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.

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

2008 ◽  
Vol 48 (9) ◽  
pp. 1168 ◽  
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.

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.

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.

Supplementation of young sheep with lupins plus sulfur and a complete mineral mix

1992 ◽  
Vol 32 (3) ◽  
pp. 267
Author(s):  
PT Doyle ◽  
RA Love ◽  
RH Dunlop ◽  
CL White
Keyword(s):  
Fibre Diameter ◽  
Potassium Sulfate ◽  
Feeding Period ◽  
Merino Sheep ◽  
Mineral Supplements ◽  
Wool Growth ◽  
Average Intake ◽  
Staple Strength ◽  
Fleece Weight ◽  
Mineral Lick

Young Merino sheep (7-8 months of age, weighing about 40.5 kg) were given weekly supplements of 1050 gfsheep of lupins, lupins coated with potassium sulfate (25 g/kg lupins), lupins and access to a mineral lick (offered at 175 g/sheep.week), or lupins coated with potassium sulfate and access to the lick. The sheep grazed an annual pasture at a stocking rate of 15 sheepha and were given the supplements between 14 December and 5 April. The amount of pasture on offer in mid December exceeded 3000 kg DMha but declined to 1500 kg DMha in late March.There were significant amounts of green feed present in December and March (>20% of pasture DM), a small amount in January, and no green feed in February. Despite this the percentage of sheep licking the minerals was over 70% in January , February; and March, with average intake being about 10 g/sheep.day. No significant differences occurred between treatments for liveweights of sheep during the feeding period or at shearing. Over the feeding period sheep lost weight at about 30 g/day. Neither the additional sulfur nor the mineral lick had any significant effects on fleece weight, mean fibre diameter of the fleece, staple length, or staple strength. Wool growth rates were not different between treatments during the feeding period. These results indicate that under good pasture conditions with some green feed available, and when lupins are supplied, responses to mineral supplements are unlikely.

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.

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.

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.

Wool and liveweight responses to nutrition by Merino sheep genetically selected for high or low staple strength

1997 ◽  
Vol 48 (8) ◽  
pp. 1129 ◽  
Author(s):  
N. R. Adams ◽  
J. R. Briegel ◽  
A. J. M. Ritchie
Keyword(s):  
Fibre Diameter ◽  
Rate Of Change ◽  
Merino Sheep ◽  
Low Protein ◽  
Wool Growth ◽  
Good Nutrition ◽  
The Difference ◽  
Staple Strength ◽  
Fleece Weight ◽  
Protein Diets

The biological mechanisms underlying differences in wool staple strength were examined in 2 groups of Merino sheep that have been genetically selected for high or low staple strength, while holding fibre diameter constant. The sheep were fed below maintenance for 87 days, and then re-fed ad libitum for 63 days with a diet containing either 9% or 23% crude protein, in a cross-over design, after which they returned to the paddock until shearing. The fleeces of the 2 groups differed in staple strength (25·2 v.17·5 N/ktex, P < 0·001) but were similar in mean fibre diameter and clean fleece weight. However, the pattern of wool growth was different. When fed below maintenance, sheep from the sound group grew more wool than sheep from the tender group (P < 0·05), but lost more liveweight (P < 0·01). During re-feeding, the sound sheep grew less wool than the tender sheep (P < 0·05), but gained more liveweight. The mean fibre diameter at the point of break was similar in both groups. Immediately after re-feeding, the fibre diameter increased more rapidly in the tender group than in the sound (P < 0·001), but a similar difference was observed between the high and low protein diets, with no effect on staple strength. The sound sheep had a lower standard deviation of fibre diameter than the tender sheep (P < 0·001), both in the whole fleece and in 3-weekly midside patches. The data indicated that the variability of fibre diameter between fibres made a larger contribution than the variability along fibres to the difference between the groups in overall variability of fibre diameter. The sheep were then grazed together at pasture for a second year and again differed in staple strength. In addition, the sound sheep grew less wool on green spring pastures and had a lower clean fleece weight (P < 0·05). The differences in wool growth rates between sheep from the sound and tender lines depended more on whether pasture was green than on the amount of pasture available. We conclude that the difference in staple strength between the sound and tender groups was most closely associated with the variability between fibres in diameter, and was also affected by a difference in variation in diameter along the fibres. Staple strength was not affected by the amount of wool at the point of break, or by the rate of change in fibre diameter after feeding. The sheep in the sound group grew less wool than those in the tender group when on good nutrition.

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