Fleece Genetics

  • A Possible Link Between Alpaca Staple Length and Depth of Color

    As part of our work using data from the Alpaca Owners’ Association (AOA) EPD database to examine whether fleece color affects the expression of fleece traits, we looked at the relationship between color and the EPDs for staple length for over 1300 Huacaya males. We found a pattern that suggests that faster fleece growth rates have a visible dilutive effect on the color we see in fawn, beige and white animals, by increasing the length of the hair relative to the amount of pigment produced to color it.More »
  • Alpaca Fiber Quality and Analysis

    I. Background and current research interests. II. Recent cooperative studies with alpacas. III. Animal fiber metrology. IV. Genetic tools that are being used to improve alpaca fiber quality and production.More »
  • Another Tool to Help Breed for Micron Uniformity

    Alpaca breeders have long noticed that as they breed for incremental fleece fineness in their animals, the standard deviation of diameter among those fibers also tends to decrease, the result of an apparent and generally favorable genetic link (or links) behind these economically important phenotypic traits. However, because the uniformity measurements they rely upon do not segregate it, they have generally paid less attention to directly managing the genetic sources of micron uniformity that are not linked to those that contribute to incremental fineness. This has been true even though those unrelated genetic sources of uniformity appear to be nearly as important to micron uniformity as those that also contribute to fineness.More »
  • Association of Microsatellite Markers With Fiber Diameter Trait in Peruvian Alpacas (Vicugna pacos)

    A total of 140 Peruvian alpacas of two breeds (Huacaya and Suri) were analyzed for 69 microsatellite markers, in order to make a first approximation to the association analysis with the alpaca fiber diameter, which is the main trait related to alpaca fiber quality. A total of 599 alleles were observed across the two breeds, with a global average of 8.68 alleles per locus. Mean gene diversity in the total population was 0.701, meanwhile both breeds exhibited similar values of 0.686 (Suri) and 0.695 (Huacaya). On the other hand, the values from the inbreeding coefficient (FIS) were 0.154 (Suri) and 0.162 (Huacaya) in both breeds, being the genetic differentiation low between these populations (FST=0.022), and with a gene flow (Nm) value of 9.3. The hierarchical AMOVA corroborated that the differentiation between both breeds only explained the 2.5% of genetic variability. The analysis of association between the microsatellite markers panel and fiber diameter trait was done following an innovative methodology, which was focused in two steps. In the first one, animals were sampled according to a selective genotyping strategy, resulting in six microsatellite markers (LCA68, GLM6, LGU50, VOLP59, LCA85 and LCA90) associated with the genotypes carrying the hypothetical major gene. In the second step, the analysis revealed four significant associations of microsatellite loci (LCA68, VOLP59, LCA9O and GLM6). The subsequent DUNCAN test was used to determine the statistical differences among the fiber diameter EBV means, that corresponded to the different alleles. Eleven out from fourteen alleles of the following loci LCA68 (199, 189, 201, 197, 203 and 205), VOLP59 (112 and110) and LCA90 (243, 229 and 227), showed positive effect (decreasing fiber diameter), and only three alleles for the following loci LCA68 (195) and LCA90 (231 and 249), gave a negative effect (increasing fiber diameter).More »
  • Characterization of the Effect of Melanocortin 1 Receptor, a Member of the Hair Color Genetic Locus, in Alpaca (Lama pacos) Fleece Color Differentiation

    Little is known about the inheritance and influence of the fleece color gene Melanocortin 1 Receptor (MC1R). Melanocortin 1 Receptor (MC1R) is a well-known gene responsible for red versus black fleece pigmentation and is hypothesized to be a candidate gene for variation in alpaca coloration patterns. Inheritance of red versus black pigmentation in the context of genetic mutation is well understood in many domesticated mammals. We characterized the MC1R gene in a population of multi-colored alpacas in order to better understand its effect on coat color in the alpaca. Our characterization of the alpaca MC1R gene revealed 11 mutations. Of these one is a 4 bp deletion, four are silent mutations and six are single nucleotide polymorphisms (SNPs) that alter the amino acid sequence (T28V, M87V, S126G, T128I, S196F, R301C). No mutation correlated completely with fleece color in alpacas at the MC1R locus. This may be due to the epistatic relationship of MC1R with other coat color genes especially agouti signaling protein (ASIP).More »
  • Fibre Diameter Measured in the Post-Weaning Age Window is Genetically the Same Trait as Yearling Fibre Diameter

