bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term population studies on the cattle tick (Boophilus microplus) on untreated cattle selected for different levels of tick resistance
Authors: Sutherst RW , Wharton RH , Cook IM , Sutherland ID , Bourne AS
Published: November 2004

Census data were collected at weekly intervals on tick populations on untreated cattle over a period of 6 years in central Queensland, near Rockhampton. Hereford x Shorthorn (British; HS) heifers and two herds of Africander (Zebu) x [Hereford and Shorthorn] (AX) heifers, one with animals of high resistance (AXH) and the other of medium (AXM) tick resistance, were grazed in separate paddocks. A herd of AX steers was added to the trial when the heifers commenced calving in 1972–73. Data were collected from the heifers for three years prior to their first calving and then for a further three years whilst they were breeding. There were large differences between the numbers of ticks in different years and a consistent seasonal pattern, the numbers being lowest from July to September and highest in the April to June quarter. The AXH herd had fewest ticks for most of the experiment, but after the first year there was little difference between the infestations on the AXM and HS herds. The resistance of all herds, measured by artificial infestations with larvae, increased during the first 3 years but declined after the cattle began breeding, and fluctuated from year to year. The resistance of some heifers did not stabilize until the animals were more than a year old, and that of some animals drifted up or down over long periods. The loss of resistance of a small proportion of the cattle in the AXH herd was responsible for the advantage of that herd being substantially reduced. Both the ranking for resistance of animals and the mean resistance of the herds, assessed with artificial infestations, agreed with the rankings and tick population sizes observed from tick counts on the cattle in the field. Changes in the mean resistance of the herds in spring in different years were highly correlated with concurrent field infestations, which suggests that changes in host resistance have important effects on tick populations. Tick counts on the calves up to weaning showed no correlation with concurrent counts on their dams, but the ranking of the counts on the calves was consistent over the 6 month period.
Slow rusting and tolerance to rusts in wheat I. The progress and effects of epidemics of Puccinia graminis tritici in selected wheat cultivars
Authors: Rees RG , Thompson JP , Mayer RJ
Published: November 2004

The effectiveness of vertical resistance to rusts in wheat as generally employed is short-lived and a more durable form of resistance is required. To examine slow rusting and tolerance, the progress and effects of epidemics of stem rust (Puccinia graminis Pers, f. sp. tritici Erikss. & Henn.) in 45 wheat cultivars have been followed during two seasons. The epidemics in each cultivar have been compared by means of the average disease assessment, area below the disease progress curve, apparent infection rate, and intercept of the logit line, and by pattern analysis. Of these measures, the infection rate was the least valuable, whilst pattern analysis allowed useful grouping of cuItivars with similar epidemic patterns. The cultivars were arrayed on a resistance spectrum and ranged from highly resistant to extremely susceptible, those between possessing various levels of slow-rusting ability. Slow rusting was at a comparatively high level in cvv. Hopps, Dural, Lawrence and Celebration. In contrast cv. Mengavi was shown to be a fast ruster. The danger of developing cultivars, such as Mengavi, with a fast-rusting tendency masked by initially effective vertical resistance is discussed. The effects of the epidemics in each cultivar have also been determined to provide a tolerance index. The percentage reduction in grain-filling period, the logit-line intercept value and the delay to 10% disease relative to a susceptible reference cultivar were the main factors associated with the effect of the epidemics on grain yield.
Slow rusting and tolerance to rusts in wheat. II. The progress and effects of epidemics in Puccinia recondita tritici in selected wheat cultivars
Authors: Rees RG , Thompson JP , Goward EA
Published: November 2004

The progress and effects of epidemics of leaf rust (Puccinia recondita Rob, ex Desm. f, sp. tritici Erikss. & Henn.) have been examined in 45 wheat cultivars over two seasons. The epidemics in each cultivar were compared by various measures and by pattern analysis. The cultivars were separated into groups ranging from highly resistant to highly susceptible with intermediate groups possessing various levels of slow-rusting ability. Cvv. Hopps, Warchief, Huguenot, Pusa 80-5c, Dural, Warput, Koolisie and Puglu were found to possess useful levels of slow-rusting ability. Fast rusting was conspicuous in Gabo and its derivatives Mendos, Mengavi, Gamenya and Gamut. The desirability of not perpetuating this defect is discussed.
Toxicity of synthetic pyrethroid insecticides to predaceous phytoseiid mites and their prey
Authors: Wong SW , Chapman RB
Published: November 2004

The toxicities of two synthetic pyrethroid insecticides (cypermethrin and fenvalerate) and azinphosmethyl to the predaceous mite species Typhlodromus pyri Scheuten, Typhlodromus occidentalis Nesbitt, Amblyseius fallacis Garman (Acari: Phytoseiidae) and one of their prey, Tetranychus urticae Koch (Acari: Tetranychidae) were determined by laboratory slide dip tests. Comparison of LC50 values showed both synthetic pyrethroid insecticides to be considerably more toxic than azinphos-methyl to all three species of predator mites, although T. urticae was less susceptible. It is likely that recommended application rates of both synthetic pyrethroid insecticides will cause considerable mortality of predator mites in the field yet exert little mortality on T. urticae.
Interacting effects of subsoil acidity and water on the root behaviour and shoot growth of some genotypes of lucerne (Medicago sativa L.)
Authors: Simpson JR , Pinkerton A , Lazdovskis J
Published: November 2004

