Heterosis or the healthy mutt

Most livestock breeders have heard the term "hybrid vigour" in which the cross between two breeds grows better than either of the two purebred lines.  Heterosis is the formal name for this.

In the sheep world, commercial producers take advantage of this by crossing two maternal type breeds such as a Rideau Arcott with a Dorset to create an F1 cross.  The F1 cross is then mated to a terminal sire breed such as a Suffolk or Hampshire.  If done well, the resulting market lamb is superior than from each of the purebred lines.

We cross our two maternal lines so our F1 cross is a North Country Cheviot/Tunis cross. This hybrid is indeed strong, vigorous and grows well.  We are still working on which terminal sire breed works best with this cross and our production system.  We are trying a Hampshire cross this year.


With heterosis comes a certain degree of unpredictability.  However that unpredictability is reduced if the two parental purebred lines used are inbred.  While you always create your cross from the best of your purebred lines, the mixing of genotypes leads to less predictability in the resulting phenotype ie how the animal will look and perform. In some extreme cases the parental genes are incompatable and the hybrid is less vigorous than the parental lines. This is where data collection is very important.


It is common practice for breeders of purebred stock to line breed, that is mate closely related relatives to enhance desirable characteristics such a growth rate or conformation type.  This increases homogeniety and predictability of the offspring but also can come at a cost known as inbreeding depression.  The extreme of this is the appearance of lethal recessives such as spider syndrome in Suffolk sheep.


The reality is that breeding selection is focussed on relatively few measurable characteristics and the rest of the genome comes along for the ride.  In some cases the changes are positive, some negative but on the whole the inbred animal is less gentically fit than an animal that is outcrossed. 

While our purebred lines (especially our Cheviots) have some very desirable measurable characteristics, in my opinion, they are too inbred and we will be searching for unrelated lines to use for an outcross.


Lately I have been reading articles on the impact of inbreeding on disease and parasite resistance in sheep and am seeing the fitness advantage of the heterozygote.


There is very little in the livestock literature on the impact of inbreeding on parasite resistance but there is information on wild populations of sheep.  In these publications, inbred lines are more susceptible to internal parasites working as a natural selection against inbred lines.

Scrapie is another instance.  At first blush it makes sense to include selection for resistant lines in your breeding program.  However it never makes sense to breed for a single characteristic.  In this case, adding resistance to your flock should be done slowly without sacrificing production characteristics.  I know that in 18th century Britain scrapie was thought to be the result of inbreeding; maybe they were right. Is heterozygosity the way to go with respect to scrapie ie gaining some resistance, not sacrificing other characteristics? At this point I can honestly say I am not sure. We will continue to genotype and use quality rams with resistance genotypes.  However, we will not sacrifice quality in a effort to maximize resistance.

Breeding livestock is not a set formula but rather a dance where you go back and forth but ultimately make your way across the dance floor.  Your goal is to move forward but that requires knowledge, research and accurate,detailed data collection. I strongly feel that a wholistic approach needs to be used where the health, longevity, fertility and welfare of the animal has to be considered.  You may not make as rapid advances in characteristics such as rate of gain but I am banking on this approach reducing your costs by producing a healthier and more "genetically fit"  animal.


TTFN,


Laurie

Why we don't go against nature at Hawk Hill

I read with interest the article in the Ontario Sheep News on fish meal supplementation to supply omega 3 fatty acids in ewe ration and its impact on the subsequent lamb's ability to withstand a bacteria toxin challenge (endotoxin).  While it was scientifically interesting, this is not the direction that our farm wants to go.

The first reason is that sheep are herbivores, not omnivores, and feeding animal-based proteins to herbivores is what got the sheep industry into problems in the first place with conditions like scrapie.  No, I am not saying that fish meal can transmit scrapie, but I am questioning a nutritional supplement that is so totally foreign to the natural diet of sheep.

The second reason is the effect of the fish supplement on the quality of the meat.  As a teenager, we lived in Sweden.  At that time, the Swedish pork industry was using a fish based feed supplement.  It was, beyond the doubt, the worst pork I had ever eaten with a distinctly fishy flavour to the meat.  We do not want to use any feed supplement that can create off flavours in the meat and reduce the quality of our product.

