bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of oestrogenic activity of pastures by means of increase of teat length in sheep
Authors: Braden AWH , Southcott WH , Moule GR
Published: November 2004

The use of increase in teat length for bioassay of oestrogens in sheep has been investigated. In wethers injected intramuscularly with stilboestrol dipropionate the best precision was obtained by measurement of the increase 9 days after the beginning of oestrogen administration. The range of doses over which the log dose-response relationship was linear was rather narrow (4–16 µg stilboestrol dipropionate per day). Applied in the field, the technique provides a means of assessing the effective intake of oestrogens by grazing sheep. Marked seasonal fluctuations in the oestrogen intake of wethers grazing a red clover pasture were recorded; the lowest level was in May and peaks occurred in August and December–February.
Body composition in vivo. IV. Comparisons of the antipyrine and N-acetyl-4-aminoantipyrine spaces in goats
Authors: Panaretto BA , Reid JT
Published: November 2004

The effects of feed and water deprivation on the antipyrine (AP) spaces were studied in five goats. Generally there was no good relationship between loss in body weight, following 24 or 48 hr of feed and water deprivation, and changes in the AP space. The AP spaces were variable and the rates at which AP disappeared from the circulations of our animals also varied. No satisfactory explanation could be given. Estimates of body water made with N-acetyl-4-aminoantipyrine (NAAP) were always smaller than the simultaneous AP spaces in any animal. Two experiments were made to study these differences in the volumes of distribution of AP and NAAP when both chemicals were injected simultaneously. Both chemicals yielded anomalous spaces in the first experiment when the ruminal contents had been augmented with water, while better results were obtained when the ruminal contents had been augmented with rumen fluid in the second experiment. Intravenously administered AP appeared in the rumen contents of the goats at greater concentration than NAAP which had been given at the same time, and the differences between the two spaces appeared to be due to this. The rates at which both substances disappeared from the circulation of these animals are given, and the relationship between their disappearance from the blood and appearance in the rumen is discussed.
Some effects of anaesthesia, lateral recumbency and diversion of saliva on the rumen function of sheep
Authors: Peel LJ , Wilson AD
Published: November 2004

The effccts of anaesthesia, lateral recumbency, and the collection of saliva on the rate of contraction, pressure, total volatile fatty acid (V.F.A.) concentration, and pH of the rumen, and on the salivary secretion were investigated. Anaesthesia depressed the rate of contraction by the rumen, significantly increased the pressure of gas within the rumen as measured at the fistula, and reduced the rate of total salivary secretion by 66%. Anaesthesia had no effect on the concentration of nitrogen in the total mixed saliva, and its effect on the concentration of rumen total V.F.A. was inconclusive. During lateral recumbency a high concentration of rumen total V.F.A. was maintained. There was no change in the rate of contraction of the rumen, but there was a rise in the gas pressure measured at the rumen fistula and a decrease in the rate of total salivation. A significant increase was recorded in the total saliva nitrogen concentration. When total saliva was collected from the oesophageal fistulae of standing sheep, the pattern of total V.F.A. concentration within the rumen was altered. There was no change in the rate of contraction of the rumen or in the gas pressure at the rumen fistula. It was concluded that the diversion of 2 1. of saliva over a 5 hr period had little effect on the sheep provided the sodium loss was subsequently restored. It is suggested that care is needed in interpreting results obtained from sheep under anaesthesia or in lateral recumbency.
Stimulation of wool growth by thyroxine implantation. I. Liveweight changes and wool growth of fine-wool Merino wethers
Authors: Lambourne LJ
Published: November 2004

Groups of 20 and 30 fine-wool Merino wethers were treated with L-thyroxine and their subsequent liveweight changes and wool production studied under a variety of grazing conditions for a year. Treatments comprised : (1) Single implantations of 60 mg in autumn, winter, spring, or summer. (2) Repeated implantations at all four seasons of 30, 60, or 90 mg. (3) Weekly subcutaneous injection of 7 mg in aqueous solution. These groups were grazed with untreated wethers on improved native pastures at one to two sheep per acre. (4) Repeated 60 mg implantations at four seasons in wethers grazed on native pasture providing a lower level of nutrition. (5) Repeated 60 mg implantations at four seasons in wethers grazed on sown pasture providing a higher level of nutrition. After every implantation there was a loss of 5–10 lb liveweight — more pronounced and more prolonged in the wethers given greater amounts of thyroxine, and more prolonged in those at lower levels of nutrition. Deaths occurred in several groups, increasing with dose rate or with poorer nutrition up to 30–50% of the group. Wool growth was not increased significantly by repeated 60 mg implants at the lowest level of nutrition, nor by the single 60 mg implant in late spring. Increases of 34% in annual fleece weight resulted from 60 mg implants in autumn and summer. Repeated implantation of 30, 60, and 90 mg in groups on a medium or high plane of nutrition increased annual fleece weight by 8, 14, and 19%, and 7 mg injected weekly by 11%. Increases in fleece weight were due partly to increased fibre length, and partly to an increase in grease and suint which reduced the clean scoured yield by 1–2%. It is concluded that line-wool Merinos, despite their lower body weight and greater specialization for wool production, react to thyroxine treatment in the same way as has been established for "dual-purpose" sheep. The safe maximum dose rate is critically dependent on the current level of nutrition, particularly for young sheep. Repeated implantations without adequate opportunity for recovery of catabolized body tissues may produce no increase in wool growth and may cause death.
A comparison of cattle tick control by "conventional" acaricidal treatment, planned dipping, and pasture spelling
Authors: Harley KLS , Wilkinson PR
Published: November 2004

