Wool Weight Research Articles

Inheritance of the resistance to compression property of Australian Merino wool and its genetic correlation with follicle curvature and various wool and body characters

Resistance to compression is primarily a measure of the crimp structure of individual fibres. Fibre crimp, as distinct from staple crimp, has been shown to be an important aspect of wool quality with requirements depending on end use and processing conditions. A precise definition of its importance under various conditions must await further evidence.The consequences of these findings for Merino breeders depend upon the heritability of resistance to compression and its genetic and phenotypic correlation with other important wool characters. Estimates of such parameters are presented and used to formulate breeding plans for the Australian Merino. Follicle curvature was included among the characters studied because it was hypothesized that it would be as good a measure of fibre crimp as is resistance to compression. The results support this hypothesis. The most important conclusion is that, if textile requirements dictate that resistance to compression as well as fibre diameter must be controlled during Merino breeding, progress in clean wool weight will be severely restricted.

Frequency of anthelmintic drenching of lambs in Waikato

Abstract Experiments in 1972 in Waikato with anthelmintics on lambs compared six drenches at monthly intervals from January to June inclusive with a drench in March, April, and May, and with no drenching. Drenching improved live-weight gains in winter and resulted in heavier fleeces at spring shearing, lowered incidence of acquired faults in wool, and heavier shorn body weights. After shearing, undrenched lambs showed compensatory growth, but it was insufficient to compensate fully for the earlier retardation, when final weighings were made in January and February. Six drenches were more effective than three, from a slight advantage in winter to more pronounced effects in wool weights and shorn body weights at October shearing. At the final weighings the beneficial effects from six drenches were more marked than from three. Wool- and body-weight increases from more frequent drenching would not necessarily have been financially beneficial.

Effect of pre- and post-weaning anthelmintic drenching on live-weight gain and wool weight in Romney ewe hoggets

Abstract During the 2-year period 1966–67 the production responses obtained from drenching young sheep with anthelmintics were examined in four trials at two sites in South Canterbury. Compared with undrenched controls, drenching at monthly intervals from November until August or September increased mean live-weight gain by 5.3 kg (range 5.1–9.2 kg) and mean greasy fleece weight by 0.62 kg (range 0.41–0.84 kg). Five drenches given in November, January, March, May, and July achieved responses averaging 68% of the live-weight gain and 73% of the increased greasy wool production from sheep drenched at monthly intervals. Starting at the end of October with 6-week-old lambs only 9% of the mean drenching response was obtained in the 2-month period before weaning in late December (0.35 kg), compared with 50% in January–February (1.05 kg), 21% in March–April (0.65 kg), and 40% in May–June (1.25 kg). No significant differences in mean live-weight gain (25.1 and 25.5 kg) or wool-weight (4.52 and 4.59 kg) were obtai...

Effect on live-weight gain and wool weights of anthelmintic and selenium drenching of mountain country Merino and halfbred ewe hoggets

Abstract In 1969, 1970, and 1971, the production responses obtained from drenching young sheep with anthelmintic and selenium were examined in 11 trials covering 6 localities in the mountain regions of South Canterbury. In six trials, at four of the sites, sheep grazed extensively and little supplementary winter feed was provided. The responses to the highest level of drenching over untreated controls averaged 1.5 kg live weight (range 1.0–1.8 kg) and 0.10 kg in greasy fleece weight (range — 0.01–0.32 kg). Most of the responses were due to selenium. In four other trials at two different sites, adequate quantities of supplementary feed were provided in paddocks. Compared with untreated animals, the response to drenching averaged 2.9 kg live weight (range 1.7–3.8 kg) and 0.30 kg greasy-fleece weight. In three of the trials most of the response was obtained from anthelmintic alone, and in the other trial only the selenium plus anthelmintic response was significant. In another trial sheep were given supplemen...

