bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on the reactions of animals to infestation with ticks. I. Tick anaemia
Authors: Riek RF
Published: November 2004

Tick anaemia appears to be caused mainly by loss of the blood ingested by the engorging ticks. It is possible that some toxic effects of the salivary secretion may help to account for the slow recovery of heavily infested animals in poor condition, even after the infestation has been removed and an adequate supply of feed provided. Animals in poor condition showed a marked fall in red blood cell concentration and haemoglobin content following heavy infestation with Boophilus microplus (Canestrini), whereas animals in moderate to good condition showed a much smaller and more temporary reduction in these components. When submitted to very heavy infestations, even animals in good condition showed a considerable reduction in these components and in serum protein, all of which, however, soon returned to normal following cessation of the infestation. Many of the heavily infested animals, especially those in poor condition, carried large numbers of translucent adult female ticks, which were filled with a clear fluid similar to bovine plasma, instead of normal ticks, which were dark in colour owing to the ingested blood.
Corrigendum - Methionine supplements in chicken diets. 1. Effects of supplementary methionine and choline on growth and folic ancid requirements of White Leghorn chickens
Authors: McDonald MW
Published: November 2004

The addition of 0.2 per cent. DL-methionine to a diet based on wheatmeal, meatmeal, and whey powder produced a 12 per cent. increase in weight a t 6 weeks in White Leghorn chickens. Although the addition of 4.4 p.p.m. of folic acid to the basal diet produced no response, the addition of folk acid to the methionine-supplemented diet produced a further 7 per cent. increase in weight. In a second experiment, supplementing the same basal diet with 0.066 per cent. choline chloride produced a 17 per cent. growth depression which was prevented by the addition of folic acid. Methionine (0.2 per cent.), added to the basal diet supplemented with 0.066 per cent. choline chloride and 4.4 p.p.m. folic acid, produced a 5 per cent. growth increase, proving that the basal diet was deficient in sulphur-amino acids. It is suggested that folk acid is required for the catabolism of methyl groups provided in excess of the chicken's requirements.
Wool follicle development in the New Zealand Romney and N type sheep. I. The relationships of development to age in the New Zealand Romney and N type sheep foetuses and a comparison with results obtained from the Merino
Authors: Stephenson SK
Published: November 2004

The development of the follicle population in New Zealand Romney and N-type sheep foetuses has been studied by comparing stages of development at different ages, using the method developed by Carter and Hardy (1947) and Hardy and Lyne (1956). Their scale has been altered so as to give a linear relationship with age, and a regression line has been fitted to the data by the method of least squares. Analysis of the N-type and New Zealand Romney mating groups and a comparison with the Merino data given by Carter and Hardy (1947) show that no marked or consistent differences occur in the age at which different stages of follicle development are completed or in the rate of development of the follicle population. Studies of different positions on the body agree with the findings of other workers that development begins first on the head and limbs and later over the trunk. Between positions the correlation between the age at which follicle development begins and the rate of development after initiation is not significant.
Relationship between follicle number and wool production
Authors: Schinckel PG
Published: November 2004

The relationship between follicle number per unit area and wool production per unit area was examined in strong-wool (South Australian) and medium-wool (Peppin) Merino sheep. In four groups of strong-wool sheep (varying in number from 103 to 197 sheep) non-significant positive correlations were observed between follicle number per unit area and the amount of clean wool delineated by a 1 in. calliper. In two groups of strong-wool sheep (178 ewes and 169 rams) and one group of medium-wool sheep (184 ewes) the relationship between follicle number and unit area wool production was inferred from the association between number and fibre weight. There was a highly significant negative correlation (r = – 0.45 approx.) between number and fibre weight in each group. Further, a highly significant difference was observed between sire groups in mean fibre weight after adjustment for differences in follicle number. It was concluded that there was a small positive correlation between follicle number and wool production. This association was so small as to be of dubious biological significance. There were strong indications of a negative genetic correlation between follicle number and wool production, although this did not attain statistical significance.
Study of wool production per unit area of skin in Australian Merino sheep
Authors: Chapman RE , Young SSY
Published: November 2004

In a study of wool production per unit area of skin of Merino sheep, two strains of ewes, one strain of rams, and five strains of wethers were examined. A marked variation in weight of wool per unit area was found over the body regions of sheep. A distinct dorsoventral gradient, and some anteroposterior gradients were observed. Sampling positions having wool weights per unit area close to the mean over the body were situated on a line from mid-shoulder to mid-thigh positions. This was consistent for all the groups of animals studied. The mean wool production per unit area varied from sheep to sheep and from strain to strain. These differences were large and highly significant irrespective of level of feeding.
Interception of light by the foliage of pure and mixed stands of pasture plants
Authors: Brougham RW
Published: November 2004