    Yearling fibre diameter profiles from the OFDA2000 instrument were used to derive records on mean and coefficient of variation (CV) of fibre diameter at multiple points in the post-weaning age window, from 20 to 90% of staple profile length. Genetic correlations were calculated between these traits and their yearling equivalents. Results showed that from 50% of the staple profile and higher, post-weaning fibre diameter is genetically the same trait as yearling fibre diameter. Although the derivation of CV of fibre diameter was less accurate, genetic correlations with the yearling expression were greater than 0.9 for all except one percentile point. The expected correlation between post-weaning and yearling fleece weight was also derived, and under simple assumptions it is not unreasonable to expect estimates of genetic correlations greater than 0.9.More »
  • Fleece Variation in Alpaca (Vicugna pacos): A Two-Locus Model for the Suri/Huacaya Phenotype

    Genetic improvement of fibre-producing animal species has often induced transition from double coated to single coated fleece, accompanied by dramatic changes in skin follicles and hair composition, likely implying variation at multiple loci. Huacaya, the more common fleece phenotype in alpaca (Vicugna pacos), is characterized by a thick dense coat growing perpendicularly from the body, whereas the alternative rare and more prized single-coated Suri phenotype is distinguished by long silky fibre that grows parallel to the body and hangs in separate, distinctive pencil locks. A single-locus genetic model has been proposed for the Suri-Huacaya phenotype, where Huacaya is recessive.More »
  • Genetic Correlations Among and Between Wool, Growth and Reproduction Traits in Merino Sheep

    Data from seven research resource flocks across Australia were combined to provide accurate estimates of genetic correlations among production traits in Merino sheep. The flocks represented contemporary Australian Merino fine, medium and broad wool strains over the past 30 years. Over 110,000 records were available for analysis for each of the major wool traits, and 50,000 records for reproduction and growth traits with over 2700 sires and 25,000 dams. Individual models developed from the single trait analyses were extended to the various combinations of two-trait models to obtain genetic correlations among six wool traits [clean fleece weight (CFW), greasy fleece weight, fibre diameter (FD), yield, coefficient of variation of fibre diameter and standard deviation of fibre diameter], four growth traits [birth weight, weaning weight, yearling weight (YWT), and hogget weight] and four reproduction traits [fertility, litter size, lambs born per ewe joined, lambs weaned per ewe joined (LW/EJ)]. This study has provided for the first time a comprehensive matrix of genetic correlations among these 14 wool, growth and reproduction traits. The large size of the data set has also provided estimates with very low standard errors. A moderate positive genetic correlation was observed between CFW and FD (0.29 +/- 0.02). YWT was positively correlated with CFW (0.23 +/- 0.04), FD (0.17 +/- 0.04) and LWEJ (0.58 +/- 0.06), while LW/EJ was negatively correlated with CFW (-0.26 +/- 0.05) and positively correlated with FD (0.06 +/- 0.04) and LS (0.68 +/- 0.04). These genetic correlations, together with the estimates of heritability and other parameters provide the basis for more accurate prediction of outcomes in complex sheep-breeding programmes designed to improve several traits.More »
  • Genetic Parameter Estimation of 16-month Live Weight and Objectively Measured Wool Traits in the Tygerhoek Merino Flock