Whole wheat grain feeding of Merino ewes. 3. Influence of level of wheat and vitamin A on wool growth in pregnancy and lactation

In experiment 1, ewes were fed three levels of wheat in pens, with or without vitamin A, from joining to weaning. The wheat levels ranged from 3.4 to 4.6 kg head-1 week-1. Control groups were run on native pasture. In experiment 2 three levels of wheat, which ranged from 3.9 to 7.1 kg head-1 week-1. were fed to ewes from joining to weaning. At each wheat level two groups were fed wheat in pens (wheat/ pen); another group was fed wheat in small paddocks (wheat/paddock). One of the wheat/pen groups received vitamin A. A control group was run at pasture. Vitamin A had no effect on wool traits except on wool yield in experiment 2. Clean wool weight and staple length increased linearly with increasing wheat intakes in both experiments. The relationship between fibre diameter and wheat level was linear in experiment 1 and curvilinear in experiment 2. In experiment 2 there were differences between wheat/pen and wheat/paddock groups in all the wool traits measured. In experiment 1, wool growth rate was reduced by 40 per cent in the wheat groups and by 44 per cent in the pasture groups during late pregnancy and lactation. In experiment 2, compared with early pregnancy, wool growth rate was reduced by 11 per cent and 31 per cent in the wheat groups during late pregnancy and lactation respectively.

Influence of Ewe Age on Productive Characters of Southdown Sheep

Data utilized for this study came from records collected over a 14-year period, 1956 to 1969 inclusive, from a purebred Southdown flock which had been closed to outside breeding since 1957 and selected for date of birth. The lamb traits studied were birth weight (BTWT), rate of gain from birth to 120 days (RB12) and 120-day weight (12WT). The ewe traits studied were lambs born per ewe exposed (LBEE), lambs reared per ewe exposed (LREE), percent ewes lambing (%ELA), lambing date (LADT), lambs born per ewe lambing (LBEL), lambs reared per ewe lambing (LREL), date of first estrus (DAES), ewe wool weight (EWWT) and ewe body weight (EBWT). For the lamb traits, age of dam was a significant source of variation for BTWT only. Lambs from 2-year-old ewes were lighter at birth than lambs from all other age of dam classes. Age of ewe was significant for all ewe traits except %ELA and LADT. In general for the various ewe traits, the mature ewes were more productive than younger ewes with the only exception being that EWWT tended to decline with advancing age.

Response to selection in Australian Merino sheep. VI. Inheritance of abnormal staple crimp; estimates of phenotypic and genetic parameters

The heritability of abnormal crimp in wool at various ages and the genetic and phenotypic cotreiations of crimp abnormality with several wool and body characters were estimated for Peppin Merino sheep. When examined by half-sib analyses of variance, the heritability of abnormal crimp scored at ages less than 4.5 years was low, whereas abnormality at 5.5 years and older was highly inherited. Heritabilities estimated by intra-sire dam-daughter regression analyses with fewer degrees of freedom did not show such a clear-cut pattern, although the estimates tended to increase with age. The genetic correlations of crimp abnormality scores at ages up to 4.5 years with scores at older ages were mainly low. Crimp abnormality scores at most ages had genetic correlations with wool and body characters at 15–16 months of age as follows: strong positive with fibre diameter, weak positive with greasy and clean wool weight, wrinkle score and staple length, and weak negative with fibre number. Genetic correlations with body weight, percentage clean yield, face cover score and crimp frequency were inconsistent. The phenotypic variance of crimp abnormality increased with age, owing almost entirely to an increase in the additive genetic variance. The environmental variance was approximately the same at all ages. Phenotypic correlations among crimp abnormality scores were generally higher between scores at close ages, and particularly at older ages. Crimp abnormality scores at all ages had positive phenotypic correlations with fibre diameter and wrinkle score and negative correlations with fibre number per unit area of skin and percentage clean yield.Crimp abnormality at old ages also had positive phenotypic correlations with greasy and clean wool weights. Environmental correlations of crimp abnormality with greasy wool weight, clean wool weight body weight and fibre number per unit area of skin were negative, and those with percentage clean yield and fibre number positive. Predicted correlated responses in crimp abnormality differed in some respects from correlated responses observed previously in groups of Peppin Merino sheep selected for high and low values of percentage clean yield, clean wool weight, fibre number per unit area of skin and fibre diameter. Methods of selection of sheep which would be expected to reduce crimp abnormality are outlined.

