Download breeding an alpaca industry

BREEDING AN ALPACA
INDUSTRY
Part 2
GENETICS — THE BEGINNING
by the Breed Development Sub-Committee
LET’S START AT THE END
POINT, WHICH IN ITSELF IS
JUST A BEGINNING…
Work has started at Penn State
University, funded by the US
alpaca industry through their ARF
(Alpaca Research Foundation), to
define the genetic make up of the
alpaca.
Called the Alpaca
Genome Project it intends to
identify the DNA stringing of the
alpaca and from that isolate certain
genes, by way of markers, that will
tell us something about the
phenotypic nature of the alpaca.
WHAT IS GENETICS?
Genes are the building blocks of every
living thing. Genetics is the science of
what makes up an individual lifeform and
how traits are passed down from
generation to generation.
GENETIC TERMINOLOGY
STATE OF THE ART KNOWLEDGE
The underlying concept of genetics is that
genes are a segment of DNA and control
nearly all the biochemical processes that
occur in an alpaca. These genes occur in
pairs called chromosomes. Alpacas have
37 pairs of chromosomes. When an animal
reproduces, it passes only 1 of its own pairs
to the offspring. The resulting offspring,
therefore, has half of its sire’s genetic
makeup and half of its dam’s. The
complete package of genes that make up
an individual is called its genotype. The pairing of genetic
information is what makes genetics “work”, with different
combinations possible at each genetic level.
Basically the South Americans did little of importance (or with
academic rigour) on alpaca research. Glancing back at “Animal
Breeding and Production of American Camelids” by Escobar
will quickly show that a lot of data was collected, but few valid
conclusions were drawn.
Genes can interact in different ways and many different
combinations are possible. Each trait is controlled by at least
two genes, however the paired genes that make up a
chromosome are not always identical. When this occurs one
is said to be “dominant” and one “recessive”.
When alpacas came to the Western World, New Zealand led
the way with Davis contributing much to early research.
RIRDC (Rural Industry Research body in Australia) put money
into research early on and in the USA the Universities soon
tagged on to the industry and set up research herds, funded by
the profits of the registry. This added considerable, weighty
and academically sound research in many areas.
Dominant genes always influence the way traits are expressed
(become obvious) as they are the dominant form of the trait.
Why is it an end point? Because
until then we have no real idea
about the genetic working of the
alpaca.
Why is it a beginning? Because
then we can start to use the results
to influence genetic selection with
some certainty .
How long will it take? Many
years, possibly between 5 and 10.
4
However, even after 15 years, apart from
the odd bit of medical and nutritional
research, most of what we know about
alpacas and alpaca genetics is a result of
translation from other species that have
been studied for so much longer.
Recessive genes are only expressed when two recessives are
present in the same chromosome.
If both genes that make up a chromosome are the same for a
trait, this is referred to as homozygous . If the genes present
in a chromosome are different for a trait then it is said that an
individual is heterozygous for that trait.
Dominant genes are expressed whether they are present as one
gene of a heterozygous pairing or present as two genes in a
homozygous pairing. Dominant genes tend to hide (or
dominate) the expression of recessive genes. The result of
this is that recessive genes can pop up as surprises when they
pair up in a mating where the two parents carry them masked
by dominant genes in the heterozygous state. (e.g two whites
producing a black offspring).
Dominant genes rarely cause surprises, as they are expressed
(seen) in one or both of the parents. Because of this dominant/
recessive nature of genes, what you see is not the complete
picture of what you get. The hidden parts may be good, or
bad. Understanding the hidden parts can be advantageous to
breeding programmes.
In alpacas a good, simplified, example of this dominant and
recessive behaviour of genes is in the way in which the multi
colour attaches to alpacas. The multi gene is a recessive gene,
so it only expresses itself when present in double doses. But it
can hide behind dominant colour genes and cause the occasional
surprise.
When representing the non-multi as capital P and a multi as
lowercase p, we can see how a mating of different animals can
produce varying results.
Full colour looking alpacas can have gene pairings of “PP”, or
“Pp”. Multi’s are all “pp”. Note we use the word “solid” here
to denote “not multi”. Could however have white feet or face.
Each offspring is heterozygous for the multi trait, none are
multi’s but all carry the recessive gene forward to later
generations. Similarly (not illustrated) a homozygous colour
alpaca (PP) over a heterozygous colour alpaca (Pp) will always
produce colours, not multi’s. 50% of the offspring will be
homozygous, 50% heterozygous.