Relationships between light interception and leaf area in the regrowth of pure stands of short-rota,tion ryegrass (Lolium perenne L. x L. multiflorum Lam.), perennial ryegrass (L. perenne), timothy (Phleum pratense L.), white clover (Trifolium repens L.), and a mixed stand of short-rotation ryegrass and white clover, were determined for cloudless conditions. The relationship between light penetration and elevation of the sun was also examined. The leaf area indices at which 95 per cent. of the incident light was intercepted about midday in midsummer mere as follows: short-rotation ryegrass, 7.1 ; perennial ryegrass, 7.1; timothy, 6.5; white clover, 3.5; and the mixed stand, 4.5. The percentage of incident light penetrating through the foliage on cloudless damp in summer changed considerably with time of day. The highest values were recorded at local noon and the lowest 2-3 hours after sunrise or before sunset. These results are attributed to the angle of incidence of the light, and suggest marked seasonal differences in the leaf area required to intercept 95 per cent. of the light. It is suggested that midwinter values are approximately one-half of mid-summer values. The results are discussed in relation to the light-intercepting capacities of the leaves of the different species, plant competition, and pasture management.
Competition between plants of different initial seed sizes in swards of subterranean clover (Trifolium subterraneum L.) with particular reference to leaf area and the light microclimate
Authors: Black JN
Published: November 2004

A study was made of the development and fate of individual plants growing from contrasting seed sizes in swards of subterranean clover (var. Bacchus Marsh). Three sets of swards were grown in boxes, from large, small, and mixed (large and small) seeds respectively, all sown at the same number of plants per unit area; the swards were harvested on five occasions. Leaf area in each 2 cm layer of the sward was determined separately and measurements of the light intensity reaching each layer were obtained at each harvest. Counts of the plants on each occasion revealed a steady drop of about 30 per cent. over the whole period; in the "mixed" swards, only plants from small seed sizes died, the number of large-seeded plants remaining unchanged. The data of leaf area and numbers in each layer showed that leaf area is concentrated in a relatively shallow band at the top of the sward, the area attained by individual leaves increasing with height in the sward and with time. Leaves are not retained in the canopy at heights below that at which light extinction occurs. An unexpected finding was that, as the sward developed, the leaf area index (the ratio of leaf area to ground covered) required for the absorption of all incident light energy increases, and it is suggested that this is due to changes in leaf morphology. The importance of the position at which leaves of individual plants are held in the canopy is stressed; although at the first sampling occasion, the small-seeded plants had 25 per cent. of the leaf area of the mixed sward, they were so located as to absorb only 10 per cent. of the incident light energy; at the last sampling occasion, the values were 10 and 2 per cent. respectively. It is concluded that the disappearance of the small-seeded plants from the mixed swards was due to shading from the large-seeded plants.
Available phosphorus in alkaline soils in relation to the growth of tick bean (Vicia faba L.Var. Minor Beck)
Authors: McEAlexander D , Woodham RC
Published: November 2004

Responses in the growth of tick bean in the field to applications of superphosphate have been related to "available" phosphorus in irrigated alkaline soils. Tick bean is grou7n as a winter corer crop between vine rows in irrigation areas of the Murray Valley. Availability of soil phosphorus was assessed by its solubility either in carbonic acid or in a solution of sodium bicarbonate. The first reagent extracted phosphorus ranging from 0.7 to 24 p.p.m. of the surface 6 in. of soil sampled from the various test areas prior to the sowing of tick bean, while the second extracted 5-91 p.p.m. Both extraction methods gave similar relations between soluble phosphorus in the soil and the response in growth of tick bean to 2 cwt superphosphate per acre applied at sowing. Thus, considering the carbonic acid extract, the increase in fresh weight yield of green herbage of bean plant ranged from about 30 per cent. for soil initially at a level of 3 p.p.m. of soluble phosphorus to about 10 per cent. for soil initially at 10 p.p.m. These phosphorus levels correspond to about 20 and 46 p.p.m. as determined by the sodium bicarbonate extraction method.
The fermentation of hemicellulose by washed suspensions of rumen bacteria
Authors: Gray FV , Weller RA
Published: November 2004

Fermentation of hemicellulose by washed suspensions of microorganisms from the rumen of the sheep produced approximately equal proportions of acetic and propionic acids, together with a small amount of butyric acid. These findings are discussed with reference to previous work with growing cultures and to the organisms responsible for hemioellulose fermentation in the rumen.
Studies on the reactions of animals to infestation with ticks. III. The reactions of laboratory animals to repeated sublethal doses of egg extracts of Haemaphysalis bispinosa Neumann
Authors: Riek RF
Published: November 2004