The effects of additions of calcium carbonate to a low-calcium, acidic subsoil, underlying a fertilized, limed surface soil, on the root and shoot growth of four lucerne genotypes were studied in deep (85 cm) soil columns. Separate surface and subsoil watering treatments were included after plants were established. A comparison showed that, at low rates of addition, calcium carbonate was more effective than magnesium carbonate in promoting root elongation, but more generally the increase in pH appeared to be the important factor. Surface droughting reduced shoot growth, but the response to subsoil lime continued as long as subsoil moisture was supplied, in accordance with the increased root penetration and ability for water uptake. Thus shoot growth under surface drought reflected (r = 0.973) the total length of deep roots (> 60 cm depth) over all genotypes and lime treatments. The genotypes, which included three from cv. Hunter River and one from cv. Siro Peruvian, differed in several respects. Our selections from Hunter River varied in root morphology, shoot:root ratios and type of response to subsoil lime. The Siro Peruvian genotype produced abundant deep, fine roots and good shoot growth under surface drought.
Genotypic variation in resistance to Kabatiella caulivora in Trifolium subterraneum subspecies yanninicum
Authors: Beale PE , Thurling N
Published: November 2004

The development of a clover scorch epidemic was studied at Denmark, W.A., by using 62 lines of Trifolium subterraneum including 29 subspecies yanninicum genotypes. Total disease development (TDD), the intrinsic rate of disease development (Rate) and time to 50% disease development (Delay) were calculated from fortnightly observations from August to December. Principal component analyses of the data lent support to the view that TDD is a good measure of disease expression. TDD ranged from 16 to 139 disease days (maximum possible 140). Nine yanninicum genotypes that had TDD values of less than 28 disease days are considered to have potential in breeding for resistance. Within these nine genotypes there was, however, considerable variation in Rate and Delay. A positive correlation between early growth and TDD, and a negative correlation between flowering date and TDD, are seen as possible problems in breeding resistant cultivars. Scoring plants once in the middle of the period of maximum disease development and also at the end of the season should provide a reasonably accurate approximation of TDD and delay.
Growth of potatoes (Solanum tuberosum L.) to the small tuber stage as related to soil temperature
Authors: Sale PJM
Published: November 2004

In experiments in a phytotron with potato cv. Sebago and in the field with cvv. Sebago and Sequoia the times for planting to emergence, new tuber initiation and small tuber stage were measured in relation to temperature. Emergence was linearly related to mean temperature and relatively independent of diurnal or periodic fluctuations up to an optimum of 22–24°C, and up to this optimum could be considered as a degree-day requirement calculated from either soil temperature at tuber depth or air temperature. For both cultivars planted with just-visible sprouts this was about 450 degree-days reckoned above a +2° minimum. At temperatures above the optimum, emergence was actively inhibited, and the relationship no longer held when appreciable periods were spent above about 24°. Once emergence had occurred, new tuber initiation and growth to the small tuber stage tended to be promoted at low temperatures especially in cv. Sequoia; phytotron treatments where night temperature was higher than day had a particularly adverse effect. It appeared that field development was adversely affected if a rapid increase in soil temperature occurred during the period of emergence.
Corrigendum - Growth of potatoes (Solanum tuberosum L.) to the small tuber stage as related to soil temperature
Authors: Sale PJM
Published: November 2004

In experiments in a phytotron with potato cv. Sebago and in the field with cvv. Sebago and Sequoia the times for planting to emergence, new tuber initiation and small tuber stage were measured in relation to temperature. Emergence was linearly related to mean temperature and relatively independent of diurnal or periodic fluctuations up to an optimum of 22–24°C, and up to this optimum could be considered as a degree-day requirement calculated from either soil temperature at tuber depth or air temperature. For both cultivars planted with just-visible sprouts this was about 450 degree-days reckoned above a +2° minimum. At temperatures above the optimum, emergence was actively inhibited, and the relationship no longer held when appreciable periods were spent above about 24°. Once emergence had occurred, new tuber initiation and growth to the small tuber stage tended to be promoted at low temperatures especially in cv. Sequoia; phytotron treatments where night temperature was higher than day had a particularly adverse effect. It appeared that field development was adversely affected if a rapid increase in soil temperature occurred during the period of emergence.
Genetic history of the pedigree Poll Hereford breed in Australia: effect of the importation ban
Authors: Toll GL , Barker JSF
Published: November 2004

Registrations of animals in 1975 were used in a study of the importance of Imported and Horned animals and of individual herds and animals, the degree of inbreeding and the generation length. Results were compared with an earlier analysis (1960) of the breed, and considered in relation to the prohibition on the importation of ruminant animals into Australia from 1959 to 1969. The rate of increase in inbreeding (0.44% per generation) and the average generation length (5.3 years) have remained relatively stable throughout the breed history in Australia. While there has been some decrease in the emphasis on Imported animals, the breed maintains a high relationship to animals imported since 1930, and six of the 15 important animals (relationship to breed greater than 2.0%) were imported. It is concluded that the importation prohibition has had little effect on the genetic history of the breed, because of line breeding to bulls imported prior to 1959.
Plant nitrogen distribution in wheat cultivars
Authors: Halloran GM , Lee JW
Published: November 2004

