Farm working Dogs in New Zealand. 7. Genetics and breeding

By Dr Clive Dalton

 

Genetics or environment - which is more important?

This is the old question of which is more important - nature or nurture?  Is it the dog’s breeding (its genetic makeup) or the way it is trained and cared for?  Both are important and no amount of training will make a top dog if the genes for performance are not there.  On the other hand, good genes will not be fully expressed under poor training.

Most working dog traits or characters are strongly inherited - in other words what you see in a dog's performance will be passed on to the next generation.  The term "heritability" is used to describe this and is on a scale from 0 - 100%.  Weakly inherited traits like fertility and litter size are below 10% and strongly inherited ones like casting would be around 30-40%.  This is a guess, as geneticists have not done much study on working dogs, despite their importance.  Research has shown that hip dysplasia averages around 30-40% heritability.

What are working traits?

Heading dog

·      "Eye" or the ability to out-stare a sheep.  Dogs vary from "strong" eye to "plain" eye but the trait seems to be strongly inherited.

·      "Heading" or the dog's ability to cast around sheep.  Some dogs will naturally take a wide cast and others will run straight at stock.  The dog trialist's ideal is a pear-shaped cast.  Again this seems to be strongly inherited.

·      "Shedding".  An ability to separate one sheep from another at close quarters.

·      Temperament.  This is the dog's "nature" and breeders say this is fairly strong in its inheritance.

·      “Early maturity” refers to the ability of a pup to start working at a young age.  Again breeders believe this trait is strongly inherited.  The fear with late-maturing pups is that they may not start to work at all.

·      Not biting or grabbing sheep is important.  Seen in some strains so must have a fairly strong genetic base.  Can be modified by training but is always there.

Huntaway

·      "Heading".  All huntaways should be able to head stock as in heading dogs.  They'll head without showing "eye".

·      "Noise.  They must bark naturally and this seems to be strongly inherited.

·      "Temperament".  Very important and generally very good in huntaways.  They are always anxious to please.

·      "Force".  A trait usually seen best in big dogs that will push among stock with no fear of getting hurt.   A fairly strong genetic trait perfected by proper training.

·      "Backing".  Where a dog will jump on the back of sheep and walk over them.  A trait which varies a bit in strains, so must have some genetic base. 

Physical traits

Breeders are concerned with such genetic defects as:

·      Undershot jaw or parrot mouth.

·      Overshot jaw.

·      Normal reproductive organs.

·      Sound bone structure - eg no hip dysplasia common in some strains.

·      Sound feet pads.

·      Normal palate ie. no cleft palate.

·      Normal leg length - no drawfism.

·      No problems with the eye retina.

Single genes - simple traits

These are simple traits controlled by single or very few genes.   When we get to the performance traits like speed, intelligence and working ability we have to deal with thousands of genes.  The dog has 39 pairs of chromosomes in its sex cells (sperm and eggs) and at present we don't know much about the thousands of genes on them. 

These thousands of genes combine when sperm and eggs are produced into millions of different combinations.   So don't expect parents to produce identical offspring unless you start splitting eggs.  In future we could see a lot more reproductive technology used in dogs and even genetic engineering where we can separate genes on a chromosome and move them around to engineer more certain combinations.  But before that we have to do some "gene mapping" to find out what genes are where on the chromosome.  This mapping the genome of the dog is underway.

 Many genes - complex traits

If you see "variation" in a group of animals (eg litter mates), then you are dealing with many genes controlling them, and to improve the next generation, you "select" the best parents from the present generation.  Sounds simple!

So in dogs you should not be surprised when some pups in a litter turn out to be good workers and some are not so good.  You will see a whole range in ability and this variation is then the raw material we use to make improvement, and the main tool we use is "selection".  Variation and selection is what has made our dogs and what will allow us to improve them.  So don't pine for dogs that are like peas in a pod, we need variation to work on and make progress.

 Cloning

Cloning where identical copies of an animal are made is now possible, and some merit can be seen for it in farm animals.  The idea is good provided that no problems will occur over time with the animals you produce - because if they do, then the entire cloned population will get it.  You have to make sure that what you are going to clone is “perfect” in all traits, and that’s asking a lot in the world of animals.  It also restricts genetic diversity for future selection.

G and E

But remember this "variation: is caused by two things.  First there's the genes or genetic variation, referred to as "G".  Then there's the environment, referred to as "E" which is the rearing, feeding and training.  Some trainers produce better E than others.  You need plenty of G to make a champion, but you'll not do it without good E.   This is the old saying that "90% of the pedigree goes down the throat."

