Selection for clean fleece weight in Merino sheep. I. Direct response to selection

1974 ◽  
Vol 25 (4) ◽  
pp. 643 ◽  
Author(s):  
WA Pattie ◽  
R Barlow
Keyword(s):  
Agricultural Research ◽  
Fibre Diameter ◽  
Initial Increase ◽  
Research Station ◽  
Environment Interaction ◽  
Response Patterns ◽  
Cross Sectional ◽  
Merino Sheep ◽  
Two Generations ◽  
Fleece Weight

Two closed selection flocks of Merino sheep consisting of 100 ewes mated to five rams each were established at the Agricultural Research Station, Trangie, N.S.W., in 1951. One flock was selected for high clean fleece weight (Fleece plus) and the other for low clean fleece weight (Fleece minus). Responses to selection in these flocks over approximately five generations were measured against a randomly selected control flock (100 ewes mated to 10–25 rams). All flocks were selected from the same base population (1700 ewes and 150 rams) and were maintained in the same environment. The response patterns were asymmetrical. In the Fleece plus flock there was an initial increase of approximately one standard deviation in the first two generations but no consistent response was observed in the following three generations. This is shown by realized heritabilities of 0.53 and 0.11 for ewes in the first two, and subsequent generations respectively, the corresponding figures for rams being 0.65 and 0.02. In contrast to this pattern, response in the Fleece minus flock was approximately linear with overall realized heritabilities of 0.44 and 0.38 for ewes and rams respectively. The average level of inbreeding increased between 4 and 5% during selection, and the pooled partial regression of inbreeding coefficient on clean fleece weight independent of the effects of selection was –0.033 kg per 1% inbreeding. This would not have been sufficient to cause a cessation of response after the first two generations. Sampling variation and genotype x environment interaction are possible causes of this response pattern. An additional explanation is suggested which is based on the fact that clean fleece weight is a complex character in which two components, fibre density and cross-sectional area, have a negative genetic correlation between them which may become stronger under selection. It is shown that this could account for a large proportion of the reduction in realized heritability. Thus it is suggested that breeding plans should aim to control fibre diameter while selecting for high clean fleece weight if continued response is to be obtained.

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.

Hybrid vigour and lamb production. 2. Effects on survival and growth of first-cross lambs, and on wool and body measurements of hogget ewes

1978 ◽  
Vol 18 (95) ◽  
pp. 753 ◽  
Author(s):  
BJ McGuirk ◽  
ME Bourke ◽  
JM Manwaring
Keyword(s):  
Agricultural Research ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Research Station ◽  
Hybrid Vigour ◽  
Body Measurements ◽  
South Wales ◽  
Survival And Growth ◽  
Lamb Survival ◽  
Fleece Weight

In an experiment at Cowra Agricultural Research Station, New South Wales, five drops of Border Leicester (BB), Merino (MM), Border Leicester x Merino (BM) and Merino x Border Leicester (MB) lambs have been compared to estimate hybrid vigour effects on lamb survival and growth, and on the wool and body measurements of ewe hoggets. Hybrid vigour has been estimated as the percentage superiority of the crossbreds 1/2(MB + BM) over the average of the purebred 1/2(BB + MM) flocks. Hybrid vigour was observed for lamb survival, with the crossbreds superior by 10 per cent in lambs weaned per lamb born (P < 0.05). The crossbred lambs were also heavier at birth (4 per cent) and weaning (6 per cent) and crossbred wether lambs were 11 per cent heavier at slaughter (all P < 0.05). The crossbred ewes were significantly superior to the average of the purebred flocks in both greasy (8 per cent) and clean fleece weight (12 per cent), liveweight (12 per cent) and chest depth (5 per cent) (all P < 0.05). There was no evidence that the crossbreds were superior in any component of wool production per unit area of the skin ; fibre length, fibre diameter or follicle density. Other evidence from this experiment indicates that the breeds and crosses differ in their susceptibility to pneumonia and that there may be heterosis for resistance. This situation could give rise to heterosis for production characters and the heterosis estimates obtained may only be applicable to first-cross flocks derived from Border Leicester studs which are susceptible to pneumonia. Lamb survival to weaning was higher for purebred Merinos (88 per cent) than for purebred Border Leicesters (73 per cent, P < 0.05). The Border Leicester lambs were heavier at all ages and in all years, although the magnitude of their superiority varied significantly between years (P < 0.05). This breed x year interaction was also significant for clean fleeca weight, but the average production of the two groups was similar over the five years. Variation, measured as the coefficient of variation, was generally lower within the crossbred flocks for those characters for which hybrid vigour effects were observed, but these differences were not statistically significant.

