Do price premiums for wool characteristics vary for different end products, processing routes and fibre diameter categories?

2016 ◽  
Vol 56 (12) ◽  
pp. 2146
Author(s):  
David Cottle ◽  
Euan Fleming
Keyword(s):  
Fibre Diameter ◽  
Price Setting ◽  
Hedonic Models ◽  
Price Premiums ◽  
Australian Wool ◽  
Breeding Selection ◽  
Staple Strength ◽  
Log Price ◽  
Using Data ◽  
Staple Length

No Australian wool price hedonic studies have separated auction data into different end product-processing groups (PPR) on the basis of all fibre attributes that affect the suitability of wool sale lots for PPR. This study was conducted to assess: (1) whether including information about PPR groupings is more useful in understanding price than clustering by broad fibre diameter (FD) categories, and (2) if the ‘noise’ of macroeconomic effects on price can be reduced by using a clean price relative to the market indicator (RelPrice) formula or a log RelPrice formula compared with log price or clean price. Hedonic models using data derived from 369 918 Australian auction sale lots in 2010–2011 were estimated for these four dependent price variables. Linear FD models predicted less of price’s variance than quadratic or exponential models. Segmenting wool sale lots into 10 PPR before wool price analyses was found to increase the proportion of price variance explained and thus be worthwhile. The change in price with a change in FD, staple length and staple strength differs significantly between PPR. Calculating RelPrice or log RelPrice appears a better price parameter than clean price or log price. Comparing the RelPrice and clean price models, the mean absolute percentage errors were 6.3% and 16.2%, respectively. The differences in price sensitivity to FD, staple length and staple strength across PPR implies a complex set of price-setting mechanisms for wool as different users place different values on these wool properties. These price-setting mechanisms need to be incorporated in hedonic models for agricultural products that possess this characteristic. The wool price premiums can be used to estimate relative economic values when constructing sheep breeding selection indexes and can help determine the most profitable wool clip preparation strategies.

Inheritance of Acid Red 1 dye absorption and its relationship to other Merino wool traits

2006 ◽  
Vol 46 (7) ◽  
pp. 943 ◽  
Author(s):  
A. C. Schlink ◽  
S. Ortega ◽  
J. C. Greeff ◽  
M. E. Dowling
Keyword(s):  
Coefficient Of Variation ◽  
Fibre Diameter ◽  
Merino Wool ◽  
Dyeing Performance ◽  
Dye Absorption ◽  
High Heritability ◽  
Acid Red 1 ◽  
Staple Strength ◽  
Wool Dyeing ◽  
Staple Length

Optimising and ensuring the reproducibility of wool dyeing is of significant economic importance to the wool industry. Midside wool from 1824 Merino ewe and ram hoggets was used to estimate the heritability of Acid Red 1 dye absorption in clean wool. Acid Red 1 absorption had a high heritability of 0.45 ± 0.07 and was phenotypically poorly correlated with fibre diameter (–0.11 ± 0.03), the coefficient of variation of fibre diameter (0.05 ± 0.03), curvature (–0.05 ± 0.03), staple strength (–0.02 ± 0.02) and staple length (–0.09 ± 0.03), yield (0.08 ± 0.03) and dust penetration (0.07 ± 0.03). It was not genetically correlated with fibre diameter (–0.05 ± 0.09), the coefficient of variation of fibre diameter (0.02 ± 0.09), curvature (–0.09 ± 0.09), staple strength (–0.07 ± 0.10) or staple length (–0.03 ± 0.08), but weakly genetically correlated with yield (0.18 ± 0.08) and dust penetration (0.24 ± 0.12). Dye absorption was also genetically negatively correlated with wool felting as measured by feltball diameter (–0.26 ± 0.09). Acid Red 1 absorption was not genetically correlated with absorption of the cationic dye Methylene Blue. We suggest that there is a biological basis for differences between wools in dyeing performance and that this variation will depend on the class of dye being evaluated for wool dyeing.