Five wheat cultivars were examined for patterns of nitrogen uptake and distribution to the aboveground plant parts at 10 different stages throughout growth up to ripeness. Patterns in the proportionate allocation of total plant nitrogen in the mature plant of each cultivar were found to differ significantly. Significant differences existed between cultivars in the nitrogen percentages of culm, glume and rachis tissue in the mature plant. Translocation efficiency, expressed as the proportion of total plant nitrogen in the head, ranged from c. 36 to 60% in the cultivars, while the proportion of total grain to total plant nitrogen ranged from c. 25 to 52%. Within-head translocation efficiency, as total grain nitrogen to total head nitrogen, ranged from c. 75 to 94%. The cultivars Argentine IX and Petit Rojo possessed comparatively high values for all three translocation estimates. Their very high values for within-head translocation of nitrogen to grain could have been due, partly at least, to more complete translocation of glume nitrogen to grain than in the other cultivars. Speculations are made on how the wheat phenotype might be structurally modified through breeding to bring about a greater efficiency of nitrogen translocation to the grain.
High temperature contact treatment of hard seed in Stylosanthes
Authors: Mott JJ
Published: November 2004

Samples of hard seed of Stylosanthes humilis, S. hamata, S. scabra and S. viscosa were agitated on high temperature metal plates in order to reduce the hard seed content. The optimum temperature for reduction of hard seed was found to be 140–150°C, with a contact period of 15–30 s, and hard seed content was reduced by up to 70%. Internal seed temperatures generally remained below 70° during this treatment, and there was little loss of viability. As with percussion treatments, imbibition took place through the strophiole, which indicates that break of hard seed occurred by mechanical stresses fracturing the palisade cells at the strophiole. On the basis of this principle of high surface temperatures and brief seed contact, a heated rotating drum was constructed and successfully used to treat bulk quantities of hard seed.
Agronomic studies on Vigna spp. in south-eastern Queensland. II. Vegetative and reproductive response of cultivars to sowing date
Authors: Lawn RJ
Published: November 2004

Vegetative and reproductive growth of 16 cultivars from four Vigna spp. (V. radiata, green gram; V. mungo, black gram; V. angularis, adzuki bean; and V. umbellata, rice bean) were studied over a range of sowing dates at Lawes in south-eastern Queensland. Seed yield and total dry matter (DM) at maturity were highest in the black grams, and lowest in the adzuki beans. Within species, vegetative development was generally higher in the later-maturing cultivars, but the same was not true for seed yield. Harvest index was negatively associated with cultivar maturity in the grams and adzuki beans. All cultivars showed substantial response to sowing date, with highest total DM and seed yield for December sowings. Delayed sowings reduced growth such that for late February sowings, total DM at maturity and seed yields were generally less than one-tenth of the maximum. Harvest index revealed an optimum type response to sowing date, with highest values for late December/early January sowings. Phenological response per se was not a useful predictor of the effect of sowing date on yield or total DM for any of the 16 cultivars, since in all cases growth rates varied substantially with sowing date, apparently in response to temperature. The linear form of the Arrhenius equation relating mean growth rate and mean prevailing temperature provided an excellent description of the response of both yield and total DM accumulation rates over sowing dates for all cultivars. Among cultivars, there was a significant correlation between the slope of the Arrhenius plots (k values) for seed yield and total DM accumulation, implying similar relative temperature sensitivity for both growth processes. For the 16 cultivars tested, the absolute magnitude of the k values for both seed yield and total DM accumulation was significantly negatively correlated with the latitude from which the cultivars were introduced, which implied greater temperature sensitivity for cultivars from the tropics. Some implications of these responses on cultivar adaptation and cultural practices are discussed.
Sire × hatching season interaction in egg production traits within flocks of domestic fowl
Authors: Yoo BH , Sheldon BL
Published: November 2004

The extent of sire x hatching season interaction in egg production characters has been studied in White Leghorn, Australorp and Synthetic flocks in which half-sib families bred from the same sires were mated largely to the same dams for spring and autumn hatchings. Interaction appeared to be more important in White Leghorn and Synthetic than in Australorp. The estimate of variance component for interaction was not consistent among the three flocks, and it was important only in certain flocks for different characters: age at first egg, part-annual hen-housed production (PHP), and egg weight at 34 and 62 (EWL) weeks of age in Synthetic; and annual survivors' production and egg specific gravity at 62 weeks of age (SGL) in White Leghorn. Comparison of within-season and across-seasons heritabilities showed that the former could be on average more than 45% higher than the latter in PHP, EWL, SGL and annual hen-housed production. As the estimates of the genetic correlation coefficient between seasons tend to be below 1.0 for many characters in White Leghorn and Synthetic, the sire x hatching season interaction may need to be taken into account and investigated further to improve the efficiency of selection for egg production.
Germination and seed survival in the woody weed, groundsel bush (Baccharis halimifolia L.)
Authors: Panetta FD
Published: November 2004