Genetic variances for liveweight and fleece traits in Merino, Dohne Merino and South African Meat Merino sheep

2001 ◽  
Vol 41 (2) ◽  
pp. 145 ◽  
Author(s):  
S. W. P. Cloete ◽  
S. J. Schoeman ◽  
J. Coetzee ◽  
J. de V. Morris
Keyword(s):  
South African ◽  
Fibre Diameter ◽  
Phenotypic Variance ◽  
Total Phenotypic Variance ◽  
Weaning Weight ◽  
Merino Sheep ◽  
Genetic Variances ◽  
Variance Ratios ◽  
Fleece Weight ◽  
Variance Estimates

(Co)variance estimates for weaning weight, yearling liveweight, clean fleece weight and fibre diameter at yearling age were obtained for Merino, Dohne Merino and South African Meat Merino flocks maintained on the same property. Direct additive genetic variances for weaning weight [expressed as a ratio of the total phenotypic variance (h2, direct heritability)] were estimated at 0.15 for Merinos, 0.21 for Dohne Merinos and 0.32 for South African Meat Merinos. Corresponding maternal variance ratios (m2, including direct maternal variance and permanent environmental maternal variance) were estimated at 0.15, 0.30 and 0.24, respectively. The correlation between direct and maternal variance ratios was high and negative in Dohne Merinos and South African Meat Merinos (–0.72 and –0.53, respectively). Direct heritability estimates for yearling liveweight were 0.30 for Merinos, 0.33 for Dohne Merinos and 0.45 for South African Meat Merinos. Corresponding maternal variance ratios were only significant in the latter 2 breeds, amounting to 0.13 in Dohne Merinos and 0.12 in South African Meat Merinos. For yearling clean fleece weight, h2 and m2 were estimated at 0.28 and 0.12, respectively, for both Merinos and Dohne Merinos. In the case of South African Meat Merinos, only the h2 estimate was significant, at 0.68. Maternal variance ratios for yearling fibre diameter were not significant in any of the breeds, while h2 ranged from 0.58 in Merinos to 0.75 in South African Meat Merinos. Selection progress for yearling traits seems likely in all breeds, depending on the breeding objectives being strived for.

The influence of selection and plane of nutrition on the components of fleece weight in Merino sheep

1958 ◽  
Vol 9 (6) ◽  
pp. 802 ◽  
Author(s):  
RB Dun
Keyword(s):  
Fibre Diameter ◽  
Fibre Length ◽  
Small Contribution ◽  
Cross Sectional ◽  
Single Character ◽  
The Mean ◽  
Low Levels ◽  
The Difference ◽  
Fleece Weight ◽  
High Level

The components of clean fleece weight were examined in five experimental flocks of medium-wool Peppin Merinos. Four single-character selection groups – clean fleece weight plus, clean fleece weight minus, crimps per inch plus, and crimps per inch minus – were examined by measuring fleece production in 18-month-old ewe progeny. Measurements were also made on progeny from the "nucleus" flock, which was selected for clean fleece weight with subsidiary selection for crimps per inch and against fold score. Data were collected in 1952 and 1954. The 1954 figures were obtained from a nutrition experiment in which sheep mere grown from weaning to 18 months on a high and on a low plane of nutrition. The mean measurements of the components of clean fleece weight (W) were compared between flocks using the "percentage deviation" technique. Four comparisons were made: (1) Nucleus/Fleece minus; (2) Fleece plus/Fleece minus; (3) Crimps minus/Crimps plus; (4) high nutritional plane/low nutritional plane. In comparisons (1) , (2), and (3), difference in weight of wool per unit area of skin (w) accounted for nearly all the difference in W. Body weight (S) made a small contribution while difference in fold score (R) was negligible. Fibre density (N) accounted for +86 per cent., and fibre cross-sectional area (A) for –28 per cent., of the difference in W in comparison (1). In comparison (2) the figures were N +47 per cent., A +21 per cent., while the figures for comparison (3) were N –26 per cent., A +121 per cent. The increase in fleece weight was invariably accompanied by a decrease in crimps per inch. In all three comparisons primary density (P) was the major cause of change in N. Fibre length (L) made a uniform contribution of approximately +15 per cent. in the three comparisons.The relative importance of the components of fleece weight was similar at both high and low levels of nutrition.The effect of a high level of nutrition was to produce large increases in A, L, and S. The increase in S was compensated by an equal decrease in P. The increase in fibre diameter was not associated with any change in crimps per inch.

