- The Optical Fibre Diameter Analyser 2000 (OFDA2000) model allows coefficient of variation of fibre diameter (CVFD) to be separated into a between fibre diameter variation component and an along fibre diameter variation component. Both traits are heritable (0.4 and 0.20, respectively) but not as heritable as CVFD on a minicored sample (0.67). Only CVFD between fibres is genetically strongly (-0.7) correlated with SS to nearly the same extend as CVFD (-0.65). It is more effective to use CVFD of wool samples as an indirect selection criterion to improve SS. In addition this will also result in a reduction in the propensity of FD to blowout along the staple. Keywords: Genetic parameters, fibre diameter variation, staple strength, micron blowout.
- There is widespread interest in the use of skin properties for the selection of superior Merino genotypes. This is despite the fact that no selection experiments to date have demonstrated beneficial effects on production traits from selection based solely on skin traits. Two studies have examined whether the inclusion of skin traits in a realistic selection program improves the rate of genetic progress towards a breeding objective emphasising fleece weight and fibre diameter. Both indicated little benefit from including the skin traits. However the impact of the skin traits will depend on their heritabilities and their genetic associations with one another and with the traits in the breeding objective. There is increasing evidence that the genetic parameters differ between the Merino strains so results from one strain cannot be extrapolated to another. In this paper we examine the effects of including classer assessed skin quality and two objectively measured skin characters, skin biopsy weight and follicle density, on the genetic and economic gain made over and above that made using a standard selection index in South Australian Strongwool Merinos. The results indicate that substantial additional genetic gain can be made by including the skin traits. This was particularly true at low micron premiums where addition of all three skin traits increased the economic gain by 25%. The genetic improvement in adult clean fleece weight by including all three skin traits at this premium, was increased from 0.9% per annum to 1.4% per annum with a corresponding slight reduction in the decrease in mean fibre diameter. At higher micron premiums the benefit of including the skin traits was substantially less, again reflecting the tendency for skin trait inclusion to influence fleece weight to a larger extent than fibre diameter. Inclusion of the skin traits had little impact on coefficient of variation of fibre diameter, staple strength and staple length. Our results suggest that consideration of some skin traits may lead to moderate genetic gains and be worthwhile including in breeding programs for Strongwool Merinos, but they do not lend support to notions that consideration of skin traits will produce dramatic increases in fleece weights with concomitant large decreases in fibre diameter.
- Genetic parameters (heritability, phenotypic and genetic correlations) were estimated for a range of visual and measured wool traits recorded from the 2008 shearing of the initial cohort of Merino progeny born into the Sheep CRC’s Information Nucleus Flock. The aim of this initial analysis was to determine the feasibility of selectively breeding Merino sheep for softer, whiter, more photostable wool and to quantify the likely impact on other wool production and quality traits. The estimates of heritability were high for handle and clean colour (0.86 and 0.70, respectively) and moderate for photostability (0.18), with some evidence of maternal effects for both handle and photostability. The phenotypic correlations between handle and clean colour and between handle and photostability were close to zero, indicating that achieving the ‘triple’ objective of softer, whiter, more photostable wool in the current generation through phenotypic selection alone would be difficult. There was evidence of an antagonistic relationship between handle and photostability (–0.36), such that genetic selection for softer wool will produce less photostable wool that will yellow on exposure to UV irradiation. However genetic selection for whiter wool is complementary to photostability and will result in whiter wool that is less likely to yellow. Genetic selection to improve handle, colour and photostability can be achieved with few detrimental effects on other visual and measured wool traits, particularly if they are included in an appropriate selection index.
- EPD trait descriptions include Average Fiber Diameter (AFD), Standard Deviation (SDAFD), Spin Fineness (SF), Percentage of Fibers > 30 Microns (%F>30), Mean Curvature (MC), Standard Deviation of Curvature (SDMC), % Medullated Fibers (%M), Mean Staple Length (MSL), Fleece Weight (FW), and Birth Weight (BW).
