bluuebunny/crossref_metadata_2025 huggingface dataset:
The maximum metabolic response of sheep to cold: effects of rectal temperature, shearing, feed consumption, body posture, and body weight
Authors: Bennett JW
Published: November 2004

Shorn, adult sheep were exposed to an ambient temperature of about 1°C and a rate of fall in rectal temperature of 0.5–2.0°C/hr was obtained by varying wind velocity and wetness of the fleece. Respiratory gaseous exchange was monitored continuously, and the records were used to calculate metabolic rate. The maximum instantaneous metabolism was 2–36% higher than the maximum metabolism averaged over a 20 min period-termed summit metabolism. Since the larger differences were due to an additive effect of voluntary muscular activity, summit metabolism was adopted as the estimate of the maximum metabolic response to cold. There was no consistent relation between summit metabolism and rectal temperatures above 37°C, but there was a direct relationship at rectal temperatures between 30 and 37°. Shearing the sheep just prior to a determination, or fasting the animal for 19–21 hr, did not influence the magnitude of the summit metabolism. Fasting for 3 days reduced the maximum response by an amount equal to the heat increment of the ration. Sheep generally remained standing during the exposure to extreme cold. While the sheep were lying down, summit metabolism was 26–28% lower than the value during standing, and heat production was reduced to a greater extent than heat loss, since the rate of fall in rectal temperature was greater than that during standing. Summit metabolism was proportional to fleece-free body weight raised to the power 0.9, and summit metabolism per unit of surface area increased with increasing body weight. When sheep were housed in a warm or thermoneutral environment prior to the tests to prevent acclimatization to cold, their summit metabolism averaged 10 watts/kg or 25 watts/kg0.75 and day to day variation in individual sheep was about 6%.
The germination and establishment of two annual pasture grasses (Hordeum leporinum Link and Lolium rigidum Gaud.)
Authors: Cocks PS , Donald CM
Published: November 2004

The germination and establishment of Hordeum lepovinum Link and Lolium rigidum Gaud., two Mediterranean annual grasses, were studied under controlled conditions. Results were related to the ecology of these species as pasture plants in southern Australia. Seeds of the two species germinated over a similar range of constant temperatures (8-30�C); Hordeum germinated much more rapidly than Lolium at all temperatures. Lolium has a marked requirement for alternating temperatures for maximum germination, while Hovdeum has a weak or nil requirement. Both species withstood prolonged wetting at high temperatures without germinating or losing all viability. Prior soaking and redrying before germination increased the rate of germination of both species. Light rains which fall before the first germinating autumn rains usually wet the seed only for short periods and this further increases the advantage of Hordeum over Lolium in rate of germination. Hordeum germinated and established much more readily on the soil surface than did Lolium, even though Lolium absorbed water more rapidly. The success of Houdeum was due both to its rapidity of germination, which allowed it to establish before the soil surface dried out, and to its ability to germinate at high moisture tensions. Because of these features Hordeum leporinum has the potential to germinate earlier, more rapidly, and more freely than Lolium rigidum in the autumn of the Mediterranean region of southern Australia.
Selection for crude protein content in Phalaris tuberosa L. III. Physiological relationships between crude protein content and seedling vigour.
Authors: Clements RJ
Published: November 2004

Seedling growth of half-sib families from two lines of P. tuberosa previously selected for high and low herbage nitrogen contents respectively was examined in a glasshouse during the autumn and winter. Seedlings from the high nitrogen line were smaller than those of the low nitrogen line but had similar whole-plant relative growth rates. Differences in the rate of nitrogen absorption by the roots (h), and in the rate of seedling weight increase per unit of absorbed nitrogen (EN), accounted for most of the variation in herbage nitrogen content between families. The heights of seedlings were closely correlated with the weights of seeds from which they originated and with EN, and when these two characters were held constant the partial correlation between nitrogen content and seedling weight was negligible (r = -0.05). Among 10 clones differing markedly in herbage nitrogen content in the field, seed weight was closely correlated with the photosynthetic area above the flag leaf node available to each seed, particularly that contributed by the spikelet (r = 0.82***). Two alternative interpretations of this result are discussed. Relationships between nitrogen content, spikelet number, and the areas of photosynthesizing organs above the flag leaf node suggest that seed weight could be maintained during selection for increased nitrogen content by concurrently selecting either for large seeds, or for large flag leaves and a reduced number of spikelets per head. Even so, some loss of actual or potentially attainable seedling vigour seems almost inevitable because of the dependence of nitrogen content on IN and EN and because EN is an important determinant of vigour.
Toxicity of malathion to the natural enemies of California red scale, Aonidiella aurantii (Mask.) (Hemiptera: Diaspididae)
Authors: Abdelrahman I
Published: November 2004

