A comparison of the topmaking performance of wool from sheep selected by index and visual methods

1999 ◽  
Vol 39 (8) ◽  
pp. 941 ◽  
Author(s):  
A. L. Vizard ◽  
K. A. Hansford
Keyword(s):  
Body Weight ◽  
Coefficient Of Variation ◽  
Selection Index ◽  
Fibre Diameter ◽  
Visual Assessment ◽  
Index Selection ◽  
Visual Methods ◽  
Merino Sheep ◽  
Fleece Weight ◽  
Index Value

Summary. The topmaking performance of fleeces from sheep that were ranked high or low on index selection using objective measurement was compared with that of sheep from the same flock that were ranked high or low on visual assessment. A flock of 451 15-month-old fine-wool Merino sheep were classed by 2 experienced fine-wool sheep classers into 3 grades: best, average and culls. Forty-four sheep were assessed as ‘best’ and 77 sheep were graded as ‘culls’ by both classers. These sheep were defined as the ‘best visual’ and ‘worst visual’ sheep, respectively. Measurements of clean fleece weight, mean fibre diameter, coefficient of variation of fibre diameter and body weight were used in a selection index to rank all sheep in the flock. The selection index was designed to rapidly reduce mean fibre diameter and slowly increase clean fleece weight, whilst maintaining staple strength and body weight. The 44 sheep with the highest index value were defined as ‘best index’ sheep and the group of 77 sheep with the lowest index or obvious physical faults were defined as the ‘worst index’ sheep. Twenty-five fleeces were randomly selected from each of the ‘best’ and ‘worst visual’, ‘best’ and ‘worst index’ sheep for individual processing through to top. The fleeces from the ‘best index’ sheep produced greater quantities of tops that were significantly finer, longer, of lower curvature and produced less noil than all other groups. In contrast to the large difference in quality between tops from the ‘best’ and ‘worst index’ sheep, there was little difference in quality between tops from the ‘best’ and ‘worst visual’ sheep. This indicates that the traditional wool producer views of wool quality are unrelated to processing performance. It was concluded that Merino sheep selected by index selection using direct measurement of fleece weight, mean fibre diameter and coefficient of variation of diameter as selection criteria produced greater quantities of wool of superior processing performance to that from sheep selected using visual assessment.

The relationship of lamb birthcoat to adult fleece structure in a strain of Merino sheep

1958 ◽  
Vol 9 (4) ◽  
pp. 567 ◽  
Author(s):  
PG Schinckel
Keyword(s):  
Body Weight ◽  
Fibre Diameter ◽  
Merino Sheep ◽  
Gene System ◽  
Weight Yield ◽  
Fleece Weight ◽  
Relationship Of ◽  
The Relationship ◽  
Staple Length

Variability of the lamb birthcoat has been studied in relation to adult fleece characteristics. Coarse birthcoats were associated with increased variability of fibre diameter and decreased crimp rate. The increased variability of fibre diameter resulted from a significant increase in the diameter of primary fibres and a small, but statistically non-significant, decrease in the diameter of secondary fibres. There was no relation between birthcoat grade and body weight, clean fleece weight, yield, staple length, follicle density, follicle ratio, mean fibre diameter, or skin folds. It is postulated that there is a gene system in the Merino the effect of which is to cause variation in the amount of wool produced by the different follicle types. Increased "dosage" of genes of the system endows primary follicles with increased productivity and secondary follicles with decreased productivity. This is expressed in the form of increased halo-hair abundance in the lamb and increased differences between the diameters of primary and secondary fibres in the adult.

Inclusion of skin follicle traits in selection indices in breeding programs improves genetic gain in Australian fine-wool Merinos

2007 ◽  
Vol 58 (9) ◽  
pp. 921 ◽  
Author(s):  
M. Asadi Fozi ◽  
J. H. J. Van der Werf ◽  
A. A. Swan
Keyword(s):  
Body Weight ◽  
Coefficient Of Variation ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Selection Criterion ◽  
Breeding Programs ◽  
Breeding Objectives ◽  
Staple Strength ◽  
Fleece Weight

Genetic parameters for skin follicle traits, wool traits, body weight, and number of lambs weaned per ewe joined were estimated for 5108 10-month-old Australian fine-wool Merinos born between 1990 and 1996. These animals were descended from 261 sires and 2508 dams. The skin follicle number index that is based on skin surface area, and primary, secondary, or total follicle density were introduced as possible early-age selection criteria estimated at 6 months of age. Heritability estimates for total, secondary, and primary follicle number index were 0.45 ± 0.04, 0.46 ± 0.04, and 0.38 ± 0.04, respectively. The genetic correlations of total follicle number index with clean fleece weight, mean fibre diameter, staple strength, coefficient of variation of fibre diameter, body weight, and number of lambs weaned were 0.16, –0.67, 0.00, 0.03, 0.22, and 0.22, respectively. Responses to selection on indices including and excluding follicle traits were calculated based on the genetic parameters estimated, and with annual responses calculated using an optimised age structure. On average, 10% greater response was predicted when total follicle number index was used as an additional selection criterion in different micron premium scenarios. In comparison, skin follicle density had a smaller effect on genetic improvement. The extra response was ~1%. Similar index responses were obtained when total follicle number index was used as a replacement selection criterion for clean fleece weight, mean fibre diameter, and coefficient of variation of fibre diameter for breeding objectives with low emphasis on fibre diameter. In objectives with high emphasis on fibre diameter, unfavourable correlated responses in staple strength and CV of fibre diameter limited the effectiveness of using total follicle number index as a selection criterion. Although the use of total follicle number index as an additional selection criterion can be favourable for some breeding objectives, measuring this trait is currently cost prohibitive to inclusion in Merino breeding programs.

