Environmental influence on Merino sheep wool quality through the lens of seasonal variations in fibre diameter

Visually assessed traits for wool quality and ease of management are important to Merino sheep breeders and need to be considered in breeding programs. The present study reports on the predicted correlated responses in visual traits from selection using a range of standard MERINOSELECT™ indices available for use in Australian Merino breeding programs. The effect of including a visual trait in the index is also reported. The visual scored traits were classer grade, wool quality (handle, character and colour), conformation (neck and body wrinkle, front and back leg structure) and fleece rot. The indices covered a range of micron premiums of varying emphasis on increasing fleece weight and reducing fibre diameter. The indices were for Merino wool enterprises (Merino 14%, Merino 7% and Merino 3.5%) and Merino dual purpose wool and meat enterprises (Dual Purpose 7% and Dual Purpose 3.5%). The breeding objectives for the indices included fleece weight, fibre diameter, coefficient of variation of fibre diameter, staple strength, bodyweight and reproduction. Selection over 10 years using the standard MERINOSELECT™ indices is predicted to result in a small correlated improvement in the wool quality traits and classer grade, with a slight deterioration in fleece rot score. The improvement in wool handle, character and colour are greater with those indices that have a greater emphasis on reducing fibre diameter than with those increasing fleece weight. Indices with more emphasis on increased fleece weight than on reduced fibre diameter are predicted to result in small increases in neck and body wrinkle scores and a slight deterioration in wool colour. Inclusion of classer grade, handle, character or colour provided slight extra gains in fleece weight for indices that emphasised reduced fibre diameter through increased accuracy of selection.

Download Full-text

Genetic parameters for visually assessed traits and their relationships to wool production and liveweight in Australian Merino sheep

Animal Production Science ◽

10.1071/ea08074 ◽

2009 ◽

Vol 49 (1) ◽

pp. 32 ◽

Cited By ~ 16

Author(s):

S. I. Mortimer ◽

D. L. Robinson ◽

K. D. Atkins ◽

F. D. Brien ◽

A. A. Swan ◽

...

Keyword(s):

Coefficient Of Variation ◽

Genetic Correlations ◽

Fibre Diameter ◽

Quality Traits ◽

Production Traits ◽

Merino Sheep ◽

Wool Production ◽

Breeding Objectives ◽

Wool Quality ◽

Staple Length

Heritability 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.

Download Full-text

Effects of site of assessment and variation in wool quality traits on the tactile assessment of textural greasy wool handle

Animal Production Science ◽

10.1071/an14422 ◽

2014 ◽

Vol 54 (10) ◽

pp. 1665 ◽

Cited By ~ 4

Author(s):

J. W. V. Preston ◽

S. Hatcher ◽

B. A. McGregor

Keyword(s):

Fibre Diameter ◽

Quality Traits ◽

Merino Sheep ◽

Diameter Fibre ◽

Wool Quality ◽

A Site ◽

Staple Length

Variation in textural greasy wool handle across the fleece of Merino sheep was explored. Results demonstrate that there were significant differences across nine sites on the fleece. The inclusion of the covariates fibre diameter, fibre diameter co-efficient of variation, staple length, dust penetration, staple structure, greasy wool colour and resistance to compression, helped to explain some of the variation in textural greasy wool handle between sites such that site of assessment was no longer a significant factor (P = 0.065). However, in practice, those involved with clip preparation or sheep selection based on textural greasy wool handle assessment are unlikely to have these measurements available. The results highlight the importance of nominating a site of assessment when recording textural greasy wool handle.

Download Full-text

Polymorphisms and association of FAT1 gene with wool quality traits in Chinese Merino sheep

Czech Journal of Animal Science ◽

10.17221/224/2019-cjas ◽

2020 ◽

Vol 65 (No. 1) ◽

pp. 31-39

Author(s):

Guang-Wei Ma ◽

Xin You ◽

Hua Yang ◽

Xiao-Hong Yan ◽

Fang Mou ◽

...

