Greasy Wool Research Articles

Assessment of contamination of wool by dark and medullated fibres using near infrared spectroscopy

Increased crossbreeding of Merino sheep in Australia, involving coloured or highly medullated sire breeds, has increased the risk of dark and highly medullated fibres in wool lots. Commercial implementation of the Dark and Medullated Fibre Risk Scheme, based on producer information, is identifying to buyers some of these risks and technology is sought to provide an inexpensive method for routine presale testing of greasy wool lots. One measurement concept assessed the ability of near infrared spectroscopy (NIRS) to predict variation in levels of pigmented fibres or highly medullated fibres in wool. The project used either ‘seeded’ wool samples or naturally contaminated samples with measured reference values as well as different methods of sample preparation of wool fibre (in air or immersed in benzyl alcohol) or the solutions from alkali hydrolysis of wool fibre and NIRS measurement (reflectance v. transmission). NIRS can predict variation in trace levels of pigmented fibre or highly medullated white fibres (kemp) in wool and, among the methods assessed, reflectance analysis of wool fibre in air was generally better than the other options considered. Calibration models for NIRS reflectance measurement of 5 g wool samples ‘seeded’ with 1–50 black-pigmented, tan-pigmented or white kemp fibres gave coefficients of determination (R2) of 0.96, 0.88 and 0.82 with standard errors of cross-validation (SECV) of 4.34, 6.97 and 7.17 fibres per 5 g sample, respectively. However, these calibration equations generally did not predict variations in the reference values for 3 other sets of naturally contaminated samples. New calibration equations determined for each of the sets of naturally contaminated samples also predicted variation in the pigmented fibre reference values, with the extent of agreement depending on the accuracy of the reference data as well as sample preparation and method of measurement. Calibration models for NIRS reflectance measurement of wool fibre from the 3 sets of naturally contaminated samples produced R2 = 0.99, 0.71 and 0.92 with SECV = 0.923, 6.43 and 4.54 pigmented fibres per 5 g sample, respectively. However, these calibrations and those obtained from various combinations of the wool sets also had limited ability to predict variation in pigmented fibre reference values in other independent or excluded samples. Refinement of the technique and development of calibrations with extensive and reliable reference data, representing all of the wool variation likely to be encountered, may allow this NIRS potential to become relevant in the presale testing of wool as an inexpensive measurement procedure for estimating dark and medullated fibre content.

Wool weathering damage as measured by Methylene Blue absorption is linked to suint content

Weather damage of wool in grazing sheep has long been recognised by the wool industry as a problem, resulting in fibre damage, fibre loss and poor dyeing performance. Merino wool from 3538 ewe and ram hoggets was used to estimate the heritability of Methylene Blue absorption. Methylene Blue absorption has a high heritability of 0.44 ± 0.04 and was strongly genetically correlated with suint index (0.88 ± 0.02) and wool moisture index (0.92 ± 0.03). Methylene Blue absorption was moderately genetically, negatively correlated with measures of clean wool colour and yield and positively with dust penetration. There was no significant correlation between Methylene Blue absorption and dust content or economically important measures of fleece value such as fibre diameter, curvature and staple strength. The strong genetic relationship between Methylene Blue absorption and suint index indicates that Methylene Blue absorption is a very good indirect measure of greasy wool suint content but may not be a satisfactory indicator trait to select for low weather damage.

Factors affecting wool scouring performance, yield and colour measurements of Western Australian fleece wools

A benchtop scouring procedure was used to evaluate the ability of conventional detergent scouring systems to adequately clean fleece samples from a selection of Western Australian Merino wools. Sixteen fleeces were selected from the Western Australian Department of Agriculture resource flocks, covering a wide range in yield (49.2 to 77.5%), wax (7.3 to 26.9%), suint (4.9 to 11.6%), and dust (1.4 to 16.3%) contents. Using a simple detergent-based system, 50% of the fleeces were classified as effectively scoured, based on residual wax content. When scouring liquor was not refreshed between subsamples drawn from the same fleece, wool wax, staple length and dust content in the greasy fleece accounted for 93% of the variation in the rate of residual wax increase observed in sequential 10 g samples of wool. Residual ash content also increased but the greasy fleece parameters measured were not statistically significant predictors of residual ash changes. The rate of scoured wool colour change, when sequential samples of greasy wool from the same fleece were scoured without liquor change, could be predicted from greasy fleece yields. The scouring efficiency of the more difficult to scour wools was improved by the addition of sodium carbonate to the main scouring bowls.