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.

The long-term influence of superphosphate and stocking rate on the production of spring-lambing Merino sheep in the high rainfall zone of southern Australia

1999 ◽  
Vol 50 (7) ◽  
pp. 1179 ◽  
Author(s):  
J. W. D. Cayley ◽  
G. A. Kearney ◽  
G. R. Saul ◽  
C. L. Lescun
Keyword(s):  
Fibre Diameter ◽  
Subterranean Clover ◽  
The Body ◽  
Stocking Rate ◽  
Gross Margin ◽  
Single Superphosphate ◽  
Merino Sheep ◽  
Predetermined Level ◽  
The Mean ◽  
Fleece Weight

The productivity of spring-lambing fine wool Merino sheep grazing pastures sown in 1977 to perennial ryegrass and subterranean clover was assessed from 1989 to 1998. The pastures were fertilised each autumn with single superphosphate at 6 levels, and were stocked at a low, medium, or high stocking rate (SR) at each level of fertiliser. The average phosphorus (P) applied annually since sowing (P ) ranged from 1.6 to 32.9 kg/ha. The SRs used varied with fertiliser level in that they were higher where more fertiliser had been applied, so that the highest SR at each level of fertiliser ensured that the pastures were well utilised. Each ewe raised 1 lamb, which was removed at weaning. The influence of fertiliser on the productivity of the sheep at 4 classes (1–4) of SR (mean SR = 7.1, 10.1, 12.6, and 18.2 ewes/ha for classes 1–4, respectively) was described by: y = A−BCP, where y represents production per sheep (kg), and A, B, and C are constants. For greasy fleece weight, estimates of B and C were 1.59 and 0.84; and for SR classes 1–4, the estimates of A were 5.06, 4.89, 4.78, and 4.46, respectively. For weaning weight of lambs, estimates of B and C were 8.4 and 0.82, and estimates of A were 23.5, 22.7, 21.5, and 20.9 for SR classes 1–4. The mean fibre diameter (µm) of the wool was described by: D = 14.18+1.48 GW, where GW is the mean greasy wool produced annually per sheep (kg) averaged over all sheep and years for each of the 18 treatments. The price (cents/kg) of wool with a fibre diameter D (P D) was given by: P D = 12197+4.94P2 + 688D−0.1945P20D − 5810√D, where 20 µm wool is P20 cents/kg. Supplements were fed if the body condition of ewes fell to a predetermined level. The supplement fed per ewe each year (S), expressed as metabolisable energy (in MJ) was described by: S = −602 − 44.1S R + 178.5P + 8.71S R P +539 √SR− 338.5√P−70.8P√SR, where S R and P represent the mean stocking rate (ewes/ha) and mean P applied annually. When a current set of costs and prices was applied to these equations, the maximum gross margin for a SR of 7.1 ewes/ha was $AU119/ha with 8.6 kg P/ha applied annually, and $AU262/ha for SR of 18.2 ewes/ha with 17.6 kg P/ha applied annually. If income derived from sheep is maintained constant, intensifying the sheep enterprise from the low to the high SR system would involve increasing sheep numbers by about 17%, but would release about 55% of the farm’s area for another purpose.