ALPASLAN DEVLET ÜRETME ÇİFTLİĞİNİN MERİNOS YAPAĞILARINA AİT BAZI FİZİKİ ÖZELLİKLERİ ÜZERİNDE ARAŞTIRMA

OZET Bu arastirma; Alpaslan DevlelOretme C1fliginde yetistirilen merinos surusunde yapagi gomlek agirligi, lule uzunlugu ve kif incelikleri ile yapagilarda bulunan tam mediilla kanalli kil nisbetlerini tesbit etmek maksadiyla yapilmisur. . Merinos surusunden, sansa balgi olarak secilen 50 ergin koyunda yapagi gomlek agirliklarinin ortalamasi 2,398 kg. olarak bulunmustur. Koyunlarin omuz, kaburga ve but bMgelerine ait numunelerinde liile uzunluklari bu siraya gore 6,13 cm.; 6,25 cm.; 6,50 cm. ve genel ortalama 6,35 cm. olarak saptanmistir. Koyunlunn degisik beden bolgelerine gore; kil inceliklerinin ortalama degerleri, omuida 24,67 mikran; kaburgada 25,66 mikron; butta 26,97 mikron ve genelortalama kil inceligi 25,77 mikron olarak tesbit edilmistir Yapagilarin kil ineclikleri ile ~omlek agirliklari arasinda istatistik olarak onemli olmayan bir korelasyon, !ule uzunlugu ile kil inceligi arasinda negat~f (r= 0,388) degerinde%i ihtimal seviyeSinde onemli bir korrelasyon bulunmustur. Tam kana/l! olan medWlali ki/lar sadece, 56's den asagi sortimnalarda bulunan kaburgu ve but numunelerinde tesbit edilmesire ragmen, bu kil/arin nisbeti binde ile ifade edilebilecek kadar az oldugu tesbit edilmistir. THE RESEARCH ON SOME PHYSTCAL PROPERIES OF MERINOWOOL RAISED IN ALPASLAN DEVLET URETME CIFTLIGI SUMMARY This research was carried out in order to find shearing wool .weight staple length, yield, fibre fineness and the amount ot the main madullated fibres in the merino breed raised in Alpaslan Fram. 1 . The determination of Oeece weigtli in wool and sampling The wool samples for this research was taken from the ewes that healthy and over two yeais old randomly, The wool of 5u selected sheep, were sheared witb machine elipper and their weight was oetermined by a seale. The averege shearing weight of wool was found 2,398 kg. 2. Staple length of wool The wool sampels were randomlytaken from rib, shoulder and thigh parts of each sheep in order to determine the staple legth in wool and 15 staples were taken from each wool sample. The staple Jenth of wool samples were measured by Stoiiet-Board and and taking 5 staples from per !iample. The taken results were to rib shoulder and thigh parts ofsheep as fol1ows 6, 13 cm ; 6,25 cm. and 6.50 cm. 3. Yeld of ~ool The samples about 20 gr. was weighed in the conditioning room by scale accurate to 0,01 gr. and their vegatasle matter was taken out by forceps. Later on, the samples were put into lebelled . cotton bags and wetted out according to the rules of wetting. After drying the c1ean sainples at 105 oC. their second weight was also measured. x: Kamgam sanayiinde kamgarn tipi iplik ve kumas yapimi icin uzun elyafli orta incelikie mutecanis vapa~ar kullanilir (Davasligil, 1960). 30 The percentage of values according to Bamard Metod were found as fol1ows: 62,29 for shoulder; 60,17 iib; 59,51 thing and general pereentage was found as 60,92. 4. Fineness of wool The fibre fineness of the samples were measured by means of Miero-Projection. The different fibre finensess values aceoding to the diffedent parts of body were detemined as fol1ows: 24,67 mierons for shoumder; 25,66 microns rib; 26,97 microns thigt. In ;iddition, the differenee between fibre fi~eness and fleece weigth statisticaeally had a insi~nifieant eorrelation effect and 'also a nefative eorrelation about 1% significant effeet between staple length and fibre fineness was (cund. The full medullated fibres were only fGund in the samples less than 56'S belonging to rib and thigt. The percentage of the madullated fibres wasfound to be less than thousand

