scholarly journals Use of part records in Merino breeding programs — the inheritance of wool growth and fibre traits during different times of the year to determine their value in Merino breeding programs

2005 ◽  
Vol 45 (4) ◽  
pp. 347
Author(s):  
J. C. Greeff ◽  
B. Paganoni ◽  
R. P. Lewer
Keyword(s):  
Genetic Correlation ◽  
Coefficient Of Variation ◽  
Selection Criteria ◽  
Fibre Diameter ◽  
Indirect Selection ◽  
Mediterranean Environment ◽  
Breeding Programs ◽  
Wool Growth ◽  
Heritability Estimates ◽  
Fibre Traits

Fibre diameter can vary dramatically along a wool staple, especially in the Mediterranean environment of southern Australia with its dry summers and abundance of green feed in spring. Other research results have shown a very low phenotypic correlation between fibre diameter grown between seasons. Many breeders use short staples to measure fibre diameter for breeding purposes and also to promote animals for sale. The effectiveness of this practice is determined by the relative response to selection by measuring fibre traits on a full 12 months wool staple as compared to measuring them only on part of a staple. If a high genetic correlation exists between the part record and the full record, then using part records may be acceptable to identify genetically superior animals. No information is available on the effectiveness of part records. This paper investigated whether wool growth and fibre diameter traits of Merino wool grown at different times of the year in a Mediterranean environment, are genetically the same trait, respectively. The work was carried out on about 7 dyebanded wool sections/animal.year, on ewes from weaning to hogget age, in the Katanning Merino resource flocks over 6 years. Relative clean wool growth of the different sections had very low heritability estimates of less than 0.10, and they were phenotypically and genetically poorly correlated with 6 or 12 months wool growth. This indicates that part record measurement of clean wool growth of these sections will be ineffective as indirect selection criteria to improve wool growth genetically. Staple length growth as measured by the length between dyebands, would be more effective with heritability estimates of between 0.20 and 0.30. However, these measurements were shown to have a low genetic correlation with wool grown for 12 months which implies that these staple length measurements would only be half as efficient as the wool weight for 6 or 12 months to improve total clean wool weight. Heritability estimates of fibre diameter, coefficient of variation of fibre diameter and fibre curvature were relatively high and were genetically and phenotypically highly correlated across sections. High positive phenotypic and genetic correlations were also found between fibre diameter, coefficient of variation of fibre diameter and fibre curvature of the different sections and similar measurements for wool grown over 6 or 12 months. Coefficient of variation of fibre diameter of the sections also had a moderate negative phenotypic and genetic correlation with staple strength of wool staples grown over 6 months indicating that coefficient of variation of fibre diameter of any section would be as good an indirect selection criterion to improve stable strength as coefficient of variation of fibre diameter for wool grown over 6 or 12 months. The results indicate that fibre diameter, coefficient of variation of fibre diameter and fibre curvature of wool grown over short periods of time have virtually the same heritability as that of wool grown over 12 months, and that the genetic correlation between fibre diameter, coefficient of variation of fibre diameter and fibre curvature on part and on full records is very high (rg >0.85). This indicates that fibre diameter, coefficient of variation of fibre diameter and fibre curvature on part records can be used as selection criteria to improve these traits. However, part records of greasy and clean wool growth would be much less efficient than fleece weight for wool grown over 6 or 12 months because of the low heritability of part records and the low genetic correlation between these traits on part records and on wool grown for 12 months.

Calculation of the heritability of spinning fineness from phenotypic and genetic parameters of the mean and CV of fibre diameter

1992 ◽  
Vol 43 (6) ◽  
pp. 1441 ◽  
Author(s):  
KL Butler ◽  
M Dolling
Keyword(s):  
Genetic Correlation ◽  
Coefficient Of Variation ◽  
Selection Criteria ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Diameter Distribution ◽  
The Mean

In sheep selection programmes where fibre diameter distribution measurements are available, such as when using the FDA method of assessing fibre diameter, spinning fineness (as defined by Anderson, S.L. (1976), J. Text. Inst., 67, 175-80) might be preferable to using mean fibre diameter as a sheep selection criteria. This paper uses a Taylor's expansion to obtain an approximation to the heritability of spinning fineness when the phenotypic and genetic parameters of only the mean and the coefficient of variation of fibre diameter are available. The approximation assumes that the mean and coefficient of variation of fibre diameter are both phenotypically and genetically independent. Approximations are also obtained for the genetic correlation between spinning fineness and mean fibre diameter, and between spinning fineness and coefficient of variation. Using the approximations, estimates of heritability of spinning fineness and of the two genetic correlations are calculated for published studies.