Rabbits and mice have been immunized or sensitized, and guinea-pigs sensitized, with saline extracts of the eggs of Haemaphysalis bispinosa. Immunization, without sensitization, invariably followed intravenous inoculation of the antigen once or twice per week for 3 weeks. Sensitization, with or without development of precipitating antibody, usually followed daily inoculation for 3 to 5 days, subcutaneous administration possibly being more effective than intravenous. Development of sensitization was capricious. Immunized animals were protected against the toxic egg extracts, but not against attachment of larval ticks. Their sera contained complement-fixing and precipitating antibody, which was not destroyed at 56°C for 4 hr. Sensitizing antibody could not be demonstrated in these sera by direct skin test or passive transfer. Sensitized animals responded to intradermal injection of antigen by a characteristic skin reaction, and were protected against effective attachment of larval ticks. Sensitization could be transferred passively by subcutaneous inoculation of serum, and was not reduced by absorbing out any precipitating antibody that may have been present. The sensitizing antibody was destroyed by heating to 56°C for 4 hr. In passive transfer tests, sera of immunized animals blocked local reaction to antigen in sensitized animals, but the blocking antibody rapidly diffused from the site, whereas sensitizing antibody remained fixed. Electrophoretic evidence suggests that the immune antibodies are principally y-globulins, whereas the sensitizing antibodies are mainly ß-globulins.
The summer nutrition of weaner sheep: The deficiencies of the mature herbage of sown pasture as a feed for young sheep
Authors: Donald CM , Allden WG
Published: November 2004

Two field studies conducted in the Mediterranean type environment of Adelaide, South Australia, are described. The first experiment was designed to assess the effects of defective summer grazing by young sheep upon current and lifetime productivity, while the second sought to define the nature of the nutritional deficiencies of the mature herbage of sown pastures in terms of energy and protein respectively. The results show that the mature herbage of the sown pastures under study was deficient in both protein and energy. However, the retarded growth resulting from grazing this herbage appeared to be of no permanent significance in average to well-grown wether weaners; summer periods of defective nutrition did not affect ultimate size nor influence subsequent productivity.
The effect of the siliceous component of decomposing rice hulls on the solubility of phosphate
Authors: Bromfield SM
Published: November 2004

The effects of decomposing rice hulls on the solubility of sparingly soluble phosphates have been examined. Rice hulls decomposed slowly and increased the solubility of ferric and aluminium phosphates. Phosphate was also released from the rice hulls alone. The increased solubility of the phosphates was shown to be due to greater hydrolysis which occurred when the pH of the cultures rose to 8 and also, in the case of aluminium phosphate, to an interaction with silica. Aluminium phosphate was dissolved in the presence of rice hulls over the pH range 5-8, with a minimum solubility near pH 7. Rice hulls also decreased the amounts of soluble phosphate adsorbed by aluminium and ferric oxides over this range. The response of plants following additions of rice hulls to soil is discussed in the light of these results.
Variation in the incidence of twin ovulation in Merino ewes on a constant plane of nutrition
Authors: Radford HM
Published: November 2004

The incidence of twin ovulation was studied in 49 Merino ewes held at constant body weight, excluding wool weight, throughout the year. Two groups were used: one (40 ewes) in which the ewes were kept apart from rams, and the ovaries examined at intervals of 10 or 12 weeks, and the other in which the occurrence of oestrus only was observed. In the former group, there was a statistically significant variation throughout the year in the ratio of twin to single ovulation. The variation fitted a curve which was sinusoidal in form, with a peak in the late autumn and a trough in the spring. There was a similarly timed but less apparent variation in the occurrence of oestrus in the ewes run with rams. It is concluded that the variation in the incidence of twin ovulation was controlled by changes in the physical factors of the environment.
The production and life span of seed of subterranean clover (Trifolium subterraneum L.)
Authors: Donald CM
Published: November 2004

At an elevation of 2040 ft on the southern tablelands of Kew South Wales, seed production by swards of subterranean clover was apparently governed by mininnnn temperatures (frequency and intensity of frosts) during the flowering period. The aggregate deficit of the daily minimum temperature below 40°F in the 21 days from the commencement of flowering showed a high correlation with seed production per unit area in four successive seasons. Spring frosts account for the altitudinal limit of about 4000 ft to which subterranean clover grows in the alps of south-eastern Australia. Lateness of flowering has specific survival value at high altitudes in this region and in such areas as the high parts of the plateau of Spain. On the average 92 per cent. of the seed crop germinated in the year following its production, with 6.3 per cent. in the second year, and with falling values to 0.07 per cent. in the fifth year. Germination thereafter was nil or negligible. The early-flowering variety Dwalganup appeared to show a genetic difference in the persistence of more of its seed into the second and subsequent years. There was a regular seasonal pattern of seed germination, with the peak of germination occurring in the late summer and autumn. The "carry over" of seed into the second and subsequent years, and the germination peak in the autumn, have each considerable ecological significance.
Considerations in experiments for the control of codling moth (Cydia pomonella (L.)) in apples
Authors: Cellier KM
Published: November 2004

A study was made of some aspects to be considered in experiments for the control of codling moth in apples. Examination of the number of fruit damaged by either deep entries or stings in samples of 100 fruit showed that the counts of damaged fruit could be considered as random samples from a Poisson (or binomial) distribution both within trees and also in plots up to a size of four test trees. An optimum plot size and sampling procedure was determined in experiments for the control of codling moth in apples. A single-tree plot with four samples per tree is optimum for unguarded plots, and plots of either one, two, three, or four trees with four samples per tree are satisfactory for guarded plots where the trees are hand-sprayed. Guarding seems an unnecessary safeguard and expense for hand-sprayed plots. Where "Air-Blast" spray machines are used, large plots with a double guard row are necessary, and it is sufficient to examine two to four samples per tree. It is suggested that Smith's heterogeneity law can be used to obtain the optimum plot size in experiments for the control of insect pests, and possibly of diseases on fruit trees. No reduction in experimental error was obtained by using the crop size of individual trees as a covariate in an analysis of covariance.
The chemical composition of the soil in a factorial experiment with citrus. I. Exchangeable metal cations and their effect on the cation content of citrus
Authors: Groenewegen H , Bouma D
Published: November 2004

