal meconium pellets originating from the piglets.
• Respiration will increase from about 54 breaths/minute 24 - 12 hours before birth, to 90/min 12 - 4 hours before birth, reducing to 25/min at about 24 hours after farrowing. This together with intermittent low grunting and jaw chomping is common.
• Sow rectal temperatures rises from about 39 - 39.5 C four hours prior to farrowing. They then stay elevated (around 40 C) for up to 24 hours after farrowing.
  

Behaviour during birth

• During birth, the sow lies on one side, and in the intervals between piglets she may change sides, stand or sit in a dog-sitting posture. These movements risk crushing or overlaying the piglets.
• Studies showed that the average time to produce a whole litter averaging 11 piglets was 2 hours 53 minutes, or 15.3min/piglet.
• But these times vary greatly with a range from 3.6 min/piglet to 44.6 min/piglet.
• Normally 55-75% of piglets are born head first and 25-45% back legs first.
• Abdominal straining is more often seen before the birth of the first pig, and less common with the remainder.
• As the sow strains, her tail is often pulled back away from the vulva, and delivery of a piglet is often accompanied by vigorous tail swishing and expulsion of gas from the rectum.
• Paddling with the legs while lying down is common.
• The sow usually just lies still as each piglet is born, and she attracts them to her head end by special grunts. She doesn't stand up and lick them and chew their birth sack like other species. She also cannot turn to lick them as they are born like a bitch as she is not as flexible.
• After the piglets are born, the sow stands up and often urinates.
• Usually the foetal membranes start to be expelled during the birth phase and they may appear in two of three lumps. Most of it is shed after the last piglet is born.
• Four hours is normally needed to expel the complete afterbirth but this varies widely from 21 minutes to 12-13 hours.

Early sow and piglet behaviour after birth

Most milk is at the front teats

• About 70% of piglets are born with their umbilical cords still attached and attached to the foetal membranes still inside the sow's genital tract.
• The cord can be stretched considerably before breaking and this helps to prevent haemorrhage.
• It takes from 1 to 30 minutes for piglets to free themselves form their cords which became shrivelled within 4-5 hours after birth. The sow rarely chews the end of a piglet's cord.
• After a brief period of 5-10 seconds of not breathing, the piglet gives 5-6 gasps and a cough. This is followed by about 20 seconds of rapid shallow panting followed by regular rhythmic breathing.
• Most piglets attempt to stand within one minute of birth, and within two minutes they can stand freely and start searching for the teats, or anything that sticks out that feels like a teat - e.g. the point of the sow's vulva.
• There's a wide interval of 3 - 153 minutes/piglet (average of 10-15) between birth and the first milk intake. Piglets clearly vary enormously in their ability to find a teat although some are greatly restricted by the trailing cord.
• Nuzzling is a very important behaviour used in teat-seeking.
• Piglets show a very clear preference for the front teats of the sow, which generally have more milk than the rear ones.
  
• So the first-born piglets get the best (front) teats, which they claim and fight for until a suckling order is established.
• The front teats are longer with more space between them and they have a greater clearance above ground level than the rear teats, so the piglet can grip them more easily.
• Clearance generally declines up to teat number 6, and as the sow ages the udder becomes more pendulous and her ability to expose the bottom teats is reduced.
• The risks of piglets being kicked by the hind feet are also greater when suckling the rear teats. There is also a danger of being kicked by the front feet.
• So the front-suckling piglets grow faster and consequently maintain their social rank in the litter.
• Piglets sort out a hierarchy in the first few days, and a clear social order is established after a week.
• As milk letdown is very rapid (about 20 seconds) and occurs about once an hour, there's little opportunity for piglets to share teats. But if space allows, they may suckle more than one teat.
• Normally breeders select females with a minimum of 12 functional teats, and preferably 14-16. In older sows, wear and tear and mastitis may reduce the number of functional teats.
• Piglet suckling behaviour moves through the following stages:
• Jostling for position along the sow's belly to find the teat.
• Squealing while jostling.
• Nosing the udder.
• Slow sucking.
• Rapid sucking.
• Final slow sucking and udder nuzzling.
• The sow's grunting increases greatly up to the slow sucking stage which is a clear signal to the piglets that letdown is imminent. Letdown starts 25-35 seconds after this signal.
• The squeal of isolated, lost, or handled piglets will alert and stress the sow and she may interrupt her suckling behaviour to investigate. So don't pick up stray piglets during suckling time.
• Piglets sleep for about 15-16 minutes every hour.
• In the wild, the sow and her piglets join the herd after a week.
  