Three comparable herds of cattle were grazed in a wet tropical area of north Queensland for the comparison of control measures against the cattle tick, Boophilus microplus. The cattle tick infestation of one herd was controlled by simulated "conventional" methods, the cattle receiving acaricidal treatment when the count of "standard" ticks (0.5 cm or more in length) on the right side averaged 20 or more per animal. The tick infestation of the second herd was controlled by dipping in acaricide at 21-day intervals, so that few of the tick larvae attaching to the cattle between dippings reached maturity. This was continued until the larval population in the pasture was greatly depleted. The procedure, for which the term planned dipping has been proposed, was repeated when the count of standard ticks on the right side averaged more than 20 per animal. The tick infestation of the third herd was controlled by grazing alternately in two adjacent paddocks, the interval between each transfer being sufficient to ensure that most of the ticks in the unstocked paddock had died. Acaricidal treatment was applied at times of paddock changes and also at other times if the tick count was more than 20 per animal. This procedure is known as pasture spelling. Over the 2 years of the experiment, planned dipping and pasture spelling resulted in increased efficiency in tick control. In comparison with the herd given conventional tick control, planned dipping resulted in no reduction in the number of acaricidal treatments, but the tick burden was reduced by 79%. Pasture spelling resulted in the number of acaricidal treatments being reduced by 60% and the tick burden by 64%.
A virosis-like proliferation (Witches' broom) of lucerne (Medicago sativa L.) caused by an eriophyid mite (Aceria medicaginis Keifer)
Authors: Stubbs LL , Meagher JW
Published: November 2004

A witches' broom condition of lucerne, characterized by foliage symptoms similar to those attributed to a leafhopper-transmitted virus, is described. The lucerne bud mite, Aceria medicaginis Keifer, has been found to be consistently associated with affected plants collected in a number of localities in northern Victoria. Mites transferred to healthy lucerne seedlings induced the leaf and foliage proliferation symptoms observed on field-collected plants. Experimentally and naturally affected plants recovered when sprayed with thiometon, which indicated that the mite was not acting as the vector of a virus. This previously unreported association of eriophyid mites with witches' broom of lucerne is discussed in relation to findings from earlier aetiological and ecological studies on the disease in Australia.
Emergence of Medicago tribuloides on moderately acid soils
Authors: Kleinig CR
Published: November 2004

Field establishment of Medicago tribuloides Desr. on moderately acid, light textured soils varied from 98% to less than 10% of untreated viable seeds sown. Seed and seedling mortality occurred mainly in the pre-emergence stage. Where emergence was poor, under conditions of low temperature or high soil moisture, or both, considerable improvement resulted from using a seed fungicide or a soil fumigant, or coating seeds with alkaline inorganic materials, of which calcium carbonate was the most effective. Under adverse conditions of temperature and rainfall, improved emergence occurred at higher soil pH values. The results indicate that pathogenic soil organisms caused pre-emergence seed and seedling mortality, and that temperature, rainfall, soil pH, and seed coating (through its pH effect) influenced pathogen activity or the susceptibility of the seedling to pathogenic attack.
Phosphate absorption and phosphate fractions in field soils of varying histories of phosphate fertilization
Authors: Kurtz LT , Quirk JP
Published: November 2004

Phosphate adsorption isotherms were determined by allowing soils to react for 18 hr with phosphate solutions of varying concentrations. Small or no reductions in adsorption maxima were found for red-brown earth samples, although a large total amount of phosphate had been applied over a considerable period of years. Some instances of lower adsorption were found, however, in the lateritic and brunizem soils which had received large, recent applications of phosphate fertilizer. Apparently applied phosphate did not permanently occupy adsorption sites but was converted to other forms which were independent of clay surfaces. Phosphate in these samples with varying histories of phosphate fertilization was determined as "aluminium-, iron-, and calcium-bonded" fractions according to the procedure of Chang and Jackson (1957). All these fractions were found to have been increased by phosphate addition, and the total gain due to fertilizer could usually be accounted for in those fractions. No quantitative relation between any of the fractions and the adsorption isotherms was apparent. The samples were also extracted with the Bray P1 reagent, which is extensively used in a rapid procedure to measure "available" phosphorus. Phosphorus removed by this extractant was approximately a constant proportion of both the "aluminium bonded" (soluble in ammonium fluoride) and the "iron-bonded" (soluble in sodium hydroxide) in fertilized samples and a lower but again nearly constant proportion in unfertilized soils. Amounts of phosphorus extracted by the Bray P1 reagent and the ammonium fluoride appeared to be in fair agreement with the phosphate status of the soils for crop growth.
The digestion of food by the grazing sheep. IV. The effect of mastication on the release of soluble plant nitrogen
Authors: Hogan JP
Published: November 2004

