Best Llamas for Profit

Genetics is the science of how traits pass down generation to generation. Many people think that genetics is a predictive science-accurately predicting the next baby to hit the ground. Alas, genetics does not work that way. Instead, genetics can be viewed as a science of possibilities. Genetics can help with predicting the overall range of expected types within the offspring of certain pairs. Genetics is pretty good at predicting what will happen over the next 100 babies, but not very good (in most instances) at predicting the details of the next one. Knowledge of genetics is an extremely powerful tool for animal breeders, although its strengths and weaknesses both need to be appreciated for it to yield the greatest benefits.

HOW GENES WORK

Genes, with few exceptions, work in pairs. This is an essential concept. Each individual gets one member of the pair from its sire, one from its dam. Each individual, in its own turn, donates one of each pair to its offspring. Genetics “works” on the basis of these pairs, and the interactions of the members of each pair, as well as the interactions of the different pairs with each other.

Each individual is the result of genes and environment, and the genetic component is the sum total of all those pairs. If the genes are considered to be the units of interest, then the population can be imagined as a “jiggling” of the genes down through the generations as they are mixed up and recombined into new combinations at each generational step. The animal breeder’s task is to use the favorable combinations more heavily than the unfavorable ones, so that the “jiggling” goes in a positive direction. Differential reproduction (some animals more than others) is the essence of selective breeding.

The pairs of genes can interact in different ways. Members of the pair can either be identical or different. If identical, then obviously that is the character (phenotype) that is expressed. If different, then a few different things can happen. One is that only one (a specific one) of the pair is expressed, and the other is hidden. In this case the one that is expressed is called “dominant” and the one not expressed is called “recessive”. This is a key issue - dominant genes essentially cover up recessive genes. This means that recessive genes can trail along for many generations without being expressed, until they are paired up with another identical recessive gene and are therefore able to be expressed. As a result, recessive phenotypes (what is expressed) tend to show up as surprises, and tend to not reproduce themselves very well unless mated to the same recessive phenotype, or a dominant phenotype that carries the recessive.

In some situations where members of the gene pair are different, each member shows up in the phenotype. These situations are called incompletely dominant, or codominant. Blood types are a great example of a codominant system - everything is expressed, nothing is hidden. Good examples of incomplete dominance are not documented in llamas, but are common in other species. Palomino horses are a good example - if both genes are “normal” or dark, the horse is chestnut (reddish). If one “dark” and one “light” gene are present, the horse is palomino (yellowish). If two doses of the “light” gene are present, then the horse is cream with blue eyes.

The critical concept for the way genes interact is that various mechanisms exist for hiding portions of the genome. The hidden parts may be good or may be bad, and breeding strategies can use them to advantage if carefully constructed.

A very common misconception is that common phenotypes are dominant, and uncommon ones are recessive. The relative frequency of a trait is simply a matter of gene frequency, or how many copies of a specific gene are represented in a population. The relative frequency has absolutely nothing to do with the dominance or recessiveness of a system. A good example is white horses. White in horses is dominant, and yet this color is very, very rare due to the gene having a very low frequency among horse populations. Chestnut in horses is recessive, and yet some entire breeds (such as the Suffok) are chestnut because selector has fixed the gene frequency at 100%

BREEDING PHILOSOPHY

A crucial first step for breeding programs is to decide upon a philosophy. Philosophies include conservation, improvement, and a host of others. A conservation philosophy is going to dictate different goals and actions than a strict animal improvement philosophy, which is also going to be different than a companion animal philosophy. No single philosophy is wrong, they are just each different. Many discussions, and even some heated arguments, can stem from different breeders having different philosophies. The variety of philosophies is probably good for the overall health of the genetic resource, since each breeder is doing something slightly different and this helps the population have desired levels of genetic diversity.

Philosophy drives goals. Why are animals being bred, and what is the mental picture of the ideal animal? Is the goal show wins? Conformation? Certain fiber characteristics? Certain colors? Without answering these questions (honestly) very little progress is possible in a breeding program. Progress is difficult enough as it is - and is definitely enhanced by acknowledging a philosophy and the goals that go along with it.

SELECTION

Selection simply means that some animals get to reproduce more than do other animals. Selection differential indicates the relative proportion of animals that do reproduce. In alpacas the selection differential for females is pretty high, since close to one hundred percent. That is, nearly every female is used for reproduction and therefore gets a chance to pass along her genes for good or ill. For llamas this is much lower.

For males the selection differential is smaller, but how much smaller varies with individual breeders. The selection differential for dairy bulls is probably the smallest of the common domesticated species, since by artificial insemination only one bull in thousands is used. For llamas the selection differential for males is smaller than for females, but still only moderate when compared to many other species.

The point of selection is that it is what dictates the form of the succeeding generations. Selection determines which traits get passed along and which do not. The results of selection are easy to demonstrate for Peruvian versus North American alpacas. While certainly individual breeder’s goals differ in both locations, the general trend is that Peruvians favor white, and favor huacaya fiber. In North America the opposite is generally true (with exceptions, of course). The result of the selection exerted in the two areas is that the gene frequencies, and phenotypic frequencies, of the two alpaca populations are going to differ because the selection pressures are different.Selection changes gene frequencies, and that limits the component genes in the population that can jiggle down to the next generations. The desirability of this is hardly debatable for disease traits (get rid of the genes, get rid of the disease), but is more subjective for other traits such as color and fleece variants.