The lethality of malathion to all stages of red scale of three different strains was tested. Scales from areas subjected to spraying were 1.87 times as tolerant as those from unsprayed areas, which in turn were 1.52 times as tolerant as the laboratory strain. Of the seven distinguishable stages of red scale only the first moult (males and females), second moult females, and young-producing females proved to be significantly more tolerant than the other stages, the second moult female being three times as tolerant as the young-producing female, or nine times as tolerant if the body weight and surface area are taken into account. The latter finding is important, because it has been customary to estimate the efficiency of spray treatments by mortality in the young-producing stage. This would leave many of the second moult females alive after spraying and the infestation would continue.
The use of growth patterns of muscle measurements, chemical data, energy, and muscle weights to differentiate between normal and recovering muscle
Authors: Lohse CL , Pryor WJ , Butterfield RM
Published: November 2004

Twenty-eight Peppin Merino wethers were equally divided into two groups, a continuously grown group and a group which suffered a 6-week period of liveweight loss followed by recovery. Wethers in the continuously grown group were slaughtered over a range of liveweights; wethers in the restricted group were slaughtered over the same range of liveweights during the recovery phase. Each animal was totally dissected and individual muscles weighed. Several linear measurements and a cross-sectional area measurement were made of the longissimus muscle (M. longissimus thoracis et lumborum). Dry matter, ether extract, nitrogen, and energy measurements were determined for the total muscle tissue. The relationship of the high impetus and low impetus muscles to total muscle weight was determined. No significant effects of treatment were shown on any of the M. longissimus measurements nor on the chemical and energy values. The relationship of the weight of the low impetus muscles to that of total muscle was not significantly different between groups, but the same relationship for the high impetus muscles was highly significantly different. It is concluded that the weight relationship of high impetus muscles to total muscle is a sensitive test to differentiate between normal and recovering muscle. It cannot of course be applied in the live animal.
Longitudinal distribution of applied calcium, and of naturally occurring calcium, magnesium, and potassium, in Merton apple fruits
Authors: Lewis TL , Martin D
Published: November 2004

When 45Ca-labelled calcium chloride solution was applied to the skin of young developing Merton apple fruits, activity in the cortex at maturity was highest in the calyx end region where bitter pit lesions most commonly develop. Fruit age at time of application affected the amount of labelled calcium absorbed but not its longitudinal distribution. Following branch injection of labelled calcium chloride solution 8 weeks before harvest, activity in mature fruits was found mostly in the stem end. Leaves and buds accounted for 95% of the recovered activity, and the fruits for 5%, of which about one-quarter was in the calyx half. The same distribution pattern was found following injection of labelled calcium chloride solution into the fruit stem. The concentration of naturally occurring calcium in the cortex of the mature fruit declined steadily from stem end to calyx end. On the other hand, the magnesium concentration was lowest near the stem end and highest at the calyx end. The potassium concentration remained fairly constant along most of the length of the fruit, with a small increase at each end. The findings are discussed with regard to the longitudinal gradient in bitter pit susceptibility within apple fruits, and to the relative effectiveness of tree sprays of calcium, as compared with soil applications, in the control of the disorder. Results suggest that calcium does not have a trace element role in the control of bitter pit.
Whole wheat grain feeding of lambs. II. Growth of Merino lambs early weaned onto wheat
Authors: McManus WR , Reynolds JA , Roberts EM
Published: November 2004

Two experiments were conducted to examine the growth characteristics of Merino lambs early weaned onto a base diet of whole wheat grain plus 1 .5 % limestone ad libitum. These data have been compared with similar information obtained for traditionally managed spring drop Merino weaners at pasture. In experiment 1, 158 lambs which were born to ewes given wheat in pens were used in a 4 x 2 factorial to examine responses to anti-white muscle disease compounds and biuret. No responses were obtained to selenium, vitamin E, or a combination of the two. The food conversion efficiency (FCE), i.e. weight units of feed ingested per weight unit increase in liveweight, was improved by addition of 3 % biuret (5.1 v. 5.5 for control). In experiment 2, 185 lambs were used in a 5 x 2 factorial where minerals and biuret were the factors. These lambs originated from groups of ewes fed on either wheat or roughage in paddocks. There was a 28.6% mortality in lambs without previous exposure to wheat when this group was early weaned onto a pasture-clover hay ration which changed over 37 days to 100% wheat. The mortality among lambs with wheat experience was 1 .5 % during this period when they were offered wheat ad libitum from weaning. Responses to biuret were small and variable, while a positive response to sodium, which was present in all four mineral treatments, was obtained. In comparison with control animals, the effects of including sodium were to reduce FCE (5.2 v. 4.7), reduce the time to finish (123 v. 111 days), and increase the rate of gain (0.84 v. 1.03 kg/week).
Establishment and growth of shoots following low and high cutting of lucerne in relation to the pattern of nutrient uptake
Authors: Hodgkinson KC
Published: November 2004