Fleece rot and body strike in Merino sheep. VI. Experimental evaluation of some physical fleece and body characteristics as indirect selection criteria for fleece rot

1993 ◽  
Vol 44 (5) ◽  
pp. 915 ◽  
Author(s):  
HW Raadsma
Keyword(s):  
Genetic Correlation ◽  
Selection Criteria ◽  
Fibre Diameter ◽  
Selection Criterion ◽  
Indirect Selection ◽  
Merino Sheep ◽  
Breeding Programmes ◽  
Fleece Weight ◽  
Indicator Trait

Indicators of staple thickness, staple weight, staple density, wool weight cm -2, crimp frequency, dust penetration, fibre diameter (mean, variability), birthcoat score, and neck and body wrinkle were evaluated for their suitability as indirect selection criteria against fleece rot and body strike. The fleece traits were assessed in 949 Merino ewe hoggets representing the progeny from 134 sires in 15 contemporarily managed flocks. Fleece rot and body strike were assessed following experimental induction. In decreasing order of importance, variability (s.d.) in fibre diameter, average staple thickness, crimp frequency, variability (c.v.) in fibre diameter, mean fibre diameter, birthcoat score, staple density, variability in staple thickness, staple weight, and neck wrinkle score, accounted for a significant component of the variation in liability of sheep to fleece rot. Body wrinkle, variability (c.v.) in staple thickness, staple length, dust penetration, and wool weight cm-2 were not important. Based on combined estimates of the heritability of the indicator trait and its genetic correlation with fleece rot, variability in fibre diameter (s.d.) and birthcoat score showed the highest potential as indirect selection criteria. Variability in fibre diameter (s.d.) also showed a similar scope for selection against body strike. Indicators of mean staple thickness, crimp frequency, dust penetration and wrinkle score showed little or no scope for indirect selection against fleece rot or body strike. The role of variability in fibre diameter (s.d.) as an indirect selection criterion for fleece rot and body strike in designed breeding programmes which include other important objectives, will need to be further evaluated, given an undesirable genetic correlation with clean fleece weight. High between-flock correlations were observed for a number of fleece traits and susceptibility to fleece rot. Susceptible flocks were characterized by fleeces with longer, heavier, thicker staples with a lower crimp frequency, and higher fibre diameter with a higher variability. Predicting the susceptibility of flocks to fleece rot and body strike, through a between flock index based on the measurement of simple fleece traits, is suggested.

Liveweight and wool growth responses to a Mediterranean environment in three strains of Merino sheep

1998 ◽  
Vol 49 (8) ◽  
pp. 1187 ◽  
Author(s):  
N. R. Adams ◽  
J. R. Briegel
Keyword(s):  
Body Composition ◽  
Fibre Diameter ◽  
The Other ◽  
Wool Fibre ◽  
Growth Responses ◽  
Mediterranean Environment ◽  
Protein Loss ◽  
Broad Group ◽  
Wool Growth ◽  
Sources Of Variation

The present study examined changes in wool growth, liveweight, and body composition in groups of fine, medium, and broad wool Merino wethers grazed together at pasture in the highly seasonal Mediterranean environment, to determine the sources of variation in wool growth that may affect staple strength (SS). Seasonal changes in wool growth were measured using 6 dyebands placed at times of seasonal change in the nutrient supply from pasture, and liveweights were recorded fortnightly. Dilution of deuterated water was used to determine changes in body composition between the beginning of summer and the end of autumn. The sheep lost liveweight over this period, but loss of protein relative to fat over this period was unexpectedly high (7 : 1). The relative changes in liveweight, and loss of its components (fat and lean) during summer and autumn, were similar in all 3 groups, even though the Broad group was heavier than the other 2 genotypes at all times (P < 0·01). In contrast to the similar pattern of liveweight change, wool growth rates and changes in the fibre diameter were less variable throughout the year in the Broad group than the other 2 groups (P < 0·001). Stepwise regression indicated that the characteristics related to SS were standard deviation in fibre diameter (SDfd; P < 0·001), mean fibre diameter (P < 0·001), and variation in diameter within a 200-mm length of wool fibre (Sdfdwithin; P < 0·05). However, the relative importance of different factors for SS differed within each group. The most important factors were mean fibre diameter in the Fine group, the variation in fibre diameter along the staple (SDfdalong) in the Medium group, and the variation in diameter between fibres (SDfdbetween) in the Broad group. It is concluded that SS is a complex characteristic, depending on both the fibre diameter and several sources of variation in fibre diameter, all of which can differ among flocks. Protein loss made a disproportionate contribution to liveweight loss over summer and autumn, but the amino acids made available did not contribute substantially to wool growth or SS.

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.

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.

scholarly journals Selection efficiency on bones and meat yeald in pigs

2011 ◽  
Vol 27 (4) ◽  
pp. 1787-1792
Author(s):  
V. Vidovic ◽  
S. Trivunovic ◽  
D. Punos ◽  
Lj. Strbac ◽  
D. Lukac ◽  
...  
Keyword(s):  
Genetic Correlation ◽  
Genetic Parameters ◽  
Economic Effect ◽  
Indirect Selection ◽  
Genetic Variations ◽  
Fixed Effect ◽  
Positive Trend ◽  
Selection Efficiency ◽  
Meat Yield ◽  
Heritability Estimates