Response to selection in Australian Merino sheep. VII. Phenotypic and genetic parameters for some wool follicle characteristics and their correlation with wool and body traits

Four numerical characteristics-follicle depth, follicle curvature, number of follicles per unit area of skin, and ratio of number of secondary to number of primary follicles-describing the size, shape, and arrangement of wool follicles have been measured in Peppin Merino sheep at 4-5 months (weaning), 15-16 months (two-tooth shearing) and at later ages ranging from 2 1/2 to 7 1/2 years. Estimates of their repeatability, heritability and phenotypic, genetic, and environmental correlations with 10 wool and body characteristics are reported. All four follicle characteristics were found to be highly inherited and sufficiently correlated with wool characteristics to be of interest to both the wool biologist and the sheep breeder. Fixed environmental effects influenced the expression of some follicle characteristics, while others, notably follicle curvature at any age, were unaffected, and therefore potentially more useful as practical selection aids. Groups of sheep selected for clean wool weight with control of (i) fibre diameter and wrinkle score, and (li) crimp frequency and wrinkle score, exhibited changes in the four follicle characteristics, which agreed with what the genetic correlation estimates would predict. The role of follicle characteristics in the biology of genetic control of wool growth is portrayed by fitting causal models invoking follicle characteristics as intermediates between the gene and the wool character. The analysis separates three independent genetic control systems, the identity of which corresponds closely to factors postulated in previous theoretical studies.

On increasing wool weight through breeding LK-type sheep

SUMMARYThe wool weight/m2 of LK progeny arising out of LK × LK matings (approximately a quarter were HK and were excluded) and HK progeny arising out of HK × HK matings (all were HK) of two coarse-wool producing breeds of sheep, Marwari and Magra, were compared with the mid-parent values. LK progenies produced significantly more than the mid-parent value in both the breeds, but there was no increase in HK progeny. The difference in wool weight between the HK progeny and their mid-parent value tended to be less for Marwari whereas it was much less for Magra breed.The results suggest that improvement in wool weight of sheep can be made by maintaining LK stock and mating LK × LK, culling the HK arising out of these matings in each generation.

The Nature and Function of the Resin in the Chlorine /Resin Shrinkproofing Treatment of Wool Tops

The only resin which has been found fully satisfactory for shrinkproofing wool tops by the chlorine/resin process on the industrial scale is a polyamide-epichlorohydrin polymer. A study has been made of the nature and function of this resin, on the wool and in isolation from it, to determine why it is peculiarly suitable. It is accepted as a premise for which there is considerable evidence that most of the shrinkproofing effect is produced by the prechlorination treatment, which softens the scales on the wool fibers, and that chlorination usually leaves some fibers undertreated, with scales hard enough to cause fiber migration and felting. It is shown that the role of the resin is to form a complete sheath over each fiber, burying or "masking" these undertreated scales. This requires an effective mean thickness which depends on the level of chlorination, but is usually greater than 0.5 μm, corresponding to about 10% of resin on the weight of wool. So high an uptake would, however, give too harsh a handle in the dry state. The peculiar advantage of the resin which has been used appears to be its capacity to swell considerably in water, to nearly 5 times its air-dry volume, while remaining solid and adhering to the wool. A 2% uptake of resin solids, measured in the air-dry state, is therefore equivalent approxi mately to the required 10% of resin gel in water. It has sometimes been found that the effectiveness of this treatment is reduced if processing oils are present. It is shown that such "oils," which contain considerable quantities of surfactants, dehydrate both the resin and the chlori nated cuticle cells. This hardens the scales and sharpens their contour while simultaneously thinning the masking films of resin and reducing their mutual adhesiveness; all these changes promote felting. Some suggestions are made as to the nature of the forces which hold the resin on the wool fibers.