The rate of release of soluble nitrogenous constituents from plant cells during the ingestion of green pasture plants has been studied. Boluses were collected either from sheep with oesophageal fistulae or from the rumen in sheep fitted with large rumen cannulae. Sheep grazing on pastures of different heights ingested food at widely varying rates. This was indicated by the rate of formation of boluses, which during 10-min collection periods ranged from 10.5 to 62.5 g/min. The rates at which bolus nitrogen reached the rumen ranged from 45 to 300 mg/min; of this, 20–45% (mean 26) was extractable with cold water. Approximately 50% of the extractable soluble nitrogen was protein nitrogen.
The free amino acids occurring in the blood plasma and rumen liquor of the sheep
Authors: Leibholz J
Published: November 2004

The concentrations of free amino acids occurring in the rumen liquor and blood plasma of the sheep have been determined. The concentrations in the blood plasma were lower than those found in monogastric animals. After feeding, the free amino acids in the plasma increased 2 to 10-fold and those in the rumen liquor up to 100-fold. These elevated concentrations were maintained for between 1 and 3 hr.
Genetic and phenotypic parameters for body weight and greasy fleece weight at weaning in Australian Merino sheep
Authors: Young SSY , Brown GH , Newton Turner H , Dolling CHS
Published: November 2004

Genetic and phenotypic parameters for body weight and greasy fleece weight at weaning were estimated in a flock of Australian Merinos. Maternal handicaps were found to be more severe at weaning than at the older age of 15–16 months. Lambs born to 2-year-old ewes were 2–3 lb lighter in body weight at weaning and 0.2 lb lighter in greasy fleece weight than the offspring of adult ewes. Twin lambs were on the average 6–7 lb lighter than singles and cut 0.5 lb less greasy wool. Greasy fleece weight at weaning was found to be fairly highly heritable but only moderately repeatable. The repeatability and heritability of weaning body weight were both low. The genetic correlations estimated here were associated with appreciable sampling errors, but the estimates strongly suggested high and positive correlations between measurements at weaning and at 15–16 months for both traits. A general consideration of the relative efficiency of direct versus indirect selection, based on the information obtained in this study, leads to the conclusion that for greater genetic gains, mass selection for greasy wool weight and body weight at weaning should be carried out on measurements at 15–16 months of age, rather than at weaning.
Root distribution of orchard trees
Authors: Cockroft B , Wallbrink JC
Published: November 2004

A survey of root distribution of peach and pear trees has been made in shallow, medium, and deep soils in Goulburn Valley orchards. Root patterns were similar in both species, and shallow (less than 36 in.) in all soils. A further survey in soil management trials showed that the influence of soil management treatments was on roots in the surface soil. Roots grew as close to the actual ground surface as was allowed by such factors as cultivation depth, competition, and soil temperature.
The intake and excretion of sodium by sheep fed on species of Atriplex (Saltbush) and Kochia (Bluebush)
Authors: Wilson AD
Published: November 2004

Penned sheep were fed ad libitum on the fresh leaves of various species of Atriplex and Kochia,and records were made of the intake and excretion of sodium by these sheep. The sodium content of the diets varied from 3.2 to 8.2% of the dry weight, the higher values being recorded in summer and the lower values in winter. The sodium intakes of the sheep varied from 25 to 97 g/day. Most of this sodium was excreted in the urine at concentrations up to 500 m-equiv./l. The voluntary water consumption of these sheep was related to the sodium intake, such that the ratio of sodium chloride intake to total water intake was within the range 1.82 to 2.17%. Voluntary water intakes varied up to 11.3 l./day. The food intake of A. nummularia decreased to less than half when the drinking water was replaced by water containing 0.9 or 1.2% sodium chloride.
Soil water relations and relative turgidity on leaves in the wheat crop
Authors: Fischer RA , Kohn GD
Published: November 2004

Trials were conducted in 1961 and 1962 at Wagga in southern New South Wales to investigate the yield physiology of the wheat crop. Various cultural treatments were applied to a single variety (Heron). The increases in evapotranspiration and associated reductions in total soil moisture content caused by early sowing, by heavier fertilizer applications, and to a lesser extent by a heavier rate of sowing were reflected in an increased plant moisture stress (reduced leaf relative turgidity) at a given time in the spring. At a given stage of development, however, relative turgidity was not much affected by time of sowing, and in fact post-flowering plant moisture stress increased with later sowing. There were only small treatment effects on the estimated depth and density of rooting. Relatively little water was extracted by crops from below 40 in.; dense crops reduced the soil moisture content throughout the root zone to less than the –15 bar value. Leaf relative turgidity at sunrise showed a consistent inverse relationship to soil moisture content in the root zone. Leaf turgidity (sunrise) was maintained at 100% until root zone moisture levels approached the –15 bar value.
Cytological investigations in the Setaria sphacelata complex
Authors: Hacker JB
Published: November 2004

