Heritability estimates of wool follicle traits in sheep skin

1984 ◽  
Vol 39 (3) ◽  
pp. 399-403 ◽  
Author(s):  
M. A. Abouheif ◽  
C. LeRoy Johnson ◽  
M. P. Botkin
Keyword(s):  
Effective Means ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Heritability Estimate ◽  
Histological Techniques ◽  
Sources Of Variation ◽  
Wool Follicle ◽  
Selection For ◽  
Heritability Estimates ◽  
Fleece Weight

ABSTRACTData were collected from 600 newborn lambs, offspring of 354 Western crossbred ewes and 26 rams, to determine heritability estimates as well as phenotypic and genetic correlations between wool follicle variables using histological techniques. Breed of sire and sire within breed were significant sources of variation in total and secondary wool follicle populations and secondary:primary (S:P) ratio. Heritability estimates calculated by regression of offspring on dam were slightly higher than by paternal half-sib correlation or regression of offspring on sire. Expressed as an average of the three methods of calculation, the heritability estimate for S:P ratio was highest (0·69), followed by estimates for secondary, total and primary wool follicles (0·52, 0·46 and 0·36, respectively). These estimates are similar to the heritabilities of fleece weight, staple length and fibre diameter. Selection for increased density, provided an accurate measure is used, is suggested as an effective means for increasing fleece weight within grade.

Selection for clean fleece weight in Merino sheep. II.* Correlated responses to selection

1974 ◽  
Vol 25 (6) ◽  
pp. 973 ◽  
Author(s):  
R Barlow
Keyword(s):  
Genetic Correlations ◽  
Fibre Diameter ◽  
Correlated Responses ◽  
Strong Negative Correlation ◽  
Fibre Density ◽  
Asymmetrical Pattern ◽  
Selection For ◽  
Fleece Weight ◽  
Positive Correlations ◽  
Staple Length

Correlated responses to selection for high and low clean fleece weight (W) in the Peppin Merino (Fleece plus and Fleece minus flocks respectively) are presented together with estimates of realized genetic correlations where appropriate. There were strong positive correlations between W and greasy fleece weight and between W and clean scoured yield, and a strong negative correlation between Wand crimp frequency. There was no consistent association between W and body weight. Selection for W caused little change in wool colour, a slight improvement in wool character, and an improvement in wool handle in the rams, but not in the ewes. There was an increase in face cover score and a decrease in birthcoat score in the Fleece minus flock, but there was no change in either trait in the Fleece plus flock. Possible reasons for these asymmetries are discussed. Most of the response in W in the Fleece plus flock arose through increases in fibre density, fibre diameter and staple length. Staple length was the major component associated with response in W in the Fleece minus flock. Decreases also occurred in fibre density and wrinkle score but there was no change in fibre diameter. Continued response in W in the Fleece minus flock was through staple length and, to a lesser extent, wrinkle score. The response in fibre density in both flocks arose through change in the ratio of secondary to primary fibres. Two-year-old and lifetime reproductive performances are reported for the two selection flocks. The Fleece minus 2-year-old ewes weaned significantly more lambs than their Fleece plus counterparts over the period studied. The lifetime reproductive performance of ewes was similar in both flocks, although there were significantly more multiple births in the Fleece plus flock. An examination of the divergence between the two flocks revealed no significant time trends. The asymmetrical pattern of response in W in these flocks is discussed in the light of the present data. __________________ *Part I, Aust. J. Agric. Res., 25: 643 (1974).

Genetic studies on growth, reproduction and wool productiontraits in Harnali sheep

2016 ◽  
Author(s):  
SPACE Lalit ◽  
Z. S. Malik ◽  
D. S. Dalal ◽  
C. S. Patil ◽  
S. P. Dahiya
Keyword(s):  
Body Weight ◽  
Growth Traits ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Reproductive Traits ◽  
Phenotypic Correlation ◽  
Reproduction Traits ◽  
Heritability Estimates ◽  
Fleece Weight