Mate the best to the best

This is what the early improvers did long before the science of genetics was born.  It worked then as it does now.  The only problem is what do we mean by "best"?

Dogs that consistently win at a range of trials, clearly have the genes needed on the farm.  They’re surely the best.   But there are some folk who think that today's trials are too artificial, and don't relate to the commercial farm with large numbers of stock per person.

The counter argument is that these trial dogs do work on commercial farms and can do all the jobs needed, as well as the fancy stuff for the trials.  They have the genes to do everything needed so there is no worry.  If they win at trials then they qualify to enter the stud book of the New Zealand Sheep Dog Trial Association (NZSDTA).  No useless dog can get into this book, and a dog’s looks and fancy points don't matter.  It's performance alone.

If you want to breed dogs that are not in the stud book, then you should make sure the parents have performed well and that you can see them working.  But remember you are trying to judge G, even if the handler has ruined it through the E provided.   In other farm livestock, many a farmer has been duped by thinking he/she was buying G when in fact they paid through the nose for E. 

Check the pedigree

Pedigrees are simply a record of ancestry - and that's all.  Never assume that a "pedigree" animal that can be registered in a studbook is genetically better than a non-registered animal.  This is where the New Zealand farm working dog is unique - they can only get into the stud book by proving good working performance.

If a pedigree is a list of names and numbers and has no record of performance - then it doesn't tell you much.  The important feature of a pedigree is that every time you go back a generation, then you halve the genetic influence of the ancestors.

So parents give half of their genes (good and bad) to their offspring.  Grandparents give a quarter, great-grand parents one eighth and so on working backward along the pedigree.  In practice, only be concerned with a pedigree as far back as grandparents, as each ancestor after that has so little influence.

Remember that if anyone is trying to tell you that an animal's superiority is due to a particular great-great-great grandsire, he has only provided one sixteenth of the genes.  Does this mean that the other fifteen sixteenth of the genes were useless?  Which would have the greater influence one sixteenth or fifteen sixteenths?

Fortunately the working dog world is free from a lot of the mumbo-jumbo about pedigree breeding that confuses other livestock.  We breed for performance and "functional traits" in working dogs and it makes life so much easier, and the end results more predictable.   Thank goodness nobody yet has started to say what a working dog should look like and formed a committee to administer this nonsense.  But that’s not to say it could happen in future.

Inbreeding

This is where "related" animals are mated.  This concentrates genes, whether they are good or bad.  Breeders are often forced to inbreed when they want a sire for a particular purpose, and they cannot find one better than their own.  So they mate related animals and live with the consequences.

There is nothing wrong with this, and it will certainly concentrate similar genes.  In the process however, as similar genes meet, they may throw up certain recessive genes that have been hidden.  It's here where undershot jaw, cleft palates, no hair, and drawfism is seen.  You can cull these out and keep on inbreeding, but as the level of inbreeding rises (called increasing homozygosity) you'll most likely find "inbreeding depression" taking its effect.

Here traits like fertility, litter size and general "fitness" are affected.  Bitches will be hard to get in pup, and they'll have small litters with “runts”(small weak pups) in them.  In working dogs we euthanase them but in the fancy dog world they keep them, often to form new breeds!

If you inbreed and strike trouble you can get out of it in one generation by making an "outcross" to some completely unrelated animal.  All those recessive problem genes will have been buried again.

So avoid high levels of inbreeding by not mating sires to daughters, sons to mothers and even as close as first cousins.  Don't go any closer than second cousins.  First cousins have common grandparents and this is generally too close, unless you have a very special reason to experiment.

Linebreeding

This is very similar to inbreeding but seems to have a better image among breeders.  It's “inbreeding done more slowly” and has the same effect as mating relatives and concentrating genes.  This is the way to go - you make haste slowly, and it gives you time to do some selection, and go back and make an outcross if you strike trouble. 

In this outcrossing, try to get a new sire from a breeder with similar objectives but slightly different genes.  Then you don't slip back too far and lose the benefits of the genes you want.

People have a great fear of inbreeding (probably because of the human religious taboo against it) but less fear of linebreeding.  So there's an old saying that if it fails call it inbreeding but if it works call it linebreeding!

The future working dog

The dog like the human is a very adaptable species and it has a great future. It can reproduce rapidly and responds well to natural or man-made selection.  As a result there is plenty of opportunity for man to change the working dog - for better or for worse.