In a factorial field experiment with citrus it was found that application of ammonium sulphate caused a greater proportionate reduction in the exchangeable calcium of the soil than in the exchangeable potassium. Short-term laboratory experiments with virgin soil, to which ammonium was added, suggested that at least two factors were involved. If solutions of high electrolyte concentrations were added, a greater release of exchangeable calcium than of potassium occurred, relative to the amounts of these ions originally present in exchangeable form. Secondly, a release of potassium from non-exchangeable to exchangeable form also occurred. In the 0–4 in. layer of the field experiment, exchangeable magnesium was reduced in the same proportion as exchangeable calcium. In the 4–12 in. layer, exchangeable magnesium was reduced relatively more than calcium. The same trend was apparent in laboratory experiments. In one experiment, for example, the original amount of magnesium was reduced by 76 per cent., and calcium by 66 per cent. A comparison between cultural treatments showed that the potassium content of the soil from a bare surface treatment was much lower than that from treatments with cover crops. The changes in soil composition had no appreciable effect on the cation content of citrus leaves, and some reasons for this are discussed.
Regulation of body temperature of sheep in a hot environment
Authors: Brook AH , Short BF
Published: November 2004

A study of the importance of sweating as a means of evaporative cooling in sheep was made by comparing the rectal temperatures of sheep with and without sweat glands, at an air temperature of 40°C and a water vapour pressure of 28.1 mm Hg. The experimental animals, all of which were shorn, comprised 2 ewes and 2 wethers without sweat glands, and 6 ewes and 4 rams with sweat glands. During the first hour the rise in rectal temperature of the sheep without sweat glands was greater than the rise in the normal animals (1.1°C v. 0.7°C). After 6½ hr. the mean rectal temperature was higher (40.6°C) in the sheep lacking sweat glands than in the normal ewes (39.9°C). The most rapid rise in rectal temperature after the first hour was that of the rams, which reached a mean value of 40.8°C. after 6½ hr. It is concluded that panting is the principal method of evaporative cooling in sheep. Sweating, though of lesser importance, is advantageous to the shorn animal, but its usefulness to sheep in wool is unknown.
The build-up of available potassium under subterranean clover pastures on a podzolic soil
Authors: Williams CH , Lipsett J
Published: November 2004

A group of podzolic soils from the Crookwell district of New South Wales was examined for potassium status by field, pot culture, and laboratory experiments. Close relationships were found between the exchangeable potassium and the potassium content of the plant material and uptake of potassium both in the field and in pot culture. However, the measured decreases in exchangeable potassium in soil during plant growth were insufficient to account for the total uptake, indicating that other sources of soil potassium were also available. It is probable that the pasture plants themselves contribute to the conversion of non-exchangeable potassium to exchangeable forms. The results suggest that the range 0.25–0.30 m-equiv. exchangeable potassium per 100 g may be critical for these soils. Exchangeable potassium built up under the subterranean clover pastures plays an important part in eliminating a potential potassium deficiency. Removal of hay from these pastures would seriously deplete this available potassium reserve.
The effectiveness of a granulosis virus applied to field populations of Pieris rapae (Lepidoptera)
Authors: Wilson F
Published: November 2004

A granulosis virus (apparently Bergoldia virulenta Tanada) which causes a highly virulent disease of the larvae of Pieris rapae, is recorded from Australia. External symptoms of the disease and the period of survival after infection vary according to larval age at infection. In four field experiments, aqueous suspensions of disease particles applied as sprays to natural infestations of P. rapae induced epizootics which persisted until the experiments ceased 3–7 weeks later. Larval populations on the disease plots were markedly lower than on the controls although the disease usually spread to the controls within a few weeks; the proportion of larvae reaching the later and more damaging instars was much lower on the disease plots, few larvae reaching the fifth instar and very few reaching the pupal stage. In one experiment in which the effects of disease and DDT sprays were compared, the levels of control were similar, although fewer larvae reached the later instars on the disease plots.
Rock phosphate and superphosphate compared as pasture fertilizers on acid soils
Authors: McLachlan KD
Published: November 2004