Data on growth, reproduction and wool traits of 1603 Harnali sheep maintained at Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar over a period of 22 years (1992-2013) were utilized for genetic analysis. The overall least squares mean for birth weight (BW), weaning weight (WW), six month body weight (SMW), age at first lambing (AFL), weight at lambing (WL), average lambing interval (ALI), greasy fleece weight (GFW), staple length (SL) and Fibre diameter (FD) were estimated as 3.35±0.02 kg, 12.41±0.08 kg, 16.30±0.12 kg, 707.05±2.07 days, 26.91±0.10 kg and 402.85±2.40 days, 1.62±0.02 kg, 5.65±0.03 cm and 25.85±0.07 μ, respectively. The effect of year of birth, sex of lamb and dam's weight at lambing were significant for all growth traits. The effect of year of birth and dam's weight at lambing were significant for all reproduction traits and GFW. No definite trend was observed over the years for body weights and reproductive traits. The effect of sex was significant for early growth traits. The heritability estimates were moderate for all the growth traits with high genetic correlations of BW and WW with SMW. Reproduction traits had lower estimates of heritability which indicated presence of lower additive genetic variance for these traits. Heritability estimates for studied wool traits were moderate to high. Positive genetic and phenotypic correlation of BW and WW with six month body weight and grease fleece weight indicated that selection for six month body weight would increase body weight and grease fleece weight.

A genetic analysis of wool characteristics and lamb performance traits in Scottish Blackface sheep

2003 ◽  
Vol 77 (3) ◽  
pp. 355-362 ◽  
Author(s):  
J. Conington ◽  
A. Murphy
Keyword(s):  
Genetic Correlations ◽  
Live Weight ◽  
Scoring Systems ◽  
Production Traits ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
Heritability Estimates ◽  
Wool Quality ◽  
Fleece Weight ◽  
The Uk

AbstractGenetic parameters were estimated for wool quality, fleece characteristics and lamb production traits for Scottish Blackface sheep reared under extensive hill conditions in the UK. In two separate studies, heritabilities and genetic correlations were estimated for wool quality traits measured on lambs at 5 months of age and again on the shorn fleece a year later. The wool traits included birth coat length (BCT), 10-point scores for proportion of grey and kemp fibres present in the fleece (grey, kemp), British Wool Marketing Board (BWMB) recommendation (REC), greasy fleece weight (FLWT), BWMB fleece grade (FLGR), and average staple length (ASL). Genetic and phenotypic correlations were estimated between lamb wool traits and lamb live weights at birth (BWT), marking (at mid lactation with an average age of 7 weeks) (MWT), weaning (at an average age of 17 weeks) (WWT) and slaughter (SLWT), average fat depth (AVFD) and average muscle depth (MD). Individual lamb carcass measurements included Meat and Livestock Commission (MLC) conformation score (CONF) and fat class (FATC). Heritability estimates measured on 2524 or more live lambs were 0·69, 0·52, 0·26, 0·42 and 0·31 for BCT, ASL, grey, kemp and REC respectively. Heritability estimates for traits measured on the shorn fleece a year later for 1415 ewes were 0·37, 0·02, 0·57, 0·43, 0·46 and 0·14 for ASL, grey, kemp, REC, FLWT and FLGR respectively. Genetic correlations between FLWT in hoggets and other wool were positive and moderate to high in magnitude, ranging from 0·22 for kemp in lambs to 0·48 for grey in hoggets. Genetic correlations between REC and live-weight traits were 0·39 for MWT, 0·37 for WWT and 0·44 for SLWT. Genetic correlation between ASL and ultrasonic fat depth was 0·15 and for ASL and ultrasonic muscle depth was -0·30. The results indicate that the simple scoring systems derived to assess these traits are useful indicators of fleece quality, are highly repeatable over time and are a good gauge of likely future wool production. The results indicate that selection for heavier, leaner lambs should not compromise fleece quality, as assessed in this study.