Genetic studies of South Australian Merino sheep. 3. Heritabilities of various wool and body traits

1982 ◽  
Vol 33 (2) ◽  
pp. 355 ◽  
Author(s):  
IP Gregory
Keyword(s):  
Body Weight ◽  
Fibre Diameter ◽  
Skin Thickness ◽  
Production Traits ◽  
Primary Follicle ◽  
Merino Sheep ◽  
Main Production ◽  
Fleece Weight ◽  
Australian Merino ◽  
Staple Length

Heritabilities have been estimated for a large number of quantitative and qualitative wool and body traits recorded on two flocks of South Australian Merino sheep over a 12-year period. Data were unadjusted for fixed environmental effects and so the estimates are applicable to the heterogeneous populations found in most practical situations. Dam-offspring heritabilities of quantitative traits ranged from 0.15 for primary follicle number to 0.63 for body weight. Greasy and clean fleece weights, percentage clean yield, staple length, crimps per inch, fibre diameter, secondary and total follicle number, skin thickness, coefficient of variation of fibre diameter and secondary/primary follicle ratio had moderate to high heritabilities. Dam-offspring heritabilities of qualitative traits ranged from 0.12 for weather damage of the fleece to 0.75 for birthcoat. Total folds, face cover and hocks had high heritabilities, and wool character, type of staple formation and wool quality had moderate heritabilities. The main production traits (body weight, greasy fleece weight, yield, clean fleece weight, staple length, fibre diameter and total follicle number) were corrected for variation due to type of birth and age of dam and their heritabilities re-estimated. No change occurred in the half-sib heritabilities; dam-offspring heritabilities increased by an average of 0.05.

Response to partial selection on clean fleece weight in South Australian strong-wool Merino sheep

1970 ◽  
Vol 21 (3) ◽  
pp. 541 ◽  
Author(s):  
O Mayo ◽  
DW Cooper ◽  
RE Brady ◽  
CW Hooper
Keyword(s):  
Body Weight ◽  
Birth Weight ◽  
Blood Group ◽  
Fibre Diameter ◽  
Skin Thickness ◽  
Merino Sheep ◽  
Fleece Weight ◽  
Australian Merino ◽  
Staple Length

The associations between 10 production characters and fertility at the R blood group, haemoglobin, and transferrin loci have been examined in two flocks of South Australian Merino sheep. The production characters were birth weight, hogget body weight, hogget wrinkle score, greasy fleece weight, clean fleece weight, staple length, degree of crimp, fibre diameter, fleece density, and skin thickness. No evidence of any real association was found. The significant associations which were found are ascribed either to chance or to the impossibility of eliminating sire effects from the analysis.

Genetic parameters for bodyweight, wool, and disease resistance and reproduction traits in Merino sheep. 2. Genetic relationships between bodyweight traits and other traits

2008 ◽  
Vol 48 (9) ◽  
pp. 1186 ◽  
Author(s):  
A. E. Huisman ◽  
D. J. Brown
Keyword(s):  
Coefficient Of Variation ◽  
Genetic Relationships ◽  
Fibre Diameter ◽  
Eye Muscle ◽  
Merino Sheep ◽  
Scrotal Circumference ◽  
Reproduction Traits ◽  
Negative Effect ◽  
Selection For ◽  
Fleece Weight

The Australian Merino is the predominant genetic resource for both the prime lamb and sheep meat industries of Australia. There are very few studies that provide good information on the relationships between wool and non-wool traits. The objective of this paper was to describe genetic relationships within bodyweight traits and between bodyweight and other traits recorded in Merino sheep. The genetic correlation between bodyweight, fleece weight and fibre diameter was positive (0.1 to 0.2). While fibre diameter coefficient of variation, staple length, staple strength, mean fibre curvature, and faecal egg count were not correlated with bodyweight. Scrotal circumference (0.4), number of lambs born (0.1), and number of lambs weaned (0.1) were positively correlated with bodyweight. Results indicate that selection for an increase in bodyweight will have a positive effect on eye muscle depth, fleece weight, and reproduction traits, while selection for an increase in bodyweight will have a negative effect on fibre diameter and fibre diameter coefficient of variation.