A cytological study of a wide range of strains of the Setaria sphacelata complex showed that diploid, tetraploid, pentaploid, hexaploid, octoploid, and decaploid races occur within the species complex. In addition, a number of plants had one or more (rarely up to 1.5) extra chromosomes which were probably B-chromosomes. No variation was recorded in the number of B-chromosomes in different root tips from the same plant, but different plants from the same strain frequently had differing numbers of B-chromosomes. Breeding problems arising from the cytological complexity of S. sphacelata are discussed.
The growth of apricot fruit. I. Morphological changes during development and the effects of various tree factors
Authors: Jackson DI , Coombe BG
Published: November 2004

A study has been made of growth in the fruit of apricot, Prunus armeniaca L. cv. Moorpark, in Adelaide, S.A. Morphological changes in the seed and mesocarp from anthesis to maturity are described. Significant positive correlations have been shown between the diameter of fruit at early pit-hardening, and that at the end of pit-hardening and at maturity. Large fruit at pit-hardening were also shown to ripen earlier. Other factors such as leaf/fruit ratio, fruit or leaf number per branch, branch diameter, and amount of light received by branches could not be correlated with fruit growth or final size. Differences were found in the rate of fruit growth during the first 3 or 4 weeks after anthesis between seasons, and also between fruit from early and late flowers. These differences were positively correlated with air temperature during this period; a constant number of "degree-days" above 5°C had accumulated when the fruit had grown to 2.3 cm in diameter. Fruit were shown to vary in volume and in the number and volume of mesocarp cells, both within and between trees. Volume differences in fruit within a tree were mainly due to differences in cell number, but between trees the contribution of cell volume was relatively more important.
Studies on copper and cobalt therapy of cattle in central coastal Queensland
Authors: Alexander GI , Harvey JM , Lee JH , Stubbs WC
Published: November 2004

Four experiments described determined the effect of copper and cobalt therapy on the growth and productivity of cattle on the marine plains of central coastal Queensland. Copper was administered by subcutaneous injections of copper glycinate, and cobalt by dosing per os with heavy cobalt pellets. The growth of weaned cattle was significantly improved by copper, particularly from June to October when limited palatable feed on the high ground forced the animals to forage on the para grass swamps. During the same period, 2-year-old heifers also showed a growth response to copper. Their conception rate increased after 19 months of copper therapy but not after 10.5 months. The growth rate of their calves bas significantly increased by copper supplementation. Liver copper concentrations were always low in untreated cattle. Copper therapy maintained these reserves at higher levels, which varied according to the season and the rate of growth of the animals. Calves born to treated cows had higher initial liver copper reserves than those from untreated cows, but in the absence of copper therapy these reserves declined to low and comparable levels in all calves at weaning. Pasture analyses suggest that the copper deficiency revealed was due to interference with copper metabolism rather than to a low copper status in the diet; this interference did not appear to be due to molybdenum. Weaned cattle appeared to respond to cobalt during 1960 but not subsequently, while the cows and calves showed no response. The vitamin B12 status in liver and serum appeared adequate in both treated and untreated cattle.
The effects of high temperatures on certain root-nodule bacteria
Authors: Wilkins J
Published: November 2004

Rhizobia present in soils from western New South Wales and from the New England Tableland were subjected to a series of high temperature survival tests. Rhizobia present in air-dry soils survived temperatures higher than would be experienced under natural conditions. In moist soils the tolerance of medic rhizobia to high temperatures was much lower. Strains of Acacia, Lotus and Psoralea rhizobia from western New South Wales survived higher temperatures than strains from the New England Tableland, but the tolerance to high temperatures of medic rhizobia did not vary with source. This suggests an ecological adaptation of the three native strains not found in the introduced Medicago rhizobium.
Poisoning of sheep and cattle in Western Australia due to species of Isotropis (Papilionaceae)
Authors: Gardiner MR , Royce RD
Published: November 2004

The distribution of the six species of Isotropis occurring in Western Australia has been delineated, with botanical descriptions of the four known to be toxic. Outbreaks of intoxication due to I. Cuneifolia or I. Drummondii, supplemented by feeding trials, were studied in detail and the basic pathological effects recorded. It is suggested that the toxic principle exerts its main effects on the glomerular capillary endothelium and the epithelium of the proximal convoluted tubules of the kidney, and on the centrilobular liver cells. Gastrointestinal and cardiovascular lesions may also contribute to acute deaths. The histopathological changes are described in detail.
Genetic and phenotypic relationships between fertility and wool production in 2-year-old Merino sheep
Authors: Kennedy JP
Published: November 2004