- The quality and quantity of alpaca fibre is affected by not only the body condition and nutrition of the animal but also by season and sex hormones. These factors can interact with the genetic potential of each animal to such an extent that they can mask the true genetic value of an animal. This RIRDC report provides scientific data that can be used by producers, consultants to the industry, and feed manufacturers to design more appropriate diets and feeding strategies that will allow the industry to make genetic progress because these management procedures will decrease the impact of nutritional and environmental factors on the expression of the animal’s genetic potential for fibre production.
Fibre Diameter Distribution Characteristics of Midside (Fleece) Samples and Their Use in Sheep BreedingThe relationship between fibre diameter mean and distribution was studied in a large dataset of midside samples from hundreds of flocks. The implications of the relationships are discussed in relation to using these measurements in sheep breeding programs. Some modifications to current phenotypic parameter estimates are suggested.
- Successful breeding programmes involve the use of many different tools to help you determine whether your breeding aims are being achieved. Fleece testing is an objective tool to monitor the changes in individual and herd fleece characteristics.
- Pacomarca is an experimental ranch founded by the INCA group to act as a selection nucleus from which basic genetic improvement of alpaca fibre can spread throughout the rural communities in the Peruvian Altiplano. State-of-art techniques in animal science, such as performance recording or assisted reproduction including embryo transfer, are applied to demonstrate their usefulness in the Altiplano conditions. Pacomarca has developed useful software (Paco Pro) to carry out the integral processing of production and reproduction data. Mating is carried out individually, and gestation is diagnosed via ultrasound. Breeding values estimated from a modern genetic evaluation are used for selection, and embryo transfer is applied to increase the selection intensity. However, the objective of Pacomarca goes beyond, extending its advances to the small rural communities. Training courses for farmers are organised while searching for new ways of improving the performance of alpacas both technically and scientifically.
Genetic Parameters for Visually Assessed Traits and Their Relationships to Wool Production and Liveweight in Australian Merino SheepHeritability was estimated for a range of visually assessed traits recorded on Merino sheep, together with the phenotypic and genetic correlations among the visually assessed traits and correlations of the visually assessed traits with measured wool production traits and liveweight. Data were derived from four research resource flocks, with a range of 12 958 to 57 128 records from animals with 478 to 1491 sires for the various traits. The estimates of heritability were high for the wool quality traits of handle, wool character and wool colour (0.33–0.34) and the conformation traits of face cover, neck wrinkle and body wrinkle (0.42–0.45), moderate for front leg structure (0.18) and low for back leg structure (0.13). Fleece rot score had low heritability (0.14), while classer grade was moderately heritable (0.20). Estimates of genetic correlations among the visually assessed wool quality traits were low to moderate in size and positive (0.17–0.47). Genetic correlation estimates among the assessed conformation traits were generally very low, except for the genetic correlations between scores for neck and body wrinkle (0.92 ± 0.01) and front and back leg structure (0.31 ± 0.09). Fleece rot score had low positive genetic correlations with neck and body wrinkle scores (0.18 ± 0.05 and 0.15 ± 0.05, respectively) and classer grade (0.26 ± 0.06). Classer grade was slightly positively correlated with the wool quality traits (0.17–0.45) and leg structure traits (0.21–0.25). The genetic correlations among the visually assessed traits were generally neutral to favourable. The visually assessed wool quality traits had low to moderate favourable genetic correlations with mean and coefficient of variation of fibre diameter (0.19 –0.47), but negative correlations with clean wool yield (–0.26 to –0.37). Face cover was unfavourably correlated with staple length (–0.27 ± 0.04) and liveweight (–0.23 ± 0.02). Neck and body wrinkle scores were genetically associated with higher greasy (0.33–0.39) and clean fleece weights (0.19–0.22), greater coefficient of variation of fibre diameter (0.24–0.26) and fibre curvature (0.27–0.28), but with reduced yield (–0.26 to –0.28) and staple length (–0.34 to –0.41). Fleece rot score was genetically correlated with clean fleece weight (0.26 ± 0.05) and coefficient of variation of fibre diameter (0.27 ± 0.04). Classer grade was favourably correlated with greasy and clean fleece weights (–0.41 to –0.43), staple length (–0.29 ± 0.04), liveweight (–0.36 ± 0.03) and coefficient of variation of fibre diameter (0.27 ± 0.03). Most genetic correlations between the visually assessed traits and the measured production traits and liveweight were close to zero and less than 0.2 in magnitude. This study provides accurate values for the parameter matrix required to incorporate visually assessed traits into breeding objectives and the genetic evaluation programs used in the Australian sheep industry, allowing the development of breeding objectives and indexes that optimally combine visually assessed performance and measured production in Merino sheep.
