Australian Angora Research Articles

Wear of permanent incisors with age on commercial Australian Angora goat farms.

To quantify if, and to what extent, permanent incisor wear differed with age of goat and farm of origin on commercial Australian Angora goat farms. Observations were made on three Angora goat farms in the wheat-sheep zone of Victoria, each managed according to the farmer's practices. Farmers provided a representative flock of does. The proportion and pattern of wear of permanent incisors were recorded and percentage wear calculated. After log(y + 10) transformation, a parsimonious general linear model was developed to relate wear to farm and age, with age considered as a continuous variate. The range in wear of the permanent incisors was 0-100%. For each farm, the most parsimonious model for permanent first incisor wear and average wear of all permanent incisors was a separate straight line relating the transformed incisor wear to the age of doe. The models accounted for 66-73% of variance. On each farm the incisor wear was similar and low for ages up to approximately 4 years. On all farms, the amount of incisor wear increased dramatically with age, although the rate of increase differed with each farm. Permanent incisor wear increased with age of goat and differed with farm of origin. Angora goat farmers need to be aware of the potential for incisor wear to affect doe production and health.

Determinants of permanent first incisor eruption in grazing Australian Angora goats

To investigate the effects of live weight, sex and other factors on deciduous (first incisor) loss and permanent first incisor development in Angora goats. Goats were part of a pen study on the effects of energy intake in Angora does during pregnancy and lactation on kid growth and development. The design was three levels of nutrition in mid-pregnancy × two levels of postnatal nutrition in 17 randomised blocks. Conception times were calculated by using artificial insemination, with ultrasound examination 43 days after insemination. Does were fed different amounts of a formulated diet in their pens. After weaning, goats were grazed in sex groups. Deciduous first incisor loss and permanent first incisor development were recorded at 11 time points from 14 to 20 months of age. For each sex, the time for visible eruption and full development of permanent first incisor declined linearly with increased live weight by 5.9 and 5.4 days/kg live weight, respectively. The time to reach similar development stages for first permanent incisors eruption was 3 months longer for the lightest animals compared with the heaviest animals. Date of birth, birth weight, doe age, growth rates, mid-pregnancy and postnatal nutrition, parity, day of weaning and weaning weight had no detectable effect. The results explain much of the substantial range in reported first permanent incisor eruption dates for small ruminants and have application in ageing of goats, marketing of kids for meat, in the selection of animals for breeding flocks and in educational material.

A quantitative trait locus for faecal worm egg and blood eosinophil counts on chromosome 23 in Australian goats

Three microsatellite markers on goat chromosome 23 adjacent to the MHC were used to test for quantitative trait loci (QTL) affecting faecal worm egg count (WEC) and leukocyte traits in ten Australian Angora and twelve Australian Cashmere half-sib families (n = 16-57 per family). Data were collected from 280 Angora and 347 Cashmere kids over a 3- and 4-year period. A putative QTL affecting trichostrongyle WEC was found in two small families at the 5% chromosome-wise threshold level. The biggest QTL effect for WEC of 1.65 standard deviations (sigma(p)) was found within the region of OarCP73-BM1258. A significant QTL affecting blood eosinophil counts at the 1% chromosome-wise threshold level was detected at marker BM1258 (at 26 cM) in two Angora and Cashmere families. The magnitude of the putative QTL was 0.69 and 0.85 sigma(p) in Angora and Cashmere families, respectively. Due to the comparatively low power of the study these findings should be viewed as indicative rather than definitive.

Estimates of genetic and phenotypic parameters for production, haematological and gastrointestinal nematode-associated traits in Australian Angora goats