The results of a study comparing rock phosphate and superphosphate as pasture top-dressings on two acid soils are presented. The trials were designed to examine the immediate response to, and the residual effects of, an initial application of both fertilizers. At equivalent levels of applied phosphorus, superphosphate was a better fertilizer than rock phosphate in the early years of the trial. Rock phosphate and superphosphate both had a good residual value, and the yields obtained with both fertilizers were not significantly different after the first few years. The total yield of pasture over the 7 year period was similar for both fertilizers. A low residual value of gypsum as a sulphur fertilizer is demonstrated. The evidence shows that where a deficiency limits plant growth and inhibits the uptake of phosphorus, the fall in the residual value of a phosphorus fertilizer is less than where plant growth is not restricted. This suggests that a major factor governing the availability of residual phosphorus to plants, from both superphosphate and rock phosphate, is the conversion of available inorganic phosphorus to organic forms, through uptake by the plants themselves. It would appear that this effect on residual phosphate can be more important than "fixation" of inorganic forms. Mixtures of rock phosphate and superphosphate, both physical and by under-acidulation of rock phosphate, were used. The results are presented and discussed.
Sweating in sheep
Authors: Brook AH , Short BF
Published: November 2004

Water loss from the sweat glands of shorn sheep was estimated as the difference between the average weight gain of desiccating capsules placed on 10 normal sheep and on 4 control sheep congenitally lacking sweat glands. At an air tempera ture of 20°C (68°F) and a water vapour pressure of 12.5 mm Hg the rate of svveating was 10.2 g/m2/hr, and at 40°C (104°F) and a water vapour pressure of 28.1 mm Hg the rate of sweating was 32.1 g/m2/hr. The maximum amount of heat a sheep could lose by sweating at the rate of 32 g/m2/hr under these conditions is c. 20 kcal/hr. It is emphasized that the rate of sweating observed in shorn sheep must not be applied unreservedly to sheep with a fleece, because the dynamics of water movement in the fleece are unknown.
Distribution of recently absorbed zinc in subterranean clover (Trifolium subterraneum L.) determined by adding radioactive zinc to the culture soultion
Authors: Riceman DS , Jones GB
Published: November 2004

The distribution of zinc recently absorbed as 65Zn into subterranean clover (T. subterraneum L. var. Bacchus Marsh) from culture solutions has been examined by means of radioautographs in normal plants and in plants recovering from a state of zinc deficiency. In normal plants which had been grown initially in cultures containing non-radioactive zinc, the recently absorbed zinc reached high concentrations in the roots, main axis, and youngest leaves but very little of it moved into the older, fully expanded leaves. In plants recovering from the deficiency, on the other hand, the recently absorbed zinc reached high concentrations in all the living organs, including the oldest leaves. Growth of the "little" leaves or other leaves affected by the deficiency was not resumed after the entry of zinc into their tissues. Recovery of the plant depended upon the production of new leaves by the leaf primordia and upon their subsequent growth and emergence.
Isolation and characterization of a hemicellulose-fermenting bacterium from the sheep rumen
Authors: Walker DJ
Published: November 2004

A strictly anaerobic, Gram-negative, rod-like organism was isolated from sheep rumen liquor by culture in hemicellulose medium. The organism fermented several carbohydrates, including hemicellulose, producing acetic and lactic acids as the main end-products. Some biochemical characteristics of the organism are described and its taxonomic placement is discussed.
The hydrolysis of wheaten hay hemicellulose by a purified enzyme from rumen microorganisms.
Authors: Walker DJ , Hopgood MF
Published: November 2004

An enzyme hydrolyzing a largely insoluble preparation of hemicellulose from wheaten hay was purified from sheep rumen microflora. The enzyme catalysed the hydrolysis of hemicellulose to xylose, xylobiose, xylotriose, and higher oligosaccharides together with glucose and arabinose. Enzyme activity was rapidly destroyed by heating at temperatures above 40� and by raising the pH above the optimum of 6.0. Purified enzyme preparations did not hydrolyse starch or cellulose. A partial inhibition of hemicellulase activity was observed in the presence of p-chloromercuribenzoate.
Observations on the copper metabolism of the domestic fowl and duck.
Authors: Beck AB
Published: November 2004

Experiments have been carried out to determine whether the concentration of copper in the liver of the domestic fowl and duck can be raised by a moderate increase of dietary copper. Groups of both species were fed for 12 weeks on the same basal diet, to which was added copper sulphate to increase the copper intake two- and fivefold. No significant increase in the liver copper concentration was noted in either species. When copper was administered to both species by intravenous injection, it was rapidly excreted. mostly in the bile. In the fowl a significant amount was excreted through the caeca, but the experiments did not suggest that these organs were important in controlling copper storage. 5tudies on the relationship between h e r copper storage and age showed that there was a rapid increase in the duck after 3 weeks of age. No such changes were observed in the foul
Studies on the carbohydrate metabolism of sheep. XIII. The interpretation of changes in the levels of metabolic intermediates after intravenous injection of propionate, succinate and malate
Authors: Reid RL , Mills SC
Published: November 2004