Effects of stocking rate in spring on liveweight and wool production of sheep grazing annual pastures

1994 ◽  
Vol 45 (2) ◽  
pp. 367 ◽  
Author(s):  
AN Thompson ◽  
PT Doyle ◽  
M Grimm
Keyword(s):  
Fibre Diameter ◽  
Stocking Rate ◽  
Wool Production ◽  
Wool Growth ◽  
Linear Relationships ◽  
Condition Score ◽  
Grazing Period ◽  
Staple Strength ◽  
Stocking Rates ◽  
Staple Length

Two experiments examined the effects of different stocking rates in spring, and hence the availability of annual pastures, on changes in liveweight and wool production in Merino wethers (Experiments 1 and 2 respectively: age 5 and 2+-year-old; liveweight 63.8 � 0.64 (s.e.m.) kg and 43.8 � 0.34 kg; condition score 3.9% 0.14 and 3.l � 0-08). In Experiment 1, stocking rates were 8, 16, 24, 32 and 40 sheep/ha from 8 August, 1989 f9r 122 days; Experiment 2 involved an additional stocking rate of 48 sheep/ha from 23 August, 1990 for 98 days. Feed on offer (FOO kg DM/ha) declined (P < 0.01) linearly as stocking rate increased. Stocking rate and initial FOO (ranging between 1100 and 7000 kg DM/ha) had no significant effects on pasture growth rate (PGR) through most of spring. Late in spring, increased stocking rates resulted in greater (P < 0.05) PGR. The total amount of pasture produced in the grazing period was not significantly affected by stocking rate (Expt 1, 7530 to 8200 kg DM/ha; Expt 2, 6390 to 6860 kg DM/ha). The relationships between liveweight change (LWC) or wool growth rates (WGR) and FO, during the period until pasture wilting at the lowest stocking rate (83 days in Expt 1; 76 days in Expt 2), were described by Mitscherlich equations. More than 74% of the variation in LWC or WGR was explained by differences in green FOO. In Expts 1 and 2 respectively, more than 90% of the maximum liveweight gain (66 and 192 g/day) was achieved at a FOO of 4000 or 3000 kg DM/ha, and sheep maintained weight at 2000 or 1000 kg DM/ha. More than 90% of the maximum WGR (22.3 and 19.0 g/day) was achieved at a FOO of 3000 or 2000 kg DM/ha. More than 70% of the variation in WGR was explained by LWC in both experiments. The slopes of the linear relationships were 0.047 g wool/g LWC in Expt 1, and 0.024 g wool/g LWC in Expt 2. At liveweight maintenance, sheep produced 15% less (Expt 1) or 25% less (Expt 2) wool than those grazed under conditions which allowed maximum rates of liveweight gain. Fibre diameter (FD) and length of wool grown were affected in the same manner as WGR by increases in FOO and hence LWC. In Expts 1 and 2 respectively, total clean wool weights were reduced by 17 and 9 g, mean FD by 0.05 and 0.02 microns and staple length by 0.35 and 0.13 mm, for each increase of one sheep/ha during the spring treatment periods. The effects of stocking rate in spring on annual wool production, mean FD and staple length were described by linear (P < 0.05 to P < 0.01) relationships. Standard deviation of midside FD (Expt 2), staple strength and position of break (both experiments) did not change significantly with stocking rate. These results indicate that grazing to a lower FOO during spring can be used to manipulate the amount and characteristics of wool produced by Merino wethers grazing annual pastures in Mediterranean climates with 600-700 mm rainfall.

Shearing Merino ewes at different stages of pregnancy: effects on fleece characteristics of progeny

2010 ◽  
Vol 50 (6) ◽  
pp. 603 ◽  
Author(s):  
E. H. van Reenen ◽  
P. R. Kenyon ◽  
R. G. Sherlock ◽  
R. E. Hickson ◽  
S. T. Morris
Keyword(s):  
Skin Biopsy ◽  
Fibre Diameter ◽  
Late Pregnancy ◽  
Secondary Follicle ◽  
Staple Strength ◽  
Fleece Weight ◽  
Yield Colour ◽  
Staple Length

