bluuebunny/crossref_metadata_2025 huggingface dataset:
Pharmacology and toxicology of carbon tetrachloride in the sheep. II. The anthelmintic and toxic effects of carbon tetrachloride given by intramuscular or intraruminal injection
Authors: Kondos AC , Southcott WH , McClymont GL
Published: November 2004

Merino wethers infected with Fasciola hepatica were given pure carbon tetrachloride (CCl4), either by intramuscular (IM) injection at dose rates of 1, 2, 4, and 8 ml or by intraruminal (IR) injection at dose rates of 1, 2, and 4 ml. Blood samples were taken before and at intervals after dosing, and plasma glutamic oxalacetic transaminase (GOT) and isocitric dehydrogenase (ICD) activities were used for quantitative indications of liver damage. Plasma GOT and ICD activities after IR administration were approximately twice as high as those recorded after IM injection of an equal dose of CCl4, and peak values in the IR groups tended to occur earlier. Plasma glucose and lactic acid levels, and histological examination of liver tissues, also indicated differences in hepatotoxic or general toxicity effects. With the exception of 1 ml IM, all dose levels of CCl4 by both routes of administration were effective in removing mature Fasciola hepatica from the experimental sheep.
The cobalt status of Tasmanian soils. I. Total cobalt in soils, and cobalt content of subterranean clover grown in pots
Authors: Nicolls KD , Honeysett JL
Published: November 2004

Total cobalt was determined in 104 samples of Tasmanian surface soils. It was moderate to high (4–82 p.p.m.) in krasnozems and lateritic krasnozems, and high (11–94 p.p.m.) in brown earths, black earths, and prairie soils, all of which were derived from basalt or dolerite. It was also high in soils of the lateritic podzolic Cressy series, but low in another lateritic podzolic, the Brickendon series. Approximately half the samples of various kinds of podzolic soils had less than 3 p.p.m. The cobalt content of subterranean clover grown in pots on 92 soil samples from Tasmania showed large differences between the soil groups. The krasnozems stood out with generally low values, ranging from 0.05 to 0.30 p.p.m., with over 60% of samples less than 0.10 p.p.m. On the various podzolic soils the cobalt content of the clover ranged from 0.08 to 2.1 p.p.m., with over 80% of the samples between 0.10 and 0.55 p.p.m. On the brown-black earth group it was generally high, ranging from 0.17 to 0.63 p.p.m. Soil pH did not account for these differences. Cobalt deficiency in sheep and cattle has been recorded on krasnozems and on podzolic soils in Tasmania but not on the brown-black earth group. It is suggested that ingestion of soil may be more important in the cobalt nutrition of the ruminant on krasnozems than on most other soils.
Observations on the residual value of accumulated phosphorus in a red loam
Authors: Hughes JD , Searle PGE
Published: November 2004

A pot trial was conducted in which tomatoes were grown in soils containing a range of total phosphorus depending on the amount of superphosphate which had been applied during the previous 9 years. Monocalcium phosphate was mixed with all soils to give 25, 75, or 150 p.p.m. added phosphorus. The above-ground portions of the plants were harvested after 47 days, and the pots seeded again without further additions of fertilizer. This crop was harvested 59 days later. It was shown that the response to current applications of phosphorus was dependent on the total phosphorus level. The addition of a given amount of phosphorus produced bigger yields on the high phosphorus soils. Moreover, the higher the level of applied phosphorus, the greater the difference in yield between soils of different total phosphorus levels. Yields were considerably lower in the second crop, but the interaction between total and applied phosphorus was still evident.It was concluded that the availability of the accumulated phosphorus was extremely low, and that the increased yields on the high phosphorus soils were due to a better utilization of applied phosphorus as a result of reduced fixation in these soils. The decrease in the rate of fixation was explained by blocking of fixation sites by the previously fixed phosphorus.
Nutritional evaluation of meat meals for poultry. II. Effect of increasing protein concentration, removal of bone, and folic acid, pyridoxine, and pantothenic acid supplementation of diets based on high and low quality meals
Authors: Sathe BS , Cumming RB , McClymont GL
Published: November 2004