    Genetic evaluation systems require the accurate estimation of genetic parameters. The genetic, phenotypic and environmental parameters for live weight and objectively measured wool traits were estimated for a South African Merino flock. Records of the Tygerhoek Merino resource flock were used to estimate these parameters. The database consisted of records of 4 495 animals, the progeny of 449 sires and 1 831 dams born in the period 1989 to 2004. The pedigree records used have been collected between 1969 and 2004. Direct heritability estimates (h²a) for 16-month live weight (LW) and objectively measured wool traits ranged from 0.20 for staple strength (SS) to 0.68 for fibre diameter (FD). Maternal heritability estimates ranged from 0.05 for LW and FD, to 0.10 for clean fleece weight (CFW). The proportion of the total phenotypic variance due to the maternal permanent environment variance (c²pe) amounted to 5% for fleece weights. The genetic correlation between animal effects for LW, greasy fleece weight (GFW) and CFW were -0.28, -0.65 and -0.70 respectively. The genetic correlation between LW and CFW was positive, but low at 0.14. The other important genetic correlations among the wool traits ranged from low to high, and were variable in sign ((for GFW with CFW (0.87) and with staple length (SL – 0.18); CFW with clean yield (CY – 0.33) and with SL (0.29); FD with CY (-0.09), with SL (0.15), with SS (0.40) and with standard deviation of FD (SDFD – 0.38):CY with SL (0.33) and with SDFD (0.10); SS with coefficient of variation of FD (CVFD – -0.57) and with SDFD (-0.28); CVFD with SDFD (0.87)). These results suggested that worthwhile responses in the objectively measured traits can be achieved through direct and indirect selection.More »
  • Genetic Parameters and Relationships Between Fibre and Type Traits in Two Breeds of Peruvian Alpacas

    Four fibre traits (fibre diameter, FD; coefficient of variation of FD, comfort factor; and standard deviation of FD) were jointly analysed with six subjectively scored type traits (fleece density, crimp, lock structure, head, coverage, and balance) in two breeds of Peruvian Altiplano alpaca (Suri, SU; and Huacayo, HU) to ascertain their genetic relationship. A total of 2405 fibre records and 2194 type scores were available for the HU breed whereas these figures were 709 for fibre records and 650 for type scores for the SU breed. Estimated heritabilities for fibre traits were moderate to high, ranging from 0.565 to 0.699 in the SU breed and from 0.255 to 0.417 in the HU breed. Genetic and permanent environmental correlations between fibre related traits were extremely similar across breeds suggesting that these traits are fairly the same. Heritabilities estimated for the type traits tended to be lower than those estimated for the fibre traits particularly in the SU breed (ranging from 0.173 to 0.272). Fibre and type traits were, in general, genetically poorly correlated except for crimp in the HU breed, which had favourable correlations, from moderate to high, for fibre traits. In Altiplano areas in which fibre performance recording could not be implemented, crimp scoring makes it feasible to carry out mass selection in the Huacayo breed and furthermore include rural communities in national or regional selection programmes.More »
  • Genetics of Fibre Production and Fleece Characteristics in Small Ruminants, Angora Rabbit and South American Camelids

    This paper reviews genetics of fibre production and fleece characteristics in small ruminants, Angora rabbit and South American camelids with a special distinction between single-coated (SC) and double-coated (DC) species. Considering the biology of fibre production, there are variations in coat composition and structure, fibre growth pattern and fibre structure and quality between these two main kinds of fibre-producing animals. In SC species, all fibres are nearly similar in dimensions and are produced from individual follicles that have a very long period, essentially permanent, of active growth without a synchronous phase of rest between follicles. In contrast, in DC species the fleece comprises a coarse outer coat and a fine inner coat with variations of coat composition and structure, and fibre growth pattern according to the season with a well-defined duration of fibre growth. Genetic basis of hair growth pattern, coat composition and fibre structure are different between species. In small ruminants, these coat characters are additive and because of several genes whereas in rabbit, several autosomal recessive genes determine fibre growth, coat composition and structure. In alpaca, the fleece type (Suri or Huacaya) is determined by a single dominant gene. This paper also reviews genetic parameters of fibre production traits in Angora goat, Angora rabbit and alpaca in which many aspects of the genetic basis of fibre production are analogous. There are many traits controlling both fibre quality and fibre quantity, and most of these traits tend to be moderately to strongly inherited so that a rapid genetic progress in any traits is possible and indeed has been achieved. However, there are differences in breeding programmes. In DC Angora rabbit, selection for one single trait, the easy measurable total fleece weight has general beneficial effects on fleece quality. However, because of antagonistic relations between qualitative and quantitative traits in SC species, achieving this goal requires a multi-trait selection index approach. Gene mapping studies have recently identified several putative quantitative trait loci and major genes affecting fibre and fleece characteristics in sheep, goat and rabbit are reviewed. The whole genome sequence of sheep and rabbit will be available in the near future and the use of high-density single nucleotide polymorphism chip will allow fine mapping and dissection of the genetic basis of many production traits including fibre production and fleece characteristics. The application of these techniques will thus contribute to improving the efficiency, profitability and sustainability of small ruminant and rabbit fibre production.More »
  • Genome-Wide Association Study for Wool Production Traits in a Chinese Merino Sheep Population