Keyword(s):

Planar Cell Polarity ◽

Fibre Diameter ◽

Fibre Length ◽

Wool Fibre ◽

Pcr Analysis ◽

Quality Trait ◽

Quality Traits ◽

Exon 2 ◽

Merino Sheep ◽

Wool Quality

FAT atypical cadherin 1 (FAT1) is a member of the atypical cadherin superfamily and is involved in the planar cell polarity signalling pathway which regulates hair follicle morphogenesis, cycling, and orientation. The purpose of this study was to investigate the sheep FAT1 gene expression, polymorphisms and its association with wool quality traits in Chinese Merino sheep. Quantitative real-time PCR analysis showed that the FAT1 mRNA was differentially expressed in the adult skin of Chinese Merino and Kazak sheep. Seven SNPs (termed SNPs 1–7) were identified in exon 2 of sheep FAT1 gene by Sanger sequencing. SNPs 2 and 7 (novel SNPs) were significantly associated with wool crimp (P < 0.05). SNPs 4 and 5 (rs161528993 and rs161528992) were significantly associated with wool fibre length (P < 0.05). SNP 7 was highly significantly associated with average wool fibre diameter (P < 0.01). Similarly, FAT1 haplotypes were significantly associated with wool crimp (P < 0.05), and the haplotypes H1–H3 and H5 were significantly associated with higher wool crimp (P < 0.05). Bioinformatics analysis showed that the wool quality trait-associated SNPs (SNPs 2, 4, 5 and 7) might affect the pre-mRNA splicing by creating or abolishing the binding sites for serine/arginine-rich proteins, and in addition, SNPs 2 and 4 might alter the FAT1 mRNA secondary structure. Our results suggest that FAT1 influences wool quality traits and its SNPs 2, 4, 5 and 7 might be useful markers for marker-assisted selection and sheep breeding.

Download Full-text

Skin wrinkles of the sire adversely affect Merino and halfbred pelt characteristics and other production traits

Australian Journal of Experimental Agriculture ◽

10.1071/ea03202 ◽

2005 ◽

Vol 45 (12) ◽

pp. 1551 ◽

Cited By ~ 4

Author(s):

D. R. Scobie ◽

S. R. Young ◽

D. O'Connell ◽

E. Eythorsdottir

Keyword(s):

Standard Deviation ◽

Fibre Diameter ◽

Production Traits ◽

Merino Sheep ◽

Leather Processing ◽

Breed Differences ◽

Wool Quality ◽

Skin Wrinkles ◽

Staple Length

The wrinkles on the skin of Merino sheep and related breeds are retained during leather processing, and the skins are known as ‘ribby pelts’ in the leather trade. Merino sires with either no skin wrinkles (smooth, n = 7) or excessive wrinkles (ribby, n = 7) were allocated at random to mating groups of 22 Merino ewes mixed with 22 Romney ewes. The progeny of ribby sires were more ribby at docking (P<0.001), at shearing (P<0.001), in the fellmongery (P = 0.001) and as pickled pelts (P<0.001). Merino progeny were more ribby than Merino × Romney (halfbred) progeny at all stages. When professionally graded as pickled pelts, smooth-sired progeny produced more pelts without ribs in both Merino (5% v. 0%) and halfbreds (69% v. 38%) than ribby-sired progeny. Wool samples collected at 7.5 months of age were not significantly different between sire groups in mean fibre diameter (P = 0.27) or staple length (P = 0.60) but they were different in standard deviation of fibre diameter (P = 0.003). Liveweight was consistently greater in the progeny of smooth sires, although this difference did not reach significance until the progeny attained a mean liveweight of 28 kg for Merinos and 32 kg for halfbreds (P = 0.016). Breed differences were observed in other traits and these are discussed. Interestingly, there were few significant sire type breed interactions, the exceptions being yield of clean wool (P<0.001), standard deviation of fibre diameter (P = 0.003) and an additional pelt trait referred to as pinhole score (P = 0.003). In summary, choosing sires without skin wrinkles can improve pelt quality, wool quality and liveweight of Merino and halfbred progeny.

