Alpaca World Magazine Summer 2005 - Classical MileEnd Alpacas

As animal breeders, what are ourgoals and objectives? Why arewe mating our animals, and whyare we doing it the way we are? Is thegoal to produce more alpacas andincrease the size of our individual herdas well as the ‘national herd’? Are webreeding animals to replace our stock?Are we attempting to breed in such away that the descendants will be ‘better’than the present generation? What isthe ‘best’ alpaca anyway? Is our goal acombination of all of these? If so, whichoutcome is the most important?Of course animal husbandry,management and veterinary practicescontribute greatly to the quantity andquality of alpacas in our herds. Othersmore experienced in these arenasthan this author have written on thesedisciplines, and I will not be addressingany of these topics directly. These aspectsof animal breeding are of inestimableimportance, yet they are all under girdedby each animal’s individual genetic makeup, and the gene frequencies in the genepool of the herd at large.The purpose of this article is todescribe ways that we can progresstoward our goals by using the principlesof genetics as they apply to animalbreeding. The author assumes thatthe reader has some knowledge of thefundamentals of genetics and Mendelianinheritance, and this article will beginto address some of the slightly moreadvanced concepts.As animal breeders there are threemain factors that we must consider inorder to produce the next generation ofoffspring: Traits, Selection and Mating.TraitsTraits refer to the characteristics of analpaca that we have an interest in andcan observe, evaluate and/or measure.Traits can be thought of in differentclasses. Willis 1 has described fi veclasses of traits. Fitness traits; whichin alpacas would be such things asconception rate, gestation length andsurvival ability. Production traits; onewould be fl eece weight. Quality traits;represented in alpacas by fi ber diameter,fi ber color, etc. Type traits; these includesuri, huacaya, pinto, etc. Behavioraltraits; these might be friendliness,aggressiveness, ease of halter training,‘mothering’ ability, etc. Willis also states,‘It is a basic principle of animal breedingthat the more traits one seeks to includein a breeding programme, the harderthe task will become. It is thus essentialto decide which traits are crucial andinclude these but keep this number tomanageable levels’.Some traits are observable andsubjective, such as color, gait, or headshape. Others are levels of performanceand lend themselves to more objectivemeasurement like birth weight, staplelength or days of gestation. A givenanimal’s value for any of these traits isreferred to as its phenotype. Sometimestraits and phenotypes are confused.One might say, ‘High fl eece density is acommon trait of this line of alpacas.’ Thetrait, of course, is fl eece density. ‘High’is the description of a phenotype forthis trait.The phenotype for any trait is theresult of the combined effects thegenes an animal has inherited andenvironmental infl uences it has beensubjected to throughout its life. As aformula we could say: P = G + EThe other two main factors, Selectionand Mating, deal with decisions thealpaca breeder makes in an attempt toimprove the phenotype seen in the nextgeneration. By utilising genetic principlesand animal breeding technology tochange the genetic portion of the aboveequation, the breeder hopes to fashiona phenotypic expression that is closer tothe goal of the ‘best alpaca’, whateverthat may be. Of course, each breeder’svisions will be different, and hence so willtheir breeding goals be different.SelectionSelection, the second major factor,affects the gene frequencies of the nextgeneration by deciding which animalswill reproduce and which ones will not.Selection also implies a process referredto as culling, which means selectingthose animals that will not be allowedto breed. Culling then means thatthe animal will not exert any geneticinfl uence on the next generation ofthe herd. Males are often culled bycastration, females by holding themout from mating. A breeder can cull ananimal from their herd’s gene pool byselling it to another breeder. While thiswill have its effect on that particularherd, the genetic infl uence of that animalis not removed from the gene pool of thebreed at large if the buyer then breedshim or her with his own stock.We want to select the animals withthe best breeding values to be in ourbreeding program. Breeding value (BV) isdefi ned as the animal’s individual valueas a genetic parent, ie, a contributor ofgenes to the next generation.The effectiveness of a breeder’sselection decisions is measured by theresultant rate of genetic change. If weconsistently select the animals with thebest breeding values to be parents, wewill maximise the rate of genetic changein our herd. Unfortunately we do notknow the true BV of our animals, butmerely some estimate of these values.The estimated breeding values (EBV)may not be very accurate, and often withalpacas may be all but non-existent formost traits. The author would suggestthat determining accurate EBV for thetraits that we want to include in ourbreeding programs should be possible,and it is an opportunity for us to makeGeneticAlpaca ImprovementWayne JarvisDr Wayne Jarvis, in addition to being an alpaca breeder, lives atSixth Day Farm in Holley, NY where he breeds Saanen dairy goatsand French Angora rabbits, Registered Cormo Sheep and NaturallyColored Corriedale Sheep. He studied chemical engineering, chemistryand biology, including genetics, as an undergraduate, and has beeninterested in genetics throughout his career as an oral and maxillofacialsurgeon treating developmental deformities of the face and jaws. Helectures frequently around the world on scientifi c topics, including thegenetics of animal breeding.36 | Alpaca World Magazine Summer 2005