    Genome-wide association studies (GWAS) provide a powerful approach for identifying quantitative trait loci without prior knowledge of location or function. To identify loci associated with wool production traits, we performed a genome-wide association study on a total of 765 Chinese Merino sheep (JunKen type) genotyped with 50 K single nucleotide polymorphisms (SNPs). In the present study, five wool production traits were examined: fiber diameter, fiber diameter coefficient of variation, fineness dispersion, staple length and crimp. We detected 28 genome-wide significant SNPs for fiber diameter, fiber diameter coefficient of variation, fineness dispersion, and crimp trait in the Chinese Merino sheep. About 43% of the significant SNP markers were located within known or predicted genes, including YWHAZ, KRTCAP3, TSPEAR, PIK3R4, KIF16B, PTPN3, GPRC5A, DDX47, TCF9, TPTE2, EPHA5 and NBEA genes. Our results not only confirm the results of previous reports, but also provide a suite of novel SNP markers and candidate genes associated with wool traits. Our findings will be useful for exploring the genetic control of wool traits in sheep.More »
  • Heritability of Individual Fiber Medullation in Peruvian Alpacas

    The aim of this research was to estimate for the first time the heritability and genetic relationship between medullation and fiber diameter in each fiber by itself. A total of 21,600 fibers from 36 samples from white fleeces, 600 fibers each sample, from males between 0.4 and 10.4 years old from Pacomarca experimental farm (Inca Group, Puno, Peru) were tested using projection microscope (PM). The individual fiber diameter (FD) and the category of medullation (CM) was recorded in each fiber. CM of each fiber was assigned to one of the five categories established in the literature. The percentage of medullated fiber ranged from 12.33% to 91.67% per sample. The correlation between OFDA 100 ® medullation percentage and PM measurements was 0.79. The statistical model used for estimation of genetic parameters for CM and FD included the age as a linear and quadratic covariate as systematic effect, and the additive genetic and the permanent environmental as random effects. The pedigree that served to predict genetic values was very robust and strong, allowing obtaining reliable and significant parameters. Univariate and bivariate models were used to estimate heritability for CM and DF, as well as its genetic correlation. Different models considering CM as continuous or categorical trait were tested. The highest heritability estimate for CM was 0.36 ± 0.13 obtained using a bivariate continuous model. Using the same model, the heritability estimate for FD was 0.35 ± 0.15 and the genetic correlation between CM and FD was 0.93 ± 0.12. These results implied that selection against medullated fiber is feasible while at the same time reducing the FD in alpacas. Since measurement of CM per fiber sample was time-consuming, PM measured by OFDA 100 ® would be useful as an indicator to reduce the number of medullated fiber in alpaca fleeces.More »
  • Inheritance of Suri and Huacaya Type of Fleece in Alpaca

    The inheritance of the two types of fleece, Suri and Huacaya, observed in Alpaca (Lama pacos L.) is still not clearly defined. The objective of this work is to investigate the patter of inheritance of these two phenotypes, throughout 588 Suri x Suri and 2126 Huacaya x Huacaya offspring. The single gene and the three two-phenotype epistatic models were tested in the 19 Suri x Suri segregating families. The single dominant gene hypothesis best fitted our segregation data and could be, therefore, accepted (Gt=20.276, P=0.378). The gene frequency of the recessive Huacaya allele was 0.295, being the frequency of the dominant Suri allele 0.705. The frequency of heterozygotes, estimated in the whole population and among dominant individuals, was 0.416 and 0.455, respectively, with a “carrier” Suri to Huacaya ratio of 4.780. In three Huacaya families, 3 Suri were born, as a result of a new dominant mutation on some germinal lines of Huacaya animals. The direct mutation rate can be estimated at 0.0014.More »
  • Pigment, Curvature, and a Caution About the Assumed Heritability of Phenotypic Fleece Character