Blood levels of pyruvic, citric, and �-oxoglutaric acids in sheep are similar to those in man. Citric acid declines markedly on fasting; levels in ewes with pregnancy toxaemia are not significantly different from those in fasted, pregnant ewes. The presence of low citric acid levels in ewes with pregnancy toxaemia in which blood glucose levels are normal or above may further support the suggestion that there is an interference with glucose utilization in pregnancy toxaemia. Intravenous injection of propionate, succinate, and malate into fasted, pregnant ewes always lowered blood ketones, but it is not known to what extent this response is merely a consequence of increased blood glucose following injection. Injected propionate disappeared more rapidly than injected acetate. Propionate injection into fed, non-pregnant ewes is followed by an immediate increase in blood glucose to high levels; the disappearance of excess glucose appears to follow the pattern of a normal glucose tolerance curve. Blood pyruvic acid increases markedly with blood glucose. Succinate and malate injections are followed by small increases in blood glucose and pyruvic acid. The difficulty of interpreting changes in blood glucose in inadequately trained experimental animals is emphasized. Consistent, significant increases in blood oxalaoetic acid did not occur in response to either propionate, succinate, or malate injection. Blood citric and a-oxoglutaric acids increased markedly after succinate and malate, but not after propionate injection. The data are discussed in relation to metabolic pathways in sheep tissues; it is concluded that this type of in vivo experiment is of limited value.
The development of cuttings of the Washington navel orange to the stage of fruit set. II. Drifts in nutrient composition
Authors: Gates CT , Bouma D , Groenewegen H
Published: November 2004

Changes in nutrient content with time, especially of nitrogen and phosphorus content, are presented and are considered in relation to the results for dry weight reported previously. It was found that drifts in nitrogen and phosphorus with time were complementary to the pattern for dry weight noted earlier. The distribution of these nutrients to the developing plant followed a like rhythmic pattern of alternate distribution to shoot and root. There appeared to be no build up of nutrient to trigger off developing of new shoots, and at all times nutrient distribution was preferentially to younger developing parts. Low phosphorus supply caused a lowering of both relative and absolute contents of phosphorus and nitrogen in all plant parts. The pattern of development was not greatly altered in character by low phosphorus but was delayed. All vegetative parts responded similarly in control and low phosphorus plants, and the younger parts did not appear to dominate the older in development. In this regard, the pattern of growth seemed to differ from that of many annuals. The proportion of tissue potassium was lowered and that of calcium raised by ammonium as the source of nitrogen. A concomitant effect on phosphorus and nitrogen metabolism was noted.
Responses of Zebu, Jersey, and Zebu X Jersey crossbred heifers to rising temperature, with particular reference to sweating
Authors: Allen TE
Published: November 2004

Zebu, Jersey, and Zebu x Jersey crossbred heifers were subjected to a rising temperature regime over the range 65 to 105°F. Sweating rates, respiration rates, skin temperatures, and rectal temperatures were measured. All breeds showed similar responses in skin temperature and rectal temperature to increase in air temperature. The increase in skin temperature was approximately linear with rise in air temperature. Rectal temperature did not commence to rise until an air temperature of 90°F and a skin temperature of 98° was reached. Breed differences in sweating and respiratory rates with increase in air and skin temperature were observed. The Jersey heifers showed an early and almost linear increase in sweating rate with rise in air and skin temperature, whereas the sweating rate of the Zebu heifers did not increase until air temperature had risen to at least 85°F and skin temperature to 95°. Two crossbreds began to increase their sweating rates at temperatures intermediate between those recorded for Zebus arid Jerseys. The remaining two behaved similarly to Jerseys. All three breeds showed similar maximum sweating rates in response to this rising temperature regime. The respiratory rate of' the Jerseys was higher than that of the Zebus at all temperatures, and particularly at high temperatures. Crossbreds respired at rates comparable to the Jerseys until an air temperature of 90°F and a skin temperature of 97°F were exceeded, when their respiration rates became intermediate between the other two breeds. The significance of these differences is discussed.
The effects of a number of management practices on chiller beef production in Victoria
Authors: Cameron NG , Robinson TJ
Published: November 2004

Analysis of data for 72 Aberdeen Angus cows and their calves revealed the following significant relationships. (1) There was an inverse relationship between the total pre-weaning liveweight increase of calves and the liveweight change of their dams during the first half of lactation (r = –0.486; P<0.001) but not during the second half (r = +0.005; N.S.). Good dams "milked the flesh" during the period of maximum calf growth. (2) This is a maternal characteristic, not caused by greater demand of greedy feeders. (3) Steers made greater bone growth than heifers at all times of the year although during store periods both sexes gained (or lost) liveweight at the same rate. (4) Cattle unsupplemented in the store period tended to catch up with supplemented animals in the spring. Even when all treatment effects, including supplementary feeding, were analysed out, there remained a significant negative partial correlation between gains in the store and the subsequent spring fattening period (r = –0.20, P=0.05). It is suggested that the relative immaturity of slow-gaining animals at the start of the fattening period accounted for their compensatory gain. (5) "Compensatory growth" appeared to be most strongly demonstrated by older cattle: those which did better in the store period entered the spring in an advanced store condition and their weight gains were high energy fatty tissues, as compared with the high protein, low energy gains of lean animals. (6) The above notwithstanding, there was a positive partial correlation between the total lifetime rate of gain and the rate in the 9 month store period (r = +0.371; P = 0.01) and in the 3 month fattening period (r = +0.557; P< 0.001) prior to slaughter.
The development of the testis of the Merino ram, with special reference to the orgin of the adult stem cells
Authors: Sapsford CS
Published: November 2004