2)
P
p
p
Pp
pp
p
Pp
pp
Parent 1 homozygous
colour
Parent 2 multi
Offspring — solid
Offspring — multi
Here the heterozygous male across a multi will throw multi
50% of the time. The other two offspring carry the recessive
gene but do not express it.
3)
P
p
P
PP
Pp
p
Pp
pp
Parent 1 homozygous
colour
Parent 2 heterozygous
colour
Offspring — solid
Offspring — multi
Here two heterozygous alpacas. looking full colour, produce
25% homozygous colour, 50% heterozygous colour and
(surprise!), 25% multi.
4)
p
p
p
pp
pp
p
pp
pp
Parent 1 Multi
Parent 2 multi
Offspring — solid
Offspring — multi
1)
P
P
p
Pp
Pp
p
Pp
Pp
Parent 1 homozygous
colour
Parent 2 multi
Offspring — solid
Offspring — multi
Here, unsurprisingly, a multi across a multi will always produce
a multi. Similarly two homozygous colour animals will always
produce homozygous colour offspring.
The breeding question is how do you know if your alpaca is
homozygous or heterozygous for colour? The answer is mate
to a multi, several times — maybe 5 or 6. If no multi offspring,
homozygous! Beware, rare in males!
Unfortunately genetics is not this simple and traits are usually
controlled by several genes at different locations working
together — empirical evidence indicates even the multi gene
may not be straight mendalian.
You can also get genes that interact with other genes in ways
to produce very negative effects (a fatal combination).
An example in horses is in “paint” horses where a white foal
carries a lethal combination of genes.
GENETICS AND SELECTION
When people talk about genetics, and selection of alpacas, they
are generally using “genetic” to mean something totally
5
different. There is no study of genes. There is a simple, and
sometimes brief, look at estimating the extent to which a known
parent can influence an offspring. Selection simply means some
alpacas get to reproduce more than others!
Selection is normally undertaken at three different “levels”.
1)
2)
3)
By assessing the progeny of the alpaca: Genetic quality
(genotype) is best judged by looking at the subject alpaca’s
offspring — not just one or two, not just the best ones
shown by the “seller”, but all of them. Consistently
good progeny will normally equate to strong genetic
strength. However many alpacas do not yet have progeny,
or especially if females, have only 1 or 2 offspring, so
other methods have to be implemented.
By reviewing the pedigree of the animal: Younger
animals, or newer studs, have no progeny. In this case
the pedigree of the alpaca (available on two registries —
USA and Australasia) can help get a view of the possible
genotype of the alpaca. South American countries have
not yet developed registries meaning imports from these
countries often have no distinct pedigree records.
Pedigree is a reasonable way of assessing genotype, but
keep in mind though that this can be inexact as, unlike
assessing progeny, there is no certainty that the parents’
attributes have passed to the offspring under
consideration.
Parents with good progeny records, siblings with show
winning records and sires used by respected breeders are
good indications that the offspring should carry the quality
traits of the parent.
Pedigree is harder for the newcomer, because it assumes
prior knowledge of world renowned bloodlines. This
means research is required. Again the Registry database
helps, and show records are now available through
Australasia.
Keep in mind though that naming a stud “Captain
Fantastic”, does not make it fantastic and a stud named
“Supreme Alpacas” does not necessarily produce them!
So when all else fails, you can assess the phenotype of
the alpaca: How an alpaca “looks”. Phenotype can be a
reasonable proxy for underlying genotype, but
unfortunately not always.
Assessment of the
phenoytpical attributes of alpacas will be covered in the
next article.
So line breeding concentrates genetic similarity in the offspring.
It concentrates good genes, and it concentrates bad genes. The
former leads to excellence and the latter to disaster.
Linebreeding often leads to the expression of two recessive
genes with lethal or fatal results. Line breeding should
therefore be practiced only with parents you know a lot about,
and that you are fairly certain have a reduced number of bad
genes. Line breeding also goes hand in hand with a heavy and
definite culling policy for “bad” progeny and their parents.
With the recognition of just a few “venerable ancestors” in the
Australasian herd we are starting to get them appearing several
times in pedigree certificates. We are also seeing more talk
especially in Australia about closer relationship line breeding.