Download Full-text

Genetic parameters for yearling wool production, wool quality and bodyweight traits in fine wool Merino sheep

Australian Journal of Experimental Agriculture ◽

10.1071/ea07425 ◽

2008 ◽

Vol 48 (9) ◽

pp. 1168 ◽

Cited By ~ 15

Author(s):

A. A. Swan ◽

I. W. Purvis ◽

L. R. Piper

Keyword(s):

Genetic Parameters ◽

Genetic Correlations ◽

Fibre Diameter ◽

Merino Sheep ◽

Wool Quality ◽

Staple Strength ◽

Fleece Weight ◽

Highly Correlated ◽

Genetic Evaluations ◽

Trait Groups

Genetic parameters were estimated for traits measured in the first year of production in a multi-bloodline flock of fine wool Merino sheep. Between 5025 and 9271 animals were measured, depending on the trait, and these animals were the progeny of up to 430 sires. Heritability estimates for fleece weight traits ranged from 0.37 to 0.49, while estimates for five wool quality traits ranged from 0.34 for staple strength to 0.66 for mean fibre diameter. For bodyweight, the heritability estimated at weaning was 0.20, and at the yearling age was 0.51. Maternal genetic effects were significant for fleece weight and bodyweight traits and were highly correlated between these trait groups, indicating that these effects are determined by similar groups of genes in both trait groups. While most genetic correlation estimates were either favourable or neutral, there were economically antagonistic correlations between fleece weight and mean fibre diameter, ranging from 0.15 to 0.30, and between mean fibre diameter and staple strength (0.26). Overall, the heritabilities and genetic correlations estimated in this fine wool population were similar to estimates from other strains, indicating that outcomes from selection programs will be similar across strains and that fine wool sheep can be included in across flock genetic evaluations with other strains.

Download Full-text

Genetic variances for liveweight and fleece traits in Merino, Dohne Merino and South African Meat Merino sheep

Australian Journal of Experimental Agriculture ◽

10.1071/ea00030 ◽

2001 ◽

Vol 41 (2) ◽

pp. 145 ◽

Cited By ~ 13

Author(s):

S. W. P. Cloete ◽

S. J. Schoeman ◽

J. Coetzee ◽

J. de V. Morris

Keyword(s):

South African ◽

Fibre Diameter ◽

Phenotypic Variance ◽

Total Phenotypic Variance ◽

Weaning Weight ◽

Merino Sheep ◽

Genetic Variances ◽

Variance Ratios ◽

Fleece Weight ◽

Variance Estimates

(Co)variance estimates for weaning weight, yearling liveweight, clean fleece weight and fibre diameter at yearling age were obtained for Merino, Dohne Merino and South African Meat Merino flocks maintained on the same property. Direct additive genetic variances for weaning weight [expressed as a ratio of the total phenotypic variance (h2, direct heritability)] were estimated at 0.15 for Merinos, 0.21 for Dohne Merinos and 0.32 for South African Meat Merinos. Corresponding maternal variance ratios (m2, including direct maternal variance and permanent environmental maternal variance) were estimated at 0.15, 0.30 and 0.24, respectively. The correlation between direct and maternal variance ratios was high and negative in Dohne Merinos and South African Meat Merinos (–0.72 and –0.53, respectively). Direct heritability estimates for yearling liveweight were 0.30 for Merinos, 0.33 for Dohne Merinos and 0.45 for South African Meat Merinos. Corresponding maternal variance ratios were only significant in the latter 2 breeds, amounting to 0.13 in Dohne Merinos and 0.12 in South African Meat Merinos. For yearling clean fleece weight, h2 and m2 were estimated at 0.28 and 0.12, respectively, for both Merinos and Dohne Merinos. In the case of South African Meat Merinos, only the h2 estimate was significant, at 0.68. Maternal variance ratios for yearling fibre diameter were not significant in any of the breeds, while h2 ranged from 0.58 in Merinos to 0.75 in South African Meat Merinos. Selection progress for yearling traits seems likely in all breeds, depending on the breeding objectives being strived for.

Download Full-text

Improving sheep wool quality

Achieving sustainable production of sheep - Burleigh Dodds Series in Agricultural Science ◽

10.19103/as.2016.0019.03 ◽

2017 ◽

pp. 53-72

Author(s):

E. K. Doyle ◽

Keyword(s):

Wool Quality ◽

Sheep Wool

Download Full-text

Effects of inbreeding on four families of Peppin Merinos

Australian Journal of Agricultural Research ◽

10.1071/ar9570299 ◽

1957 ◽

Vol 8 (3) ◽

pp. 299 ◽

Cited By ~ 16

Author(s):

JM Doney

Keyword(s):