Genetic evaluation of production traits between and within flocks of Merino sheep. I. Hogget fleece weights, body weight and wool quality

1989 ◽  
Vol 40 (2) ◽  
pp. 433 ◽  
Author(s):  
SI Mortimer ◽  
KD Atkins
Keyword(s):  
Body Weight ◽  
Environmental Effects ◽  
Genetic Variance ◽  
Research Centre ◽  
Production Traits ◽  
Merino Sheep ◽  
Wool Production ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Fleece Weight

Wool production traits were measured on Merino hogget ewes in an unselected multiple-bloodline flock over a 7-year period at Trangie Agricultural Research Centre, N.S.W. The traits measured were greasy fleece weight (GFW), skirted fleece weight (SKFW), yield (Y), clean fleece weight (CFW), fibre diameter (FD), body weight (BWT) and staple length (SL). These measurements were used to examine genetic differences between and within flocks of Merino sheep, and to estimate heritability of and genetic and phenotypic correlations among these traits. Significant strain, flock within strain and flock effects were present for all traits. Interactions between these effects and year were non-significant. Within-flock genetic variance was always larger than between-flock within strain genetic variance for each trait. The influence of environmental effects on these traits was also examined. The environmental effects of birth-rearing type, age at observation and age of dam together accounted for about 7-10% of the total within-flock variation in fleece weights and body weight.After adjusting for significant environmental effects, paternal half-sib heritability estimates were 0.29 �. 0.06 for GFW, 0.22 � 0.05 for SKFW, 0.35 � 0.05 for Y, 0.30 �0.06 for CFW, 0.48 �0.07 for FD, 0.34 �. 0.06 for BWT and 0.44 �0.07 for SL. Estimates for genetic and phenotypic correlations were in agreement with published estimates except for the genetic correlation between CFW and FD (0.40 �. 0.11), and the genetic correlations involving BWT, which were essentially zero. The implications of the results of this study for the genetic improvement of Merino sheep for wool production are discussed.

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

2001 ◽  
Vol 41 (2) ◽  
pp. 145 ◽  
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.

The value of production from a clipped measured area as an index of fleece weight.

1955 ◽  
Vol 6 (1) ◽  
pp. 91 ◽  
Author(s):  
FHW Morley ◽  
LW Lockart ◽  
EC Davis
Keyword(s):  
Body Weight ◽  
Correlation Coefficient ◽  
Unit Area ◽  
Multiple Correlation Coefficient ◽  
Multiple Correlation ◽  
Merino Sheep ◽  
Wool Production ◽  
Fleece Weight ◽  
Selection Of

The correlation between greasy wool production per unit area, obtained by clipping and measuring an area of about 100 cm² on the midside, and greasy fleece weight at shearing was about 0.58. Wool production from such an area over periods of 7½ or 3½ months was almost as useful as production for 11 months for predicting greasy fleece weight. The multiple correlation coefficient between greasy fleece weight as the dependant variable and production per unit area and 11-months' body weight was 0.79 in 66 rams and 0.71 in 82 ewes. The inclusion of fold score did not improve prediction appreciably. The equation W = P/110 + B1 /12 may be used to predict greasy fleece weight (lb), W, where P is production over 11 months of greasy wool (mg/cm²) and B1 is 11-months' body weight (Ib). A table of this function is included so that values may be read directly. The technique may be a useful aid to selection of Merino sheep if recording of actual fleece weights is difficult or impossible. Nevertheless it should not be regarded as more than a moderately accurate substitute for actual fleece-weighing.

Effects of inbreeding on four families of Peppin Merinos

1957 ◽  
Vol 8 (3) ◽  
pp. 299 ◽  
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.

Genetic studies of South Australian Merino sheep. 2. Environmental effects on wool and body traits at 15-16 months of age

1981 ◽  
Vol 32 (4) ◽  
pp. 657 ◽  
Author(s):  
IP Gregory ◽  
RW Ponzoni
Keyword(s):  
Body Weight ◽  
Surface Area ◽  
Multiple Birth ◽  
Production Traits ◽  
Merino Sheep ◽  
Main Production ◽  
The Difference ◽  
Fleece Weight ◽  
Main Components ◽  
Australian Merino

The effects of years, sex, type of birth (i.e. whether or not multiple birth) and age of dam on 26 wool and body traits of South Australian Merino sheep were estimated by least-squares analysis. Years and sex had highly significant effects on all traits. Of the main production traits, type of birth had a significant effect on body weight, greasy and clean fleece weight and total wool follicle number, while age of dam only had a significant effect on body weight and greasy fleece weight. The possible consequences of failing to correct body weight and greasy and clean fleece weights for type of birth and age of dam were considered and it was concluded that, although in some years correction of these traits may not be warranted, in other years correction may be necessary to prevent selection against fecundity and an increase in the generation interval. The main components contributing to the 6.0 % difference between fleece weights of singles and twins were surface area, total follicle number and wrinkle score. The difference between fleece weights of animals from older ewes and animals from maidens was only 1.5 %; surface area was the main contributor to this deviation.

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