    People who process alpaca fiber into products are well aware that dark fleece behaves differently than lighter fleece in processing as well as in many final products. Even if the fineness and uniformity of a batch of dark fleeces is identical to that of a batch of white, for instance, the yarns made from those fleeces will be denser (and heavier) at the same gauge and exhibit less memory, making its performance in end products different than yarns made from light fiber. The reason for the difference is that the fibers making up the fleeces at the darker end of the spectrum of alpaca colors have less curvature than those from lighter-colored fleeces of similar fineness and length. The question is, why? The analysis below hints at a possible answer.More »
  • Quantitative Genetic Analysis of Micron Blowout in Alpacas - Fact Sheet

    For alpacas, as is the case with many fibre-producing species, the finest fibre is of the greatest value. It has been well established in many fibre-producing species that fibre diameter increases with increasing animal age; a phenomenon known as micron blowout. In addition, micron blowout can also be caused by over-nutrition, or by a combination of both factors. The results of this research confirm that micron blowout has a moderate genetic component in alpacas. Therefore, it may be possible for breeders to select animals that do not exhibit the trait (or do not exhibit it as strongly), thereby improving the yield of high quality fibre over the lifetime of an animal.More »
  • Quantitative Genetic Analysis of Micron Blowout in Alpacas - Final Report

    Some alpacas maintain fine fibre throughout life, while others suffer from significant coarsening of fibre as they age, a trait known as micron blowout. Micron blowout results in reduced productivity, through reduced yield of high quality fibre over the life of an animal. Data from a well-established alpaca herd in Peru was used in a complex quantitative genetics analysis to determine if genetics plus environment, or environment alone was responsible for micron blowout in alpacas. This project has shown that micron blowout has a moderate heritability in alpacas, and that selection against micron blowout would be successful in reducing the extent of the problem. This report is targeted at Australian alpaca breeders.More »
  • Suri and Huacaya Alpaca Breeding Results in North America

    The segregation of suri and huacaya fleece types in alpacas in the United States deviates from that expected from results of previously published studies from other regions. Suri × suri matings produced 278 huacaya and 1702 suri offspring. Suri × huacaya matings produced 89 huacaya and 56 suri offspring. Huacaya × huacaya matings produced 19,633 huacaya and 4 suri offspring. No linkage or other influence of sex was noted. These results are consistent with a single autosomal dominant gene controlling suri fleece production, with an additional relatively common genetic mechanism that can suppress the suri phenotype in some animals. These results are especially important in cases where the two fleece types are crossed with one another, as they result in a relative underproduction of suri fleeces.More »
  • The Inheritance of and Associations Among Some Production Traits in Young Australian Alpacas

    Phenotypic and genetic parameters for young Australian Alpacas are presented and compared with Alpaca reports in the literature, as well as with estimates for South Australian (SA) Merino sheep. The traits studied were greasy and clean fleece weight (GFW and CFW), fibre yield (YLD), mean fibre diameter (FD), coefficient of variation of FD (CVFD), staple length (SL) and live weight (LW). Most mean values fell within those found in the literature, except for YLD, which was greater in our study. YLD, FD, SL and LW were greater than for Merino sheep, whereas the opposite was true for GFW and CFW. The heritability was high (0.37 or greater) for all traits. The estimate for LW fell within the range in the literature, whereas for GFW and SL our values were greater. Relative to those for SA Merino sheep our estimates were greater for GFW, CFW, CVFD and LW, whereas they were lower for the remaining traits, except for SL, which had the same value. Phenotypic correlations from the literature were in broad agreement with ours. Those from SA Merino hoggets, except for some correlations involving YLD and SL, were in remarkable agreement with ours. The practical implications of the findings are discussed.More »