Fibre Diameter ◽

Genetic Effect ◽

Direct Consequence ◽

Specific Gene ◽

Single Strain ◽

Merino Sheep ◽

Fibre Number ◽

Per Se ◽

Fleece Weight ◽

Australian Merino

The influence of inbreeding on several fleece and body characters in a strain of Australian Merino sheep is reported. The four families from which data were taken were derived from a single strain of Peppin Merinos. Inbreeding without selection has been carried on since the foundation of the families between 1939 and 1944. Inbreeding is responsible for a reduction in body size, fertility, greasy and clean fleece weight, and wrinkle score, but has relatively little influence on the fleece components (yield, staple length, fibre diameter, and density of fibre population). It follows that the reduction in fleece weight is a direct consequence of a decrease in total fibre number. Since the reduction in fibre number is likely to be a correlated effect of low pre-natal and early post-natal growth rates, it is suggested that the inbreeding has had no genetic effect on the several independent systems involved in adult wool production but has affected only those associated with fitness and vigour. The depression due to inbreeding therefore may not be caused by specific gene fixation but by increased homozygosity per se.

Download Full-text

The long-term influence of superphosphate and stocking rate on the production of spring-lambing Merino sheep in the high rainfall zone of southern Australia

Australian Journal of Agricultural Research ◽

10.1071/ar98198 ◽

1999 ◽

Vol 50 (7) ◽

pp. 1179 ◽

Cited By ~ 18

Author(s):

J. W. D. Cayley ◽

G. A. Kearney ◽

G. R. Saul ◽

C. L. Lescun

Keyword(s):

Fibre Diameter ◽

Subterranean Clover ◽

The Body ◽

Stocking Rate ◽

Gross Margin ◽

Single Superphosphate ◽

Merino Sheep ◽

Predetermined Level ◽

The Mean ◽

Fleece Weight

The productivity of spring-lambing fine wool Merino sheep grazing pastures sown in 1977 to perennial ryegrass and subterranean clover was assessed from 1989 to 1998. The pastures were fertilised each autumn with single superphosphate at 6 levels, and were stocked at a low, medium, or high stocking rate (SR) at each level of fertiliser. The average phosphorus (P) applied annually since sowing (P ) ranged from 1.6 to 32.9 kg/ha. The SRs used varied with fertiliser level in that they were higher where more fertiliser had been applied, so that the highest SR at each level of fertiliser ensured that the pastures were well utilised. Each ewe raised 1 lamb, which was removed at weaning. The influence of fertiliser on the productivity of the sheep at 4 classes (1–4) of SR (mean SR = 7.1, 10.1, 12.6, and 18.2 ewes/ha for classes 1–4, respectively) was described by: y = A−BCP, where y represents production per sheep (kg), and A, B, and C are constants. For greasy fleece weight, estimates of B and C were 1.59 and 0.84; and for SR classes 1–4, the estimates of A were 5.06, 4.89, 4.78, and 4.46, respectively. For weaning weight of lambs, estimates of B and C were 8.4 and 0.82, and estimates of A were 23.5, 22.7, 21.5, and 20.9 for SR classes 1–4. The mean fibre diameter (µm) of the wool was described by: D = 14.18+1.48 GW, where GW is the mean greasy wool produced annually per sheep (kg) averaged over all sheep and years for each of the 18 treatments. The price (cents/kg) of wool with a fibre diameter D (P D) was given by: P D = 12197+4.94P2 + 688D−0.1945P20D − 5810√D, where 20 µm wool is P20 cents/kg. Supplements were fed if the body condition of ewes fell to a predetermined level. The supplement fed per ewe each year (S), expressed as metabolisable energy (in MJ) was described by: S = −602 − 44.1S R + 178.5P + 8.71S R P +539 √SR− 338.5√P−70.8P√SR, where S R and P represent the mean stocking rate (ewes/ha) and mean P applied annually. When a current set of costs and prices was applied to these equations, the maximum gross margin for a SR of 7.1 ewes/ha was $AU119/ha with 8.6 kg P/ha applied annually, and $AU262/ha for SR of 18.2 ewes/ha with 17.6 kg P/ha applied annually. If income derived from sheep is maintained constant, intensifying the sheep enterprise from the low to the high SR system would involve increasing sheep numbers by about 17%, but would release about 55% of the farm’s area for another purpose.

Download Full-text