The use of visible (VIS) and near infrared (NIR) reflectance spectroscopy to predict fibre diameter in both clean and greasy wool samples

AbstractAbstract Visible (VIS) and near infrared (NIR) reflectance spectroscopy combined with multivariate data analysis were explored to predict fibre diameter in both clean and greasy Merino wool samples. Fifty clean and 400 greasy wool samples were analysed. Samples were scanned in a large cuvette using a NIRSystems 6500 monochromator instrument by reflectance in the VIS and NIR regions (400 to 2500 nm). Partial least square (PLS) regression was used to develop a number of calibration models between the spectral and reference data. Different mathematical treatments were used during model development. Cross validation was used to assess the performance and avoid overfitting of the models. The NIR calibration models gave a coefficient of determination in calibration (R2) > 0·90 for clean wool samples and a R2 < 0·50 for greasy wool samples. The values for the residual predictive value, RPD (ratio of standard deviation (s. d.) to the root mean square of the standard error of cross validation (RMSECV)) were 3 for clean and 0·6 for greasy wool samples, respectively. The results indicated that fibre diameter in greasy wool samples was poorly predicted with NIR, while clean wool showed good relationships.More research is required to improve the calibration on greasy wool samples if the technology is to be used for rapid analysis to assist in the selection of animals in breeding programmes.

Indirect selection criteria against clean wool colour in Corriedale sheep and their effects on wool production traits

The potential of greasy wool colour subjective assessment Visual Colour Score (VCS) and the yellow predictive test (YPC) as indirect selection criteria for reduction of clean wool colour (CWC) in Corriedale sheep was examined. The heritability of these wool colour traits and the wool production traits, greasy (GFW) and clean fleece weights (CFW), and mean fibre diameter (MFD) and the phenotypic and genetic correlations among these traits were estimated from a Corriedale flock using AIREML procedures. A high genetic correlation between YPC and CWC was observed, indicating that YPC could be a suitable indirect selection criterium for CWC. However, direct selection against CWC was predicted to produce faster genetic improvements in CWC than that expected under indirect selection via YPC. Single trait selection based on VCS or YPC were expected to reduce the response in CWC to 51% and 49% of that estimated for direct selection. The positive genetic correlations of CWC, YPC and VCS with CFW and MFD would cause a reduction in both MFD and CFW to result from selection that reduces wool colour. The results showed that the most effective way to genetically improve CWC was through indirect selection to reduce MFD, CFW or GFW, followed by direct selection, but the premiums for CWC in the Corriedale breed may not be sufficient to justify the expected losses in CFW.

Merino wool contamination from rearing of Damara crossbred lambs

Recent importations and promotion of Damara sheep has raised concerns and debate about potential for Merino wool contamination. This project examined Merino ewe wool contamination arising from the mating of Damara rams and rearing of Damara crossbred lambs. Shirley-blended core samples from 3 commercial greasy wool sale lots known to involve Merino ewes shorn with Damara crossbred lambs at foot (2 lots), or shorn 3 weeks after weaning, were assessed. Contaminant fibres were above commercial expectations for Merino wool and present in every core sample measured. There was no significant difference found between these sale lots. From an experimental flock, composites of fleece samples were carded and the effects of mating or rearing alone assessed. No detectable increase of pigmented or heavily medullated fibres, above very low background levels, were detected among the Merino ewes mated to Damara rams (1 ram per 65 ewes). However, high concentrations of contaminant fibres were found in the Merino ewe wool at weaning of their Damara crossbred lambs and also 3.5 months after weaning; with reduced levels post-weaning. The management strategy of restricting wool exposure to mating effects alone may offer advantage but delaying shearing of ewes after weaning to reduce the contaminant fibre burden was, in this case, not sufficient to overcome potential concerns for wool processing. However, in view of the many potential contributing factors, actual contamination may vary widely between cases and require the advancement of presale measurement to gain buyer confidence and accurate appraisals.