Lucerne plants (Medicogo sativa cv. Hunter River) were either frequently or infrequently cut down and subsequent differences in shoot regrowth were compared in two experiments. The first experiment demonstrated that differences in final shoot weights arose from differences developed during the first 7 days of regrowth. High level cutting (15 cm) increased the shoot yield of frequently but not of infrequently cut plants. Net uptake of both nitrogen and phosphorus was related to the growth rate of shoots until commencement of flowering, when uptake ceased for c. 15 days even though both roots and shoots continued to gain weight. Towards the end of flowering uptake of nitrogen and phosphorus recommenced and accumulation of both nutrients occurred in the tap-root and lateral roots. The relative nitrogen and phosphorus content of leaves on crown shoots was highest on day 7 and the same for frequently and infrequently cut plants. Leaves on crown and stubble shoots 7 days after high level cutting had a significantly lower relative nitrogen and phosphorus content than leaves on plants cut low. Thereafter the relative nitrogen and phosphorus content of a11 leaves declined with the greatest decline occurring after the commencement of flowering. In the second experiment early morphogenesis of the shoot population was investigated. Establishment of shoots was completed between 3 and 5 days after cutting. Higher shoot weights on infrequently cut plants were accounted for by a larger number of small shoots at the time of cutting. Relative growth rates of shoots did not appear to be influenced by prior cutting frequency. The relative nitrogen content of buds and shoot apices was low at cutting but doubled within 2 or 3 days and then declined after day 7. These results are discussed in relation to the role of 'plant factors' in shoot regrowth of lucerne.
Identifying the mating performance of individual rams in field flocks
Authors: Knight TW , Lindsay DR
Published: November 2004

A method is described for identifying the individual rams which mate with each ewe in a mating flock. Different metallic elements were incorporated into raddles worn by each ram. The elements were identified by X-ray spectrophotometry from samples of raddlemarked wool taken from ewes and hence indicated the rams with which any ewe had mated. When this method was tested under field conditions there were found to be significant linear increases both in the non-return rate (P r. 0.05) and in the number of ewes lambing (P < 0.01) as the number of rams marking each ewe increased. In the four flocks examined, individual rams mated with 4.3 to 96 % of the mated ewes in each flock. Between 21 and 88 % of the ewes were marked by four or more rams. These flocks contained c. 3 % rams.
Proportions of carcass and offal components in Jersey and Friesian bulls in relation to plane of nutrition
Authors: Leche TF
Published: November 2004

Sixty Jersey and 48 Friesian bull calves were reared from birth on either of two planes of nutrition. Three calves of each treatment group were slaughtered at liveweights arranged in logarithmic progression between birth weight and 249 kg. The weights of dissectible body parts were regressed on empty body weight after logarithmic transformation of both variates. Treatment effects were tested by comparing the slopes and intercepts of the regression equations. Development of the head, legs, kidneys, and kidney fat differed significantly between these breeds. All of these parts matured earlier in the Jersey. Plane of nutrition affected development of the liver, kidney fat, caul fat, and urogenital tract. These parts were heavier in high plane calves than in low plane calves of the same breed and empty body weight, with the exception of the urogenital tract, where the converse was true. In general, the effects of breed and plane of nutrition on the proportions of carcass and offal components were of minor economic significance.
Grain yields in wheat per unit area, and per unit of silicon — as a measure of water transpired. I. Initial results from South Australia
Authors: Paltridge TB , Vries MPCde
Published: November 2004

In an attempt to provide a common basis for comparing wheat yields at different sites and the response to selected nutrients (specifically nitrogen and phosphorus), silicon in the glumes from wheat heads has been used as a measure of water transpired. Silicon yields in the glumes of wheat plants are clearly related to the amount of water transpired by crops in the field and the ratio yield/silicon is a sensitive measure of treatment effects that does not vary from year to year, despite marked difference in seasonal rainfall. Optimal values for yield/silicon (i.e. yield per unit of water transpired) could be used to define specific regions, or sites, where recorded grain yields are far below what might be expected from a wheat crop under prevailing climatic conditions.
Flowering in Dactylis glomerata. II. Interaction of temperature and photoperiod
Authors: Broue P , Nicholls GH
Published: November 2004

Controlled environment studies investigated the interaction between temperature and photoperiod in relation to floral initiation in seedling populations of the temperate perennial grass Dactylis glomerata L. High temperature inhibited flower formation, but this effect was confined to the early part of the terminal LD treatment, i.e, to the actual transition of the shoot apex from vegetative to floral development. During earlier stages of vegetative growth, including SD vernalization, high temperature was not inhibitory. Of the treatment parameters studied, two exerted a dominant influence on the level of flowering. These were (i) the duration of SD vernalization, and (ii) the temperature level during the terminal LD treatment. A model is presented to explain flowering response in terms of an interaction between these components.
The use of ordination techniques in the preliminary evaluation of Stylosanthes accessions
Authors: Williams WT , Edye LA , Burt RL , Grof B
Published: November 2004