Response to selection in Australian Merino sheep. IV.* Reproduction rate in groups selected for high clean wool weight, with a ceiling on degree of skin wrinkle and either fibre diameter or crimp frequency

Reproduction rate (number of lambs weaned per ewe joined) and its components (proportion of ewes lambing, lambs born per ewe lambing, and lamb survival rate) are compared for 2-year-old and adult Australian Peppin Merino ewes in a random control group and two groups under selection since 1950 for high clean wool weight, with limits on high wrinkle score and either high fibre diameter or low crimp frequency. The conclusion is that there has been no correlated response in reproduction rate to selection for high clean wool weight. The difference between the selected and control groups was expressed as a percentage deviation from the control. These percentage deviations for all four characteristics fluctuated considerably and there was no consistent trend. Mean percentage deviations were calculated for ewes born in an initial period of years, soon after selection began, and a final period, at the end of the time for which data were available. Any difference between such means would indicate a selection response. For both 2-year-old and adult ewes in both selection groups, means of the percentage deviations in number of lambs weaned were negative and in most cases large during the initial period (–19.4 and –3.4 for 2-year-old and adult ewes in one group, –17.6 and –11.9 in the other), but smaller and sometimes positive in the final period (+ 4.6 and –3 30 in the first group, + 3.3 and –8.7 in the second). The main contributor to the low number of lambs weaned for 2-year-old ewes in the initial period was a low proportion of ewes lambing. For adult ewes, the number of lambs born per ewe lambing (twinning rate) was lower in the final compared with the initial period, but showed no signs of continuing to fall. The fall was compensated by an increase in lamb survival rate in the selected groups compared with the control, which was not due solely to the lower incidence of twins but was present when only single lambs were considered. Possible reasons for a lower incidence of twinning and a higher lamb survival rate are discussed. The conclusion that reproduction rate has shown no consistent change under selection for high clean wool weight would have been predicted from the zero genetic correlation between the two characteristics previously estimated in the same flock. Comparisons are made with the negative estimates of genetic correlation reported by other authors, and reasons for differences discussed. Although no negative correlated selection response has been found in these groups, it is recommended that reproduction rate should always be considered when selecting for high clean wool weight in commercial practice. __________________ *Part III, Aust. J. Agric. Res., 21: 955 (1970)

Response to selection in Australian Merino sheep. V.* Inheritance of abnormal staple crimp: Crimp abnormalities in groups of breeding ewes selected for high and low values of clean wool weight and its components

Correlated responses in crimp abnormality in wool (i.e. irregularity of staple crimp frequency, to which the term "doggy" wool or "rough fleece" is applied when the crimp frequency is markedly reduced) are reported for two groups of Peppin Merino sheep selected for high clean wool weight, and for eight pairs of groups under selection for high and low values of the following single characters: clean wool weight per head, clean wool weight per unit area of skin, body weight, wrinkle score, fibre number per unit area of skin, fibre diameter, staple length, and percentage clean yield. In the first two groups the correlated responses in crimp abnormality were small and for practical purposes negligible. However. there appeared to be slight increases in crimp abnormality following changes in selection criteria, although this period coincided with adverse seasonal conditions. In the eight pairs of groups selected for single characters, correlated increases in crimp abnormality occurred in the groups selected for high clean wool weight per head, high and low fibre number per unit area of skin, high fibre diameter, and low percentage clean yield, and correlated decreases occurred in the groups selected for low clean wool weight per head, low fibre diameter, and high percentage clean yield. The responses were due mainly to the initial, intense selection of the foundation animals, and the responses to continuing selection were small. Environmental factors (year of fleece growth, maternal handicap, and lambing performance) did not have large effects on crimp abnormality. Crimp abnormality increased with age, and the rate of change was altered by selection in each of the single character groups in which correlated responses in crimp abnormality occurred, the responses being more pronounced at older ages.

