Factors influencing the time required to shear Merino sheep and its importance as a breeding objective

1981 ◽  
Vol 21 (111) ◽  
pp. 387 ◽  
Author(s):  
BJ McGuirk ◽  
R Ponzoni ◽  
KD Atkins ◽  
AR Gilmour ◽  
FHW Morley ◽  
...  
Keyword(s):  
No Production ◽  
Merino Sheep ◽  
First Order ◽  
Merino Wool ◽  
Breeding Objective ◽  
Skin Fold ◽  
Fleece Weight ◽  
Time Required ◽  
Wool Industry ◽  
Australian Merino

Two sets of observations have been made on the time required to shear (TRS) Merino sheep. The first, in 1951, involved 98 rams and 75 ewes from one medium Peppin bloodline. Then, in 1975, TRS was recorded on 79 rams and 143 ewes from five different bloodlines, from a number of Merino strains. The effect of different production characters on TRS was estimated by least squares analysis, in models that included the effects of shearer, sex, bloodline (1975 only) and all first order interactions. In the 1951 data, TRS increased with increasing greasy fleece weight and with increasing skin fold in the rams (P <0.05). No production character had a significant effect on TRS in the ewes. In the 1975 data, TRS increased with increasing greasy fleece weight, skin fold, face cover and body weight in at least one sex, and when data from the two sexes were pooled (P <0.05). Skin fold and greasy fleece weight had the largest and most consistent effect. There were also significant differences between the bloodlines in TRS, which were found to be associated with differences between the bloodlines in skin fold, greasy fleece weight, and to a lesser extent, face cover. After studying the likely economic benefit of reducing TRS by selection, we concluded that under current economic situations, where any reduction in TRS would lower only the ancillary costs associated with shearing (shed hands, classing, etc.). TRS is not an important breeding objective for the Australian Merino wool industry.

Predicted responses in Merino sheep from selection combining visually assessed and measured traits

2010 ◽  
Vol 50 (10) ◽  
pp. 976 ◽  
Author(s):  
S. I. Mortimer ◽  
K. D. Atkins ◽  
S. J. Semple ◽  
N. M. Fogarty
Keyword(s):  
Fibre Diameter ◽  
Selection Combining ◽  
Breeding Programs ◽  
Dual Purpose ◽  
Merino Sheep ◽  
Merino Wool ◽  
Wool Quality ◽  
Staple Strength ◽  
Fleece Weight ◽  
Australian Merino

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.

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.

The Agouti gene: a positional candidate for recessive self-colour pigmentation in Australian Merino sheep

1999 ◽  
Vol 50 (6) ◽  
pp. 1099 ◽  
Author(s):  
Y. M. Parsons ◽  
M. R. Fleet ◽  
D. W. Cooper
Keyword(s):  
Comparative Mapping ◽  
Economic Importance ◽  
The Self ◽  
Positional Candidate ◽  
Chromosome 13 ◽  
Merino Sheep ◽  
Merino Wool ◽  
Agouti Gene ◽  
Mapping Information ◽  
Australian Merino

The occurrence of self-colour pigmentation in the Australian Merino wool flock is of considerable economic importance. The Agouti gene is believed to be responsible for the recessive expression of pigmented fleece. Using comparative mapping information we have investigated the putative homologous ovine map positon of the Agouti gene for linkage to the recessive self-colour phenotype of Australian Merino sheep. Significant results were observed with microsatellites previously mapped to ovine chromosome 13. Comparative data suggest that the ovine Agouti gene would map to the same chromosome, making the Agouti gene a positional candidate for the self-colour phenotype.

Genetic studies of South Australian Merino sheep. 4. Genetic, phenotypic and environmental correlations between various wool and body traits

1982 ◽  
Vol 33 (2) ◽  
pp. 363 ◽  
Author(s):  
IP Gregory
Keyword(s):  
Great Increase ◽  
Fibre Diameter ◽  
Skin Thickness ◽  
Primary Follicle ◽  
Genetic Studies ◽  
Environmental Correlations ◽  
Merino Sheep ◽  
Selection For ◽  
Fleece Weight ◽  
Australian Merino

Genetic, phenotypic and environmental correlations were estimated between 23 quantitative and qualitative wool and body traits of South Australian Merino sheep. Clean fleece weight was significantly correlated genetically with greasy fleece weight (0.62), yield (0.47), staple length (0.41), crimps per inch (-0.34), secondary/primary follicle ratio (0.37) and skin thickness (0.39). No significant half-sib genetic correlation was found between clean fleece weight and fibre diameter and the dam-offspring correlation was quite low, although significant (0.16, P < 0.05). This indicates that selection for clean fleece weight should not lead to any great increase in fibre diameter. Skin thickness is discussed as a possible early indicator of clean fleece weight.

Selection for economic characters in Australian Merino sheep. VI. Inheritance and interrelationships of some subjectively graded characteristics

1955 ◽  
Vol 6 (6) ◽  
pp. 873 ◽  
Author(s):  
FHW Morley
Keyword(s):  
Genetic Correlation ◽  
Reproductive Efficiency ◽  
Agricultural Experiment Station ◽  
Merino Sheep ◽  
Experiment Station ◽  
Agricultural Experiment ◽  
Selection For ◽  
Fleece Weight ◽  
Australian Merino

Genetic and phenotypic relationships among subjectively graded characteristics were examined in a flock of Merino sheep a t Trangie Agricultural Experiment Station. Estimates of heritability were: wool handle, 0.30; wool colour, 0.63; wool character, 0.38; back wool, 0.00; hocks, 0.14; face cover, 0.38. The genetic correlation between face cover and fleece weights suggested that selection for fleece weight would increase "wool-blindness", with possible diminution of reproductive efficiency. Selection for wools of good character (well-defined crimp) would improve softness and would not decrease fleece weight. The conclusion emerging from this and previous studies is that intense selection for high fleece weight will be rewarded by substantial increases, and will be offset only partly by adverse changes in a few of the several characters investigated.

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.

Phenotypic and genetic parameters for lamb and hogget traits in a flock of South Australian Merino sheep

1987 ◽  
Vol 27 (2) ◽  
pp. 205 ◽  
Author(s):  
JRW Walkley ◽  
RW Ponzoni ◽  
CHS Dolling
Keyword(s):  
Genetic Parameters ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Merino Sheep ◽  
National Performance ◽  
Adjustment Factors ◽  
Fleece Weight ◽  
Parameter Values ◽  
Australian Merino ◽  
Birth Type

The heritability of and phenotypic and genetic correlations among weaning weight (WW). greasy fleece weight (GFW), scouring yield (YLD), clean fleece weight (CFW), fibre diameter (FD), crimps per inch (CR) and staple length (SL) were estimated in a flock consisting of a control and 2 selection lines of South Australian Merino sheep. The effects of type of rearing, age of dam and sex were also examined. Estimates were compared with those currently in use in WOOLPLAN (National Performance Recording Scheme for non-pedigreed sheep) and in other studies. In general, agreement between the present study and other estimates was good, but there were some exceptions, namely: (i) standard deviation of GFW and FD; (ii) 'adjustment factors' for day of birth, type of rearing and age of dam for GFW, CFW and liveweight traits; (iii) heritability of YLD; (iv) phenotypic correlations of GFW and CFW with FD, and between YLD and CFW and (v) genetic correlations of WW with GFW, CFW and FD. It is concluded that special attention should be given to these exceptions in order to decide whether alterations to current 'accepted' parameter values are justified.

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.

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