Production responses of two genetic different types of Merino sheep subjected to different nutritional levels

The primary selection objective in the South African Mutton Merino is meat production, while wool plays a secondary role. The Merino, on the other hand is selected for wool production. Respectively 20 and 23 of each genetic different type of ewes were used in a 15-week indoor study to quantify the influence of nutrient intake on certain production traits when fed at different levels of their respective requirements during late pregnancy (last 6 weeks) and lactation (first 6 weeks). Results were used to provide production parameters for the two types of ewes and their lambs at different levels of nutrition. Lambing percentage (per ewe lambed) of SA Mutton Merino ewes was 171% compared to 135% for Merino ewes. Live weight gains for meat-wool and wool-type ewes during late pregnancy amounted to 15.9 and 21.9%, with corresponding live weight losses of −8.3 and −1.1% during the first 6 weeks of lactation. Greasy wool production during the last 9 weeks of pregnancy and the first 6 weeks of lactation amounted to 1.57 kg ewe −1 (meat-wool type ewes) and 2.84 kg ewe −1 (wool-type ewes). Milk production 17 days post partum was 2.33 kg/day and 1.84 kg/day for the two types of sheep. Lambs of the meat-wool type ewes had a mean birth weight of 4.1 kg and an average daily gain (ADG) of 270 g/day to 42 days of age. Lambs of the wool-type ewes had a mean birth weight of 4.9 kg and a 42-day ADG of 192 g/day. There were clear differences in production traits of the two types of Merino sheep, which were in accordance with their genetic differences. The study gave practical production norms for meat-wool and wool-type Merino ewes and their lambs when subjected to different nutritional levels.

Birth weight responses to shearing ewes in early to mid gestation

AbstractThis study compared the effect on foetal growth of shearing ewes in very early pregnancy (day 50) with the effect of shearing later in pregnancy (day 70 or 100). One hundred and sixty ewes were allocated at day 49 of pregnancy to four ‘time of shearing’ treatments — pregnancy day 50 (P50), P70, P100 (no. = 45 ewes per treatment) and unshorn (shearing of this group occurred 43 days after weaning) (no. = 25); two methods of shearing (by standard comb and cover comb); and two levels (1 or 2) of pregnancy/rearing rank. All ewes had been mated over a 28-day period and grazed pasture throughout the trial. The mid point of lambing was 27 August 1996. Live weights of ewes (corrected for fleece weight) were not influenced by shearing time at any stage except at day 45 of lactation when ewes shorn at P50, P70 or P100 were about 3⋅0 kg lighter than unshorn ewes. Shearing method had no effect on ewe live weight. Time of shearing and shearing method had no effect on ewe greasy fleece production or wool tensile strength. Shearing significantly (P < 0⋅05) influenced the birth weight of single- (by 0⋅7 to 0⋅8 kg) but not twin-born lambs. Maternal plasma triiodothyronine concentration increased proportionately by 0⋅47 to 0⋅85 (P < 0⋅05) and lasted for at least 20 days in response to shearing irrespective of time of shearing. No difference in plasma insulin concentration was detected between shearing groups but plasma glucose concentration proportionately increased by 0⋅06 to 0⋅16 (P < 0⋅05) for 10 to 20 days after shearing. These results indicate that shearing between day 50 and 100 of pregnancy can increase lamb birth weights and that the response is associated with an increase in thyroid hormone concentrations in the maternal circulation.