In the ram, as in other mammals, the sex cords are made up of two types of cell: indifferent cells (derivatives of the coelomic epithelium) and primordial germ cells. In the cords, each type pursues a separate and independent line of development to become respectively the Sertoli cells and the stem cells (type A spermatogonia) of the adult testis. The principal changes taking place in the primordial germ cells (gonocytes) are a reduction in the size and number of the Feulgen-positive particles in the nuclei, the appearance and subsequent fusion of the nucleoli, and, finally, an increase in the size of the nuclei. While these changes are taking place, the cytoplasm increases in volume and inclusions become more numerous. Cells which have undergone all these transformations have been called prospermatogonia. The cells of the germ line are at first more centrally placed in the sex cords than the indifferent cells. Just before spermatogenesis begins, they migrate to the basement membrane of the seminiferous tubules. All germ cells in tubules in which spermatogenesis has been initiated are seen as prospermatogonia. These cells become flattened against the basement membrane, and their nuclei become more oval in shape. They thus become identical with the stem cells of the adult. Little change is evident in the nuclei of the indifferent cells until puberty. Feulgen-positive material is found in the form of coarse granules at earlier stages of development. At puberty, these granules become dispersed to give a much more homogeneous nucleus. Concurrently, nuclei increase in size, and single or double true nucleoli can be identified. During development, increases in cytoplasmic volume take place. Although cell boundaries between indifferent cells cannot be seen in fixed material, phase contrast observations of fresh material have demonstrated that some forms exist as mononucleate units. It could not be determined whether the same was true in the case of Sertoli cells. No striking change in the relative numbers of glandular interstitial cells could be observed at different stages of development.
Follicle productivity and wool production in Romney ewes
Authors: Ross DA
Published: November 2004

Fibre diameter and fibre length arrays of monthly samples of 10 mature Romney ewes were each subdivided into seven groups such that group 1 contained the coarsest or longest 15% of fibres and group 7 the finest or shortest 15% of fibres. A study was made of the relation between the characteristics of these seven groups and the level of wool production over a period of 18 months.There was a linear relationship of the form y = a + bx between fibre cross-sectional area d², fibre length per day l , or fibre volume per day d²l (y), and the level of wool production (a), at each of the seven levels within the array. A similar linear relationship held between the change in d², l , or d²l associated with a change in the level of wool production and the corresponding value of d², l, or d²l on which this change was based. In three of the 10 ewes the change in fibre length associated with a change in wool production was constant over the array; in the other ewes the absolute length change increased in the faster-growing fibres. In all ewes the percentage change in d², l , or d²l decreased with increasing fibre size. In four of the five ewes whose wool was free from medullation the change in fibre volume per unit area of fibre cross section associated with a change in the level of wool production was a constant over the array. Some aspects of follicle efficiency and follicle competition are discussed. It is concluded that in mature ewes all follicles have the same "efficiencies" and do not compete for fibre substrate. The spatial relationship of the follicles did not, affect wool production. The concept of a "basic pattern" of wool production is introduced and discussed.
Mineral nitrogen fluctuations in soils under improved pasture in Southern New South Wales
Authors: Simpson JR
Published: November 2004

Soils under improved pasture on the Southern Tableland of New South Wales accumulated nitrate in substantial quantities during the summer and autumn. In this respect they behaved quite unlike the pasture soils which have been studied in most of the earlier literature, and they resembled cultivated fallow soils, which usually accumulate nitrate at the same time of the year. The nitrate was produced mainly in the top inch of soil; ammonium also accumulated under certain conditions. The precise sequence of climatic events, particularly the period of drying between consecutive wettings, was of primary importance in the nitrate accumulation. The nitrate produced during summer and early autumn disappeared from the topsoil after heavy rain in autumn and winter. The seasons could therefore be distinguished as a nitrogen-rich summer and autumn, a nitrogen-depleting winter, and a nitrogen-poor early spring, with an increasing supply of mineral nitrogen during late spring. No appreciable fluctuations in mineral nitrogen were found in soils resown directly from native pasture with less than 0.10% total nitrogen at 0-2 in.
The use of chromium oxide to estimate the faecal output of Merinos
Authors: Lambourne LJ , Reardon TF
Published: November 2004