The working dog is by no means perfect - despite what some enthusiasts would argue.  For example some people on today's farms with the range of pressures that did not exist in the old days, say it takes too long to train.  Today's shepherds don't want to spend hours after work and at weekends training dogs.  They want a quick learner - to save time, money and food.  And they want fewer failures, which there are despite all the breeding wisdom.  So there’s an interesting challenge for breeders, geneticists and behaviourists in the future.

Some people are concerned that the genetic base of our working dogs may be getting too narrow with the influence of too few top animals.  They fear some inbreeding depression which can be expressed in less robust animals for the hard life on the farm, as opposed to the short run at the trials.  This fear has come to pass recently with a rapid increase in the incidence of hip dysplasia (HD).  It has clearly been spread by the popularity of some top trial dogs, through linebreeding to them.

There's certainly plenty of technology waiting to be used in future dog breeding if the breeders or the market demands it.  It has been here for some time.  Examples are artificial insemination (AI) to allow more people cheap access to top genes, multiple ovulation and embryo transfer (MOET), egg splitting to produce clones of identical animals, and embryo storage and transfer. 

We are now on the threshold of using genetic engineering to move individual genes around.  There has been little discussion on how genetic engineering could be used in the working dog but the opportunity is there.  Indeed the scientific community in the past has shown little interest in the working dog in relation to its importance to the economy. 

New Zealand has a very high health status in the world and could become a genetic reservoir and storage repository for the world's top working dog genes - and that includes all dogs classed as "workers".    There is no reason why New Zealand could not become the Mecca for working dogs like we are for shearing. 

New Zealand agricultural history. No 12. Importing exotic sheep breeds

 Selection of sheep in Scandinavia

 Where the sheep came from

By Dr Clive Dalton

Selection of sheep in Scandinavia

Dr Leyden Baker

Dr Leyden Baker from MAF Ruakura Genetics was assigned responsibility to travel to Denmark and Finland to select the sheep for the 1984 importation, accompanied by MAF veterinarian Dr Stuart MacDiarmid.  Their first task was to find the sheep (both ewes and rams) for purchase or lease, and then before organising their assembly at central locations in each country ready for mating and the collection. to  check veterinary details and organise the collection of embryos (undertaken by Dr Robin Tervit – see other blogs).

Leyden had good contacts in Scandinavia as he had done post-Doctoral research in Norway in 1976 and again in 1983, and traveled extensively to animal breeding institutes in Denmark Sweden and Finland.  

 When in Norway in 1983, Leyden was very surprised to get a phone call from Ruakura Director Ken Jury to say that off the record at that stage, it was starting to look as if the importation ‘sheep show’ was on the road again, and would he stay a few more weeks (salary provided) to have a nosey around to see what sheep there were in Denmark, Sweden and Finland of the breeds New Zealand wanted – mainly Texels, Oxford Downs and Finnish Landrace.  Norway didn’t qualify as they didn’t have any of these breeds at this time.

Having Leyden in Scandinavia at that time was an enormous bit of good fortune for the NZ government and MAFTech, as it wasn’t hard to find out what was going on in the sheep business because of his contacts with genetics mates who all knew each other, and were involved in a lot of cooperative work. 

Leyden said the Finn and Texel flocks were small, the place was crawling with vets with about one for every ten farms, and the farmers were great hosts just like Kiwis being very willing to cooperate to sell sheep to New Zealand.   

There was no official recording scheme like we had in New Zealand and the records farmers kept were mainly pedigrees.  But they knew every sheep and how it had performed if you asked them.  Denmark had a central ram progeny test station where some useful data could be obtained.  It was decided that there was nothing to be gained in trying to access these breeds in Sweden, and in addition facilities for embryo transfer work were limited.

So after Leyden came back on New Zealand in 1983 to carry on his cattle and sheep breeding work at Ruakura genetics section, when the sheep importation became a real deal, it made sense for Director Ken Jury (pictured left) to get Leyden to go back to Scandinavia and get down to the serious business with Stuart MacDiarmid and Dr Robin Tervit of finding the sheep, getting them to central locations to do all the reproductive wizardry.

Leyden tells the tale of going to one lady breeder of Finn sheep in Finland and the sheep were not around as it was summer and they were in the paddock.  With one call the whole mob came racing over as they’d been brought up with a feed bucket spending five months indoors every year during winter.  But the big laugh was when Leyden asked about a particular ewe to inspect her.  All the breeder did was call  the sheep’s name and out she trotted from the mob to be examined!  Every sheep in the flock answered to its name!

Leyden also remembers going to one Finn breeder to buy three rams, and after the negotiations, they said they’d be back to collect them as they only had a car. No problem said the breeder who put each ram in a sack tied at the neck before putting it in the car boot! 