Kikuyu (Pennisetum clandestinum) pasture for sheep. 2. Production and nutritional status of ewes with or without lupin (Lupinus albus) supplementation

Kikuyu pasture was grazed continuously for 12 months by 20 dry and 40 producing South African Mutton Merino (SAMM) and Merino ewes at a stocking density of 23 ewes ha−1. Supplementary sweet lupin seed was supplied to one group of producing ewes of each breed during pregnancy and lactation at a rate of 0.5% of the liveweights of the ewes. Rumen fluid samples for the determination of pH, volatile fatty acids (VFA), and ammonia‐nitrogen (NH3‐N) were collected from rumen‐fistulated wethers corresponding to the periods of late pregnancy and early lactation of ewes. Rumen NH3‐N concentrations (8.7 mg 100 ml−1 and 5.4 mg 100 ml−1) were low during both periods of sampling. Rumen VFA concentrations (12.3 mmol 100 ml−1 and 9.2 mmol 100 ml−1)were within normal ranges. Supplementation significantly increased blood urea concentration of ewes. Supplemented ewes lost less weight than the unsupplemented ewes (P ≤ 0.02) during the experimental period. Pregnancy (P ≤ 0.001) as well as lactation (P ≤ 0.0001) reduced greasy wool production. Supplementation increased birthweight of lambs by 21% (P ≤ 0.0007). Rumen parameters indicated no severe deficiency in either protein or energy intake. A lack of response in wool and lamb growth due to lupin supplementation was primarily ascribed to a high CP degradability of lupin seed. Production of the different breeds was in accordance with their respective genetic potential.

Production and oxidation of wool grease after shearing.

To measure the production and amount of oxidation of wool grease secreted immediately after shearing. To identify components of wool grease that might act as a carrier to facilitate lateral diffusion of topically applied insecticides. Fine-wool Merino sheep were shorn and residual greasy wool was collected from the sheep's flank. The quantity of grease produced, and the amount of oxidation was measured during 18 days after shearing. Wool grease was fractionated into five component groups based on their polarity and the degree of oxidation in these fractions determined. There was a 24% increase in grease production within 2 days after shearing but secretions returned to pre-shearing amounts after 4 days. During this period wool grease oxidized rapidly. Of the grease fractions examined, sterol and wax esters remained essentially unoxidized whereas free sterols such as cholesterol and lanosterol, fatty acids and polar lipids, aldehydes and alcohols were extensively oxidized within 7 days after shearing. The transient increase in grease production after shearing may facilitate diffusion of topically applied synthetic pyrethroid insecticides. Oxidation of grease components may then contain the insecticide and limit further diffusion. Incorporating the insecticide in non-oxidising fractions of wool grease may make insecticide dispersion more efficient.

Modelling pesticide residues on greasy wool: using organophosphate and synthetic pyrethroid survey data

Summary. Several surveys have examined the relationship between organophosphate and synthetic pyrethroid residues in wool and associated treatments. These have been combined and summarised using a model of on-farm survey data. The model estimated the amount of chemical taken up by the wool at application. This was based on experimental breakdown rates of these pesticides on wool determined in controlled trials. For about 10% of survey results the chemical measured on the wool did not match the chemical the producer said was applied. A further 5% of results were excluded because the amount of chemical detected on the wool was inconsistent with the stated time of treatment and shearing. With the remaining results there was a very high variation in residues resulting from the same (stated) treatment. It is clear that many producers do not know what chemicals they have used or how much they applied. The wide variation in results suggests that some producers may apply excessive amounts of pesticides while others use too little to have a useful effect. The model estimated the amount of pesticide taken up by the fleece using the residue left at shearing and the known breakdown rate for a given method and chemical group. When organophosphates were applied by dipping, the amount of chemical taken up by the fleece appeared to increase as the length of the wool increased. This was generally higher than would be anticipated from label dose rates but was consistent with the stripping characteristics of these chemicals. Therefore dipping as soon as possible after shearing left much lower residues (<10 mg/kg wool) than delayed treatment (often 10–30 mg/kg wool). In contrast the survey results suggest that the amount retained by sheep as a result of jetting decreased in longer wool. Jetting treatment rates appear to be lower than recommended, particularly for sheep with more than 6 months wool. Therefore jetting (as used by producers) left much lower residues in wool than dipping (with similar length wool) and was usually only above 10 mg/kg wool if carried out in the last 5 months before shearing, or if the same sheep received repeated treatments. The residue of synthetic pyrethroid retained in the fleece after dipping or long wool backliner application increased as the length of the wool increased at treatment, and appeared generally consistent with label recommendations. Current long wool backline products usually left residues of synthetic pyrethroid above 10 mg/kg on the wool. Short wool dipping left less than 10 mg/kg wool while off-shears backliners usually left average residue concentrations of about 2 mg/kg wool. Although the actual on-farm results vary 4-fold above and below the average, the model can be used to estimate the expected residue concentration and likely range of results from most standard on-farm organophosphate and synthetic pyrethroid treatments. This will allow improved provision of advice so that most producers can meet specified industry standards. It will allow wool buyers to estimate the risk of purchasing high residue wool based on producers’ statements about treatments applied.