Genetic parameters for liveweight (LWT), greasy fleece weight (GFW), mean fibre diameter (MFD), standard deviation of MFD (MFD-s.d.), mean fibre curvature (CURVE) percentage of medullated (%MED) and kemp (%KEMP) fibres, faecal worm egg count (WEC), packed cell volume (PCV), mean corpuscular volume (MCV) mean corpuscular haemoglobin content (MCHC), circulating anti-nematode IgG (IgG) and counts of circulating eosinophils (EOS), lymphocytes (LYM), neutrophils (NEU), basophils (BASO) and monocytes (MONO) up to 18 months of age were estimated in Australian Angora goats (608 animals, 14 sires 3 years of birth). Measurements were made during a period of natural parasite challenge up to 5 months of age, or following artificial challenge with 10 000 infective larvae of Trichostrongylus colubriformis at 5.25 months of age. Year of birth had a significant impact on production and parasite-associated traits at all ages studied. Sex had a marked effect on production and erythrocyte traits. Birth type had no effect on any traits in animals older than 6 months. Maternal effects were not significant except for LWT at 3, 5 and 6 months and for IgG at 3 months. Most production traits were highly (LWT, GFW, MFD, %MED) or moderately (CURVE, MFD-s.d.) heritable (range 0.17–0.59) with only %KEMP having a low heritability (0.02–0.14). The heritability estimates (±s.e.) for CURVE are novel for goats and ranged from 0.18 ± 0.09 at first shearing to 0.44 ± 0.14 at third shearing. Heritability estimates were low for WEC (0.02–0.16) and for specific IgG during natural infection (0.14–0.15) but higher for IgG following artificial challenge with T. colubriformis (0.42 ± 0.13). Of the haematological variables NEU and all red cell traits were highly heritable (0.45–0.71), LYM and MONO were moderately to highly heritable (0.31–0.55), and EOS was weakly to moderately heritable (0.06–0.28). Strong phenotypic correlations existed between production traits. MFD was positively correlated with GFW and negatively correlated with CURVE, indicating that finer fibres have a higher crimp or wave count. WEC had consistent negative phenotypic correlations with PCV, LYM and EOS, and positive correlations with NEU. Correlations with IgG were positive up to 5 months and negative thereafter. Phenotypic correlations between WEC and LWT as well as with GFW and MFD were negative. Heritability estimates for production traits were generally consistent with other studies. Haematological and fibre curvature findings are completely novel for Angora goats. Estimates of heritability for WEC fell in mid range of published findings for other goat breeds, and these results suggest that there is some scope for breeding for worm resistance in Angoras but the response is likely to be slow.

Variation of mohair staple length across Angora goat fleeces: implications for animal selection and fleece evaluation

SUMMARYThe present study aimed to determine how the average mohair staple length (SL) differences between nine sampling sites vary between sex and flock, to identify differences in SL variability between sampling sites as a result of between-animal and between-sire variability and to determine SL correlations between sampling sites in between-animal and between-sire variability. Australian Angora goats (n=301) from two farms in southern Australia were sampled at 12 and 18 months of age at nine sites (mid side, belly, brisket, hind flank, hip, hock, mid back, neck and shoulder). Staples were taken prior to shearing at skin level and stretched SL determined. For each shearing, differences in SL between sampling sites, how these differences were affected by farm, sex and sire, and the covariance between sites for sire and individual animal effects were investigated by restricted maximum likelihood (REML) analyses. The median mid-side SL at 12 and 18 months of age was 110 and 130 mm, respectively, but the actual range in mid-side SL was 65–165 mm. There was an anterior–posterior decline in SL with the hock being particularly short. There was no evidence that the between-site correlation of the sire effects differed from 1, indicating that genetic selection for SL at one site will be reflected in SL over the whole fleece. However, low heritabilities of SL at the hock, belly and brisket or at any site at 12 months of age were obtained. There was more variability between sites than between sires, but the between-animal variation was greater. The hip and mid-back sites can be recommended for within-flock (culling) and genetic selection for SL due to their low sampling variability, moderate heritability and ease of location.

DNA-based parentage verification in two Australian goat herds

This study aimed to evaluate a set of DNA markers for their effectiveness in parentage inference, to quantify the level of pedigree errors in Australian Angora and Cashmere goat herds using different pedigree recording methods, and to investigate genotype mismatches between parent and offspring. The 14 microsatellite markers evaluated in this study provided a high level of power (probability of exclusion, PE >99.70%) for parentage testing. The extent of PE depended on polymorphic information content ( PIC) and number of alleles for each marker. The minimum number of MS markers essential for accurate determination of parentage was 12, when neither parent is known ( PE1) and 10, when one parent is known ( PE2). In both populations, the error rates of recorded sire and dam pedigree were significant, averaging around 12%. The error rates of sire and dam pedigree varied considerably between the two populations, reflecting management differences on the two properties. Of 14 MS markers, one locus, SRCRSP07, had null alleles present in the heterozygous state. This null allele was revealed by mismatches of genotypes of parent-offspring pairs. Highly significant deviation from Hardy–Weinberg Equilibrium and significant heterozygote deficiency was also observed at this locus.