Effect of implanted testosterone propionate on the growth and wool production of Merino wethers

The effect of subcutaneous implantation of testosterone propionate in fine-wool Merino wethers at pasture was studied in four experiments over a 5-year period. The wethers were maintained virtually free of posthitis so that the observed responses to implantation were physiological in origin. In nine comparisons two implants of 70 mg testosterone propionate per annum increased liveweights significantly. Annual greasy wool weights increased by amounts ranging from 0.03 to 0.25 kg per head, the differences being significant on five occasions. Annual clean wool weights increased by a maximum of 0.13 kg per head. Fleece weight indices used as a measure of the gross efficiency of wool production were similar in the implanted and control wethers in all experiments. Also no significant change in efficiency was recorded where direct measurements were made of wool grown and food intake. Implantation tended to reduce the percentage yield of clean wool, the effect being greatest in the first year of treatment. Measurement and assessment of wool traits of commercial importance showed negligible differences between treated and control wethers and the average value per kilogram greasy wool was similar.

Response to selection in Australian Merino sheep. III. Single character selection for high and low values of wool weight and its components

Direct and correlated responses are reported for 10 traits in eight pairs of lines under selection for high and low values of single characteristics : clean wool weight per head, clean wool weight per unit skin area (measured only in the groups under selection for it), body weight, wrinkle score, fibre number per unit skin area (adjusted for body weight), fibre diameter, staple length, and percentage clean yield. All groups showed overall divergence in the character under selection, though response was not always symmetrical, and in two cases (long staple and low fibre number) there was no continuing response after the initial response to extreme selection of the base parents. In all except one case, whenever previous estimates of genetic correlation were at the level of 0.2 or higher, correlated responses were in the predicted direction, though not always symmetrical in magnitude. The exception was a previously reported negative correlation between fibre number and staple length, which was not exhibited under selection for either character. Where two characters of a pair were under selection, reciprocal responses agreed in sign; magnitude will be examined in a later paper. Wool per unit area was shown to have a greater influence on clean wool weight than that of surface area, with staple length on this occasion being the most important component of wool per unit area. Reasons for an apparent decrease in the relative importance of fibre number are discussed. Three other points of importance in sheep breeding are again emphasized by these results : 1. Crimp in several pairs of groups was a poor indicator of fibre diameter. 2. Increases in clean wool weight were associated with falls in crimp number, even though fibre diameter actually became finer; diameter, not crimp, should therefore be used as a guide to wool quality. 3. The absence of genetic correlations DL and NL indicates that selection can be for high N (fibre number) with high L (staple length) and low D (fibre diameter) -in other words, a desirable fleece -with no impeding genetic correlations.

Genetic and phenotypic parameters for wool characteristics in fine-wool Merino, Corriedale, and Polwarth sheep. II. Phenotypic and genetic correlations, heritability, and repeatability

Estimates of heritability, repeatability, and phenotypic and genetic correlations were calculated from data involving about 1050, 720, and 250 dam-daughter pairs for Merino, Corriedale, and Polwarth breeds respectively; data on daughters were taken at both 18 and 30 months of age. Phenotypic and genetic correlations in general were of the same order of magnitude and similar between breeds; the estimates substantiated the results obtained by other workers. Estimates of repeatability of most fleece traits between 18 and 30 months of age were significantly lower than estimates based on later ages. However, the differences were not large, and the use of a single figure for repeatability, either the younger age estimate or a pooled estimate, would give a reliable prediction for subsequent performance. Estimates of heritability of all traits in each breed were high; however, the heritabilities of greasy and clean wool weights of Merino and Polwarth ewes were about 40% smaller at 18 months than at 30 months, the estimates at 30 months being generally similar to previous estimates at 18 months. Relative to selection at 18 months, wool production, either greasy or clean, would increase at a greater rate per annum with selection of Merinos and Polwarths at 30 months; for Corriedales, selection at 30 months is more efficient for greasy, but not for clean wool production.