Records of the lambing and weaning performance (fertility) of 2-year-old Peppin Merino ewes were analysed. Repeatability and heritability of number of lambs born and weaned were low. Heritability of number of lambs born was significantly different from zero (0.20 ± 0.10). Phenotypic and genetic correlations between the fertility traits and greasy wool weight, all measured at approximately 15 months of age, were calculated. Phenotypic correlations between number of lambs born or weaned and greasy wool weight were negative and significant. The phenotypic correlation between number of lambs weaned and clean wool weight was negative and significant. Significant negative genetic correlations were found between number of lambs born and both greasy wool weight and clean wool weight. Genetic correlations between number of lambs weaned and the fleece and body traits had very large standard errors. The results were used to estimate correlated responses in fertility resulting from selection for greasy wool weight, clean wool weight, and body weight of –0.08i, –0.13i, and 0.03i respectively.
The histopathology of the reactions of calves to experimental infection with the nodular worm, Oesophagostomum radiatum (Rudolphi, 1803). II. Reaction of the susceptible host to infection with a single dose of larvae
Authors: Elek P , Durie PH
Published: November 2004

The histopathological aspects of the host response to Oesophagostomum radiatum were studied in calves, reared worm-free, following a single dose of 5000–10,000 infective larvae. The penetration of larvae caused mainly productive changes in the gut tissue and was not followed by overt clinical symptoms. Five to seven days after infection, obliteration of small blood-vessels by endothelial proliferation and perivascular accumulation of histiocytes and lymphocytes occurred, \ particularly in the vicinity of the histotropic larvae, resembling a delayed type hypersensitivity reaction. The ensuing inflammation appeared to facilitate the termination of the histotropic phase by disorganizing the tissue produced around the third-stage larva during its development. The migration of fourth-stage larvae to the colon and subsequent moult to the fifth stage was accompanied by infiltration of eosinophil leucocytes into the gut tissue with accumulation of these cells around and within the mucosal glands, particularly in the colon. The resultant crypt abscessi, which resembled the active lesions found in ulcerative colitis, showed protracted healing, with formation of granulomas containing giant cells. Plasma cell production characteristic of a secondary response occurred only in the lymph nodes draining inflamed sections of the large intestine where adult worms were located. Healing of the acute enteritis resulted in fibrosis and hyperplasia of the gut wall.
Effects of early drought and transplanting on the subsequent development of the tobacco plant
Authors: Hopkinson JM
Published: November 2004

Detailed studies were made of the growth of tobacco plants during and after the experimental imposition of water stresses similar to those of commercial hardening and transplanting. During water stress (due to root damage, drought, or both) all growth rates were depressed, but, a short time after the relief of stress, relative leaf expansion rates, net assimilation rates, and relative growth rates rose to higher values than were reached by untreated plants at comparable stages of development. As a result, all stressed plants rapidly recovered from their period of adverse conditions. The plants that had originally been subjected to the most severe treatments overhauled those that had suffered less and finally acquired the greatest total leaf areas and dry weights. The increase was due to: (1) a change in the distribution of leaf surfaces, which occurred when leaf initiation was retarded relative to leaf expansion and resulted in increased growth of the lower leaves; (2) a delay in flower initiation, which took place at a higher node, increased the number of leaves, and prolonged the period of vegetative growth.
Red cell volume and blood volume in beef cattle
Authors: Springell PH
Published: November 2004

Twenty-four steers, comprising British (Herefords and Hereford x Shorthorn crosses), Zebu (Africander), and Zebu cross (British x Brahman or Africander) breeds, were maintained either on pasture or yarded, and fed on diets of a low and a high nutritional value. Blood volumes were determined on five occasions at intervals of 3 months by the 51Cr labelling technique, plasma and red cell volumes being then derived from the venous haematocrit. The blood plasma, and red cell volumes are all very significantly, correlated with, and represent respectively 4.97, 3.27, and 1.70% of, the fasting body weight. To avoid the confounding effect of body weight, the parameters are expressed as "contents", i.e, in terms of volume per kilogram fasting body weight. In the grazing group breed differences were generally absent. This may in part be due to the fact that the Zebu crossbreds belonged mostly to the F2 and partly to the F3 generation. In the yarded group, where F1 crossbreds were compared with British steers, breed differences were more frequent. British steers tended to have higher plasma contents, but lower red cell contents and haematocrits. Nutrition had no effect on plasma contents, but good nutrition was generally associated with higher haematocrits, as well as with elevated blood and red cell contents. Seasonal differences were in evidence, and all parameters generally reached minimal values in winter or spring. The significance of these findings in relation to adaptation to a tropical environment is discussed. The haematocrit does not necessarily reflect changes in the red cell volume. There is also some indication that the water and plasma contents may be related. The possible usefulness of the red cell volume for predicting the body composition is discussed.
Some metabolic effects of cold stress on undernourished non-pregnant ewes
Authors: Panaretto BA
Published: November 2004