Deal done!  But on the way home Leyden and driver stopped in a forest to check the rams, and on opening the boot, one ram that had got out of its sack jumped out and headed for home.  It took hours to catch him Leyden said.

Leyend remembers Roger Marshall's assistance

Roger  Marshall went to Europe representing NZ sheep breeders and was  with Eric Claussen and I during the selection of the Texels and Oxford Downs in Denmark. As Roger's report showed he went to Finland before I did and inspected some of the sheep there and sent me a report on this trip.

Where the sheep came from?

Here’s a summary of the actual flocks and numbers

Breed	Country	Flock source	No. Flocks	Ewes mated	Rams mated	Donor ewes	No embryos
Oxford	Denmark	Industry	17	46	14	21	64
Texel	Denmark	Industry	18	47	11	31	136
Texel	Finland	Peksala	1	23	5	5	95
Finn	Finland	Industry	12	29	9	23	126
Finn	Finland	Kuuma	1	18	8	16	127

After being tested on each farm for maedi visna, Chlamydia and brucella ovis, the Danish sheep were assembled in a barn near Copenhagan and the Finns in a barn near Jokioinen to carry out all the treatments needed to finally end up with frozen embryos fit for transport to New Zealand. All ewes were purchased by the NZ Government except the Kuuma Finns which were leased.

Breeding sheep to eliminate dags and worms. 4.

By Dr Clive Dalton

PART 4

Selecting female replacements from the A team

Docking ewe lambs

• Do NOT drench any ewe (or ram) lambs at docking - and this means both the A team and commercials. At this stage, the lambs’ immunity is starting to develop and anthelmintic drenching will damage it.
• Vets will not agree but we don’t know enough about the complex immune system, and until we do, don’t drench. The only exception would be a major animal health crisis, confirmed by a veterinarian.
• Mark all the ewe lambs with ear-markers to cut a bit out of the ear or punch a hole. Hopefully they will all be twins, but don’t worry about any singles in the mob.
  

Weaning ewe lambs

Polled Dorset weaned lambs being picked for slaughter

• Barring obvious culls, all the A team ewe lambs should be keepers and need priority.
• You’ll need to keep more of them as replacements than normal to apply intense selection pressure and cull heavily from weaning on.
• Hopefully you won’t need to go too deeply into the ewe lambs from the single scanned (SS) ewes to make up numbers. But this will depend on twinning rate, the season and the size of the nucleus you want. Don’t be too ambitious at this stage.
• As a target, plan to cull around 30% of the ewe lamb crop, but this will depend on the final numbers needed. There’s a fair way to go before they reach two-tooths and their final selection.
  

Drenching

NO drenching at weaning, unless you have a crisis confirmed by a veterinarian.

• Do NOT drench any A team ewe lambs at weaning.
• If any pack up around weaning, then cull them.
  
• The exception would be an outbreak of Barber’s Pole worms in the whole lot, but make sure you seek veterinary advice for a correct diagnosis (after Faecal Egg Counts) before drenching. Use a specific Barbers Pole drench and not a broad spectrum one.
• Any ewe lambs for sale from the remainder of the flock can be drenched with a conventional combination drench if they look wormy, and this is confirmed by a FEC on a sample. Decide if this will improve their sale prospects.
• Before sale and after conventional drenching, run these sale ewe lambs separately from the A team ewe lambs. You don’t want any cross-contamination of worms.
• But don’t run the A team ewe lambs on clean pasture. Put them on pasture that has had sheep on it to challenge their immunity.
  

Tapeworms

• Seeing tapeworms can panic people as they look so big.
  
• Don’t drench unless you have clear evidence of ill thrift, or if their scouring is attracting blowfly.
• If a drench is justified because the lambs look poor, use a product specific to tapes and not a broad spectrum one.
• Mark for culling any ewe lambs from the A team that have physical defects or fail to meet your standards.
  

Developing natural immunity

It's an easy enough job running hoggets through the yards and drafting off the dirties, even if some are keen to escape!

• By weaning, all lambs should be well on their way to developing natural immunity, so expect great variation in the number of daggy backsides you’ll see.
  
• You’ll see these ‘dag storms’ with feed changes, which are great to challenge immune development. Be ruthless, especially on dirty backsides that never clear up.
• It’s good to see those that go through a daggy stage and then permanently dry up. It’s the ones that don’t that you need to mark for culling.
• So make your final decision in early autumn when they are hoggets (see below).
• Nutrition of young growing animals is critical so make sure there are well fed in this.
• Minerals and trace elements are well known to enhance immunity so give these a boost.
  