BREEDING STRATEGIES

Breeding strategies include inbreeding and outbreeding. There are varying levels of these, and each has an appropriate place in a healthy population structure. Each does something different, and they are value neutral - being good or bad in different situations and for different goals.

Inbreeding includes any mating in which the mated animals have ancestors in common. That is, the mating “doubles up” on certain ancestors. This can happen to varying degrees. When first-degree relatives (parent to offspring, sibling to sibling) are mated, the result is generally regarded as inbreeding. When more distant matings are accomplished (grandparent to grand offspring, aunt to nephew) the matings are more likely to be considered linebreeding. There is no magic point at which the boundary between inbreeding and linebreeding is drawn.

Inbreeding tends to make animals more genetically uniform. That is, the pairs of genes are more likely to be similar than they are likely to be different. This has a variety of consequences, which can be good or bad depending on what goes into the mix. That is, good things become consistent, or bad things become consistent. Therefore, inbreeding must be accompanied by selection. Very, very good and consistent populations of animals in a variety of species have been accomplished by inbreeding to varying degrees. The key strength of an inbred or linebred animal is that since the gene pairs are generally alike, the animal produces very uniform offspring. This is one of the main strengths of a linebred animal - predictability.

A very important aspect of inbreeding is that as it proceeds and the gene pool gets narrower and narrower, traits of general fitness tend to suffer in a population. These include reproductive traits, milk production, growth rates, and size traits. Also disease resistance traits may well suffer, although this is going to vary. The point here is that inbreeding, especially if not associated with selection, has consequences that may not be all that good.

Outbreeding tends to do the opposite of inbreeding. It tends to make populations more variable by matching up unlike members in the gene pairs. Outbred animals, since they have unlike gene pairs, tend to produce variable offspring.

Outbred matings are those that do not have ancestors in common. Outbreeding or outcrossing can vary in extent, just like inbreeding. The widest outbreeding is to mate a llama to an alpaca, guanaco, or vicuña. The trick to outbreeding is that the products of the initial cross are very likely to be very uniform. If 100 babies were produced, they may actually end up looking like near copies of one another (to the extent possible in any animal related endeavor). So where is the variability? It is locked up in the fact that for each of these outbred animals the gene pairs are unlike, and so when these uniform animals are used for reproduction they in turn produce extreme variability.

Outbred animals can therefore be very, very productive animals. The initial outbred product can be uniform, and they also have excellence for those very traits that suffer under inbreeding: vitality, reproduction, and growth. The peculiar qualities of inbreeding and outbreeding are used to great advantage in some animal industries. Egg laying chickens, for example, are the result of crossing inbred parental or grandparental lines. The resulting hens are uniform as a consequence of the linebreeding behind the parents, which constrains each gene pair to be one each of specific genes. They are also vigorous since the gene pairs are unlike. And - they are useless for anyone else to breed from, since they will produce uneven offspring. This tactic protects the investment of the breeder companies; since it does not matter into whose hands the actual laying hens fall.

So which is best - inbreeding or outbreeding? Depends entirely on the breeder’s goals. Inbreeding tends to bring recessive genes to the light of day by forcing them into pairing with one another. That can be good or bad, depending on the trait and the selection imposed on it. Alternatively, outbreeding tends to hide recessive genes. Note well, though, that these genes are still in the population, and in a form against which selection cannot occur since they are not expressed. Some deleterious genes could therefore become very widespread in a population before even discovered. A good example is the combined immunodeficiency of Arabian foals. About 20% of Arabian horses carry this gene, resulting in about 4% affected foals being born. The gene was allowed to get to this high frequency by lack of selection on the part of breeders.

FIBER CHARACTERISTICS

Fiber characteristics are very important to alpacas, especially if they are to enter mainstream production agriculture. The alpaca fiber is unique, and its uniqueness is important to foster and enhance. Llamas can have fiber the equal of alpacas, though when taken as a whole, llamas in general have poorer quality fiber. That means that llama breeders interested in high-quality fiber production have their work cut out for them.

Fleece quality varies in a host of ways, many of them strongly influenced by genes. The main list of traits that are largely genetic includes growth rate, density, fineness, uniformity, handle (texture, feel), and color. Color is the easiest, but the most important traits are probably growth rate, density, uniformity, and fineness. All of these are affected by environment as well as by genes, but fortunately the genetic component is relatively large and so selection can be based on individual performance. That is, looking at the animal itself is accurate enough, and progeny testing does not add much.

SURI

The suri fleece variant is a most interesting variant, since the resultant fleece is unlike any other mammalian fiber. As a spinner I find it something like silk, and very different from other mammalian fibers. Suri inheritance is complicated. The suri variant is reported to be inherited as a dominant trait by some Australian researchers. This means that huacaya to huacaya should never (and one is reluctant to use that word) produce suris, while suri to suri could well produce a proportion of huacaya offspring.