Implications for the conservation of genetic diversity in mohair goats from a comparison of a relic island population with breeds farmed in Australia

The genetic relationships between an abandoned population of mohair-style, fibre-producing goats from the remote semi-arid Faure Island, Western Australia and 3 modern breeds of Angora goats (Australian, southern African and Texan) were investigated. Faure Island goats originated from stock introduced in the 1890s, reputedly from South Africa. Farmed Faure goats were abandoned on the island about 1918, but their fine mohair fleece has since generated commercial interest within the Australian mohair industry. Nineteen microsatellite loci were used to compare Nei’s genetic distance between and variation within the breeds. Faure Island goats are more similar to southern African and Texan Angoras than to Australian Angoras. Genetic variability was lower in Australian Angoras than in Faure Island, southern African and Texan Angoras (lowest proportion of polymorphic loci, mean heterozygosity and mean number of alleles). Current Faure Island mohair-style goats are more closely related to modern southern African Angora goats than to traditional Australian Angora goats, while the reduced variability in the latter may have resulted from inbreeding. These results have implications for the genetic improvement of fibre-producing goats and for the conservation of genetic material from island populations of goats.

Caprine blood groups. 2. The C, G, H, I, J, K, L, N, and Q systems.

Nine blood group systems of goats were identified using 12 caprine reagents produced by absorption of alloimmune antisera. The caprine C blood group system, possibly homologous to the ovine C blood group system, was characterized by two reagents and shown to be controlled by three alleles, C12, C25, and C-. A more complex blood group system of goats, designated G, was identified using three reagents and shown to be controlled by six codominant alleles (G10.19.20, G10.19, G10.20, G10, G19, G20) and a recessive allele (G-). A further seven one-factor two-allelic systems were identified by seven reagents. The nine genetic systems provided exclusion probabilities of 0.479, 0.492, 0.548, and 0.572 in Australian Angora, Dairy, Cashmere, and Texan Angora goat breeds, respectively.

Caprine blood groups. 1. The B system

Twelve of 24 monospecific caprine reagents produced by absorption of alloimmune antisera identified a complex blood group system of goats which was designated B, based on the results of a small comparison test with ovine reagents. The frequencies of the 12 B factors differed significantly among the Australian Angora, Texan Angora, Cashmere, and Dairy goat breeds. Three of the antigens detected by the reagents were shown to be related as linear subtypes, designated Ba1, Ba2, and Ba3, and inherited as alleles. The segregations of B factors in 80 sire groups involving 1086 offspring demonstrated that groups of B factors (phenogroups) segregated as products of allelic genes.

A new transferrin allele in Australian goats.

Subdivision of TF B into two variants, B1 (faster) and B2 (slower) in Australian goat breeds was accomplished by high voltage, thin layer polyacrylamide gel electrophoresis at pH 7.9. The genes controlling the caprine transferrins were shown to be autosomal codominant alleles, TFA, TFB1, TFB2 and TFC and in the various breeds of goats, the alleles were in Hardy-Weinberg equilibrium. TFA was the most common allele in the Australian and Texan Angora, Cashmere and Dairy breeds with gene frequencies ranging from 0.652 to 0.977. TFB1 and TFB2 occurred in all four breeds while TFC was only observed in very low frequencies in Australian Angora and Cashmere breeds.

Genetic polymorphism of plasma vitamin D-binding protein (GC) in Australian goats.

Polymorphism at the GC locus in goats was detected using isoelectric focusing (pH 4.5-5.4) and immunoblotting with antiserum to human GC. Three variants, designated A, B and C in order of decreasing mobility to the anode, were detected and were shown to be controlled by three codominant alleles, GCA, GCB and GCC. GCA and GCB occurred in all four breeds (Australian and Texan Angora, Cashmere and Dairy) with GCA being the most common and having gene frequencies ranging from 0.851 to 0.993. GCC was found only in Australian Angora and Cashmere animals. The products of the three GC alleles had isoelectric points in the range pH 4.63-4.95 and M(r) of approximately 54,375. The major isoforms of the three alleles were shown to contain sialic acid. Linkage between the GC and albumin loci was unable to be demonstrated due to the low frequency of ALBA (0.02) in the Cashmere breed.