This should be approached with caution. A review of the register
will still point to a number of genetic mistakes or unexplained
faults occurring with offspring from the best and most used
studs. It is understood that genetic fault is at a fairly high level
in South American herds, and our alpacas are not many
generations out of that continent.
In some breeds, a sire is tested across 11 of his daughters and
if nothing untoward occurs he is considered OK for
linebreeding, maybe some similar approach should be taken
by those who want to line breed alpacas successfully?
As with all linebreeding programmes there is a need for “new
blood” every so often to bring back “hybrid vigour” to the
offspring.
When thinking about linebreeding keep in mind the old saying,
linebreeding is called inbreeding when it goes wrong!
GENETICS AND OUR INDUSTRY
The most talked about genetic influences in the industry today,
are
1) Fibre genetics
2) Colour genetics
3) Suri/huacaya (fibre) genetics
These genes are only a very small minority of the genetic pack,
and no-one has a clue which genes have what influence in what
combination.
Line breeding is practiced in most established livestock
industries, and this can be close (father/daughter), or more
remote where there are common ancestors.
So when we talk about fibre genetics we actually start talking
about one aspect only. Heritability of fibre traits — the degree
to which attributes, such as fineness, density, staple length,
lustre, character or crimp etc, get passed on from parents to
offspring.
Because each party to a mating contributes 50% of the genes
each, the more the genes are similar in the two parents, the
more likely it is to have uniformity and similarity of genes
passed to the offspring. Uniformity is generally something
In alpacas we latch onto the fibre heritabilities of merino sheep,
which appear (given limited comparative data) to have similar
heritabilities to alpacas. Fortunately these heritabilities appear
to be comparatively strong, and there appears to be a high
GENETICS AND LINEBREEDING
6
breeders like to see in a mating situation and leads to the
expression “peas in a pod” when the offspring turn out to be
very similar in the characteristics they display.
chance of some of these fibre traits being passed along.
This allows us to select parents for traits such as fine fibre for
example and there is a high likelihood that fine fibre will result
in the offspring.
When we talk about colour genetics, we are basing our
information on at least three theories on colour genetics, two
of them right down to gene identification and interaction (see
the article on a comparison of these theories in this issue).
However it is disappointing that there is little commonality
between the results of the three theories! Certain helpful
pointers come out of each study, and there are one or two points
of agreement but nothing to give confidence that we, as
breeders, have got it anywhere near right yet.
You may think that the theories on Suri/Huacaya (fibre)
genetics which are rooted in a basic 2 gene dominant/recessive
mendalian relationship, are fairly well accepted by now, but
beware as there are some new controversial challenges about
to be thrown out in this area that may cause a “think again”.
Watch this space!
Don’t forget that genes control all other positive and negative
attributes including but not limited to size, temperament and
fertility, and any attributes can be selectively bred for.
GENETICS AND THE FUTURE
What it comes down to is that genetic study is a huge and
imprecise science. Indeed genetics is not a science of prediction
of the specific, but rather a science of the prediction of the
range of possibilities. Even when genetic makeup is far better
understood than it is now, it will be great at predicting the
average and range of an attribute across the next 100 crias, but
not what the next one will be.
As alpaca breeders we have much to gain by understanding
the genetic make up of our animals. By selecting for the most
favourable gene combinations and conversely eliminating the
worst ones, we can influence nature’s natural gene “jiggling”
to bias towards a more positive and required outcome. Not
genetic engineering, but certainly more than natural selection!
To finish with a couple of quotes, take from them what you
will:
“As the industry develops, and becomes more discerning,
studs with proven genetic superiority will prosper over those
who display pseudo genetic hype” — G Davis, AgResearch.
“If you aim for the middle of the road, all you get is run
over” — Anon
FOR LIVESTOCK INSURANCE REQUIREMENTS
• All risk mortality cover.
• Full policy extensions available including:
•
•
•
•
•
Permanent Infertility for males.
Import/Export cover.
Tuberculosis extension.
Herd cover at reduced rates.
Obligation free quotes.
• Underwritten by London based long
established insurers.
Contact Paul Harper or Tracey Cairns.
Tel: (021) 933-164
A/H: (03) 980-3940, Fax: (03) 337-9221
Email Paul: [email protected]
Email Tracey: [email protected]
P.O.Box 28167
Christchurch
New Zealand.
www.mistyridgealpacas.co.nz
7