Modelling pesticide residues on greasy wool: use of farm records at the time of treatment to predict residues

A model has been used to predict expected pesticide residues on wool at shearing after normal on-farm treatments. If wool producers keep accurate records of treatments at the time they are carried out, the model can predict the residue with greater accuracy and precision than if treatment records are less specific. The expected range is halved and the predicted residue is lower where wool producers have kept treatment records, compared with wool from previous surveys where only the usual farm information was available. If declarations by wool producers are used to assist wool buyers who require wool with low pesticide residues, these declarations will have more value if they are supported by documentation of treatments used on the sheep.

Modelling pesticide residues on greasy wool: surveys of the insect growth regulators triflumuron and diflubenzuron

Surveys have examined the relationship between louse and flystrike treatments on farms and the resulting residues of insect growth regulators on greasy wool. These results have been summarised using a model of the on-farm survey data. The model estimated the amount of chemical taken up by the wool at application. This was based on experimental breakdown rates of these insecticides on wool determined in controlled trials. The data indicated that the backliner, triflumuron, when used off-shears within 24 h of shearing, was normally applied at slightly higher than the recommended rate on-farm and left an average residue of 30 mg/kg greasy wool at the following shearing 12 months later. Diflubenzuron, applied by dipping or jetting, was usually applied at lower than the recommended rates, and left an average residue of 40 mg/kg on the wool at shearing 12 months later. When treatment was applied to very short wool (<3 weeks after shearing) the residue was only about 20 mg/kg, but when applied at later times after shearing the residue at the following shearing was not closely related to the time of treatment. The model can be used to estimate the expected residue level and likely range of results from most standard insect growth regulator treatments. This will improve advice to producers so most can meet specified industry standards.

Pesticide use and residues on Queensland wool.

To determine practices for control of louse infestation and blowfly strike in Queensland sheep flocks that are associated with organophosphorous and synthetic pyrethroid residues on wool. Information on residues was obtained from a survey of Queensland wool clips. Information on pesticide use was obtained from a trace-back postal survey. The association between pesticide use and residues was assessed using generalised linear models, controlling for potential confounding by flock location. Between 1995 and 1997 Queensland wool clips were randomly sampled. Samples were tested for the presence and amount (mg per kg of greasy wool) of organophosphorous and synthetic pyrethroid pesticides. A questionnaire seeking information on flock characteristics and pesticide use was sent to the manager of each flock from which a wool sample was tested. The median amount of OP and SP residue was 0.8 and 0.25 mg/kg, respectively, and 91 and 95% of wool samples contained < 8 mg/kg of OP and SP residues, respectively. The frequency of OP pesticide use for louse control was significantly (P = 0.005) associated with mean OP residue amount, and the timing of SP use for louse control, in relation to shearing, was significantly (P < 0.001) associated with mean SP residue amount. Most Queensland wool clips have acceptable amounts of residues after the use of OP and SP pesticides, but wool growers can further reduce residues by effectively controlling louse infestation with pesticide applications early after shearing and the use of non-chemical methods of ectoparasite control.