- Felting of wool is a major problem in the manufacture of knitted and woven products, as it is related to yarn shrinkage, which is a critical problem of the finished product. Felting is a unique property of animal fibres and a desirable characteristic in the making of felted products. However, felting is a particular problem with fine wools. Non-shrink woollen products are currently produced using chemical treatments during processing. Chlorination is the first step and it degrades the fibre surface. Fibres are then coated with polymers to cover degraded scale structures and/or to bond fibres together to prevent felt shrinkage. This process minimises frictional effects on wool fibre surfaces, limits relative motion of fibres in all directions, and increases hydrophilic properties of the fibre surface (Chen et al., 2000). Although these processes have been highly successful in shrink-proofing wool, they are expensive and detrimental to the fibre. Furthermore, the chlorination process is environmentally unfriendly and there are difficulties with residue disposal. Greeff and Schlink (2001) have shown that felting is a heritable trait, which implies that altering the ability of wool to felt through breeding may make a considerable contribution to wool’s processing properties and will enhance wool’s clean and green image. However, felting is strongly influenced by fibre curvature, fibre diameter (Scheepers and Slinger, 1968 ; Hunter et al., 1982 ; Kenyon et al., 1999 ; Veldsman and Kritzinger, 1960) and clean yield (Schlink et al., 2000). Lipson and Rothery (1975) showed that Merino wool has a significantly higher felting ability than Polwarth wool in spite of the fact that there were no differences in fibre surface friction, scale frequency or elastic properties between the breeds.They did note significant differences between the breeds in “swellings and necks” at intervals along the fibres, but conclusions were not clear because these wools differed in micron and curvature was not recorded. The OFDA2000 (Brims, 1997) has algorithms to measure variability and unevenness traits along the fibre which may be used to identify samples that may cause spinning problems. The objective of this study was to identify whether these along fibre variability traits influence felting and whether they are heritable.
- An example from two alpaca breeders looking for generational fleece trait improvements using skin biopsy data as an aid to making better breeding choices.
Influence of Sire Breed, Protein Supplementation and Gender on Wool Spinning Fineness in First-Cross Merino LambsOur objectives were to evaluate the effects of sire breed, type of protein supplement, level of supplementation and sex on wool spinning fineness (SF), its correlations with other wool characteristics and prediction accuracy in F1 Merino crossbred lambs. Texel, Coopworth, White Suffolk, East Friesian and Dorset rams were mated with 500 purebred Merino dams at a ratio of 1:100 in separate paddocks within a single management system. The F1 progeny were raised on ryegrass pasture until weaning, before forty lambs were randomly allocated to treatments in a 5 x 2 x 2 x 2 factorial experimental design representing 5 sire breeds, 2 supplementary feeds (canola or lupins), 2 levels of supplementation (1% or 2% of liveweight) and sex (wethers or ewes). Lambs were supplemented for six weeks after an initial three weeks of adjustment, wool sampled at the commencement and conclusion of the feeding trial and analyzed for SF, mean fibre diameter (FD), coefficient of variation (CV), standard deviation, comfort factor (CF), fibre curvature (CURV), and clean fleece yield. Data were analyzed using mixed linear model procedures with sire fitted as a random effect, and sire breed, sex, supplementary feed type, level of supplementation and their second-order interactions as fixed effects. Sire breed (P
Is Fibre Diameter Variation Along the Staple a Good Indirect Selection Criterion for Staple Strength?The coefficient of variation of fibre diameter (CVFD) within the mid-side fleece sample is currently used to predict staple strength (SS) in Merino sheep (4.5 year old ewes). CVFD measures fibre diameter variation both between fibres and along wool fibres. It has been suggested that selection to improve staple strength should concentrate on reducing fibre diameter ariation along the staple, rather than CVFD. Our results indicate that measurements of fibre diameter variability along the staple had low heritabilities to moderate (0.01 to 0.20) and a low to moderate (0.15 to -0.43) phenotypic correlation with staple strength. In comparison, CVFD was highly heritable (0.78) and had a moderate (-0.44) phenotypic correlation with S. This suggests that there would be no advantage in using measures of fibre diameter variability along the staple as an indirect selection criterion for SS compared with the information provided by CVFD measured in a mid-side fleece sample.