Effect of stocking rate on fleece measurements and their relationships in merino sheep

1976 ◽  
Vol 27 (1) ◽  
pp. 163 ◽  
Author(s):  
DH White ◽  
BJ McConchie
Keyword(s):  
Fibre Diameter ◽  
Major Determinant ◽  
Stocking Rate ◽  
Merino Sheep ◽  
Wool Production ◽  
Rate Experiment ◽  
Fleece Weight ◽  
One Year ◽  
Staple Length

The wool characteristics of Merino wethers were measured for 6 years in a stocking rate experiment. The decline in fleece weight due to increasing stocking rate from 4.9 to 12.4 sheep per hectare was usually accompanied by a reduction in fibre diameter and staple length and an increase in staple crimp frequency. The magnitude of these responses differed considerably between years; in one year clean fleece weight was reduced by 50%, with an associated reduction of 5 µm in mean fibre diameter and one of 2 cm in staple length. In four of the six years of the experiment, variation in fibre diameter accounted for at least 50% of the variation in wool production between stocking rate treatments. The relationships between clean fleece weight and fibre diameter were similar between years, mean fibre diameter being reduced by about 1.8 �m for each kilogram reduction in clean fleece weight. Fibre diameter is the major determinant of wool price, and this information should improve the prediction of economic responses to changes in stocking rate.

A comparison of the topmaking performance of wool from sheep selected by index and visual methods

1999 ◽  
Vol 39 (8) ◽  
pp. 941 ◽  
Author(s):  
A. L. Vizard ◽  
K. A. Hansford
Keyword(s):  
Body Weight ◽  
Coefficient Of Variation ◽  
Selection Index ◽  
Fibre Diameter ◽  
Visual Assessment ◽  
Index Selection ◽  
Visual Methods ◽  
Merino Sheep ◽  
Fleece Weight ◽  
Index Value

Summary. The topmaking performance of fleeces from sheep that were ranked high or low on index selection using objective measurement was compared with that of sheep from the same flock that were ranked high or low on visual assessment. A flock of 451 15-month-old fine-wool Merino sheep were classed by 2 experienced fine-wool sheep classers into 3 grades: best, average and culls. Forty-four sheep were assessed as ‘best’ and 77 sheep were graded as ‘culls’ by both classers. These sheep were defined as the ‘best visual’ and ‘worst visual’ sheep, respectively. Measurements of clean fleece weight, mean fibre diameter, coefficient of variation of fibre diameter and body weight were used in a selection index to rank all sheep in the flock. The selection index was designed to rapidly reduce mean fibre diameter and slowly increase clean fleece weight, whilst maintaining staple strength and body weight. The 44 sheep with the highest index value were defined as ‘best index’ sheep and the group of 77 sheep with the lowest index or obvious physical faults were defined as the ‘worst index’ sheep. Twenty-five fleeces were randomly selected from each of the ‘best’ and ‘worst visual’, ‘best’ and ‘worst index’ sheep for individual processing through to top. The fleeces from the ‘best index’ sheep produced greater quantities of tops that were significantly finer, longer, of lower curvature and produced less noil than all other groups. In contrast to the large difference in quality between tops from the ‘best’ and ‘worst index’ sheep, there was little difference in quality between tops from the ‘best’ and ‘worst visual’ sheep. This indicates that the traditional wool producer views of wool quality are unrelated to processing performance. It was concluded that Merino sheep selected by index selection using direct measurement of fleece weight, mean fibre diameter and coefficient of variation of diameter as selection criteria produced greater quantities of wool of superior processing performance to that from sheep selected using visual assessment.

scholarly journals Comparative Study of AMMI- and BLUP-Based Simultaneous Selection for Grain Yield and Stability of Finger Millet [Eleusine coracana (L.) Gaertn.] Genotypes

2022 ◽  
Vol 12 ◽  
Author(s):  
N. Anuradha ◽  
T. S. S. K. Patro ◽  
Ashok Singamsetti ◽  
Y. Sandhya Rani ◽  
U. Triveni ◽  
...  
Keyword(s):  
Finger Millet ◽  
Agricultural Research ◽  
Harmonic Mean ◽  
Relative Performance ◽  
Research Station ◽  
Environment Interaction ◽  
Average Yield ◽  
Stability Parameters ◽  
Early Maturity ◽  
Simultaneous Selection