Shearing strong-wool ewes at different stages of pregnancy has been shown to influence the follicle population of the offspring which may result in a finer, heavier fleece. The aim of this study was to investigate the effect of shearing time of Merino ewes on the liveweight, fleece characteristics and follicle population of their progeny. Pregnant Merino ewes were allocated to one of three shearing times; mid-pregnancy (d106; 106 days from the introduction of the ram), late-pregnancy (d141) and post-lambing (d191). A skin biopsy was taken from the mid-side of 128 lambs at d359 (~7 months of age) and analysed for primary and secondary follicle density. Mid-side wool samples were collected at d359, d499 and d716. Samples from d359 and d716 were analysed for washing yield, colour and fibre diameter. Greasy fleece weight was measured on d499 and a mid-side sample was taken to measure staple length and staple strength. Shearing time of Merino ewes had no effect on lamb liveweight at any stage of the experiment. Lambs born to ewes shorn during pregnancy had a lesser (P < 0.05) follicle density, secondary follicle density, follicle number index (FNI) and secondary FNI than those born to ewes shorn post-lambing. However, there was no effect (P > 0.05) of dam shearing treatment on fleece characteristics of progeny. The results indicate that, under the conditions of this study shearing Merino ewes in mid-to-late pregnancy did not alter the fleece characteristics of their progeny.

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.

Genetic parameters for bodyweight, wool, and disease resistance and reproduction traits in Merino sheep. 4. Genetic relationships between and within wool traits

2009 ◽  
Vol 49 (4) ◽  
pp. 289 ◽  
Author(s):  
A. E. Huisman ◽  
D. J. Brown
Keyword(s):  
Coefficient Of Variation ◽  
Genetic Relationships ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Selection Decisions ◽  
Different Ages ◽  
Reproduction Traits ◽  
Staple Strength ◽  
Fleece Weight ◽  
Staple Length

The aim of this paper was to describe the genetic relationship among expressions at different ages of seven wool traits: greasy and clean fleece weights, fibre diameter, coefficient of variation of fibre diameter, staple length and strength, and mean fibre curvature. Genetic correlations among measurements at different ages for the same trait were moderate to high, and ranged from ~0.6 for both fleece weights to 0.9 and higher for mean fibre diameter and curvature. Generally, low to moderate genetic correlations (0.3–0.4) were estimated between fleece weights and fibre diameter, clean fleece weight and staple length, and fibre diameter and staple strength. Small positive genetic correlations (0.2) were estimated between greasy and clean fleece weight with fibre diameter coefficient of variation, and between fibre diameter and staple length. Mean fibre curvature had a negative genetic correlation (approximately –0.4) with most other wool traits, the exceptions were staple strength (~0.0) and coefficient of variation of fibre diameter (approximately –0.1). Fibre diameter, staple length and staple strength had negative genetic correlations with coefficient of variation of fibre diameter (–0.15, –0.10, and –0.61, respectively). The results indicate that for most wool traits only one measurement across ages is required to make accurate selection decisions. The relationships between traits are generally moderate to low suggesting that simultaneous genetic improvement is possible.

scholarly journals The effects of pasture inputs and intensive rotational grazing on superfine wool production, quality and income

2013 ◽  
Vol 53 (8) ◽  
pp. 750 ◽  
Author(s):  
D. Cottle ◽  
C. A. Gaden ◽  
J. Hoad ◽  
D. Lance ◽  
J. Smith ◽  
...  
Keyword(s):  
Soil Fertility ◽  
Management Strategies ◽  
Fibre Diameter ◽  
Production Quality ◽  
Grazing Management ◽  
Rotational Grazing ◽  
Wool Production ◽  
Staple Strength ◽  
Fleece Weight ◽  
Staple Length