It is suggested that ordination is preferable to classification if two sets of data are to be rigorously compared. Ordination techniques have been applied to data from 154 Stylosanthes accessions grown at two contrasted sites. Eleven agronomic attributes were recorded for each site. Each set of data was submitted separately to a principal component analysis, and the first three components in each case are described and discussed. Techniques are explained as well as the way in which the components can be used for predicting the most promising accessions. The two sets of components were compared by canonical procedures, and although the between-attributes-between-sites correlation coefficients are everywhere low, the canonical coefficients are extremely high. There is, therefore, a robust attribute- pattern, common to the two sites, but exemplified by different species in each instance. If a desirable performance can be defined in terms of the canonical components, it follows that accessions can always be found that will meet it, but different species will be required at different sites. The results strongly suggest that, among the set of accessions tested, there may be forms potentially capable of out-yielding even the best of the existing cultivars.
The effect of calcium supply on bur set and seed formation in subterranean clover (Trifolium subterraneum L.)
Authors: Ozanne PG , Howes KMW
Published: November 2004

In a glasshouse experiment subterranean clover plants were grown in soil at various levels of calcium nutrition. The developing burs were buried in separate soil containers to which no nutrients, calcium sulphate, calcium carbonate, or potassium sulphate were applied. When subterranean clover was growing in soil low in calcium, top yield was little affected; but bur and seed formation were greatly reduced. However, when the reflexed flowers were buried in soil to which a calcium salt had been added, bur and seed yield increases of up to 500% were obtained The increase in seed yield resulted from a greater percentage of flowers forming bur, more seed per bur, heavier seed, and less rotten seed. Similar results were obtained in a second glasshouse experiment in which a different soil was used to grow the clover. The beneficial effect of calcium ions around the developing bur was independent of the associated anions, or of the soil pH; nor could it be produced by the substitution of potassium or magnesium for calcium. It seems likely that commercial seed yields and subterranean clover persistence in many areas may be reduced by calcium deficiency in apparently lush healthy pastures. The similarity of this disorder to calcium deficiency in peanuts suggests that other crop and pasture species forming buried seed may also be especially susceptible.
Effect of experimental manipulation of circulatory cortisol levels in lambs on their growth rate and carcass quality
Authors: Purchas RW
Published: November 2004

Relationships between the activity of the adrenal cortex and the productivity of lambs were investigated by administering cortisol acetate or melengestrol acetate. Initial experiments indicated that cortisol acetate administered every second day effectively maintained elevated levels of serum cortisol and that the administration of melengestrol acetate brought about some suppression in the levels of serum cortisol. However, when administered to growing lambs over an 8-week period, melengestrol acetate at a rate of 0.6 mg every second day had no measurable effect on serum cortisol. Cortisol acetate at a dosage of 50 mg every second day increased serum cortisol concentrations for the first 4 weeks only, after which they declined to the levels in the control lambs. In the group treated with cortisol acetate, serum and adrenal levels of cortisol at slaughter were significantly lower than the control group, but there were no differences in meat tenderness. Elevated levels of cortisol at slaughter were obtained by acute administration of cortisol acetate at the rate of 150 mg/day for 3 days. Meat from these animals was appreciably more tender than that from the controls. It is concluded that the negative relationships reported to exist between endogenous cortisol levels and growth rate or meat tenderness of cattle, either do not exist in lambs or they are not the simple cause and effect type.
Silicon content of wheat husks in relation to water transpired
Authors: Hutton JT , Norrish K
Published: November 2004

The possibility of using the silicon content of wheat as a measure of transpiration in the field has been investigated. Silicon is concentrated in the husks, containing about one-third of the total silicon in the plant, and so the husks were used for most measurements. Samples, from field trials extending over several seasons and from a number of localities, showed that the percentage silicon (% Si) in the husks is closely related to water transpired. The equation, water used(cm) = 7.4+4.6(%Si) (r = 0. 99 , n = 8), should be applicable to most of the wheat-growing areas of southern Australia, but the addition of fertilizers, particularly nitrogen, modifies the equation. The relationship between weight of silicon in the tops and water transpired is consistent with the known solubility of Si(OH)4 in soils, but the correlation is poorer than that using percentage silicon.
The influence of density and nitrogen on the outcome of competition between two annual pasture grasses (Hordeum leporinum Link and Lolium rigidum Gaud.)
Authors: Cocks PS
Published: November 2004

The hypothesis that the outcome of competition between Hordeum leporinum Link and Lolium rigidum Gaud. depended predominantly on the density of Hordeum was tested in two experiments. In the first experiment it was postulated that increasing the density of Hordeum increased its competitive ability; in the second experiment the interaction between soil nitrogen and density was studied. Under the conditions of the first experiment the hypothesis was shown to be true. The competitive ability of Hordeum was closely related to its density, and neither the density of Lolium nor the total density had a significant effect. Hordeum was most competitive when its density was highest. The second experiment showed that soil nitrogen was an important modifying factor. At low nitrogen Hordeum was the successful competitor, but its competitive ability decreased with increase in its density. At high nitrogen Lolium became the successful competitor, although the effect of Hordeum density was similar to that in experiment 1. At the lower levels of nitrogen the density of Lolium also affected the outcome of competition, but its effect was never as great as that of the density of Hordeum. The results are explained in terms of the original hypothesis and of the different abilities of the two species to absorb soil nitrogen.
Studies on the productivity of tropical pasture plants. V.* Effect of shading on growth, photosynthesis and respiration in two grasses and two legumes
Authors: Ludlow MM , Wilson GL , Heslehurst MR
Published: November 2004