Four very fat and four moderately fat ewes were undernourished for 33 days, during which time the mean decrement of body weight was 8%. The sheep were then shorn and two each of the fat and moderately fat sheep were exposed to an air temperature of 3°C while the others remained at 21 ± 5°C. The same limited quantity of food was offered at both temperatures.Three out of the four cold ewes died, whereas none of the ewes at 21°C died. The moderately fat cold ewes died within 110 hr. They showed marked protein catabolism for 24–48 hr prior to death and rapid losses in body weight accompanied by large losses in body water, urinary nitrogen, creatine, and potassium. Both animals contained substantial amounts of fat at death. One of the fat ewes died on the 10th day of cold, showing an increase in urinary nitrogen but no elevation of uninary volwne or urinary potassium. The other cold, undernourished fat ewe survived after showing increased protein catabolism during the first 10 days of cold.Transaminase activity was elevated in all cold-stressed ewes; lysosomal hydrolase activity was elevated in the circulation of animals in the cold, especially in the fat ewe that died.These results suggest that previous undernutrition alters the response of sheep to a cold stress and that a cold stress and a degree of undernutrition, each alone readily tolerated by the sheep, may together prove fatal.
Factors limiting the intake of feed by sheep. IV. The intake and digestion of mature ryegrass
Authors: Weston RH , Hogan JP
Published: November 2004

Intake and digestion studies were conducted with sheep fed on ryegrass hay containing 6% crude protein and having an organic matter digestibility of 58%. The intake of ryegrass was little affected when additional protein was provided both as a dietary supplement and as an infusion per abomasum. When supplements containing adequate amounts of protein and minerals were given, the intake of the hay was still comparatively low at 780 g organic matter per day. Grinding and pelleting the diet of hay + supplements permitted a higher feed intake. It was concluded that feed intake was limited by the resistance of the organic matter of the hay to removal from the rumen. Digestion studies were conducted at a level of feeding equal to approximately 90% of the ad libitum intake. The quantity of organic matter apparently digested in the stomach was equal to 60% of the organic matter digested in the alimentary tract; about 80% of the digestion of fibre took place in the stomach. There was a net daily gain of 7.5 g of nitrogen during the passage of digesta through the stomach, and part of this gain appeared to be due to the passage of endogenous nitrogen into the rumen. The apparent digestibility in the intestines of nitrogen that left the stomach in digesta was 73%; 1.6 g of nitrogen was apparently digested in the intestines per 100 g organic matter intake. Values of certain parameters relating to the movement of digesta through the stomach were similar to those previously recorded with a low quality cereal hay.
The effect of drought feeding with whole cottonseed, and vitamin therapy, on the serum lipids and liveweight changes of beef cattle in North-western Australia
Authors: O'Kelly JC , Robinson DW
Published: November 2004

An experiment with 79 Shorthorn cattle was carried out in the Kimberley region of north-western Australia, to study the influence of drought feeding with whole cottonseed, and of vitamin therapy, on blood lipid components and liveweight changes in cattle during the dry season. The blood serum levels of total, free, and esterified cholesterol, triglycerides, and phospholipids were elevated as a result of cottonseed supplementation, as compared with levels at the end of the following wet season. In general the levels of these blood lipids were higher in the animals fed on cottonseed for longer periods. Neither the level of free fatty acids nor the ratio of free to esterified cholesterol was affected significantly by cottonseed supplementation. Liveweight responses were proportional to the duration of the supplementation period. There were no differences in liveweight changes or the blood components measured which could be attributed to vitamin therapy.
Some effects of water restriction on apparent digestibility and water excretion of cattle
Authors: Thornton RF , Yates NG
Published: November 2004

An experiment is described in which digestibility and water excretion were investigated in cattle during periods of unrestricted feed and water, of water restriction, and of feed restriction. During water restriction: (a) Increased dry matter and acid detergent fibre digestibilities could not be wholly accounted for by decreased intake of dry matter. (b) Reduced faecal water output was more important than changes in urine output in conserving water. It is suggested that the hind gut has a regulatory role in the observed responses to water restriction.
Response of plant species to concentrations of zinc in solution. I. Growth and zinc content of plants
Authors: Carroll MD , Loneragan JF
Published: November 2004

When eight plant species were grown in a flowing culture system over a range of constant zinc concentrations, all species produced maximum yields at concentrations of zinc in solution below those usually considered adequate for plant growth. All species made good growth at a concentration of 0.01 µM zinc and maximal growth at 0.25 µM zinc or less. Toxicity effects were also induced at lower concentrations (1–6 µM) than previously reported. Differences in yield response among species did not agree in all cases with previously reported responses in standard culture and in the field. Disagreement between results in the flowing culture method used here and the standard methods of nutrient culture may arise from the contrasting characteristics of zinc supply under which deficiency develops. It is considered that results from both methods have relevance to the absorption of zinc by plants from soil solutions.
Alkaloids as a possible cause of ryegrass staggers in grazing livestock
Authors: Aasen AJ , Culvenor CCJ , Finnie EP , Kellock AW , Smith LW
Published: November 2004