Phenotypic and genetic parameters of fleece traits and live weight in South Australian Angora goats

Heritability and phenotypic correlations for traits of Angora buck and doe yearlings (mean age 13 months) were derived from 572 half-sib records of 30 sires. Estimates of heritability ranged from 0 for percentage of medullated fibres (MF) to 0.45 for greasy fleece weight (GFW). Oven dry yield (ODY) was not very heritable (0.02), live weight (LW), staple length (SL) and fibre diameter (FD) lowly heritable (0.13, 0.13 and 0.14, respectively), while face cover score (FC), kemp score (K) and clean fleece weight (CFW) had moderate to high heritabilities (0.24, 0.36 and 0.38, respectively). Most phenotypic correlations among different fleece traits and with live weight were positive and significant. GFW was strongly correlated with CFW (0.99), whereas GFW and CFW were moderately correlated with LW, FD and SL. Correlations of FD with LW, SL, ODY and MF were positive with values of 0.23, 0.28, 0.30 and 0.39, respectively. Heritability estimates were obtained for production traits of does ranging in mean age from 13 to 73 months. Estimates were similar to those obtained for yearling bucks and does, except for MF, which was greater than 0 (0.39). Repeatability values for the same production traits of does were also estimated, being moderate (0.39 to 0.45) for GFW, CFW and MF, low (0.18 to 0.30) for FD, K, FC and LW and very low (0.03 to 0.08) for ODY and SL. The heritability estimates suggest that GFW and CFW would respond effectively to mass selection at yearling age, but that genetic responses to selection in FD, SL and LW would be smaller. Selection against medullated fibres in the fleece (at ages greater than yearling) and face cover on the animal should also result in genetic improvements in these traits.

Fleece and skin characteristics of selected Australian Angora goats

Greasy fleece weights (GFW) and shorn body weights (BW) of two generations of a herd of Angora goats were measured at their second shearing at 15 months of age. Skin samples yielded data on primary and secondary follicle density and fibre diameter (FD), the proportion of fibres that were medullated and the ratio of secondary to primary follicles ( S P ratio). Fleece samples were used to assess yield and staple length. There were large differences in all traits except primary follicle density between the two generations. Does had a lower incidence of medullated fibres, a greater density of primary and secondary follicles and a lower fibre diameter than bucks. Parameters of fleece quality compared favourably with Texan and South African Angoras, but fleece weight was inferior. Important positive phenotypic correlations were found between GFW and both BW and S P ratio, and between medullation and both primary and secondary follicle density, while GFW and BW were negatively related to follicle density. No correlation could be found between GFW and FD.

Environmental effects on fleece and body traits of South Australian Angora goats

Data on fleece traits and body weight of South Australian Angora goats were collected from 1979 to 1984. Traits studied were greasy and clean fleece weights, oven-dry yield, fibre diameter, staple length, percentage of medullated fibres, kemp score, face cover score and body weight. Estimates of the effects of some environmental factors on these traits were made for two groups of animals. The first comprised kid and yearling females and males, whereas the second consisted of females ranging in age from 6 to 73 months of age. Year of birth significantly influenced all fleece traits and body weight of 6 and 13-month-old females and males, whereas age of animal was a significant source of variation for all traits except staple length and percentage of medullated fibres. Neither age of dam nor type of birth had a significant effect on any of the kid or yearling traits. Age of animal had a significant effect on all fleece traits and body weight of females observed from 6 to 73 months of age. The mean greasy fleece weight of females increased from 0.73 kg at 6 months to 1.46 kg at 73 months, whereas mean body weight increased from 18.1 kg to 37.7 kg over the same period. The mean fibre diameter increased from 26.7 microns at 13 months to 35.5 microns at 73 months. No consistent trend with age of female was present for either oven-dry yield or staple length. These results suggest that comparisons among young goats of the same sex for fleece traits and body weight should be based on production records adjusted for age of animal, but not necessarily for age of dam or type of birth. Comparisons among females of varying age should take account of the effects of age of animal on fleece traits and body weight.