Two grasses and two legumes were grown at three illuminances: one grass and one legume in a growth cabinet (100, 50 and 34% relative illuminance) and one of each in a glasshouse (100, 30 and 10% relative illuminance). The response to shading was investigated by using classical growth analysis techniques, and the photosynthesis-respiration balance obtained by Watson and Hayashi's method. Shading caused a reduction in the proportion of root and a corresponding increase in the proportion of leaf, and an increase in the shoot/root ratio in all species except green panic. The relative growth rates of grasses (which were only clearly superior at the highest illuminance) were affected more by shading than were those of legumes, and the greater shading effect resulted from a greater decrease in net assimilation rate, and to a lesser extent, from a smaller compensatory increase in leaf area ratio in the grasses than in the legumes. The greater sensitivity of net assimilation rate of grasses to shading arose from a stronger dependence of the photosynthetic rate on illuminance. The significance of these findings for pasture production is discussed. Both tiller and runner production were dependent upon the total amount of radiant energy received by the plant, and in the growth cabinet, at least, were independent of its intensity, duration and sequence.

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*Part IV, Aust. J. Agric. Res., 25: 415 (1974).
Host specialization of powdery mildew, Erysiphe cichoracearum, from Chondrilla juncea
Authors: Hasan S
Published: November 2004

The host specialization of Erysiphe cichoracearum from skeleton weed, Chondrilla juncea, was studied in Europe. Plant species comprising a number of cichoriaceous plants closely related to Chondrilla, and cultivated plants belonging to 23 families particularly including the cultivated Compositae, Cucurbitaceae, Solanaceae, and Leguminosae, on which forms of this fungus have been recorded, were inoculated with conidia of the mildew. Moreover, three cultivars of all cultivated species recorded as hosts of any form of E. cichoracearum were tested. The powdery mildew from C. juncea did not develop on any of these plants.
Urinary sediments in sheep feeding on oestrogenic clover. III.* The identification of 4′-O-methyl equol as a major component of some sediments
Authors: Nottle MC , Beck AB
Published: November 2004

Chemical identification has been made of two types of sediment formed in the urine of sheep ingesting clovers high in formononetin. One type, described previously, consists of the calcium salt of the glucuronide of 4′-O-methyl equol (4′-methoxy-7-isoflavanol). The other contains unconjugated 4′-O-methyl equol associated with small amounts of equol, formononetin and biochanin A. This is the first report of the isolation of optically active 4′-O-methyl equol. The present findings indicate that, under some conditions, at present undefined, 4′-O-methyl equol may replace equol as the main metabolite of formononetin. When administered subcutaneously into mice, 4′-O-methyl equol is slightly less oestrogenic than equol, and its possible role in 'clover disease' of sheep is discussed.

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*Part II, Aust. J. Agric. Res., 23: 693 (1972).
Protein-energy relationships in the digestion products of sheep fed on herbage diets differing in digestibility and nitrogen concentration
Authors: Egan AR
Published: November 2004

The digestion of organic matter and nitrogen in 17 herbages was studied in sheep fitted with duodenal re-entrant cannulas. Each herbage was in chopped form, and was given at levels close to ad libitum but offered at an even rate hourly by automatic feeder. Diets ranged from 0.4 to 5.1% nitrogen and from 49 to 79% digestibility of organic matter (OM). At the levels of intake achieved, the apparent digestibility of OM in the stomachs ranged from 28 to 45%; between 54 and 72% of the apparently digested OM disappeared before the duodenum. Though the percentage of the digestible OM digested across the stomachs tended to increase with decreasing overall digestibility, the relationship was poor (r² = 0.25). Of the OM apparently digested between duodenum and faeces, 5ndash;40% could be accounted for as crude protein. Non-protein OM digested in the intestines contributed about 25% of total apparently digested OM. The nitrogen intakes extended over a range of 1.8–57.1 g/day, and the apparent digestibility of nitrogen rose from negative values to 84% with increasing nitrogen intake. Small gains (1–3 g) in nitrogen at the lower end and substantial losses of up to 40% of nitrogen at the upper end of the dietary range resulted in yields of non-ammonia nitrogen (NAN) of 2.4–32 g/day at the duodenum, of which 75–80% was accounted for as α--amino nitrogen. Crude protein yielded at the duodenum ranged from 10.3 to 42.5 g/100 g OM apparently digested across the stomachs. Metabolic faecal nitrogen losses were estimated at 0.65 g/100 g OM entering the duodenum of which 0.60 g was estimated to arise in the intestines. Over all diets the estimated mean true digestibility of NAN entering the intestines was 84%. Crude protein truly digested in the intestine contributed 5.6–21.2 g of each 100 g OM apparently digested, or an estimated 5.3–20 g of each 100 g OM truly digested. This would have provided from c. 7% to c. 24% of digestible energy as protein, or 14–45 g truly digestible true protein/Mcal metabolizable energy (ME) to the animal. While a 12-fold range of dietary crude protein concentration was condensed to a fourfold range of protein concentration in the OM digested by the animal, it is suggested that diets 1–13 still provide insufficient protein per unit energy to meet requirements for normal lamb growth even if adequate ME intake could be achieved, and that diets 1–8 would not provide adequate protein for maintenance. The protein yield as grams truly digested true protein per Mcal ME (P) was related to the dietary nitrogen concentration, expressed as grams per 100 g digestible OM (N), by the equation
P = 11.50 + 4.58N (?3.19; r² = 0.88)