Fostering piglets

• When sows are farrowed separately but in batches, litter sizes can be adjusted by taking piglets from large litters and giving them to sows with plenty of milk and small litters.
• Care is needed as sows vary in their acceptance of foster piglets.
• Best results are obtained if piglets from both sows are the same age and under one week old before teat preferences have been established.
• For success- remove all the piglets from the sow that is going to be given the extras.
• Wait till they are really hungry and she is anxious to have them back.
• Rub the rear ends of the removed piglets over the anogenital area of the strangers to be added. The sow usually smells this area.
• Use the afterbirth for this job if it's still available.
• Then put them all with the sow and watch to make sure she lets them all suckle and accepts them.
• Fostering will probably disrupt the whole nursing process, because of renewed competition for teats. You'll see this in the uneven growth of the litter up to weaning.
• When sows farrow together in the open, piglets seem to mix freely from birth without any problems. The main concern for the farmer is to make sure that each sow has a similar number of piglets.
• Behaviour of dry sows It's important that dry sows have their diets carefully controlled to ensure their nutritional needs are carefully monitored and met.
• The need to have strict control over a sow's diet has led to the development of systems that restrict their movement, and these have large behavioural and welfare implications.
  

The systems used are:

• Sow stalls - the sow is held in a narrow stall, allowing her to move to and fro but not turn round. There is total environmental control.
• Sows tethered in stalls by a neck strap or a strap around her chest. She cannot turn round. There is total environmental control.
• Sows at pasture in groups with communal shelters.
• Sows at pasture in individual runs or tethered to individual kennels.
• Sows in groups of 6-10 in a yard with kennel-type shelter and individual feeders.
• There is an active national campaign in many countries (including New Zealand) to make sow stalls and tethering illegal because of the stress it causes the animals. This practice has been banned in some European countries.
• Sows in stalls and tethered sows tend to develop "bar biting" when they bite the front bars of the stall, and also show a "paddling" behaviour often seen by bored tethered animals.
• Research has shown that even in stalls, providing some straw gave some enrichment to their existence.
• The ultimate in luxury, (judged with an anthropomorphic view) is to keep dry sows in large yards in deep straw. But sows can have savage fights to establish a social order when housed loosely, and it adds greatly to costs of production. This is a classical example of what the domestic contract should provide.
  

The male

• In the wild or in extensive pig keeping systems, the male pig, (unlike males in other species) does not initiate sexual behaviour. He waits for initial signals from the female.
• Boars reach puberty about 6 months of age, but are generally not used for service till 7-8 months old. These ages can vary a lot depending on the feeding level.
• They start learning their courting behaviour and show elements of sexual behaviour while still suckling and as part of play with pen mates. They develop these behaviours even more if mixed with strangers.
• Boars reared in isolation are much slower to develop successful courting behaviour. Group reared boars are better than those reared in individual pens, and intensive stocking will encourage aggression as well as sexual behaviour.
• Boars reared intensively in homosexual groups maintain this relationships for many months after parting, and they can often show abnormal sexual behaviour.
• The boar's courting ritual includes:
• Chasing the sow.
• Nuzzling her head, flanks, shoulder and anogenital area.
• Occasional pushing or leaning on the sow to test her state.
• Drinking her urine.
• He urinates frequently.
• He grinds and chomps his teeth salivating and frothing at the mouth.
• This courting ritual has an important effect on improving the conception rate of the sows being mated. In outdoor pigs boars often have rings inserted in their noses to stop them rooting up the pasture. This affects their courting ritual when it comes to nuzzling the sow and causing a negative response.
• When the boar mounts, he rests his belly along the sow's back and grasps her with his forelegs. Inexperienced boars will head mount, side mount and dismount frequently before intromission (penis entering the vagina).
• Ejaculation occurs when the cork-screw penis of the boar locks in the sow's cervix. This can take considerable time - averaging about 7 minutes but it can last up to 25 minutes.
• The boar thrusts and rests many times and eventually ejaculates up to 500 ml of sperm. Other farm species produce a 5-15 ml ejaculate.
• 
  