- The opportunity exists to utilise our knowledge of major genes that influence the economically important traits in wool sheep. Genes with Mendelian inheritance have been identified for many important traits in wool sheep. Of particular importance are genes influencing pigmentation, wool quality and the keratin proteins, the latter of which are important for the morphology of the wool fibre. Gene mapping studies have identified some chromosomal regions associated with variation in wool quality and production traits. The challenge now is to build on this knowledge base in a cost-effective way to deliver molecular tools that facilitate enhanced genetic improvement programs for wool sheep.
- One of the benefits of objective measurement of phenotypic alpaca traits is that the resulting measurements can be collected and analyzed for additional insights that can benefit the industry as a whole. Breeders who commission these analyses of their animals, as well as the organizations that provide them, play an important role in advancing the understanding of alpaca trait relationships and their possible underlying genetic links.
- 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.
- 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.
Sources of Variation in Fibre Diameter Attributes of Australian Alpacas and Implications for Fleece Evaluation and Animal SelectionSources of variation in fibre diameter attributes of Australian alpacas and implications for fleece evaluation and animal selection were investigated using data collected in the years 1994–97, from 6 properties in southern Australia. Data were analysed using REML (multiple regression analysis) to determine the effect on mean fibre diameter (MFD) and coefficient of variation of MFD (CV(FD)) of age, origin (property), sex (entire male, female), breed (Huacaya, Suri), liveweight, fibre colour, individual, and interactions of these effects. The mean (n = 100) age (range) was 4.2 years (0.1–11.9), liveweight 72.0 kg (12.0–134 kg), MFD 29.1 μm (17.7–46.6 μm), CV(FD) 24.33% (15.0–36.7%). A number of variables affected MFD and CV(FD). MFD increased to 7.5 years of age, and correlations between MFD at 1.5 and 2 years of age with the MFD at older ages were much higher than correlations at younger ages. Fibre diameter 'blowout' (increase with age) was positively correlated with the actual MFD at ages 2 years and older. There were important effects of farm, and these effects differed with year and shearing age. Suris were coarser than Huacayas with the effect reducing with increased liveweight; there was no effect of sex. Fleeces of light shade were 1 μm finer than dark fleeces. CV(FD) declined rapidly between birth and 2 years of age, reaching a minimum at about 4 years of age and then increasing; however, CV(FD) measurements on young animals were very poor predictors of CV(FD) at older ages, and the response of CV(FD) to age differed with farm and year. Suris had a higher CV(FD) than Huacayas on most properties, and MFD, liveweight, and sex did not affect CV(FD). Fleeces of dark shade had higher CV(FD) than fleeces of light shade in 2 of the years. It is concluded that there are large opportunities to improve the MFD and CV(FD) of alpaca fibre through selection and breeding. The potential benefit is greatest from reducing the MFD and CV(FD) of fibre from older alpacas, through reducing the between-animal variation in MFD and CV(FD). Sampling alpacas at ages
- In many wool-growing businesses, Staple Strength (SS) is an important profit driver affecting clean price. SS is heritable and good responses to direct selection have been shown over a reasonable number of years. However direct measures of SS on individual animals is expensive and for many years breeders have used Coefficient of Variation of Fibre Diameter (FDCV) as a proxy for direct measurement of SS, since FDCV is measured and reported automatically when Fibre Diameter is now measured. FDCV is genetically moderately strongly correlated with SS. This makes FDCV a useful indirect indicator of SS, without incurring the expense of measuring individual sheep directly for SS. In recent years, breeders have been measuring their sheep at earlier ages and in shorter wool. There have been questions raised regarding the effect Staple Length (SL) has on the accuracy of SS breeding values.
- Two breeders' use of follicle density as a selection tool for fineness and uniformity.
- Understanding fleece measurements as tools to make better sire selections in merino sheep with applications to alpacas.