Studies on Western Australian Merino sheep. II. Genetic and phenotypic parameter estimates for objectively measured traits on ram and ewe hoggets using different model types

1994 ◽  
Vol 45 (4) ◽  
pp. 829 ◽  
Author(s):  
RP Lewer ◽  
RR Woolaston ◽  
RR Howe
Keyword(s):  
Environmental Effects ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Parameter Estimates ◽  
Merino Sheep ◽  
Phenotypic Correlations ◽  
Average Fibre Diameter ◽  
Heritability Estimates ◽  
Fleece Weight ◽  
Western Australian

Data from a Western Australian experimental flock of Merino sheep were used to estimate genetic and phenotypic parameters for clean fleece weight (CFW), greasy fleece weight (GFW), average fibre diameter (FD), and clean yield (Y) from hogget fleeces as well as liveweights at birth (BWT), weaning (3WT), 8-9 months (8WT), 11-12 months (11WT) and 14-15 months (14WT) of age. The estimates were derived for male and female hoggets using restricted maximum likelihood REML. Simple models were fitted in which most environmental effects were omitted for comparison with results from models containing all recorded significant environmental effects. There were no significant differences amongst heritability estimates between models or sexes. Genetic correlations were calculated between sexes for each trait, with none being significantly different to unity. Ranges of heritability estimates across models and sexes were: GFW, 0.30-0-42; CFW, 0.26-0.44; Y, 0.46-0.59; FD, 0.47-0.59; BWT, 0.16-0.33; 3WT, 0.32-0.39; 8WT, 0.22-0.36; llWT, 0-27-0.44; 14WT, 0.27-0.50. Estimates of genetic and phenotypic correlations were in reasonable agreement with other literature values. As with the heritability estimates, the model fitted did not result in important differences in either genetic or phenotypic correlations.

Direct and maternal genetic (co)variances for hogget liveweight and fleece traits in Western Australian Merino sheep

2002 ◽  
Vol 53 (3) ◽  
pp. 271 ◽  
Author(s):  
S. W. P. Cloete ◽  
J. C. Greeff ◽  
R. P. Lewer
Keyword(s):  
Genetic Correlation ◽  
Coefficient Of Variation ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Phenotypic Variance ◽  
Selection For ◽  
Fleece Weight ◽  
Variance Estimates ◽  
Western Australian ◽  
Australian Merino

(Co)variance estimates for hogget liveweight, greasy fleece weight, clean fleece weight, clean yield, fibre diameter, and the coefficient of variation of fibre diameter were obtained for a Western Australian Merino resource flock. The flock encompassed 16 medium wool bloodlines and data were available for the period 1982–93. Direct additive genetic variances (h2) — expressed as a ratio of the total phenotypic variance within bloodlines — were estimated at 0.52 for hogget liveweight, 0.44 for greasy fleece weight, 0.42 for clean fleece weight, 0.63 for clean yield, 0.71 for fibre diameter, and 0.62 for coefficient of variation of fibre diameter. Maternal genetic variance estimates were significant (P < 0.05) only in hogget liveweight and fibre diameter, but components within bloodlines were low (0.05 for liveweight and 0.02 for fibre diameter). Direct within-bloodline genetic correlations of hogget liveweight as well as greasy and clean fleece weight with fibre diameter were positive (0.17, 0.31, and 0.31, respectively), suggesting that selection for bigger and heavier cutting sheep would generally lead to a broader fibre diameter. Liveweight was unrelated to clean yield and negatively related to coefficient of variation of fibre diameter (–0.17). Greasy fleece weight was negatively related to clean yield (–0.20). The genetic correlation of clean fleece weight with clean yield was positive (0.37). Wool quantity was, in general, positively related to coefficient of variation of fibre diameter, although the estimated genetic correlations were low (0.12 for greasy fleece weight and 0.07 for clean fleece weight). The genetic correlation between fibre diameter and coefficient of variation of fibre diameter was negative, and fairly low (–0.10). These results are discussed with reference to sheep breeding.

Heritability estimates and genetic and phenotypic correlations of lamb production parameters with hogget liveweight and fleece traits in Western Australian Merino sheep

2002 ◽  
Vol 53 (3) ◽  
pp. 281 ◽  
Author(s):  
S. W. P. Cloete ◽  
J. C. Greeff ◽  
R. P. Lewer
Keyword(s):  
Genetic Correlations ◽  
Fibre Diameter ◽  
Breeding Strategy ◽  
Total Weight ◽  
Coefficients Of Variation ◽  
Reproduction Traits ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates ◽  
Fleece Weight ◽  
Western Australian