However, despite the high correlation, prediction on this basis would not separate diets in the mid-range of nitrogen concentration (i.e. 3.0 g N/100 g digestible OM) which provided, in terms of
eventual protein yield per unit energy, 19–42 g truly digestible true protein per Mcal ME (or roughly 11–22% of calories).
Selection for clean fleece weight in Merino sheep. I. Direct response to selection
Authors: Pattie WA , Barlow R
Published: November 2004

Two closed selection flocks of Merino sheep consisting of 100 ewes mated to five rams each were established at the Agricultural Research Station, Trangie, N.S.W., in 1951. One flock was selected for high clean fleece weight (Fleece plus) and the other for low clean fleece weight (Fleece minus). Responses to selection in these flocks over approximately five generations were measured against a randomly selected control flock (100 ewes mated to 10–25 rams). All flocks were selected from the same base population (1700 ewes and 150 rams) and were maintained in the same environment. The response patterns were asymmetrical. In the Fleece plus flock there was an initial increase of approximately one standard deviation in the first two generations but no consistent response was observed in the following three generations. This is shown by realized heritabilities of 0.53 and 0.11 for ewes in the first two, and subsequent generations respectively, the corresponding figures for rams being 0.65 and 0.02. In contrast to this pattern, response in the Fleece minus flock was approximately linear with overall realized heritabilities of 0.44 and 0.38 for ewes and rams respectively. The average level of inbreeding increased between 4 and 5% during selection, and the pooled partial regression of inbreeding coefficient on clean fleece weight independent of the effects of selection was –0.033 kg per 1% inbreeding. This would not have been sufficient to cause a cessation of response after the first two generations. Sampling variation and genotype x environment interaction are possible causes of this response pattern. An additional explanation is suggested which is based on the fact that clean fleece weight is a complex character in which two components, fibre density and cross-sectional area, have a negative genetic correlation between them which may become stronger under selection. It is shown that this could account for a large proportion of the reduction in realized heritability. Thus it is suggested that breeding plans should aim to control fibre diameter while selecting for high clean fleece weight if continued response is to be obtained.
The relative success of strains of Trifolium subterraneum L. in binary mixtures under field conditions
Authors: Rossiter RC
Published: November 2004

Mixtures of Dwalganup/Northam A, Dwalganup/Uniwager, Dwalganup/Daliak, Yarloop/Daliak and Yarloop/Seaton Park were grazed over a 6-year period. An additional mixture (Yarloop/Woogenellup) was abandoned after 2 years of grazing because of contamination by unsown strains. The principal finding with respect to the initial 50/50 mixtures was that Uniwager differed from the other new strains Northam A, Daliak and Seaton Park in that it was not successful. When grown with the three latter strains the proportion of Dwalganup and Yarloop, measured during the growing season, fell to about 10%. This result was considered very promising in connexion with the 'clover disease' problem which occurs on pastures dominated by Dwalganup and Yarloop. The factors influencing success and failure are discussed briefly, and the importance of the seedling establishment phase is emphasized.
The utilization and excretion of sulphur in cattle fed on tropical roughages
Authors: Kennedy PM
Published: November 2004

The effect of additions of sulphateh to the diet of cattle given tropical spear grass (Heteropogon contortus) and Townsville stylo (Stylosanthes humilis) was studied in three experiments. In one experiment there was a small increase in the digestibility of dry matter, but the intake of feed was not affected. The concentration of volatile fatty acids in ruminal liquor from cattle offered spear grass was increased by supplemental sulphate; there was a concurrent small decrease in the proportions of propionic and isovaleric acids. Excretion of faecal sulphur varied with the intakes of total sulphur, organic matter, and digestible organic matter, while urinary sulphur excretion varied with the sulphur and organic matter intakes. Excretion of organic sulphur and total sulphate in urine and faeces increased with sulphur intake. The ratio of nitrogen to sulphur in faeces declined when sulphate was given. The retention of nitrogen was correlated with sulphur retention. It was concluded that the intake and digestion of the hays were not limited by the intake of sulphur.
Studies of grain production in Sorghum bicolor (L. Moench). III.* The relative importance of assimilate supply, grain growth capacity and transport system
Authors: Fischer KS , Wilson GL
Published: November 2004