The effect of increasing the protein and B vitamin concentrations in chicken diets based on wheat, milk powder, and high and low quality meat meals, and of removing bone from such meals, has been studied. Meat meal protein provided approximately 50% of the total protein of 20% protein diets, and up to 85% of the protein of higher protein diets. Without additional pyridoxine and folic acid, increased growth was obtained by increasing the proportion of high quality meat meal in diets providing up to 35% protein (metabolizable energy calorie/protein ratios of 32–33). With low quality meat meals, increased growth was observed on diets containing up to 25 or 30% protein. Severe growth depression and high mortality rate was observed on low quality meat meal diets containing 30–35% protein. Addition of 5 p.p.m. pyridoxine and 8.8 p.p.m. folic acid to low quality meat meal diets containing 30–35% protein significantly improved growth and decreased mortality. This improvement was mainly due to folic acid, and in one case to folic acid and pyridoxine. The available evidence did not indicate whether the response was due to an increased need for or decreased intake of these vitamins, or both. Although growth was significantly improved by the removal of bone from both a high quality–low ash and a low quality–high ash meat meal, the removal did not significantly affect the (calculated) proportion of the total collagen protein in the diet. From this and other evidence, it is concluded that growth depression on high bone content diets is mainly due to excessive calcium content, and not because high bone content is associated with a high proportion of collagen provided by bone protein. Even after removal of bone, however, growth on the low quality meat meal diet did not approach that on a high quality meal diet, which indicated that higher bone content was not the main cause of the low growth-promoting ability of the low quality meal. Addition of meat meal ash to diets depressed growth, but not sufficiently to account for most of the variability in growth-promoting ability of meat meals when they supplied 50% or more of the total protein in the diet. It is tentatively concluded that the growth-promoting ability of meat meals in chick diets is mainly a resultant of:

(i) Any effect of excess ash (particularly the calcium component) contributed. (ii) The quality (digestibility or biological value, or both) of their protein, which is not related to the proportion of collagen;

and of course the proportion of meat meal protein in the diet, and the extent to which it is complemented by other proteins in the diet. (iii) At high levels of meat meal protein, the folic acid and/or pyridoxine contents of the diets and/or the requirements of the chicks.
Influence of ambient temperatures on the heat production of pregnant ewes
Authors: McCGraham N
Published: November 2004

Two Merino ewes were kept on constant diets throughout pregnancy and, after shearing, were exposed to a series of ambient temperatures between 10 and 35°C on several occasions before lambing and once afterwards. Their heat production and urinary nitrogen output were determined at each temperature, and some blood constituents were also measured. Metabolizable energy intakes were 1300 and 1900 kcal/day. The estimated critical temperatures (minimal heat production) of the sheep ranged from 28 to 35°C, being lower at the higher level of feeding and also during pregnancy. A general relationship between thermoneutral heat production per sq. metre and the critical temperature of shorn sheep was derived; the heat increments of gestation and feeding merely increase thermoneutral heat production and so decrease the critical temperature. The heat increment of gestation was 80 and 90 kcal/24 hr/kg lamb at the high and low feeding levels respectively. Fat oxidation (as indicated by the respiratory quotient) and heat production increased up to twofold at subcritical temperatures. At 10°C there was no heat increment due to pregnancy or feeding; blood glucose was increased by 6–9 mg/100 ml in one sheep, and plasma free fatty acid content was highest at 10° in both sheep (0.9 m-equiv./l.). Heat production also tended to be elevated at the highest temperature. The change was greatest (8%) during pregnancy and at the higher level of feeding. Urinary nitrogen increased at the same time only when the sheep were not pregnant. Improved nitrogen economy during gestation was also apparent at other temperatures.
The summer nutrition of weaner sheep: Herbage intake following periods of differential nutrition
Authors: Allden WG , Young RS
Published: November 2004