Freshly produced achenes of groundsel bush (Baccharis halimifolia L.: Asteraceae) lacked innate dormancy, and fluctuations in temperature and light were necessary to elicit a full germination response. Under conditions of intermittent light, a fluctuation amplitude of less than 1°C was sufficient to promote germination to 50% of its maximal value. Although an increase in the proportion of far-red to red wavelengths inhibited germination under conditions of constant temperature and continuous irradiance, with the introduction of fluctuations in the levels of these factors the inhibiting effect was no longer observed. Germination was minimal at constant temperatures in the absence of light, but the introduction of a 7.5°C temperature fluctuation induced germination in c. 25% of the seed. Under conditions of enforced dormancy brought about through burial, seeds persisted for a minimum period of 2 years.
Sulfur and methionine metabolism in sheep. III.* Excretion and retention of dietary and supplemented sulfur, and production responses to intraruminal infusions of DL-methionine
Authors: Doyle PT , Moir RJ
Published: November 2004

Two experiments were carried out to study the excretion and retention of nitrogen and sulfur when intraruminal infusions of DL-methionine were given to sheep. Merino wethers were fed on a 50:50 oaten chaff: lucerne chaff ration at different levels of dry matter intake (DMI), either as chaff or ground and pelleted, and with or without intraruminal infusions of DL-methionine. Liveweight gain in experiment 1, and the rate of wool growth and sulfur incorporation into wool were also measured. [35S]L-methionine was used to trace sulfur excretion from the supplement. Increasing the DMI increased (P < 0.001) nitrogen and sulfur excretion in both faeces and urine, but also increased (P < 0.001) the apparent retention of nitrogen and sulfur. The excretion of nitrogen and sulfur was not significantly affected by the form in which the basal ration was supplied, but sulfur retention did improve (P < 0.05) when the ration was given as chaff. DL-methionine supplements resulted in large increases (P < 0.001) in the excretion of total and inorganic sulfate sulfur in urine, and there was a tendency for urinary neutral sulfur excretion to increase. The amino acid supplement did not affect faecal sulfur excretion except at the lower level of feed intake in experiment 2. Differences in the amount of sulfur, from DL-methionine and [35S]L- methionine injections given into the rumen, excreted in faeces and urine indicate possible differences in the metabolism of the amino acid isomers. Increasing DMI resulted in improved (P < 0.001) rates of liveweight gain and wool growth; DL-methionine infusions had no effect. Further, estimates of sulfur incorporation into wool indicate that very little supplementary methionine was utilized at the follicular sites despite increased sulfur retention. The patterns of sulfur excretion suggest that the added methionine was rapidly and virtually completely dissimilated in the rumen. It is concluded that production responses to dietary methionine supplementation occur only under sulfur-deficient conditions or occasionally where degradation is avoided.

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*Part II, Aust. J. Biol. Sci., 32: 65 (1979).
Carcass characteristics of heavyweight crossbred lambs. III.* Distribution of subcutaneous fat, intermuscular fat, muscle and bone in the carcass
Authors: Thompson JM , Atkins KD , Gilmour AR
Published: November 2004

Distribution patterns of subcutaneous fat, intermuscular fat, muscle and bone were examined in a total of 108 lamb carcasses from six genotypes (Dorset Horn and Border Leicester rams mated to Merino, Corriedale and Border Leicester x Merino first cross ewes), two sexes (wethers and ewes) and three slaughter weights (34,44 and 54 kg liveweight). The distribution of half-carcass components was based on five joints (hindlimb, loin, thorax, forelimb and flank) from the left side of each carcass. Muscle distribution was also assessed on the 10 standard muscle groups. The distribution of subcutaneous fat, intermuscular fat and muscle in the carcass was directly related to the total amounts of the respective tissues (P < 0.01) and was not affected by genotype or sex. Bone distribution was affected by sex and breed of dam, although it was suggested that the breed of dam effect was due to errors in halving the carcass. The sex effect was such that wethers had 2.8% more bone in the forelimb, while ewes had 1.9% more bone in the hindlimb, at the same total bone weight (P < 0.05). Growth coefficients for subcutaneous fat, intermuscular fat, muscle and bone all exhibited distoproximal growth gradients.

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*Part II, Aust. J. Agric. Res., 30: 1207 (1979).
Response of wheat to deep placement of nitrogen and phosphorus fertilizers on a soil high in phosphorus in the surface layer
Authors: Alston AM
Published: November 2004