In field and glasshouse experiments with grain sorghum (cv. RS610), the assimilate supply was varied by increasing or decreasing radiation and carbon dioxide supply; the potential grain storage capacity was altered by spikelet removal; and the transport system was reduced by incision of the culm. Plants grown at four population densities in the field were manipulated to increase (by removing neighbouring plants) or decrease (by shading) the supply of photosynthates during grain filling. These treatments affected grain size and thus yield. Removal of some of the spikelets at three-quarter anthesis resulted in a significant increase in the size of those grains remaining at maturity. From anthesis onward, a reduction in the capacity of the transport system in the culm had no significant effect on grain yield. These results are interpreted as evidence that grain yield is not limited by the storage capacity of the grain, or by the transport system involved in moving material from the stem to the grain. Treatments which altered the demand for assimilates by the grain, relative to the supply, did not affect net photosynthesis. Dry matter produced in excess of grain requirements accumulated in other plant parts, including the root. Potential grain size was influenced by interspikelet competition operating within 1 week after three-quarter anthesis.

*Part II, Aust. J. Agric. Res., 22: 39-47 (1971).
Nitrogen in temperate crop and pasture plants
Authors: Gladstones JS , Loneragan JF
Published: November 2004

Nitrogen concentrations were determined in the tops of 24 annual crop and pasture varieties grown together in ungrazed plots on a lateritic gravelly sand at Gidgegannup, W.A., and sampled at three stages during growth and at maturity. All legumes had higher nitrogen concentrations in the tops than all non-legumes, but considerable variation was evident within each group. Among pasture legumes, Ornithopus compressus and O. sativus had the highest concentrations, especially towards maturity, and Trifolium subterraneum cv. Yarloop and Clare the lowest. Nitrogen concentrations in all Lupinus spp. fell rapidly towards maturity, and they were unique in suffering substantial net nitrogen losses from the tops. The herb Erodium botrys grew better and took up more nitrogen under conditions of deficiency than did the grasses. Its nitrogen concentration was nevertheless very low. Among the grasses, Bromus rigidus consistently had the highest nitrogen concentration and Lolium rigidum the lowest. There was some evidence among non-legumes of a correlation between high nitrogen concentrations and/or total uptake and observed adaptation to sandy soils. The superior adaptation of legumes in the experimental environment was demonstrated. It is suggested that crop legumes could make a more important agronomic contribution than hitherto in this and similar environments.
Regional and temporal variations in wheat yield in Western Australia and their implications in plant breeding
Authors: Goodchild NA , Boyd WJR
Published: November 2004

The average annual wheat yields (bushels/acre) for each major wheat-producing shire in Western Australia were studied for a 40-year period from 1932 to 1971. Simple correlation coefficients provided an inadequate representation of the yield fluctuations over time and of regional differences. The data were then analysed by principal component analysis of the variance-covariance matrix. The order and magnitude of the vector coefficients provided clearly interpretable results distinguishing between-season from within-season components of variation and regional differences in respect of the magnitude of their relative contributions. Thus the method provided information that would otherwise be unavailable and the implication of these findings in the formulation of breeding programs is discussed.
The differential response of barley genotypes to nitrogen application in a Mediterranean-type climate
Authors: Gardener CJ , Rathjen AJ
Published: November 2004

The response of 12 barley cultivars to nine levels of nitrogen was studied in the field at Adelaide, S.A. The cultivars were selected from a world collection according to origin, number of spikelet rows and maturity, and their response was measured in terms of yield components, harvest index and straw and grain yield. The optimum nitrogen level for grain production differed greatly between cultivars, some giving a maximum yield at 0 kg N/ha, others showing a typical parabolic response, and others giving increasing yields up to 275 kg N/ha. Although grain yields by cultivars at their optimal level differed the highest-yielding cultivars with optima at 0,70 and 275 kg N/ha had similar yields, which indicated that it would be more profitable to grow different cultivars in areas naturally low or high in soil nitrogen than to apply additional nitrogen to cultivars adapted to higher fertility levels. Some cultivars, previously considered as intrinsically lower-yielding, may normally receive suboptimal fertilization. Variation in yields of cultivars with nitrogen reflected variation in ear numbers. The grain weight per ear remained relatively constant in 11 cultivars, as changes in weight per grain compensated for changes in number of grains per ear. In contrast, a single cultivar believed to be adapted to fertile prairie conditions was extremely susceptible to nitrogen deficiency, showing a large reduction in the number and aggregate weight of grains per ear. The reduction in ear numbers at high nitrogen levels in some cultivars appeared to be related to temporary crop lodging in the juvenile stage prior to stem elongation. Late cultivars with many long, narrow leaves per tiller and many tillers were most prone to this pseudostem lodging.
Pathways for losses of fertilizer nitrogen from a Rhodes grass pasture in south-eastern Queensland
Authors: Catchpoole VR
Published: November 2004