A farmlet experiment was conducted between July 2000 and December 2006 as part of the Cicerone Project, which sought to enhance the profitability and sustainability of grazing enterprises on the Northern Tablelands of New South Wales, Australia. A self-replacing Merino enterprise was grazed as the dominant livestock enterprise, together with ~20% of the carrying capacity as cattle, on each of three farmlet treatments: higher levels of soil fertility and pasture renovation with flexible rotational grazing over eight paddocks (farmlet A), moderate soil fertility and pasture renovation with flexible rotational grazing over eight paddocks (farmlet B) and moderate soil fertility and pasture renovation with intensive rotational grazing over 37 paddocks (farmlet C). Prior to commencement of the trial, the three 53-ha farmlets were allocated equivalent areas of land based on soil type, slope and recent fertiliser history. This paper describes the effects of the three pasture and grazing management strategies on the production, quality and value of the wool produced per head, per ha and per farmlet. Up until 2001 there were no differences in wool production between farmlets. Thereafter, significant differences between farmlets emerged in greasy fleece weight per head and price received per kg of fleece wool. For example, the clean fleece value averaged over the 2003–05 shearings for all hoggets, ewes and wethers was 1531, 1584 and 1713 cents/kg for farmlets A, B and C, respectively. There were small but significant differences, which varied between sheep class and year, between the farmlets in average fibre diameter and staple length but less so with staple strength. In general, while the differences between farmlets in staple strength varied over time, farmlets A and B tended to have wool with longer staple length and broader fibre diameter than farmlet C and this affected wool value per kg. Differences in wool income per ha between farmlets grew in later years as the farmlet treatments took effect. In spite of farmlet A having a slightly lower wool value per kg, after taking into account its greater fleece weight per head and its higher stocking rate, the total wool income per ha was higher than on either farmlets B or C. The average gross wool income per ha from 2003 to 2005 was $303, $215 and $180 for farmlets A, B and C, respectively. The highest amount of greasy wool produced was in 2004 when 38.2, 26.5 and 21.5 kg/ha was harvested from farmlets A, B and C, respectively. The fibre diameter profiles of 2-year-old ewes showed similar profiles for farmlets A and B but a significantly finer fibre diameter profile for farmlet C ewes due to intensive rotational grazing. However, sheep on all three farmlets produced wool with high staple strength. Multivariate analyses revealed that greasy fleece weight, staple length and staple strength were significantly positively correlated with the proportion of the farm grazed at any one time, and with soil phosphorus, legume herbage and green digestible herbage thus highlighting the significant influence of pasture and soil inputs and of grazing management on wool production and quality.

Differences in fibre diameter profile characteristics in wool staples from Merino sheep and their relationship with staple strength between years, environments, and bloodlines

2002 ◽  
Vol 53 (4) ◽  
pp. 481 ◽  
Author(s):  
D. J. Brown ◽  
B. J. Crook ◽  
I. W. Purvis
Keyword(s):  
Fibre Diameter ◽  
Alternative Interpretation ◽  
Merino Sheep ◽  
Explanatory Variables ◽  
Diameter Variation ◽  
Diameter Fibre ◽  
Staple Strength ◽  
Profile Characteristics ◽  
Diameter Change ◽  
Staple Length

This study examined differences in fibre diameter profiles (FDPs) and midside characteristics of Merino sheep in 2 environments, 4 bloodlines, 3 years, and 44 sire groups. Environment significantly (P < 0.05) influenced all characteristics except one measure of fibre diameter change and staple length. Bloodline also significantly (P < 0.05) influenced all characteristics except staple strength. The maximum fibre diameter, one measure of fibre diameter change, and staple length were significantly different (P < 0.05) between sires. Variation in fibre diameter profile characteristics between bloodlines and sires changed across the environment in which the sheep are maintained. Despite these differences between bloodlines and sires in the FDP, midside mean fibre diameter, fibre diameter variation, and staple length, there were no significant differences between bloodlines in staple strength. The relationships between the FDP and midside characteristics with staple strength were also examined over these bloodlines and environments. Along-staple variation in fibre diameter (r = –0.32 to –0.50), between-fibre fibre diameter variation (r = –0.25 to –0.48), rate of fibre diameter change (r = –0.16 to –0.38), and midside variation in fibre diameter (r = –0.25 to –0.51) were all negatively correlated with staple strength. Maximum fibre diameter (r = 0.08 to 0.18), minimum fibre diameter (r = 0.25 to 0.49), and midside mean fibre diameter (r = 0.09 to 0.35) were positively associated with staple strength. FDP characteristics explained 5–30% more variation in staple strength than could be explained using the standard midside characteristics of mean fibre diameter, fibre diameter variation, and staple length alone. These relationships were also different between environments and bloodlines. The inclusion of the FDP characteristics as explanatory variables provided an alternative interpretation for how absolute fibre diameter and fibre diameter variation combine to explain staple strength. These results suggested that animals and sires might be able to be selected on FDP characteristics to improve staple strength. More detailed genetic studies are required before these selection strategies can be recommended.

