Genetic parameters and trends in a selection experiment for increased clean fleece weight involving South African Merinos

1998 ◽  
Vol 38 (5) ◽  
pp. 427 ◽  
Author(s):  
S. W. P. Cloete ◽  
J. J. Olivier ◽  
M. A. Snyman ◽  
E. du Toit
Keyword(s):  
Fibre Diameter ◽  
Control Group ◽  
Selection Line ◽  
Additive Effects ◽  
Genetic And Phenotypic Correlations ◽  
Estimate Heritability ◽  
Fleece Weight ◽  
Estimated Breeding Values ◽  
Change In Mean ◽  
Genetic Trends

Summary. Data of 3603 to 7385 progeny of a Merino line selected for an increased clean fleece weight with a limitation on fibre diameter in sires and an unselected control group were used to estimate heritability for liveweight and wool traits. Estimated breeding values were obtained by backsolution and averaged within birth years to obtain genetic trends. Direct additive heritability (± s.e.) estimates were 0.29 ± 0.02 for clean fleece weight, 0.52 ± 0.03 for liveweight, 0.68 ± 0.02 for clean yield, 0.35 ± 0.02 for staple length, 0.63 ± 0.02 for fibre diameter and 0.42 ± 0.03 for total fold score. Fitting maternal additive effects to the model of analysis resulted in an improvement (P≤0.05) in the log likelihood ratio for clean fleece weight and liveweight. These effects were relatively small in magnitude, resulting in maternal additive effects (± s.e.) of 0.04 ± 0.01 for both traits. Genetic and phenotypic correlations of clean fleece weight with the other traits were positive. Genetic trends for fleece traits in the control group were less than 0.1% of the overall phenotypic mean per year. A substantial increase, depicted by a regression (± s.e.b) amounting to 0.14 ± 0.01 kg/year (0.28% of the phenotypic mean) was, however, found for liveweight (r = 0.91). The direct response in clean fleece weight in the selection line amounted to 0.039 ± 0.001 kg/year (r = 0.99), or 0.97% of the overall phenotypic mean. Correlated responses ranged from 0.78% of the overall phenotypic mean (r = 0.97) for liveweight to 0.17% per year (r = 0.51) for clean yield. The genetic change in mean fibre diameter (the trait under observation because an increase was unwanted) amounted to 0.020 ± 0.002 m/year (r = 0.69) or 0.10% of the overall phenotypic mean. The relaxation of the limitation on fibre diameter in sires used during 1986–90 probably contributed to this trend. A substantial increase in clean fleece weight was thus possible while unwanted increases in fibre diameter were limited.

Genetic changes generated within the Katanning Merino Resource flocks

2006 ◽  
Vol 46 (7) ◽  
pp. 803 ◽  
Author(s):  
J. C. Greeff ◽  
G. Cox
Keyword(s):  
Body Weight ◽  
Phase 1 ◽  
Fibre Diameter ◽  
Linear Unbiased Prediction ◽  
Genetic Changes ◽  
Breeding Values ◽  
Best Linear Unbiased ◽  
Fleece Weight ◽  
Estimated Breeding Values ◽  
Genetic Trends

Genetic changes for clean fleece weight, fibre diameter and hogget body weight were determined in the Katanning Merino Resource flocks from 1982 to 2004. From 1982 to 1992 genetic trends are presented for individual studs that used mainly subjective classing selection methods (Phase 1) and the genetic trends from 1997 to 2004 demonstrate the genetic changes that can be achieved from using estimated breeding values calculated from best linear unbiased prediction (BLUP) mixed methodology (Phase 2). The results during the first phase show that very few genetic changes occurred in most studs, except for the 4 studs of the Performance Sheep Breeding strain which showed genetic increases in hogget body weight. The genetic trends show that some studs generated change towards their breeding objective, while others show no changes or changes in the opposite direction. In contrast, the use of BLUP estimated breeding values resulted in positive changes in clean fleece weight, fibre diameter and body weight in accordance with the defined breeding objectives.

Genetic evaluation of production traits between and within flocks of Merino sheep. II. Component traits of the Hogget fleece

1993 ◽  
Vol 44 (7) ◽  
pp. 1523 ◽  
Author(s):  
SI Mortimer ◽  
KD Atkins
Keyword(s):  
Agricultural Research ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Matter Content ◽  
Research Centre ◽  
Production Traits ◽  
Merino Sheep ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Fleece Weight

Components of the fleece and wool quality traits were measured or assessed 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 recorded were face cover score (FC), leg cover score (LC), neck fold score (NF), body fold score (BF), wax content (W), suint content (S), vegetable matter content (VM), dust penetration (D), follicle density (N) and follicle ratio (RA). Genetic differences within and between flocks of Merino sheep were examined for the traits, and estimates of heritability and within-flock genetic and phenotypic correlations and between-flock genetic correlations among the traits were obtained. Genetic and phenotypic correlations were also estimated between these traits and the major wool production traits: greasy fleece weight (GFW), clean fleece weight (CFW), fibre diameter (FD), body weight (BWT) and staple length (SL). Significant strain. flock within strain and flock effects were wresent for all traits. The influence of environmental effects (birth-rearing type, age at measurement and age of dam) on the traits was estimated, with the birth-rearing type being significant and the largest effect for most traits. Paternal half-sib heritability estimates were 0.44� 0.06 for FC, 0.35� 0.06 for LC, 0.24�0.05 for NF, 0.23�0.05 for BF, 0.38�0.07 for W, 0.42�0.07 for S, 0.06�0.04 for VM, 0.22�0.06 for D, 0.20� 0.07 for N and 0.21�0.07 for RA. Estimates of within-flock phenotypic and genetic correlations were in broad agreement with available published estimates. The implications of the results for Merino breeding programs are discussed.