Changes in Wool Colour. Part III: Processing

The clean and ‘as-is’ colours of seven lots of Australian merino fleece wool and three lots of Australian merino skirtings were measured before processing and at various stages during scouring and topmaking. The incubated colours of the raw wool and the ‘as-is’ colours of rewashed top and blank-dyed top were also measured. The ‘as-is’ brightness values, averaged over all lots, for scoured wool, carded silver, gilled sliver, combed sliver, top, and blank-dyed top were 59.8, 61.2, 62.5, 63.5, 63.7 and 61.9 Y units, respectively, compared with the clean colour of raw, greasy wool (62.6 Y units). The ‘as-is’ yellowness values, averaged over all lots, for scoured wool, carded sliver, gilled sliver, combed sliver, top, and blank-dyed top were 2.0, 3.4, 3.4, 3.3, 3.3 and 4.4 (Y − Z) units, respectively, compared with the clean colour of greasy wool (2.4 (Y − Z) units). Clean-colour (Y − Z) of raw wool was similar to the colour of scoured wool, whereas top yellowness was closer to the incubated colour of raw wool (3.6 (Y − Z)). The results suggest that the wool trade should be able to use raw-wool colour measurements (clean colour and incubated colour) to assess the processing potential of wool. The estimate of within-bale variance for clean-colour (Y − Z) was higher (×2) than the single previously published estimate, which forms the basis of sampling-precision estimates for yellowness in the Australian Standard AS-3546 and IWTO-14 (E). The within-bale variance of incubated-colour (Y − Z) was much higher (×3) than the clean-colour within-bale variance estimate.

Changes in Wool Colour. Part II: Dumping and Storage

The changes in colour, after storage for a period of two years, of fifteen lots of merino and crossbred wool of varying types and appraised levels of discoloration are reported. The relationship between incubated colour and clean colour during the two-year period and the effects of storage on staple length and strength, resistance to compression, potassium content, and pH of water extraction were also examined. The effect of dumping method before storage (tripacks, single-dumped bales, and farm bales) on colour change was also assessed. Clean yellowness changed on average by +0.05 (Y − Z) unit per month (r2 = 0.18). This change varied significantly between lots, ranging from −0.01 to +0.11 unit per month. These changes were less than half the rate of change in greasy-colour (Y − Z), which suggests that the yellowness that developed in greasy merino wool, stored for two years at Sydney during 1990–92, was mainly scourable. The change in clean yellowness after two years appeared to be lower (−1.1 (Y − Z) unit) in wool stored in farm bales (e.g. stored on farm) than in that stored in more densely pressed bales (e.g. dumped wool in the reserve stockpile). This difference was even greater for incubated colour (−2.6 (− (Y − Z) units), since incubated yellowness of wool in farm bales was similar to the clean colour of wool in dumped bales. If the incubated colour predicts blank-dyed top colour, it is of concern that dumped stored wool may scour satisfactorily but could deteriorate in colour during later processing. The incubated yellowness of wool deteriorated on storage at a similar rate to greasy yellowness. Thus the difference between incubated and clean colour of wool samples taken at the same time increased during storage (+0.13 (Y − Z) unit per month). The clean colour approached, but remained about one (Y − Z) unit lower than, the incubated colour of the sample taken at zero time. The storage conditions during the two years therefore appeared to be less challenging, in terms of colour development, than those occurring during the test-incubation challenge.

Quantitative genetic studies on wool yellowing in Corriedale sheep. 1. Wool yellowing susceptibility and wool production traits—genetic parameter estimates

The potential for the reduction of wool yellowing susceptibility (YPC) in Corriedale sheep via selection was examined. The heritabilities of YPC and greasy fleece weight (GFW) and clean fleece weight (CFW), yield percentage (Yield), mean fibre diameter (MFD), and subjective greasy wool colour assessment (Visual), and phenotypic and genetic correlations among these traits were estimated from records on 1492 progeny of 53 sires of a Corriedale flock by using restricted maximum likelihood procedures using an average information algorithm. The heritability of YPC was 0·27 ± 0·06. Genetic correlations between YPC and GFW, CFW, Yield, MFD, and Visual were 0·20 ± 0·14, 0·11 ± 0·14, –0·15 ± 0·13, 0·24 ± 0·14, and 0·95 ± 0·06, respectively. Phenotypic correlations were low between these traits and YPC. Visual had a heritability of 0·30 ± 0·06 and medium-high genetic correlations with all traits, except CFW. Heritability estimates of GFW, CFW, Yield, and MFD were 0·55 ± 0·07, 0·52 ± 0·07, 0·51 ± 0·07, and 0·52 ± 0·07, respectively. The expected correlated responses to selection against YPC are likely to cause reductions in CFW and MFD. Correlated responses from the reduction of Visual are predicted to be greater for all production traits than those from the reduction of YPC. Responses in YPC are predicted to be slightly higher when selection is on Visual (–0·21 score/year) than when selection is on YPC itself (–0·19 score/year). A selection index, including CFW, MFD, and YPC as aggregate breeding and breeding objective traits, calculated at I = +3·26CFW – 0·14MFD + 0·03YPC, predicted a YPC increase, worsening the problem.