Wheat was grown in a series of field experimenls on a sandy red-brown earth that was well supplied with phosphorus in the top 10 cm, and deficient in nitrogen. Nitrogen (0-60 kg ha-') as ammonium sulfate or urea, and/or phosphorus (0-100 kg ha-1) as triple superphosphate were applied at various depths down to 30 cm. In one experiment the response to fertilizer placement was examined under dryland and irrigated conditions. The dry weights and the concentrations of nitrogen and phosphorus in the plants were determined, and in one experiment root lengths were also measured. In none of the experiments did placement of fertilizers at depth increase grain yields to a greater extent than placement at 5 cm. While the concentrations of nitrogen and phosphorus in the plants were increased by the application of nitrogen and phosphorus fertilizers respectively, the depth at which the fertilizers were placed was immaterial. Application of phosphorus fertilizer increased root length, but only at the site of placement. Irrigation increased yields, but there was no interaction with depth of fertilizer placement. The soil disturbance (ripping) associated with deep placement of the fertilizers affected shoot growth in all experiments, but the effects were not consistent. Ripping had no effect on root length. Residual effects of the fertilizer treatments on growth and composition of the wheat were small. Deep placement of fertilizer is not recommended for wheat where the nutrient content of the topsoil is high and the topsoil remains wet during the early part of the season.
An appraisal of practical alternatives to legume seed inoculation: field experiments on seed bed inoculation with solid and liquid inoculants
Authors: Brockwell J , Gault RR , Chase DL , Hely FW , Zorin M , Corbin EJ
Published: November 2004

Sixteen field experiments were conducted to assess whether inoculant applied as a liquid or in solid form separately from the seed but into the seed bed could be used as a substitute for conventional methods of legume seed inoculation. The experiments were done over a period of 8 years, on several soil types, with both crop and pasture legumes. Criteria used to measure response included success of the applied strain of rhizobia in forming nodules, quality of nodulation, seedling establishment, foliage dry matter production, and seed yield. Under favourable conditions for sowing, solid and liquid inoculants were generally as good as seed inoculation at similar total rates of application in promoting root nodulation and plant growth. However, when conditions were unfavourable for survival of rhizobia, e.g. when seed was dusted with toxic fungicide or when germination was delayed owing to environmental circumstances, solid or liquid inoculant gave better nodulation and very often better plant growth and seed yield than seed inoculation. The implications of these findings on alternatives to conventional seed inoculation and how they might be applied to agricultural practice are discussed.
Limitations imposed by nitrogen deficiency on the productivity of subterranean clover-based annual pasture in southern Australia
Authors: Cocks PS
Published: November 2004

Potential productivity of pasture in the Mediterranean environment of southern Australia and limitations imposed on productivity by nitrogen deficiency were studied on grazed subterranean clover-based annual pasture at Kybybolite, S.A. Estimates of monthly growth, botanical composition and nitrogen uptake were made on the basis of growth in open and closed quadrats. Ammonium and nitrate nitrogen in the top 10cm of soil were measured frequently, and six estimates of the response of pasture to nitrogen were made during the growing season. Potential herbage productivity was assumed to be 5 % of photosynthetically active radiation. Grazed pasture yielded 12.6 t of dried herbage per hectare compared with a calculated potential of 28.7 t ha-1. It was calculated that nitrogen deficiency probably accounted for about 59 % of the shortfall. Maximum rates of growth in mid spring (October) reached 160 kg ha-1 day-1 in the presence of added nitrogen compared with a calculated potential of 180 kg ha-1 day-1, and measured growth of only 98 kg ha-1 day-1 in the absence of nitrogen. Pasture responded least to added nitrogen in autumn even though, in that season, grasses and herbs dominated subterranean clover. Low responsiveness was associated with high levels of mineral nitrogen in the soil before and for 2 weeks after the first autumn rains. Thereafter mineral nitrogen remained very low, and pasture increasingly responded to nitrogen until it matured in late spring. During this time the proportion of legume steadily increased until, by the end of spring, it reached 50 %. In all, it was calculated that soil released 184 kg nitrogen, and clover fixed 146 kg nitrogen, per hectare over the growing season. In order to reach its potential productivity the pasture needed a further 406 kg nitrogen per hectare. In the absence of fertilizer nitrogen, economically unacceptable on the annual pastures of southern Australia, subterranean clover will need lo fix this extra nitrogen if annual pastures are to reach their potential productivity.
Urea and meat meal in the diets of ruminant calves - the sites of digestion and the nitrogen requirements for microbial protein synthesis
Authors: Leibholz J
Published: November 2004

Nine Friesian calves between 11 and 30 weeks of age were fed on diets based on barley supplemented with 0, 1.75 or 3.5 % urea or with meat meal. In a further experiment a purified diet was supplemented with 3-5.25 % urea and 20-50% wheat straw. The replacement of meat meal by urea reduced the flow of nitrogen to the duodenum and the apparent absorption of amino acid in the intestines. It was calculated that diets containing no meat meal would be limiting the growth of calves by a deficiency of sulfur amino acids and possibly threonine. With purified diets it was also calculated that the sulfur amino acids would be the first limiting amino acids for growth. The apparent digestion of amino acids in the small intestine varied from 66 to 76% for diets containing at least 1.8% nitrogen. The apparent digestion of essential amino acids was greater than that of non-essential amino acids. A nitrogen content of 1.8 % as urea in a purified diet was sufficient to maximize the efficiency of microbial protein synthesis in the rumen to 23-24 g nitrogen per kg of dry matter fermented. This is equivalent to 1.7 g nitrogen per MJ of metabolizable energy in the diet and corresponds to a concentration of ammonia in the rumen of 120 mg/l. The dietary nitrogen content required in barley and urea diets for maximum microbial protein synthesis was greater than with purified diets owing to the incomplete breakdown of the nitrogen in barley in the rumen. The efficiency of microbial protein synthesis in the rumen was similar for diets containing 8.3-11.0 MJ of metabolizable energy per kg of diet. The apparent digestion of a-linked glucose polymers in the rumen was lower for diets containing 1.3 % nitrogen than for those containing at least 1.8 %. As the metabolizable energy content of diets increased, there was a decrease in the apparent digestion of a-glucose polymers in the rumen.
Relationships of circulating cortisol levels with growth rate and meat tenderness of cattle and sheep
Authors: Purchas RW , Barton RA , Kirton AH
Published: November 2004