Wool staple tenacity in New Zealand Romney sheep: heritability estimates, correlated traits, and direct response to selection

2012 ◽  
Vol 52 (7) ◽  
pp. 448 ◽  
Author(s):  
D. R. Scobie ◽  
A. R. Bray ◽  
M. C. Smith ◽  
J. L. Woods ◽  
C. A. Morris ◽  
...  
Keyword(s):  
New Zealand ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Selection Line ◽  
Control Line ◽  
Response To Selection ◽  
Direct Response ◽  
High Line ◽  
Line Selection ◽  
Fleece Weight

A flock of New Zealand Romney sheep was established and selected as yearlings on the basis of fleece staple tenacity. The foundation flock was screened from contributing source flocks, with outliers of high or low staple tenacity as yearlings relative to the source flock mean contributing to a ‘high’ line and a ‘low’ line, respectively. A randomly selected control line was established because staple tenacity was known to be affected by yearly changes in feed supply. Staple tenacity of yearling fleeces was found to be heritable (0.41 ± 0.03). After 10 years of within-line selection, the line selected for increased staple tenacity had staples 53% stronger (33.9 N/mm2) than the control (22.1 N/mm2), while staples were 38% weaker in the line selected for decreased staple tenacity (13.8 N/mm2). Staple tenacity was genetically (0.67 ± 0.04) and phenotypically (0.44 ± 0.02) correlated with fibre diameter, and also with staple length (0.38 ± 0.07 and 0.32 ± 0.02, respectively). Longer, thicker fibres likely contributed to positive genetic (0.31 ± 0.07) and phenotypic (0.29 ± 0.02) correlations between staple tenacity and clean fleece weight. The indirect aim of selection was to improve fibre length after carding. Pooled wool samples were prepared from selection line groups of yearlings within sex each year, and a relationship between fibre length after carding measured on these samples and mean staple tenacity of the groups was observed (R2 = 0.514, P < 0.001). Within the tenth (last) year of selection, the high staple tenacity line produced the longest carded fibres (Hauteur: 103 mm) and the decreased staple tenacity line produced the shortest (87 mm), with the control line intermediate (96 mm).

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.

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.

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 parameters of Barki sheep raised under semi-arid conditions

1969 ◽  
Vol 11 (3) ◽  
pp. 361-367 ◽  
Author(s):  
M. H. Fahmy ◽  
E. Salah E. Galal ◽  
Y. S. Ghanem ◽  
S. S. Khishin
Keyword(s):  
Genetic Parameters ◽  
Genetic Correlations ◽  
Research Station ◽  
Phenotypic Correlations ◽  
Arid Conditions ◽  
Body Weights ◽  
Genetic And Phenotypic Correlations ◽  
Fleece Weight ◽  
Semi Arid ◽  
Desert Research

SUMMARYRecords on 695 lambs were collected over a period of 5 years from 1961/62 to 1965/66, at Ras El-Hekma Desert Research Station, 230 km west of Alexandria. The characters studied were birth, weaning and yearling body weights, pre- and post-weaning daily gains and greasy fleece weight.Birth, 120-day and 365-day body weights were 3·4, 18·2 and 33·4 kg respectively. Greasy fleece weight at 16 months of age was 3·29 kg. Heritability estimates of birth, weaning, yearling weights, pre- and post-weaning daily gains and greasy fleece weight were 0·22, 0·45, 0·41,0·45 and 0·29 respectively. Genetic and phenotypic correlations between birth, weaning and yearling weights were all positive and significant. Genetic correlations between fleece weight and body characteristics were negative and low.

A randomized controlled clinical trial to evaluate safety and efficacy of a Unani formulation in the management of Kalaf (Melasma)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ifra Abdul Qaiyyum ◽  
Mohammad Nawab ◽  
Munawwar Husain Kazmi
Keyword(s):  
Quality Of Life ◽  
Test Group ◽  
Control Group ◽  
Safety And Efficacy ◽  
Randomized Controlled ◽  
End Point ◽  
Intergroup Comparison ◽  
And Control ◽  
Change In Mean

Abstract Objectives Kalaf (Melasma) is an acquired facial hypermelanism. It has direct impact on patient’s quality of life and leads to development of various personality disorders. Lack of effective treatment and recurrences have drawn the attention of researcher to find alternative treatment. This study aimed to evaluate safety and efficacy of a topical Unani formulation in the management of melasma. Methods We conducted a prospective randomized controlled clinical study on the participants diagnosed with melasma. The participants (n=72) randomized into test (n=36) and control (n=36) groups. Sixty participants (n=30 in each group) completed the duration of therapy. The participants of the test group were treated with a classical Unani formulation and control group with hydroquinone 4%. The primary end point was change in mean MASI score and secondary end point was improvement in quality of life after eight weeks of treatment. Results The Unani formulation reduced 40.5% mean MASI score (17.31 ± 9.58 to 10.28 ± 5.92) in comparison to 32% reduction in mean MASI score (20.58 ± 9.49 to 13.92 ± 7.38) in the control group after eight weeks of treatment. When comparing with baseline the difference in MASI score was found statistically significant in both groups (p<0.05). On intergroup comparison, the change in MASI score between both groups was not statistically significant (p>0.05). In addition, MQOL and DQLI also improved significantly in both groups. Conclusions This study concluded that the Unani formulation and the control drug were equally effective and safer in the management of melasma.

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