Man's manipulation of domestic animals is but a moment of time in the evolutionary scale.  That is especially true with respect to recent manipulations for the more intensively raised livestock.

Sheep have evolved to breed at a time so that the lambs were born when vegetation is young, supporting the increased nutritional demands for a lactating ewe as well as for a rapidly growing lamb.  In our climate's case (and the British and European breeds that have evolved for our climate) that means a birth in April or May.   Not surprisingly, omega-3 fatty acids in forage peak at the same time as lambing.  Forage sugars and proteins also peak at that time.

All this begs the economic and in some cases physiological costs of trying to paddle against nature's current.  In my opinion the way to minimize health problems and economic costs in your flock is to quit trying to breed out of season. 


The demand for Easter lamb actually originated in the Mediteranean  where the climate naturally produces lamb in that season.  So is it reasonable to expect production systems in a northern climate using breeds developed in northern climates to try to mimic a Mediteranean production system using Mediteranean breeds?  My opinion is no.


 Does that mean only seasonal availability of lamb?  Sure, but it is a long season from spring lamb in May, June to heavy lambs from September to January or even later.  Off season, there is hogget and mutton, two very good meats that need to be promoted again. 


Each shepherd must make their own decision as to the production system they want but they must recognize going against our climatic realities comes at an economic and management cost. At Hawk Hill, we acknowledge the realities of our climate, our breeds and our forage production season and manage our breeding and marketing to reflect that reality. 


TTFN,
Laurie

Ramblin' Prose

We attended a couple of lectures hosted by Ontario Sheep's District 9 last Saturday.  One session was on nutrition and the other on ram assessment and care. The lecture on ram assessment gave us not only things that we need to consider when we purchase our next rams but also what we offer in breeding stock.

 We have 4 rams here at Hawk Hill and since we have half of our flock bred purebred this year, we may be reserving the best of our ram lambs to sell as breeding stock.  When we have purchased rams in the past, there have been criteria that we have been looking for such as production records, conformation etc.  However after the lecture this past week I think we can do a better job in evaluating rams before purchase.  While we like the rams that we have I do think there is room for improvement.  However it will probably be a year or two before we purchase another ram so we do need to consider the characteristics in ram lambs we have to offer.  These are draft characteristics we would like to see in animals we purchase so why not offer this in animals we sell.


Here are some of our preliminary ideas:

• purebred, registered ram lambs will not be offered until they are at least 6-8 months of age
• all purebred, registered rams to be offered will be assessed for breeding soundness by a vet (only ones that pass the examination will be offered), all others will go into our market lamb stream
• all breeding ram lambs offered will have a minimum of 30 cm scrotal circumference
• all registered ram lambs will be genotype tested for scrapie resistance and be at least QR for codon 171
• all ram lambs offered will have production records.

 We will need to consider what we offer for purebred, non-registered or crossbred ram lambs.  While only superior animals will be kept, we will not be genotype testing nor bringing in a vet to assess them for breeding soundness.  Assessment will be the responsibility of the purchaser for these ram lambs.


Still lots to think about.


TTFN,
Laurie

 

Don't forget to have fun

It is WAY too easy to get overwhelmed with everyday life and responsibilities to forget why we are doing this in the first place.  We work to live not the other way around.  And living means spending time with friends and family and HAVING FUN!! 

 

Having fun is exactly what we did last weekend.  The Glengarry Pioneer Museum celebrated its 50th anniversary by holding a Pioneer Ball.  All were encouraged to dress in period costumes or Scottish attire.  I would say that 30% dressed in heritage dress and another 30% dressed in Scottish attire. In this community most residents have a kilt tucked into their closet. Close to 230 people danced, ate and drank their way through a wonderful evening.


Hmm it has been so long since I have been in a dress I felt like I was in drag.




TTFN
Laurie

Another lightbulb comes on

When I look at the time ahead and the time behind me I realize that I have less in front than behind.  Oh well.

I have so much to learn about farming in general.  I don't know how farmers do it in one generation, especially if they are like the current generation and don't want to learn from their elders but I suppose we all muddle along as best we can.