Boar behaviour and handling

• Treat all boars with respect and treat them as individuals.
• Handle them carefully and de-tusk them every 6 months (with veterinary advice).
• Remove the front accessory claws to protect the sow from injury during mating (with veterinary advice).
• Don't overwork the boar - one boar to 20 sows is most common.
• Four services a week are plenty till the boar is 12 months old. Don't let him serve more than 6 times a week as this will lower his fertility and subsequent litter size from the sows mated.
• Too frequent use of a boar as a teaser to locate sows coming into heat, may frustrate him too much and he may not serve when needed.
• Mate young boars to old sows in peak oestrus, and old boars to gilts.
• Don't let young boars get injured during their early matings.
• After layoffs of longer than a month, libido may drop and a boar may need the stimulus of an old sow in peak oestrus that has already been served by another boar.
• Spreading some ejaculate from another boar along the sow's back will help to stimulate a boar.
• Take the sow on heat to the boar so he doesn't waste time investigating a new environment. Otherwise he'll waste time in an elaborate ritual of urinating, rubbing scent from his body on the walls, marking the territory with salivary foam and fight the sow to establish dominance.
• Boar pens should provide a good foothold for the boar but not so rough as it will cause foot problems.
• Boars should be kept within sight, sound and smell of sows. However this assumes the boar is the dominant animal in the herd. He may be considerably stressed with other boars near by, as in the wild each boar would be solitary.
• Boars get very large and need regular exercise to keep fit. It's a good idea to have a system where the boar walks daily to the sow's accommodation to help stimulate oestrus and identify sows on heat.
• Regular quiet handling by the stockperson is ideal, walking behind with a pig board for protection, and talking in quiet reassuring tones.
  

Boars and Artificial Insemination (AI)

• AI in pigs is now well established in commercial pig improvement and is a specialist operation.
• At AI centres boars are trained to mount dummy sows and serve into an artificial vagina as this is less complicated than using a live sow.
• Boars may be harder to train if they have mated sows first. But again this varies with the personality of the boar.
• Gentle, reassurance by the stockperson is the secret of success to get a good semen sample from the boar.
• Boars will show courting behaviour to the dummy by nuzzling its flank and rear end.
• Libido varies greatly between boars, and is related to frequency of use.
• Boars can be stimulated more by giving them false mounts, or by observing a collection from another boar.
• It's a good idea to allow the sow or gilt 10-20 minutes contact (through a pen) with a boar after insemination.
  

Behaviour of housed boars

• In less intensive systems where sows are kept in straw yards (and not in stalls), boars often run with them and few problems arise.
• If a boar is put in among a group of unfamiliar loose-housed sows, he will waste time investigating the environment and not checking for sows on heat.
• In intensive pig farming, the boar does not spend time in social contact with sows and opportunities to consort with females are decided by the human in charge.
• Here, sometimes the boar pens are arranged between pens of six loose-housed sows to achieve maximum physical presence of the male.
• In other systems, including where sows are tethered or in stalls, the boar is walked daily in front of them to test for oestrus.
  
• When boars walk behind stalled sows a boar may be confused by the fact that they are immobile and hence displaying an invitation to be mounted. This can be very time-wasting.
• It's well established that depriving boars and sows full opportunity to indulge in their full courting behaviour affects pregnancy and litter size.
  

Boar behaviour problems

• Serving into the rectum instead of the vagina can be a problem. Avoid this by supervising young boars in their early work to make sure they are aligned correctly.
• Extremes of heat may affect the boar's enthusiasm. Delay his work till evening.
• Masturbation by coiling the penis inside the diverticulum of the prepuce. Make sure the boar's penis has actually entered the sow and he is not masturbating.
• Boars that masturbate persistently should be culled although the prepuce can be surgically removed.
• Some boars behave normally up to the point of mounting and then squat down on the floor and ejaculate. Great care is needed to help these boars achieve success as they may persist in this habit.
• Aggression. Boars are always potentially dangerous and need to be handled with care. Nervous and aggressive boars should be culled. Some boars will show aggression with strangers but not with their regular handlers.
• When strange boars meet, they strut shoulder to shoulder, head raised and hair bristling along their backs. Deep grunts, jaw chomping and mouth frothing continues.
• In a fight, boars face each other with their shoulders in opposition and apply sideways pressure. They circle around, biting and slashing at each other with their tusks. They may charge each other with mouths wide open and bite. The loser turns and runs away squealing.
• Subsequently after a win, the winning dominant boar need only grunt to get submission. Newly-mixed boars fight less if they are both put in a strange environment.