Heritability estimates (h2) for weight of lamb weaned and number of lambs weaned totalled over 3 reproduction opportunities were estimated in a multi-bloodline Western Australian medium wool resource flock. These traits were defined to give an indication of lifetime lamb production (the ewes were retained in the breeding flock for a maximum of 4 lambing opportunities). Both reproduction traits were highly variable, as suggested by coefficients of variation of approximately 50%. The between-bloodline variance ratio was significant (P < 0.05), but failed to exceed 5% of the total across-bloodline phenotypic variation. Within-bloodline h2 ( s.e.) was estimated at 0.154 0.040 for total weight of lamb weaned, and at 0.141 0.040 for total number of lambs weaned. Within-bloodline genetic correlations of both traits with hogget liveweight were positive and significant (P < 0.05; 0.58 0.11 and 0.26 0.13, respectively). Within-bloodline genetic correlations of the reproduction traits with wool production were generally positive, being 0.26 0.11 for the correlation between total weight of lamb weaned and clean fleece weight, and 0.29 0.15 for the correlation between total number of lambs weaned and clean fleece weight. Clean yield was genetically unrelated to both measures of reproductivity. The genetic correlation of total weight of lamb weaned per breeding ewe with fibre diameter was positive in sign, but smaller than twice its standard error (0.17 0.10). The corresponding estimate for total number of lambs weaned was 0.16 0.12. It was concluded that the reproduction traits investigated would respond to selection in Western Australian Merinos if it should form part of a breeding strategy. Genetic correlations with hogget liveweight and wool traits were generally favourable.

Selection for ultrafine Merino sheep in New Zealand: heritability, phenotypic and genetic correlations of live weight, fleece weight and wool characteristics in yearlings

2001 ◽  
Vol 72 (2) ◽  
pp. 241-250 ◽  
Author(s):  
T. Wuliji ◽  
K. G. Dodds ◽  
J. T. J. Land ◽  
R. N. Andrews ◽  
P. R. Turner
Keyword(s):  
New Zealand ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Live Weight ◽  
Production Traits ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
Staple Strength ◽  
Fleece Weight ◽  
Staple Length

AbstractMerino yearling records from 1988 to 1992 birth years in ultrafine wool selection and random control flocks at Tara Hills High Country Station, New Zealand were analysed for live weight, fleece weight and wool characteristics. Estimates of heritability, genetic and phenotypic correlations among traits using REML methods are presented. Heritabilities (h2) of birth, weaning, autumn, spring and summer live weights and greasy and clean fleece weights were estimated as being 0·35, 0·34, 0·44, 0·43, 0·49, 0·24 and 0·28 respectively; while h2 of yield, fibre diameter, coefficient of variation in fibre diameter, staple crimp, staple length, staple strength, position of break, resistance to compression, bulk, CIE Y and CIE Y-Z were estimated to be 0·58, 0·59, 0·60, 0·45, 0·71, 0·13, 0·18, 0·46, 0·38, 0·38 and 0·42 respectively. Genetic correlations were found to be high among the live weights but low to moderate among fleece weight and wool characteristics. Heritability estimates of fibre diameter, fibre diameter variation and staple length were found to be higher in New Zealand fine wool Merinos than most of those reported in the literature. The results indicate that selection for reduced fibre diameter will have little effect on other major production traits such as live weight and fleece weight.

Resistance to nematode parasites in Merino sheep: correlation with production traits

1998 ◽  
Vol 49 (8) ◽  
pp. 1201 ◽  
Author(s):  
S. J. Eady ◽  
R. R. Woolaston ◽  
R. W. Ponzoni ◽  
R. P. Lewer ◽  
H. W. Raadsma ◽  
...  
Keyword(s):  
Variance Components ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Correlated Response ◽  
Production Traits ◽  
Merino Sheep ◽  
Nematode Parasites ◽  
Faecal Egg Count ◽  
Selection For ◽  
Fleece Weight