Ryegrass staggers has been observed in sheep and cattle grazing pastures consisting solely of ryegrass seedlings or new shoots. Ryegrass from these toxic pastures contained a much higher alkaloid content (0.15–0.25%) than more mature grass (0.02–0.06%). A high alkaloid content appears to occur consistently in seedlings and new shoots. The alkaloid content of seedlings rises to a maximum at the sixth to the eighth day after germination and then falls. In the decline period and probably in mature grass, the alkaloid content is subject to wide daily fluctuation thought to be due to meteorological factors. In mature grass the alkaloid is nearly all perloline, but in seedlings halostachine (Ph–CHOH–CH2–NHCH3) may also be present as a major constituent. Parenteral administration of perloline to guinea-pigs and sheep produces effects resembling the symptoms of ryegrass staggers and including tetanic spasm, at a dose level of 30 mg/kg which could be attained in sheep grazing toxic grass. On oral administration at 100–200 mg/kg, perloline produces the same effects in guinea-pigs out has no effect in sheep. Halostachine is known to have sympathomimetic properties but produced only mild effects in sheep and guinea-pigs at similar doses. The two alkaloids together, given either simultaneously by the oral route or in sequence (halostachine intravenously followed by perloline orally), did not lead to disturbances resembling staggers.
The summer nutrition of immature sheep: The nitrogen excretion of grazing sheep in relation to supplements of available energy and protein in a Mediterranean environment.
Authors: Allden WG , Jennings CC
Published: November 2004

The nitrogen excretion of 24 yearling Merino sheep grazing the summer herbage of annual grass-subterranean clover (Trifolium subterraneum L.) sown pastures was measured over four consecutive periods of 28 days in relation to supplementation with available energy (E) and nitrogen (N). The experiment was of change-over design and included nine combinations of supplement E1, E2, E3 x N1, N2, N3 and an unsupplemented (control) treatment; the respective daily allowance of E was 11 3, 227, and 340 g total digestible nutrients daily, and of N supplied as protein 4,8, and 12 g/day. Unsupplemented sheep grazing mature pasture herbage excreted 23.4 g N/day in urine and faeces. Supplementary energy produced an N-sparing effect whereas added protein was associated with an increased excretion of N. Urinary N accounted for all the changes in N excretion, the faecal N component remaining constant throughout the four periods. Relative changes in herbage intake were estimated: as the level of E (dry matter) increased the estimated herbage intake of sheep was observed to fall linearly, but no significant change in estimated herbage intake was associated with changing N. Significant increases in wool production (P<0.05) were associated with supplementary N. Direct and indirect estimates of the N turnover of the grazing sheep are compared, and a crude N balance sheet is presented. Supporting data are presented which suggest that the N intakes of sheep grazing the mature herbage of sown clover-grass pastures in southern Australia are commonly of the order of 12-18 g N/day.
The digestion of pasture plants by sheep. III. The digestion of forage oats varying in maturity and in the content of protein and soluble carbohydrate
Authors: Hogan JP , Weston RH
Published: November 2004

A comparison has been made of the composition, intake, and digestion of forage oats grown with and without the application of nitrogen fertilizer and harvested at three stages of maturity. The chemical composition of the forages showed the usual changes with maturity. Fertilizer application had little effect on the levels of cell wall constituents but, as expected, decreased the levels of soluble carbohydrate and increased those of total nitrogen, alcohol-soluble nitrogen, and nitrate. The digestibility of organic matter, cell wall constituents, and nitrogen declined with advancing maturity, all three parameters being little affected by the fertilizer treatment. Feed consumption declined only with the most mature diet and was not affected by the fertilizer treatment even though the high nitrogen (HN) diets supplied 4–5 g nitrate nitrogen per day and relatively small amounts of soluble carbohydrate. There was a loss of dietary nitrogen from the stomach with the HN diets and a gain with the low nitrogen (LN). The amount of nitrogen in the digesta leaving the stomach per unit intake of nitrogen increased with maturity. The quantities of protein leaving the stomach were too great to be accounted for as microbial protein, and hence appreciable quantities of plant protein must have passed through the stomach. The digestibility of crude protein in the intestines was not affected either by maturity of the forages or by fertilizer treatment. There was little effect of advancing maturity or fertilizer application on: (a) the extent of digestion of organic matter and the structural carbohydrates in the stomach relative to that occurring in the intestines; (b) the proportion of digestible organic matter derived from rumen volatile fatty acids and amino acids; � the potential value of the metabolizable energy from volatile fatty acids and amino acids to provide net energy for fattening; (d) most parameters associated with the movement of digesta through the stomach. Advancing maturity of the diets was associated with increased expenditure of time in chewing activities.
Response of plant species to concentrations of zinc in solution. II. Rates of zinc absorption and their relation to growth
Authors: Carroll MD , Loneragan JF
Published: November 2004