Plasma or serum levels of cortisol have been measured in cattle and sheep in four experiments and have been related to growth rates and meat tenderness. Significant treatment effects on cortisol levels included: (i) higher values in samples taken at slaughter from 30-month-old Angus steers (n = 30) than Hereford steers (n = 30) (P < 0.001); (ii) higher values in samples taken at slaughter from Cheviot sheep (n = 51) than Romney sheep (n = 48) (P < 0.02); (iii) higher values in jugular samples taken from a lighter group of lambs (n = 16) than a heavier group (n = 28) (P < 0.005); (iv) higher values following a period of stress induced by restraint for wether lambs (n = 23) than ram lambs (n = 21) (P < 0.02). Plasma cortisol levels in a group of 10 lambs sampled three times a week over a period of 11 weeks remained reasonably consistent for both stressed and unstressed animals. Relationships between cortisol levels and growth rate were significant for the cattle (r = -0.44**, n = 60), but were very low for all the groups of sheep. The relationships with meat tenderness (Warner-Bratzler shear) were significant only for cold-shortened samples of beef (r - 0.29*, n = 45).
The use of progesterone and oestrogen concentrations in the diagnosis of pregnancy, and in the study of seasonal infertility in sows
Authors: Williamson P , Hennessy DP , Cutler R
Published: November 2004

Plasma concentrations of progesterone and oestrogen in sows 18 days after mating were examined, firstly, as a method of pregnancy diagnosis, and secondly, for indication of any abnormal endocrine patterns that may have been involved in the aetiology of seasonal infertility in sows. Progesterone levels were the most relevant indicator of ovarian function. For the diagnosis of pregnancy, progesterone levels were accurate (97 %), but for the diagnosis of non-pregnancy, especially where a high degree of early embryonic death and/or cystic follicles was suspected, as in this trial, progesteronc levels were not as accurate (60%). Oestrogen levels were of use only in confirming the type of infertility suffered by non-pregnant sows. This study shows that seasonal infertility in mated sows is a complex of several forms of infertility, each manifest in a common physical symptom of delayed return to oestrus after a normal mating to a fertile boar. The forms of infertility involved appear to be early embryonic death, luteinized ovarian cysts, small ovarian cysts and silent oestrus.
The effects of a continued water supply during and beyond seed development on seed production and losses in subterranean clover swards
Authors: Collins WJ , Quinlivan BJ
Published: November 2004

Four strains of subterranean clover were grown in swards and mown regularly until the beginning of flowering. During the period of flowering and seed development, the swards were irrigated as required to prevent moisture stress. Watering was then continued to keep the burrs and seeds moist for a further 5 months. Depending on the strain, seed yields reached a peak between 74 days and 86 days after the onset of flowering (late August-early September). Then followed a sudden and marked decline in both the amount and number of seeds present in the four strains. By the end of February less than 20% of the seeds produced were still present in the soil. Seed germination accounted for less than 50% of the seed losses. The remainder (unrecovered seed) was presumably lost as a result of attack by pathogenic microorganisms in the soil. The results suggest that it may be difficult to obtain maximum seed yields in swards of subterranean clover. Even a relatively small (3 weeks) decrease or increase in the period for which moisture is available, compared with the optimum, can lead to markedly reduced seed yields.
Infection of seed of subterranean clover and allied species by species of Fusarium
Authors: Kellock AW , Stubbs LL , Parbery DG
Published: November 2004

Fusarium avenaceurn (Corda ex Fr.) Sacc. was shown for the first time to be carried in the hilum of subterranean clover (Trifolium Subterraneum L.) seed. Scanning electron microscopy and thin-section techniques showed that the fungus occurred only as dormant mycelium in parenchyma cells of funicle scar tissue. It emerged from these tissues after a 12 h incubation at 24�C and in 48 h penetrated internal parts of the seed through the hilum fissure. After 21 days on moist blotting paper, seedlings grown from infected seed developed lesions on their roots similar to those of root-rot of subterranean clover in the field. Fusarium spp. were also detected in the hilum of seeds of white (T. repens L.) and strawberry (T. fragiferum L.) clover and barrel medic (M. truncatula L.). It was demonstrated experimentally that all parts of the burr, incl~tding the funicle, became infected with F. avenaceuni when subterranean clover plants grown from healthy seed in pasteurized soil buried their burrs in soil inoculated with the fungus. Use of optical brighteners failed to trace seed infection because the compounds, although absorbed by the pathogen in culture, were not translocated.
Variation in energy and nitrogen utilization by sheep between weaning and maturity
Authors: Graham NMcC
Published: November 2004