Finger millet, an orphan crop, possesses immense potential in mitigating climate change and could offer threefold security in terms of food, fodder, and nutrition. It is mostly cultivated as a subsistence crop in the marginal areas of plains and hills. Considering the changes in climate inclusive of recurrent weather vagaries witnessed every year, it is crucial to select stable, high-yielding, area-specific, finger millet cultivars. Sixty finger millet varieties released across the country were evaluated over six consecutive rainy seasons from 2011 to 2016 at the Agricultural Research Station, Vizianagaram. The genotype × environment interaction (GEI) was found to be significant in the combined ANOVA. Furthermore, the Additive Main effects and Multiplicative Interaction (AMMI) analysis asserted that genotypes and the GEI effects accounted for approximately 89% of the total variation. Strong positive associations were observed in an estimated set of eleven stability parameters which were chosen to identify stable genotypes. Furthermore, Non-parametric and Parametric Simultaneous Selection indices (NP-SSI and P-SSI) were calculated utilizing AMMI-based stability parameter (ASTAB), modified AMMI stability value (MASV), and Modified AMMI Stability Index (MASI) to identify stable high yielders. Both methods had inherent difficulties in ranking genotypes for SSI. To overcome this, the initial culling [i.e., SSI with culling strategy (C-SSI)] of genotypes was introduced for stability. In the C-SSI method, the top ten genotypes were above-average yielders, while those with below-average yield were observed in NP-SSI and P-SSI methods. Similarly, the estimation of best linear unbiased prediction (BLUP)-based simultaneous selections, such as harmonic mean of genotypic values (HMGV), relative performance of genotypic values (RPGV), and harmonic mean of relative performance of genotypic values (HMRPGV), revealed that none of the top ten entries had below-average yield. The study has proven that C-SSI and BLUP-based methods were equally worthy in the selection of high-yielding genotypes with stable performance. However, the C-SSI approach could be the best method to ensure that genotypes with a considerable amount of stability are selected. The multi-year trial SSI revealed that entries Indaf-9, Sri Chaitanya, PR-202, and A-404; and VL324 and VL146 were ascertained to be the most stable high-yielding genotypes among medium-to-late and early maturity groups, respectively.

Corrigendum - Response to partial selection on clean fleece weight in South Australian strong-wool Merino sheep

1969 ◽  
Vol 20 (1) ◽  
pp. 151
Author(s):  
O Mayo ◽  
JC Potter ◽  
RE Brady ◽  
CW Hooper
Keyword(s):  
Fibre Diameter ◽  
Index Method ◽  
Visual Method ◽  
Merino Sheep ◽  
Index Group ◽  
Agricultural College ◽  
Selection For ◽  
The Difference ◽  
Fleece Weight ◽  
Selection Of

This paper reports the results of an experiment carried out at Roseworthy Agricultural College from 1953 to 1966 comparing two bases of selection of rams: (1) visual appraisal (the "visual" method); (2) visual culling of 70% of rams followed by selection of breeding animals from the remaining 30% on the basis of clean fleece weight (the "index" method). No selection for fleece weight was practiced on ewes. Seven rams were used in each of the two flocks, and six of the seven were replaced each year by 16-month-old animals from the succeeding drop, the seventh being a year older. Rams used for breeding in the Index flock were significantly higher in clean fleece weight than those of the Visual flock, and were higher, though not always significantly so, in greasy fleece weight. This led to a divergence between the flocks for clean fleece weight (P < 0.05), with an increase of c. 0.05 lb per year per head for the Index animals over the Visual animals. The Index rams were more wrinkly and lighter, on the whole, than the Visual rams, and the wrinkly effect carried over into their offspring with a slight divergence apparent, the Index animals becoming more wrinkled than the Visual (P < 0.05). In fibre diameter there were no differences between selected animals or between flocks. Visual rams tended to have more crimps per inch in their wool, and this was observed in the flocks also, but the divergence was not significant (P > 0.05). Index rams had longer wool than Visual rams, with the difference generally significant within years, and this tendency carried over in a lesser manner to the flocks. Fleece density was generally greater in the Index group, though not usually significantly so. This experiment did not include a randomly bred control flock, but was rather designed to compare two practical methods of selecting rams. Merits of this scheme are discussed in the light of both groups' failure to show increases in fleece weight over the course of the experiment

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