Trial were conducted at 5 farms, on 5 breeds of pigs in itch farm, in a period from 2000 to 2010. To analyzed data, the MME LS model was used to correct FYS and Breed as fixed effect and Sire as random one. Genetic parameters were estimated from half siblings group. Bones had significantly smaller weight in Pietrain pigs compared to all other breeds. Furthermore, daily and life gains at the Pietrain breed were significantly smaller compared to other breeds. Heritability estimates were significantly different for three breeds, higher for bones, higher for meat yield. The pheneotipic and genetic variations were similar for all traits. Economic effect of selection can be analyzed and expected with a positive trend. Genetic correlation showed expected trend. It is possible to use the effect of indirect selection as well.

scholarly journals Realized Sampling Variances of Estimates of Genetic Parameters and the Difference Between Genetic and Phenotypic Correlations

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1409-1416 ◽  
Author(s):  
Kenneth R Koots ◽  
John P Gibson
Keyword(s):  
Genetic Correlation ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Phenotypic Correlation ◽  
Parameter Estimates ◽  
Sampling Variance ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Heritability Estimates

Abstract A data set of 1572 heritability estimates and 1015 pairs of genetic and phenotypic correlation estimates, constructed from a survey of published beef cattle genetic parameter estimates, provided a rare opportunity to study realized sampling variances of genetic parameter estimates. The distribution of both heritability estimates and genetic correlation estimates, when plotted against estimated accuracy, was consistent with random error variance being some three times the sampling variance predicted from standard formulae. This result was consistent with the observation that the variance of estimates of heritabilities and genetic correlations between populations were about four times the predicted sampling variance, suggesting few real differences in genetic parameters between populations. Except where there was a strong biological or statistical expectation of a difference, there was little evidence for differences between genetic and phenotypic correlations for most trait combinations or for differences in genetic correlations between populations. These results suggest that, even for controlled populations, estimating genetic parameters specific to a given population is less useful than commonly believed. A serendipitous discovery was that, in the standard formula for theoretical standard error of a genetic correlation estimate, the heritabilities refer to the estimated values and not, as seems generally assumed, the true population values.

Genetic importance of fat and eye muscle depth in Merino breeding programs

2016 ◽  
Vol 56 (4) ◽  
pp. 690 ◽  
Author(s):  
D. J. Brown ◽  
A. A. Swan
Keyword(s):  
Carcass Traits ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Economic Index ◽  
Parasite Resistance ◽  
Eye Muscle ◽  
Breeding Programs ◽  
Dual Purpose ◽  
Internal Parasite ◽  
Reproduction Traits

Australian Merino breeders have traditionally selected animals for breeding predominately on the basis of wool characteristics. Over recent decades, an increasing proportion of Merino breeders are interested in producing a ewe that can be used for prime-lamb production, but that also performs well for wool characteristics. Correlations between ultrasound carcass traits and other traits such as wool, internal parasite resistance and reproduction traits, are not very well known. The aims of this study were three-fold: (1) to estimate the genetic relationships between ultrasound carcass traits and wool, internal parasite resistance and reproduction traits, (2) to determine the value of recording ultrasound carcass traits in Merino breeding programs, and (3) to evaluate the impact of improving ewe genetic merit for fatness on their reproduction performance. Ultrasound fat and eye muscle depth had small to moderate genetic correlations with most traits, with positive correlations observed for bodyweight, fibre diameter, fibre curvature and reproduction, and negative correlations observed for fleece weight, fibre diameter coefficient of variation, worm egg count and breech wrinkle. As expected on the basis of these genetic correlations, estimated breeding values for fat depth of ewes had a positive association with their observed reproduction performance, but the effect explained only minimal variation in reproductive performance, and was extremely variable among flocks and years. A range of measurement scenarios was investigated for three standard MERINOSELECT indexes. Measuring fat and eye muscle depth resulted in 3%, 4% and 21% additional economic index gain for the fine, medium and dual purpose indexes, respectively, whereas measuring reproduction traits directly resulted in 17%, 27% and 45% additional gain in the economic index. Dual purpose index gains benefited more from measuring ultrasound carcass traits as it is the only index with a direct economic value placed on carcass traits. Measuring fat and eye muscle depth also resulted in a greater reduction in worm egg count. The results indicated that desirable genetic progress can be made in wool, ultrasound carcass, internal parasite resistance and number of lambs born and weaned simultaneously using multiple trait selection to account for the mix of favourable and unfavourable correlations between these traits. These results also demonstrated that the best method to maximise economic gain is to measure as many traits (or closely correlated traits) in the breeding objective as possible.

Spectral Reflectance Indices as a Potential Indirect Selection Criteria for Wheat Yield under Irrigation

Crop Science ◽  
2006 ◽  
Vol 46 (2) ◽  
pp. 578-588 ◽  
Author(s):  
M. A. Babar ◽  
M. P. Reynolds ◽  
M. van Ginkel ◽  
A. R. Klatt ◽  
W. R. Raun ◽  
...  
Keyword(s):  
Spectral Reflectance ◽  
Selection Criteria ◽  
Wheat Yield ◽  
Indirect Selection ◽  
Reflectance Indices ◽  
Spectral Reflectance Indices
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