Rates of zinc absorption by eight plant species grown for 46 days increased almost linearly from 2 to 400 ng atoms Zn/g fresh roots/day as zinc concentration in flowing culture solutions increased from 0.01 to 6.25µM At particular zinc concentrations, rates of absorption were about one-tenth of those reported for excised roots and up to 50 times greater than calculated rates of absorption from standard culture solutions. Reasons for these discrepancies arc discussed. At rates of zinc absorption of 2–4 ng atoms/g fresh roots/day many species developed symptoms of zinc deficiency and no species made maximal growth. Increasing rates of absorption to 10 ng atoms/g/day increased the growth of all species to maximal or near-maximal growth. Increasing rates of absorption beyond this slightly increased the yield of some species, but between 20 and 100 ng atoms/g/day there was no effect on the yield of any species. Rates in excess of 240 ng atoms/g/day were associated with depressed yields in all legumes but not in any cereals. Differences in rates of zinc absorption contributed to, but could not solely account for, differences among species in response to zinc concentrations in solution. The extent to which other factors may have modified the relationship between rate of absorption and yield is discussed.
Photosynthesis of wheat under field conditions. II.* Effect of defoliation on the carbon dioxide uptake of the community
Authors: Puckridge DW
Published: November 2004

A field assimilation chamber was used to measure the carbon dioxide uptake of wheat plants in the field before and after defoliation or ear removal. At anthesis and 10 days later only the top three leaves were effective in photosynthesis. Removal of the two leaves below the flag leaf reduced photosynthesis of the community by 25–28% and further removal of the flag leaf reduced the community photosynthesis by an additional 24–30%. The estimated contribution of the ears depended on the technique of measurement and varied from 7 to 15%. After removal of the leaf laminae and ears, the stems and leaf sheaths assimilated carbon dioxide at a rate of 44% of that of the whole community. For defoliated plants, photosynthesis of the ears and stems increased with increasing elevation of the sun, which indicated a greater efficiency of photosynthesis with an increased horizontal component of radiation. This was opposite to the response of the undefoliated community. The techniques of estimating the contribution of individual organs to total photosynthesis of the wheat plant are discussed in relation to variability of results and the effects of compensation.

* Part I, Aust. J. Agric. Res., 1968, 19: 711.
Sulphur metabolism in sheep. I. Preliminary investigations on the movement of sulphur in the sheep's body
Authors: Bray AC
Published: November 2004

In a series of experiments with sheep maintained on high sulphur rations, measurements were made on the levels of 35S in urine, faeces, and various body fluids following single intravenous infusions of sodium [3%]sulphate and single infusions of sodium [35S]sulphate or sodium [353]sulphide into the gastrointestinal tract. Sulphide was rapidly absorbed from the duodenum and post-duodenal intestinal tract, an estimated 40–90% of the dose being absorbed within 60 min. Absorption of sulphate from the same region was much slower, 25% or less being absorbed over a 60-min interval. An attempt to use antibiotics to eliminate the effects of the intestinal bacteria on the metabolism of [35S]sulphate before absorption was not conclusive. Following intravenous administration of sodium [35S]sulphate, 12–19% of the dose was recovered in the faeces within 6 days. This activity appeared to be due to secretion into the post-ruminal tract rather than to return of 35S by salivary secretion or by passage across the rumen wall. Sodium [35S]sulphate was reduced to sulphide in the rumen and appreciable amounts appeared to be absorbed from this organ. The variations in total sulphur and sulphide of rumen digesta, urinary total sulphur, and blood inorganic sulphate levels during the day appeared to be related. Whole blood inorganic sulphate sulphur levels varied between 2 and 6 mg%. Urinary excretion following intravenous administration of 35S was extremely rapid, at least 70% of the dose being collected within 24 hr.
The absorption and distribution of nitrogen after floret initiation in wheat
Authors: Rawson HM , Donald CM
Published: November 2004

The pattern of absorption and distribution of nitrogen after floret initiation in wheat was examined with the aid of labelled nitrogen with a view to determining the importance of sterile tillers as a source of nitrogen for the fertile parts of the plant. Tertiary tillers were found to be of no importance as direct importers of nitrogen from the growth medium; absorption by these tillers was almost entirely via the roots of the main stem and the primary tillers. In conditions of high nitrogen supply the tertiary tillers continued to receive nitrogen from the main stem and primary tillers, but the tertiary tillers of low nitrogen plants were starved of nitrogen and soon senesced. When the sterile, tertiary tillers died there was a remobilization of most of their nitrogen, apparently to the fertile parts (main stem, primary and some secondary tillers) of the plant, but a small quantity of nitrogen was also lost to the nutrient solution. It is concluded that although sterile, tertiary tillers act as a temporary nutrient reservoir for the fertile plant parts, they are in fact of little or no value and may well be regarded as a useless vestige of perenniality in the wheat plant.
The measurement of the concentration and distribution of Ceratocystis paradoxa (De Seynes) moreau in soil
Authors: Aberdeen JEC , Patil-Kulkarni BC
Published: November 2004

A baiting technique making use of sugar-cane discs was used to estimate the concentration, and presence of aggregations, of spores of Ceratocystis paradoxa in the soil. The technique was based on the probability of infection from small samples of soil. A concentration of six spores per gram of soil was readily detected. A number of sugar-cane fields were surveyed. The equivalent random concentration of spores varied from 0 to 148 per gram of soil for samples taken 4–8 in. below the soil surface. The greatest concentrations of spores were at 3–6 or 6–10 in. depths.