The importance of surface run-off water, leaching and evolution of gases on losses of nitrogen fertilizer from a Rhodes grass pasture in south-eastern Queensland were assessed. Field microplots encased in steel tubes 21 cm in diameter and 60 cm deep were equipped to collect surface run-off, fertilized with 15NH415NO3 prills at the rate of 150 kg nitrogen ha-1 and destructively sampled at 4, 8, 12, 16 and 40 weeks after fertilizing. The recovery of 15N in the soil-plant system, losses of 15N in surface run-off and movements of 15N down the soil profile were measured. Open pasture plots were fertilized with NH4NO3 at rates of 0 and 150 kg nitrogen ha-1 and harvested at the same times as the microplots. The results were used to calculate the apparent recovery of fertilizer nitrogen by the plant tops. Pasture cores of 11.5 cm diam. and 12.0 cm deep were given the same fertilizer treatment as the microplots, placed in gas-tight growth chambers for periods of 4 weeks starting at 0, 4, 8, 12 and 16 weeks after fertilizing, and used to measure gaseous losses of 15N. The effects of soil water content ranging from field capacity to waterlogged on these losses were studied on a second series of cores. The apparent recovery of fertilizer nitrogen and the recovery of 15N in plant tops were usually well below 20%, and the recovery of 15N in the soil-plant system of the microplots was always below 50% of the amount applied. Most of the loss of 15N occurred during the first 4 weeks. A large part of the 15N lost from the field microplots was not traced, but the results demonstrated that surface run-off and leachate should not be ignored during nitrogen balance studies on pastures in south-eastern Queensland. Surface run-off generally removed less than 5% of the 15N, but the loss was 40% from one microplot. Losses due to leaching were not quantified, but a small significant excess of 15N in soil layers below 60 cm suggested that they did occur. Gaseous losses of 15N from waterlogged pasture cores reached 27%, but they were small or absent from cores with a soil water content at or below field capacity. Detailed work in the gas-tight growth chambers to define the soil conditions associated with gaseous losses of nitrogen are needed to relate laboratory findings to field conditions.
The control of time of oestrus and ovulation and the induction of superovulation in cattle
Authors: Moore NW
Published: November 2004

In an attempt to induce superovulation at predetermined times 140 mature parous cows and 27 heifers were treated with progesterone by intramuscular injection (40 mg/day for 17–30 days) or prostaglandin F2α (PG) by intrauterine injection on each of two consecutive days (500 µg/injection) between the 8th and the 14th day of the oestrous cycle. All animals were given pregnant mare serum gonadotrophin (PMSG) or an equine anterior pituitary extract (HAP) at one of three doses, and human chorionic gonadotrophin (HCG) at a standard dose of 1500 i.u. was given to two-thirds of the cows on either the second or third day after the final progesterone or first PG injection. Following treatment the animals were run with entire bulls and all were slaughtered within 7 days of the end of treatment. During treatment progesterone effectively inhibited ovulation, while PG caused luteolysis in the vast majority of animals. Ninety-eight cows and 23 heifers were in oestrus within 6 days of the final progesterone or first PG injection, and the majority (87%) within 2–4 days. All 27 heifers and 129 of the 140 cows ovulated within a few days after treatment, and there was no apparent difference in either time of ovulation or ovarian response between animals which did, and did not, exhibit oestrus. PMSG and HAP were equally effective in inducing superovulation, but in heifers HAP gave more unruptured large follicles than did PMSG. Overall, the ovulatory response of heifers was greater than that of cows. HCG, irrespective of when given, had no effect upon either incidence of oestrus or ovarian response. In cows and heifers which were in oestrus, the respective percentages of eggs shed that were recovered from the reproductive tract, and the percentages of recovered eggs that were fertilized, were 73 and 79, and 78 and 95. There was no effect of any factor other than HCG on either recovery or fertilization rates. In cows but not in heifers, HCG treatment at either time appeared to reduce recovery and fertilization rates. Where numbers of fertilized cow eggs are required, it is suggested that PMSG in conjunction with PG provides the most simple treatment. Further, it seems desirable to restrict treatment to heifers or young cows.
Physiological responses of semiarid grasses. I. The influence of phosphorus supply on growth and phosphorus absorption
Authors: Christie EK , Moorby J
Published: November 2004

Experiments were carried out under controlled conditions to investigate the physiological bases for species differences in yield and nutrient responses to variations in phosphorus supply. Buffel grass (Cenchrus ciliaris), and to a less extent Mitchell grass (Astrebla elymoides), showed a much larger yield response to increasing phosphorus supply than mulga grass (Thyridolepis mitchelliana). Mitchell and mulga grasses had much lower relative growth rates than buffel grass. Mulga grass required a lower external phosphorus concentration for optimal growth than Mitchell and buffel grasses; this was attributed to its superior system for absorbing and transporting phosphate from low concentrations, but was not associated with any yield advantage, yield being related more to the photosynthetic than to the nutritional characteristics of the plants. Differences between species in their external phosphorus requirements for growth and their distribution in semiarid Queensland are discussed.