Vital statistics for an experimental flock of Merino sheep. III. Factors affecting wool and body characteristics, including the effect of age of ewe and its possible interaction with method of selection

1966 ◽  
Vol 17 (4) ◽  
pp. 557 ◽  
Author(s):  
GH Brown ◽  
HN Turner ◽  
SSY Young ◽  
CHS Dolling
Keyword(s):  
Body Weight ◽  
Fibre Diameter ◽  
Vital Statistics ◽  
Fibre Volume ◽  
Age Changes ◽  
Factors Affecting ◽  
Fibre Number ◽  
The Mean ◽  
Selection For ◽  
Staple Length

Estimates were made of the effects of the following factors on 10 fleece and body characteristics measured on breeding ewes aged 1½ to 10½ years in three mating groups over a period of 15 years: age of ewe, single or twin birth, age of dam, the ewe's own lambing performance, the year in which measurements were made, and the year in which each set of ewes was born. Two groups (S and MS) were under selection for high clean wool weight at 15–16 months, with a ceiling on wrinkle score and fibre diameter, while the third (C) was a random control. Changes with age were present in all characteristics and were similar in the three groups. The finding that selection on wool weight at an early age had no effect on subsequent age changes in any characteristic is of considerable importance. Greasy and clean wool weight reached a maximum at 34 years, then declined by 0.3–0.2 1b per year. Percentage clean yield, fibre diameter, body weight, and wrinkle score had maxima at 5½ to 6½ years. Staple length fell consistently by approximately 0.2 cm per year, while face cover rose consistently but slightly. Crimp number rose, fell, and rose again, while fibre number rose, fell, and remained constant from 4½ years. The chief source of increase in wool weight from l½ to 3½ years was an increase in the total number of fibres. The chief source of the subsequent fall was a decrease in fibre volume, with a minor contribution from a fall in total fibre number after 6½ years. Twin-born ewes cut 0.21 lb (4.2% of the mean) less clean wool per year over their lifetime than single-born ewes, while the progeny of 2-year-old ewes cut 0.32 lb (6.4%) less than the progeny of adults. The main source of lower weight in each case was a lower total fibre number. Pregnancy lowered clean wool weight more than lactation, the separate effects being 0.87 and 0.38 lb respectively (17.4 and 7.7% of the mean) and the combined effect 1.25 1b or 25.1%. Pregnancy lowered total fibre number but lactation had no further effect. Mean clean wool weights over all ages in the C group varied from year to year, the range being from 1.08 lb (21.6%)below the mean to 0.97 lb (19.4%) above. Differences in total fibre number contributed between one-third and two-thirds of the variation. Ewes born in consecutive years in the S and MS groups showed marked upward trends in clean wool weight, fibre number, and staple length, with a marked downward trend in crimp number and a slight upward trend in body weight. These trends demonstrate direct and correlated responses to the strong selection for high clean wool weight at 15–16 months of age, and the associated slight selection against fibre diameter and wrinkle score. The mean annual increases in clean wool weight were 0.15 and 0.11 Ib (3.0 and 2.2%) in the S and MS groups, approximately 40% of the increase arising from increased total fibre number and 40% from increased staple length. The effects of age and lambing performance can be used to predict productivity in flocks of differing age structures. As the casting age rises to 54 years changes in productivity are negligible. With a rise in casting age to 7½ years the average clean wool weight of the flock would fall by 0.14 lb, with a slight decrease in staple length and crimp number. These changes need to be balanced against any increased lambing percentage or decreased annual genetic gain due to increased generation interval. Comparison with other available figures indicates that age changes may vary from one area to another.