Effect on wool growth in N.Z. Romney of dietary supplements

An experiment was conducted to determine the effect of chemically treated casein supplements on winter wool growth. All sheep were housed in individual pens and fed a basic diet of chopped hay and oat grain at two levels-half the sheep received a maintenance ration calculated on body weight, and the other half received a half-maintenance ration. Within each of these two groups, a further subdivision was effected. One group received 30 g of untreated casein, one group 60 g of untreated casein, a third group was fed 30 g of treated casein and the fourth group received 60 g of treated casein per day. This situation was similar at both levels of basic diet. All sheep were weighed each week and their weights were recorded. Small but positive increases in body weight were noted, and the relationship between casein and this increase is discussed. A comparison of treated versus untreated casein was made each month for five months, commencing in April 1968, and concluding in September 1968, and this comparison was considered in terms of wool weight, fibre length and fibre diameter. Similarly, a study of energy levels and treatment of casein was made and the significance of these results are discussed.

17—WOOL-BALE TIE TENSIONS AND STRENGTHS

The tensions in steel ties around compressed Australian-wool export bales vary with the type and weight of wool, the amount of compression, and the tightness of application of the ties. A cube law relating the tie tension and the clean-wool shipping density of a compressed bale has been found. Design data for a variety of packages of wool are presented from which probable tie tensions in projected high-density wool bales may be predicted. Some aspects of safe working practice in banding compressed-wool bales are considered.

Relationships between body weight and some follicle and fleece characters in an Australian fine-wool Merino flock

Phenotypic correlations between body weight, follicle characters, and fleece characters have been investigated in a flock of 95 fine-wool non-Peppin Merino wethers, reared in the same locality under the same conditions. The results indicated that three follicle characters, follicle chord, follicle depth, and the index of follicle bending, were independent of body weight. It was found, in agreement with the results of other workers, that body weight was highly correlated with both greasy and clean wool weights (r = 0.53 and 0.51 respectively). It was also found that follicle characters were significantly correlated with most of the fleece characters which contribute to the clean fleece weight per unit area of skin. The correlation coefficient of wool weight per unit area of skin with follicle chord was 0.33, with follicle depth 0.28, and with follicle bending index –0.35. The follicle characters were also correlated with greasy and clean fleece weights. Crimp number per inch was predicted for individual animals by using as criterion the length of the follicle chord. A highly significant correlation coefficient of 0.67 was obtained between predicted and observed crimp number. The close relationship between crimp chord and follicle chord reported in previous work was confirmed. It is suggested that simultaneous selection for body weight and certain follicle characters may have an additive effect on the production of clean wool. It is also suggested that the genetic antagonism between clean wool weight and number of crimps per inch can be explained in anatomical terms.

Genetic and phenotypic parameters for wool characteristics in fine-wool Merino, Corriedale, and Polwarth sheep. I. Influence of various factors on production

Estimates are given of the change in the level of production of 10 fleece characteristics of four Merino, one Polwarth, and three Corriedale flocks, in Victoria associated with variation in property, breed, season, property x season, age, and reproductive status. There was a decrease with age of characteristics associated with wool weight, and a decline in general wool quality. The decline was approximately linear for most characteristics from ewes of 3 years of age. Lactation was generally more severe than pregnancy in reducing wool production. The estimates of the effect of age on wool characteristics are used to assess the likely quantity and quality of wool produced by flocks of different age structures. These estimates may be used in conjunction with reproductive performance data to plan for maximum wool production.