Unfortunately this simple pattern does not tell the whole truth, since (if rarely) huacaya to huacaya matings produce suri offspring. In addition, the results of mating suri to huacaya consistently produce more huacayas than expected. These phenomena point to a genetic mechanism for inhibiting suri expression in at least some huacayas.

Given the present state of knowledge on Suri genetics, the best recommendation at this time is that most matings involving Suris should be Suri to Suri. This avoids complicating the gene pool by producing ‘hidden’ Suris within the Huacaya gene pool. It is important to realize that in some instances it makes perfect sense to use Suri x Huacaya matings. This is especially for introduction of certain fiber or color characters into the Suri, or for a handful of other helpful and appropriate reasons. Matings between the two types, though, should generally be for reasons other than simply increasing Suri numbers, since that strategy will eventually complicate things more than it will help them.

Suri llamas, in contrast, bring a host of more complicated issues with them - largely because of their rarity. For suri llamas it is unreasonable to eliminate suri x nonsuri (one hesitates to indicate “huacaya” in this sense) matings. However, the nonsuri mates should be carefully chosen in order to maximize the production of high quality suri offspring. A few strategies that can do this are to assure minimal guard hair is present. One very good strategy is to preferentially use nonsuris that have been produced by suri parents. These animals, by virtue of their genetic background, are likely to have a number of characteristics that lead to good suri phenotype when paired up with the major suri-producing genes.

DEFECTS

A variety of physical defects occur in llamas, and are important to breeders of llamas since the production of defective babies has two negative aspects. One negative is the loss or suffering of the baby. The second loss is the tarnished image of the parents producing the defective baby. Few (if any) defects have yet to be proven genetic in origin, but certainly some are very good candidates: choanal atresia, angular limb deformities.

In the event that some defects are shown to be due to simple single genes, then selection becomes pretty easy. The affected animals can be culled, and with modern genetic techniques it is reasonable to expect there to be blood or DNA tests developed to spot carriers. Carriers can then be used wisely in reproduction. If a carrier is only average, the best idea is to cull. If a carrier has some other excellent traits, then the carrier could be used on a limited basis, hoping to replace the carrier with a noncarrier offspring that is excellent. The key to the single gene traits is that on average half of the offspring will be carriers, but the other half will not. A single gene can therefore be tracked, and eliminated with careful breeding practices.

Other defects are due to polygenes. These traits include some, such as cardiac defects, where animals have no defect until the number of genes passes some threshold. Above the threshold the defect is expressed, and with increasing numbers of genes the severity of the defect is increased. The trick with these, though, is that since the defect is associated with many genes it is impossible to use breeding practice to eliminate these. Any animal with the defect, and any animal that is a first degree relative (parent, sibling) is more likely to have lots of these genes than is a random member of the population. That means that with few exceptions selection should be sure and firm against bearers of such defects as well as their first degree relatives. Again, philosophy will come into play here.

It is critically important to react to defects appropriately - worry about them when it is worthwhile, and ignore them if they are very rare. The incidence rate of defects is therefore important, and usually unknown. If a defect occurs in only one of 200 births or fewer, it is probably not worth worrying about. If 1 in 100 or 1 in 50, then it is worth worrying about. Some sort of anonymous, accurate tracking system is needed simply to track the incidence of these, so that an increase can be met with appropriate action, while rare ones can largely be ignored.

MATING OF EXTREMES (assortative mating)

The issue of defects brings up the subject of “assortative mating”. This simply means the deliberate mating of animals that are similar (positive assortative mating) or very different (negative assortative mating).

Positive assortative mating, when accomplished with conformational traits, translates into the mating of similarly extreme animals. This, in many species, can include the mating of the very large to the very large, very small to very small, or any other peculiarities of conformation (cute, short heads, on and on). In many species, dogs being the best example, this ends up giving us extreme breeds such as the dachshund, Boston terriers, Irish Wolfhounds, Saint Bernards, and a host of others that fall outside the norm for the original species. This can be bad or good, but frequently brings along associated defects. Some of this depends on exactly what goes into the original mix.

In cats, for instance, short-headedness is desired in the Persian, and these animals have very little problem (unless the extreme end has some trouble breathing). Selection for a similar head shape in the Burmese has included a single gene that results in brain abnormalities in some of the kittens. The lesson here is that extremes can cause animals to trespass over the limit of soundness. This is especially so for conformational extremes, and usually not for extremes of fiber quality.

The take-home lesson is that overall soundness and conformational quality needs to be the bottom line minimum when selecting breeding stock, and that slow progress with soundness is better than fast, extreme progress that might well leave overall soundness behind.

About the Author:

Dr. Sponenberg is Professor of Pathology and Genetics at the Virginia-Maryland Regional College of Veterinary Medicine. Genetics contributions includes publications in peer-reviewed journals and the book Equine Color Genetics. He is the convener of the color group of the International Committee on Genetic Nomenclature of Sheep and Goats. He is active in rare breed conservation, and serves as the technical coordinator for the American Livestock Breeds Conservancy. dpsponen@vt.edu; (540) 231-4805.

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