The pattern of chromium oxide (Cr2O3) excretion was studied in Merino wethers. The sheep were dosed twice daily with Cr2O3 at fixed times. In the main series of experiments, sheep were fed fresh herbage in metabolism pens. An oaten chaff diet was also employed. In all cases a diurnal pattern of Cr2O3 excretion in the faeces was observed. The pattern was not consistent from day to day, nor was there any consistent effect of level of intake or feeding frequency on the excretion pattern. Distributions of Cr2O3 were examined in eight grazing sheep killed ½–4 hr after dosing. In six of the animals high concentrations of the marker were found to be mixed with the reticuloruminal ingesta, while low concentrations were observed in the other stomachs. In the remaining two animals high concentrations were observed in the omasum and abomasum, from which it was inferred that the dose had by-passed the main bulk of the reticulorurninal ingesia. It seems unlikely that any real advantage is to be gained by painstaking selection of particular times for dosing and faeces sampling in different environments; and it is suggested that convenient fixed times — say 6 a.m. and 3 p.m., or 9 a.m. and 5 p.m. — should prove satisfactory in estimating output of faeces of grazing animals under a wide range of conditions. In 40 sheep-periods of 10–14 days, the mean daily output of faeces organic matter by pen-fed wethers was estimated with mean 101% and error ±12% of the true figures, by analysis of a single bulked sample obtained by dosing and grab sampling at about 9 a.m. and 5 p.m. daily. In 40 periods when samples were bulked over 5–7 days the average estimate was 102 ± 14% of the true figure. Comparison under extensive grazing conditions showed that estimates obtained by dosing and sampling only once per day were generally some 15% higher than those obtained by dosing and sampling twice daily.
Studies on trichostrongylosis of sheep plasma volume, haemoglobin concentration, and blood cell count
Authors: Gallagher CH
Published: November 2004

The plasma volume of worm-free crossbred wether lambs was found to vary from 33 to 56 ml/kg during normal growth from 8 to 12 months of age. An inverse relationship was found to exist between plasma volume relative to body weight and body weight for lambs of this age. Infection of lambs with Trichostrongylus colubriformis, even when fatal, did not produce any alteration of plasma volume except that due to change in body weight. For all determinations made on all 26 sheep used, the mean plasma volumes were: 13–25 kg body weight, 46.83 ± 3.7 ml/kg; 26–30 kg body weight, 43.2 ± 3.2 ml/ kg; 31–38 kg body weight, 41.2 ± 3.8 ml/kg. The differences in plasma volume between the three body weight ranges were statistically significant (P < 0.001). The clinical syndrome in these experimental cases of trichostrongylosis was characterized by unthriftiness with failure to grow normally, loss of weight, and emaciation. None of the sheep showed diarrhoea. All infected sheep developed a moderate to severe degree of anaemia due to decreased numbers of erythrocytes. It is concluded that diarrhoea is an incidental clinical sign in trichostrongylosis, and is not essential for the disease to terminate fatally. The data presented suggest that water loss is not an important component of the syndrome.
The role of time of emergence in determining the growth of individual plants in swards of subterranean clover (Trifolium subterraneum L.)
Authors: Black JN , Wilkinson GN
Published: November 2004

An experiment was carried out which enabled a separate assessment to be made of the influence of, firstly, pre-emergence growth rate, and secondly, the competitive environment at emergence on the subsequent growth of individual plants of subterranean clover. Swards of the Bacchus Marsh variety were grown in large seed boxes at the Waite Agricultural Research Institute, Adelaide. Four different sowing treatments were applied whereby the sowing of alternate plants in a checkerboard grid was delayed by 0, 2, 4, and 8 days. Emergence date and final dry weight were recorded individually for each plant in the experimental swards. There was considerable overlap in emergence times between the earlier and the later-sown plants. Consequently by a comparison of the separate regressions for earlier and later-sown plants of yield per plant on day of emergence for each treatment, it could be demonstrated that plants with very different pre-emergence growth rates but emerging on the same day in the same sward, and hence into the same competitive environment, gave essentially the same subsequent growth. In other words, in the absence of differential competitive effects, there was no detectable influence of pre-emergence growth rate on subsequent growth. On the other hand, the final dry weights of individual plants were very strongly related to day of emergence. A delay in emergence of 5 days brought about a reduction in final yield of about 50%, and a delay of 8 or 9 days of at least 75%. In view of the negligible influence of pre-emergence growth rate, per se, this reduction is attributable solely to the increased severity of competition from plants already emerged. In spite of the wide variation in emergence patterns, the total yields of all swards were very similar, indicating an almost complete compensation between plants in the utilization of available growth factors.
Studies on the nutritional role of selenium. I. The distribution of radioactive selenium in mice
Authors: Jones GB , Godwin KO
Published: November 2004

Lucerne (Medicago sativa L.) in which the proteins were labelled with radioactive selenium was fed to mice. The distribution of 75Se among the various organs was studied. On the basis of 75Se activity per unit wet weight, the importance of the liver and kidney as metabolic sites is confirmed, and attention is directed to the pancreas, endocrines, and the stomach wall as additional sites where selenium is present in comparable concentrations. The relative importance of the above organs is supported by the results of autoradiography; in addition, this demonstrates the high concentration of 75Se in the cell nuclei, where selenium may play a fundamental role. Radioactive selenium from labelled lucerne was found in the milk of a lactating mouse within 4 hr of it being fed. Within 24 hr approximately 20% of the selenium absorbed by the dam had been transferred to the young mice through the milk.