A diet was given at several levels to four sheep at 2,4 and 10 months of age (fasting, fleece-free liveweights 15-28 kg) and to six adult sheep (6-year-old; 47 kg). Complete balances of energy and matter were measured at each feeding level and during fasting at each age, to determine whether energetic efficiency changed as the animals matured. Despite variation amongst sheep, when intakes were expressed relative to body weight an overall inverse relationship was apparent between digestibility and plane of nutrition, but the effect of increasing intake diminished as the sheep grew. The partition of digestible energy between losses (urine and methane) and metabolizable energy (ME) varied with level of feeding except in the youngest animals, but was not otherwise affected by the age of the sheep. The net result was that ME per unit intake was maximal when dry matter intake was c. 2 % of liveweight, and the decrease at higher planes of nutrition diminished with age. Allowing for the effect of intake, energy balance in MJ/day decreased as liveweight increased, but per unit metabolic size (kg +) energy balances were greater in the adult sheep. The efficiency of use of ME for maintenance was 73-80% with no consistent age trend. Efficiency of utilization of surplus ME for growth increased from 32 �- 2 % at 2 months to 55 � 2 % at 10 months and 6 years as the contribution of protein synthesis to energy balance decreased from 50 to 13 %. Partition of ME between maintenance, protein gain and fat gain gave 76-95 and 56-60 kJ/g as the estimated cost of protein and fat synthesis respectively.
Cattle and sheep production on an Atriplex vesicaria (Saltbush) community
Authors: Wilson AD , Graetz RD
Published: November 2004

A comparison was made between the productivity of sheep and cattle grazing on a semiarid saltbush (Atriplex vesicaria Heward) community (median annual rainfall 303 mm) over a 4 year period. Hereford cattle were grazed at 11.7 and 17.5 ha/cow and Merino sheep were grazed at 1.7 and 2.5 ha/ewe. The cows and ewes were joined annually so that they calved and lambed in the May- June period. Calves were weaned at 7-8 months, and the lambs were weaned at c. 4 months. Both calves and lambs were then retained on separate plots for a further 12 months. The saltbush community consisted of a low shrub layer containing 250-750 kg A. vesicaria forage per ha and a herbage layer containing 25-650 kg of forage per ha. Despite the higher digestibility and nitrogen content of the sheep diets, the sheep and cattle had similar productivity. The production of body weight to weaning was a mean of 10.6 and 15.1 kg/ha/year (low and high stocking rates) for the cattle and a mean of 9.4 and 13.2 kg/ha/year for the sheep. After correction for metabolic mass (kg0.9/ha), the body weight production of sheep was raised to 12.4 and 17.3 kg/ha/year. At 12 months after weaning, the equivalent values were 12.9 and 19.4 kg/ha for cattle, and 13.4 and 20.1 kg/ha (corrected) for sheep. Thus differences are small and arise from the stocking rate chosen rather than from biological differences in productivity. There was no relative change between sheep and cattle in body weight growth between good and moderately poor seasons. The livestock numbers for equivalence of grazing pressure were calculated as 9.2 sheep to 1 cattle. The cattle drank an average of 46,300 litres of water each in a year, while sheep drank only 3300 litres per year. On this basis the water supply for cattle grazing would need to be 50% greater than for sheep grazing on the same saltbush land. In addition to body growth, the sheep produced 1.4-2.0 kg clean wool per ha, which provides a substantial economic advantage for sheep in these lands.
The bulbing response to day length and temperature of some Australasian cultivars of onion (Allium cepa L.)
Authors: Steer BT
Published: November 2004

Onions (Allium cepa L.) were grown in the Canberra phytotron from seed to bulb in three day lengths (11, 14 and 17 h) and five temperature regimes (day/night 18/10�, 22/14�, 26/18�, 30/22�, 34/26�), The cultivars Creamgold, Braeside Golden Globe, Gladalan Brown and Early Lockyer Brown were used. There was a significant interaction of cultivar, day length and temperature on bulbing. Bulbing was most rapid at the highest temperature and longest day length. Creamgold exhibited a temperature dependence in bulbing, so that at 18/10�C bulbing did not occur at any day length. The other cultivars bulbed at low temperatures. Lateral buds developed in Braeside Golden Globe, but not at low temperatures (18/10�) or in long day lengths (14 or 17 h) where normal bulbs were produced. In an attempt to simulate field conditions more closely, some plants were transferred to different day length and temperature treatments between sowing and harvest. During development, neither bulbing ratio (leaf base diameter/neck diameter) nor final bulb size was significantly different from those of plants grown from seed to maturity in one regime. Bulbing required the continual presence of bulb-inducing conditions: bulb development ceased on transfer to unfavourable conditions (short day lengths, low temperature).
Runoff and soil and nutrient losses from an improved pasture at Ginninderra, Southern Tablelands, New South Wales
Authors: Costin AB
Published: November 2004