Comparison of secale with other perennial grasses under grazing at a cool site in the high rainfall zone of New South Wales

Summary. In 2 field experiments on the southern highlands of New South Wales, the short-lived perennial grass secale (Secale montanum Guss. cv. Black Mountain) was grazed by Merino wether weaners at stocking rates of 10–17 animals/ha to test the suggestion that persistence might be enhanced by occasional deferment of grazing to encourage seedling germination. In the first of these experiments (experiment 1), designed to compare secale and phalaris, when accompanied by white and subterranean clovers, growth and survival of both grasses was poor, despite the application of &gt;600 kg/ha superphosphate and the experiment was abandoned after 2 years. A subsequent pot trial (experiment 2) with secale grown in soil from the experimental site, where the fertiliser had been applied, showed a large growth response to additional phosphorus. Because inadequate soil fertility may have been the cause of poor grass persistence in experiment 1, a second field experiment (experiment 3) was established on the same site to compare secale, perennial ryegrass and cocksfoot, each accompanied by white and subterranean clovers and with the application of a further 850 kg/ha superphosphate over 3 years. Initial growth of all the grasses was good and animal production on the secale and ryegrass plots was high (up to 100 kg/ha greasy wool and 300 kg/ha liveweight gain). Secale failed to survive more than 3 years, despite deferment of grazing and it may be that persistence depends more on the reliability of autumn rainfall. However, mean weight gain from the clovers and volunteer grasses on the secale plots in the fourth year was as high as from the ryegrass plots and double that from the cocksfoot plots, which became increasingly cocksfoot-dominant. While the results indicate a need for more work on the fertiliser requirements of perennial grasses on these soils, they also raise questions about whether these grasses benefit animal production sufficiently to justify the cost of establishing them.

The Development and Role of Objective Measurement in the Marketing of Australian Wool

Objective measurement has been an integral component of the Australian wool-selling system since the introduction of Sale-by-Sample and presale testing in 1972. Today, virtually all wool is tested for yield, vegetable matter and mean fibre diameter; 72% of all combing wool is tested for staple length and staple strength; and 23% is measured for average yellowness. A commercial service for diameter variation was introduced in 1996. The remaining parameters likely to be specified are those which will improve the prediction of processing performance and/or provide a more complete objective specification of greasy wool prior to sale. Electronic access to information stored in the presale test data base provides buyers with on-line up-to-date intelligence regarding wool due for sale and has facilitated the development of electronic selling systems.

Legumes, herbs or grass for lamb performance?

Lamb performance was evaluated for three consecutive summer-early autumn periods on ryegrass (Lolium perenne), white clover (Trifolium repens), chicory (Cichorium intybus), plantain (Plantago lanceolata) or lotus (Lotus corniculatus). Lamb liveweight gains, fasted liveweights at slaughter and hot carcass weights tended to be highest on legumes and chicory and lowest on plantain and ryegrass. Greasy wool weights were significantly higher on lotus and white clover than on chicory, plantain and ryegrass. Greasy wool weight was significantly related to fasted liveweight (R2=0.94-0.99). Protein (%) in herbage accounted for 83-92% of the variability in animal performance; food intake accounted for 57-69% of the variability and was negatively correlated with hemicellulose and cellulose (R2=97.2 and 80.9%, respectively). Thus quality of feed was more important than intake alone in determining animal performance. Keywords: carcass weight, Cichorium intybus, greasy wool weight, intake, lamb performance, Lotus corniculatus, Lolium perenne, Plantago lanceolata, Trifolium repens