One of the ways we can reduce our cost of production is to improve the quality of our crops especially our forages and pastures.  We have effectively mined the land for the last 14 years by taking hay crop after hay crop.  While putting some manure back on the fields I am not sure that we have returned as much as we have removed.  It is time to get back to basics.  It goes beyond being a grass farmer with a by-product of lamb.We are bacteria and fungi farmers with a by product of soil. The rest just is icing.

The industry standard with horses is to bed with shavings or sawdust.  This stuff just does not break down.  Why?  It takes a carbon:nitrogen ratio of 25-35: 1 to begin composting manure and bedding.  Fresh sawdust and shavings are 500:1; even rotted sawdust is 200:1.  It will actually pull nitrogen out of your soil in order to break down.  No wonder horse facilities have mountains of this stuff hanging around.

We stopped using shavings  6 years ago and now bed the horses in straw when they come in ....which is very seldom. We now put 1-2" of sawdust on the bottom to absorb urine and then bed the rest in straw.  We do the same with the sheep, though with the hay waste, we seldom have to add more straw.  Unlike with the horses, we let a pack build up for the sheep and clean it out in the spring.

This winter we have our chores down to a fine art form; whizz in and out.  It leaves a lot more time to read up about soil care and feeding.  Maybe I will learn enough by the time I join the complement of fertilizers.

TTFN,
Laurie

I am a slow learner

We have had horses for 12-13 years now and it has taken us this long to figure things out for the good of the horses, our pocket books and us.  When we started we spent a lot of money getting the barn renovated for box and standing stalls, bought tons of blankets, etc. Lots of money was wasted.
 Now we: 

• leave the horses out 24 hours a day year round with a run in shed
• bed the run in shed with coarse sand instead of straw (it stays drier and is a lot easier to pick clean)
• insulate the stock tank and use a bucket heater to keep it open in the winter
• throw a handful of pennies in the stock tank to control the algae
• feed in a round bale slow-feeder net in a tombstone feeder
• fecal test 4-5 times a year and only deworm as required
• only vaccinate the minimum for a closed herd
• trim as required instead of on schedule (changes with season and ground conditions)
• 99% of diet is forage, supplement based on analysis
• adjust diet based on body condition 

They are healthier and less stressed and so are we.  I am looking forward to the time we have the same breakthroughs for the sheep. I hope it doesn't take 12 years.

TTFN,
Laurie 

A Shepherd in Winter

As I lay nestled under the duvet listening to the morning weather - “-23 with a wind chill of -30” – I chant my winter shepherd mantra – “What the hell were you thinking?”.  At -40 I add “I could have been in a villa in Tuscany right now”.  I drag myself out of bed in a house that was built in an era when upstairs heat and insulation were considered optional.  Fleece PJs and fluffy socks – a TSC vision of loveliness.

If I am lucky Bob has the stove going before I get downstairs. There is oatmeal for breakfast with a bit extra for the chickens.  I am training them to come when they are called with oatmeal bribes. (see the former post) If you think that you look like a fool herding sheep without dogs, try chickens.

Now the ordeal of getting dressed for chores: insulated coveralls, my dork hat with ear flaps, neoprene gloves, neoprene boots, ice cleats.  If I ever give up farming I could find employment as a dominatrix.

A stilt legged shuffle to the barn.  Oh, you say, the warmth of sheep wafting over me when I open the door.  No, the barn was built by the same folks that thought heat in the house was for wusses.  It is a drafty, old bank barn where we house very few sheep but keep the hay, the water and the feed.  The sheep are in paddocks with run-in sheds scattered around the barnyard.  Water sloshing over my coveralls freezes instantly.  I recite the mantra again.

I look over the breeding groups: a red butt here, a blue butt there.  It is starting to look a lot like Christmas and the tune comes to mind.  I am jostled by the sheep as I fill feeders; the guardian dogs are prancing in the snow.  I am starting to wake up, to warm up.

Like with childbirth, I know I will forget all of this when I see the lambs frolicking in the spring pastures.  A pushy ewe dumps the bucket down my boot; here comes the mantra again.