Ewe hoggets

• Now the top ewe lambs from the A team ewes have grown into hoggets, they should be looking good, and it’s time to put more Dag-Free and Worm-Free selection pressure on them.
• Do NOT drench them.

These ewe hoggets have never had an anthelmintic drench in their lives. They have only had a nutritional supplement containing minerals to boost immunity.

• Keep going through the hoggets every 2-3 weeks (a month is too long), for the first three months after weaning, and draft off any tail-enders for culling.
• Mark for culling any hoggets that are regularly daggy. Any that get daggy and dry up quickly are OK as they’re still be developing their immunity under the natural worm challenge, and the ‘autumn rise’ of worm larvae is an ideal time for this.
• The tail end culls. If you think any of these need a drench, then use a conventional combination drench and finish them for sale.
• After drenching, don’t mix the drenched hoggets with the replacements.
  
• They should be run under your normal farming conditions on paddocks that have been regularly grazed by sheep.
• Don’t run these ewe hoggets on clean pasture. They need a worm challenge all the time.
  

Ewe hoggets -initial check for worms

Hoggets intensively selected for Dag-Free and Worm-Free traits.

March/April

• This is a good time to do an initial FEC to see what kind of parasite load the hoggets are carrying.
• It’s the ‘autumn rise’ of worm larvae which will give the hoggets’ immune system a really good challenge.
• January/February is too early to do this in my view, but many WormFEC™ breeders do it at this time, arguing that they want to find sheep with early immune development. It’s too ambitious in my view.
• Do a FEC from a composite sample mixed from 10 fresh droppings from the paddock. Send the sample to a recognised lab through your vet.
• Use a trigger level of 500 epg to see how things are going.
  
• If the sample is way up in the thousands, then don’t panic, as this would suggest that little immunity to worms had developed yet.
• Don’t be tempted to drench if the hoggets are looking healthy and growing well.
• The only reason to drench would be if their health and welfare were at risk, confirmed by FECs and your veterinarian.
  
• Barber’s Pole worms would be a classical reason to drench, making sure you used a drench specific to that parasite and not a broad spectrum one.
• If the sample is below 500 then that’s good news, but again don’t get excited, as it’s only one sample, and look at the animals to see how they are doing.
• Veterinarians use 500 epg as a trigger to drench the whole mob. Don’t be tempted as you are involved in a ‘breeding project’ and you’ll need to point this out to your vet.
• Again, keep a note of any hoggets that get dirty and mark for culling any that don’t dry up, as their immune systems are not coping.
  

Ewe hoggets - Serious check for worms


May/June

• After the initial check in March/April during the ‘autumn rise’, early winter (May/June) is the ideal time to put more selection pressure on these replacement hoggets for dags and worms, as worm burdens are a big challenge to these young sheep in winter.
• Get an individual FEC done on each hogget.
• This will cost around $5/sample. This must be corrected for Faecal Consistency Score (FCS) so remember to record this at the time of sampling, and build the score number into the sample ID number.
• See Part 8 for details of how to do this.
• If the cost of the FEC is going to be a major issue, just do a FCS on them.
• Ewe hoggets producing marbles need to be marked as the top group, followed by hand grenaders. Then anything below this with sloppy dung needs to be given a separate mark as potential culls.
• Keep the drench gun locked away unless there is a worm blow-out (e.g. Barber’s pole) and animal welfare is compromised and confirmed by your vet.
• Good feeding is vital during this winter period so don’t confuse worms with under nutrition.
• If you haven’t put a good permanent ID tag (numbered and readable from a distance) into these hoggets, then do it now. They are your top genetics.
  
• It would pay to put a duplicate tag (eg a numbered brass tag) in them to be doubly sure of ID incase the initial plastic tag comes out. This cost is well worthwhile.
  

Ewe hogget weight

Clean hoggets that could be further culled on weight.

• If you have more hoggets than you need and have to find a reason for reducing numbers, you can always use weight.
• Find the range by weighing a few of the smallest then a few of the biggest, and then decide a cut-off ‘target’ weight.
  

Ewe hogget fleece weight

• In the past it would have been worthwhile recording fleece weight and culling the lowest – but don’t bother. Just cull hoggets with the ‘off-type’ fleeces.
• Hoggets with high liveweight will also have the genes for high fleece weight (the genetic and phenotypic correlations between the two traits are highly positive).
• If you breed fine wool, then it would certainly be worth culling on hogget fleece weight and quality.