Plot and catchment measurements of runoff and of soil and nutrient losses were carried out on a moderately to heavily grazed (12-30 sheep/ha) phalaris-subterranean clover pasture at Ginninderra. The effects of an intense summer storm were examined by applying artificial rains of 20 mm/ 15 min on 5.6 m2 runoff plots in 1964. The pasture topsoils had high infiltration capacities (50-75 mm/h), and when dry could absorb more than 40 mm of water. Surface runoff and soil loss were inversely related to cover (as pasture, detached litter, and sheep dung). Cover values less than about 70% were associated with some large increases in runoff and soil loss, whereas at higher cover values there was relatively little reduction in runoff and soil loss. Most soil losses were small (< 5 g m-2) when runoffs were less than about 15 %, but increased rapidly with increasing runoff. Acceptable conditions of ground cover were mostly maintained on the improved pasture but their potential for soil and nutrient losses was greater than on native pasture. Pasture renovation substantially reduced surface runoff. The effects of natural rains on runoff and soil and nutrient losses were measured from 1966 to 1971 on a 88 ha experimental catchment. The amount of runoff varied with the amount and season of rainfall, from less than 1 mm (0.2% of rainfall) in a dry year to 51 mm (7%) in a wet year, with an average of 29 mm (4%) per year. Most runoffs in autumn and summer were relatively small, reflecting the high infiltration capacity of the surface soil when topsoil moisture storage was available. In spring and winter, when the topsoil was mostly wet, runoffs were greater, reflecting the much lower infiltration capacities (c. 5 mm/h) of the subsoil. Soil losses were related to the runoffs. They ranged from 4 kg to 376 kg/ha/year, with an average of 179 kg. Most of the soil was in fine suspension, little as bed load or coarse floating debris. Losses of nitrogen, phophorus, potassium and sulfur were at average rates of 0.62, 0.12, 1.93 and 0.06 kg/ha/year. The present rate of soil loss is less than the estimated past rate of topsoil development, and the rates of loss of nitrogen, phosphorus and sulfur are less than the inputs from fertilizers and legumes. With management to retain adequate ground cover, the Ginninderra pasture effectively controls runoff and soil and nutrient losses, and could be used in similar environments as a standard for soil and water conservation, as well as livestock production.
Some effects of rust infection and moisture stress on growth, diffusive resistance and distribution pattern of labelled assimilates in sunflower
Authors: Siddiqui MQ
Published: November 2004

Greenhouse experiments, where sunflower plants (cv. Peredovic) were inoculated with Puccinia helianthi at the vegetative stage of plant growth, showed that the effect of rust on growth parameters varied according to the moisture stress to which plants were subjected. Rust infection caused a marked reduction in the diffusive resistance of leaves in darkness. However, the diffusive resistance in light of leaves not stressed or subjected to mild moisture stress was unaffected by rust infection. In uninfected plants subjected to moderate moisture stress, the diffusive resistance in light increased markedly, whereas in rust-infected leaves it remained the same as in leaves not stressed or subjected to mild moisture stress. Carbon-14 uptake by the first pair of true leaves of non-stressed plants or those subjected to mild moisture stress was unaffected by a low level of rust infection (9% disease rating). Carbon-14 uptake by uninfected leaves was reduced when they were subjected to moderate moisture stress. Rust infection and moderate moisture stress caused a reduction in the rate of translocation of labelled assimilate from leaves fed with 14CO2 and also altered the distribution pattern of labelled translocate to various sinks.
A kinetic model of copper metabolism in sheep
Authors: Weber KM , Boston RC , Leaver DD
Published: November 2004

A three-compartment model was developed to provide a simple kinetic description of the metabolism of copper in six sheep with liver copper concentrations of 433�51 ppm ( mean � SD dry weight). This was achieved by measuring the radioactivity in samples of blood, liver, urine and bile as a function of time after the intravenous administration of c. 1.4 mCi of 64Cu. Sizes of compartments, flow rates and rate constants were evaluated and validated experimentally by measuring the excretion of copper in urine and bile and its accumulation in the liver. The model postulates two separate mechanisms for the handling of copper by the liver, and biliary copper excretion was not related to total liver copper content. The model was tested in sheep with a wider range of liver copper concentrations, and the copper in the two compartments (C2 and C3), attributed to liver, corresponded to the actual liver copper content when this was between 30 and 70 mg. The rate constants also responded consistently to increased liver copper status. Within the 'normal' liver copper range of 50-70 mg, the three-compartment model was closed but outside this range, the undefined parameter K03 was no longer zero. This response suggests that copper is moving from C2 and C3 to either supply tissue requirements or be redistributed in an additional storage compartment.
N-[5-(4-Aminophenoxy)pentyl]phthalimide as a potential defleecing agent and its effect on wool growth
Authors: Tunks DA , Rigby RDG , Downes AM , Lamberton JA , Panaretto BA , Reis PJ
Published: November 2004

Merino sheep, offered feed at two levels of intake, were given an oral dose of N-[5-(4-am1nophenoxy)- pentyllphthahmide at rates varying over 100-800 mg/kg body weight. Consistent defleecing was obtained at dose rates of 400 nig/kg and above. Feed intake did not Influence defleecing activity. lntravenous infusion of smaller amounts also allowed defleecing. Wool growth rate following dosing was not affected by a dose of 100 mg/kg, but doses of 200 and 400 mg/kg caused depressions of c. 15 and c. 70% respectively in the rate of wool growth in the 2 weeks after dosing. Blindness was observed In one sheep dosed at 400 mg/kg and In all sheep dosed at higher rates