Merino sheep representing a range of bloodlines in resource flocks located across Australia were tested for resistance to gastro-intestinal nematodes. These flocks included the JB Pye Flock (Camden, NSW), Katanning Base Flock (Katanning, WA), Turretfield Merino Resource Flock (Rosedale, SA), and the CSIRO Finewool Flock (Armidale, NSW) and included a total of 328 sire groups. Resistance to nematodes was measured by faecal egg count (FEC). Data were also available for greasy and clean fleece weight (GFW and CFW, respectively), fibre diameter (FD), and body weight (BW) at a range of ages from weaning to 21 months. Variance components were estimated by restricted maximum likelihood, fitting an animal model and estimating covariances in a series of bivariate analyses. Phenotypic correlations between FEC0·33 and production traits were all close to zero ( –0·09–0·02). Genetic correlations between FEC0·33 and production traits were –0·20, –0·18, and –0·26 for weaning weight, 10-month BW, and 16-month BW, respectively; 0·21, –0·06, and 0·21 for 10-month GFW, 16-month GFW, and 21-month GFW; 0·21, –0·05, and 0·07 for 10-month CFW, 16-month CFW, and 21-month CFW; and –0·09, –0·12, and 0·04 for 10-month FD, 16-month FD, and 21-month FD. When estimates were pooled for all fleece traits and all BW traits, the genetic correlations between FEC0·33 and GFW, CFW, FD, and BW were 0·15, 0·10, –0·06, and –0·21, respectively. Using pooled estimates for CFW, FD, and BW, selection for a breeding objective based on production traits alone would lead to an unfavourable correlated response in FEC0·33 of approximately 1% per year.

Comparison of three Australian Merino strains for wool and body traits. II. Estimates of between-stud genetic parameters

1970 ◽  
Vol 21 (5) ◽  
pp. 837 ◽  
Author(s):  
N Jackson ◽  
JW James
Keyword(s):  
Genetic Correlations ◽  
Fibre Diameter ◽  
Short Term ◽  
Breeding Values ◽  
Genetic And Phenotypic Correlations ◽  
Selection For ◽  
Fleece Weight ◽  
Subsequent Selection ◽  
Australian Merino

Data from two-tooth rams and ewes representing seven Australian Merino studs were analysed to provide estimates of between-stud genetic variances and between-stud genetic correlations for 20 wool and body traits. The estimates were used to compare two methods of choosing foundation animals for a new stud: selection within one stud or selection within each of several studs. Where only one trait was considered in selection, and provided that accurate estimates of stud mean breeding values were available, selection from a single stud was superior, although there were some differences between traits in the degree of superiority. Where more than one trait was considered the conclusion depended on the relative magnitudes and signs of the between and within-stud genetic and phenotypic correlations. In the particular case of selection for high clean fleece weight and fine fibre diameter, a strong unfavourable between-stud genetic correlation shifted the emphasis more toward selection from several studs, but selection from a single stud was still superior when accurate estimates of stud mean breeding values for clean fleece weight were available. When response to subsequent selection, as well as immediate gain in choice of founders, was considered, the conclusions were reversed. For a single trait, selection from several studs was always superior in the long term (three or more generations), and also in the short term when accurate estimates of stud mean breeding values were not available.

Estimates of genetic and phenotypic parameters of some weight and fleece traits in a coarse-wool breed of sheep

1982 ◽  
Vol 99 (2) ◽  
pp. 277-285 ◽  
Author(s):  
R. A. Guirgis ◽  
E. A. Afifi ◽  
E. S. E. Galal
Keyword(s):  
Body Weight ◽  
Genetic Correlations ◽  
Phenotypic Correlations ◽  
Body Weights ◽  
Heritability Estimates ◽  
Fleece Weight ◽  
Staple Length

SUMMARYA study using 1150 lambs to estimate genetic and phenotypic parameters of some weight and fleece traits was carried out on coarse-wool Barki sheep. The weight traits were birth, weaning, yearling weights and daily gains whereas fleece traits included kemp score, staple length and greasy-fleece weight.Heritability estimates of weight traits were within the range 0·25–0·30. Those of fleece traits were 0·16, 0·21 and 0·43. The repeatability estimates of fleece traits were 0·18, 0·38 and 0·53 for staple length, greasy-fleece weight and kemp score respectively.Phenotypic correlations between body weight and fleece traits were mostly positive. Genetic correlations between greasy-fleece weight and body weights were mostly positive and of medium values. Those between kemp score and body weights were mostly negative, ranging from medium-high to high.

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