Staple strength of fine, medium and strong wool Merino wethers under drought conditions

2006 ◽  
Vol 46 (9) ◽  
pp. 1123
Author(s):  
M. A. Friend ◽  
G. E. Robards
Keyword(s):  
Coefficient Of Variation ◽  
Management Strategies ◽  
Fibre Diameter ◽  
Summer Rainfall ◽  
Arid Environment ◽  
Strongly Correlated ◽  
Rainfall Events ◽  
Treatment Groups ◽  
Effect Of Treatment ◽  
Staple Strength

Fine, medium and strong wool Merino wethers (n = 72, 4 years old) were grazed together on drought-affected pastures in a semi-arid environment. In order to examine the hypothesis that restricting liveweight gains at the break of drought would improve staple strength, sheep were allocated to restricted grazing in a 5-ha paddock (drought group), or unrestricted grazing in a 20-ha paddock (drought-break group) when it was judged that the drought had broken in the region. Wool staples from all sheep broke at a point coinciding with summer rainfall events before allocation to treatment groups, and staple strength did not differ between treatments. Medium wool sheep (22.0 ± 1.6 N/ktex) produced wool of lower (P<0.001) staple strength than fine (30.0 ± 1.6 N/ktex) or strong (30.2 ± 1.6 N/ktex) wool sheep. Restricting the measurement of staple strength to the period when treatments were applied revealed no effect of treatment on staple strength, despite the fact that wethers in the drought-break group experienced a greater (P<0.001) liveweight gain (6.62 ± 0.37 kg) after allocation to their treatment than those in the drought group (–3.24 ± 0.37 kg). Staple strength was most strongly correlated with coefficient of variation of fibre diameter (r = –0.65; P<0.001); a result that was observed for all strains and treatment groups. The results indicate that coefficient of variation of fibre diameter is correlated with staple strength regardless of strain, and that management strategies designed to limit fibre diameter variability during a drought need to be applied not only at the break of a drought.

Corrigendum - Response to selection in Australian Merino sheep. I. Selection for high clean wool weight, with a ceiling on fibre diameter and degree of skin wrinkle. Response in wool and body characteristics

1968 ◽  
Vol 19 (1) ◽  
pp. 79
Author(s):  
HN Turner ◽  
CHS Dolling ◽  
JF Kennedy
Keyword(s):  
Fibre Diameter ◽  
The Other ◽  
Correlated Response ◽  
Mass Selection ◽  
Skin Area ◽  
Response To Selection ◽  
High Degree ◽  
Second Period ◽  
Final Selection ◽  
Staple Length

Direct and correlated responses are reported for two groups of sheep selected for high clean wool weight. The work covers two periods. In the first (1950–59), both groups had selection against high average fibre diameter and high degree of skin wrinkle, but in one group (S) the performance of the ram's half-sibs was considered as well as his own, while in the other (MS) mass selection was practiced for rams. For ewes, mass selection was practiced in both groups. In the second period (1961–64), mass selection was used for both sexes in both groups, with selection against high diameter and degree of wrinkle in one group (S), and against low crimp frequency and high degree of wrinkle in the other (MS). In both periods response to selection was assessed by comparison with a random control group. In the first period, response in clean wool weight was similar in S and MS, both for rams measured at 10–11 months, when a preliminary selection on them was carried out, and for ewes measured at 15–16 months, when final selection was made for both sexes. The annual rates of increase in clean wool weight for S and MS were 2.1 and 1.8% for rams and 2.4 and 2.7% for ewes, the lower rate in rams being due to the fact that response at 10–11 months is a correlated response to the final selection at 15–16 months. As the rates of increase in the two groups are similar, it can be concluded that examination of half-sibs is not worth while; this would in fact have been predicted from the high heritability estimates for clean wool weight. There were negligible trends in fibre diameter and wrinkle score, indicating that counter-selection has been effective in preventing an increase in these characteristics. Fibre number per unit skin area made the greatest contribution to the increases in clean wool weight, the annual rates of increase for S and MS being 2.0 and 2.2% for rams and 2.0 and I .8% for ewes. Greasy wool weight, percentage clean yield, body weight, and staple length also showed increases with increasing clean wool weight in both selected groups. In spite of the fact that fibre diameter did not increase, crimp number per unit of staple length decreased in both groups. This is a further confirmation of the strong negative genetic correlation between clean wool weight and crimp number, and of the lack of a strong association between crimp number and fibre diameter. In the second period, no further response was observed. It is impossible to say at this stage whether a selection plateau has been reached or whether drought conditions interfered with response.

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