The influence of previous nutrition on both the intake of herbage and the body weight changes of grazing sheep was examined in two field experiments. In the first experiment, herbage intake and weight changes were compared at different stocking rates (three, six, and nine sheep per acre). The second experiment was designed to examine the influence of previous undernutrition on the digestive capacity of sheep and on their rate of consumption of herbage in the field. As compared with previously better-fed sheep under similar grazing conditions, the previously undernourished animals showed a capacity to compensate for their nutritional handicap at all stocking rates. Within a short time they reduced the body weight advantage held by their better-fed mates to a non-significant margin. Compensatory growth was associated with a significantly (up to 20%) greater herbage intake by the undernourished animals, but this higher feed intake did not cause an increase in wool production. Undernutrition did not influence the apparent digestibility of a diet, but was associated with an increased rate of herbage consumption under field conditions.
Nutrient potential and capacity. I. The concepts of nutrient potential and capacity and their application to soil potassium and phosphorus
Authors: Barrow NJ , Ozanne PG , Shaw TC
Published: November 2004

The theoretical basis for the measurement of nutrient potential is examined and its application to soils is discussed. It is suggested that nutrient potential should be measured in standardized units by defining chemical potential relative to a given standard state, such as the usual standard state of solution chemistry. The unit for all nutrient potentials would then be calories per equivalent. The nutrient capacity is regarded as the ability of a soil to resist change in potential. It is therefore indicated by the shape of the curve relating potential to the quantity of the nutrient in the solid phase. For potassium the relationship between potential and exchangeable potassium was found to be curvilinear, so that each decrement of potassium makes the next decrement more difficult to remove. Curves for five soils differed from each other. This was not only because of differing cation exchange capacities but also because of differences among the types of colloids. The relationship between phosphorus potential and phosphorus sorption was also found to be curvilinear and the slopes for the various soils again differed from each other. During equilibration with phosphate, microbial activity caused biological immobilization of phosphorus. This could be controlled by adding mercuric chloride or chloroform, but toluene was less effective.
Soil acidity and growth of a legume. I. Interactions of lime with nitrogen and phosphate on growth of Medicago sativa L. and Trifolium subterraneum L.
Authors: Munns DN
Published: November 2004

Lucerne grew poorly without lime on several acid soils on which subterranean clover grew normally. On the moderately acid soils, of pH 5.5–6.0, most of the lime response by lucerne could be attributed to improvement in nodulation and could be eliminated by supplying ammonium nitrate. Strains of medic Rhizobium differed in ability to nodulate lucerne plants in acid soils sufficiently to suggest practical advantage in selecting strains for superiority in this respect. On the more acid soils, of pH 5.0–5.5, lucerne responded to lime or potassium carbonate even when not nitrogen-deficient. This lime response was eliminated by large applications of phosphate. The interaction between lime and phosphate could indicate aluminium toxicity.
Selection schemes for improving both reproduction rate and clean wool weight in the Australian Merino under field conditions
Authors: Young SY , Newton Turner H
Published: November 2004

Theoretical consideration has been given to 28 selection schemes which might readily be applied for the improvement of both number of lambs born and clean wool weight per head in Australian Merino sheep under field conditions. Two sets of relative weights were used, one lamb being considered equivalent to 5 or 10 lb of clean wool, and when both characters were selected in one sex, equal selection pressure was applied to each. Quality of wool is assumed to be safeguarded by preliminary culling of off-types. The schemes were investigated at two levels of twinning (15 and 30%). At both levels, the optimal method of ram selection was to select on clean wool weight among twin-born rams. At the lower level, the optimal method of ewe selection was to save twin-born ewes and to make up numbers by selecting on clean wool weight among those born as singles. At the higher level, this scheme was slightly exceeded in total genetic gain by one involving selection of ewes on their own 3-year-old reproduction rate. After 10 years of selection under the optimal scheme, an increase of about 40 lambs born per 100 ewes joined would be expected in reproduction rate, and about 1.2 lb clean wool in the cut per head. The gain in wool weight will be less (about 1 lb) if more rigorous culling on crimp is practiced, but the relative efficiency of the schemes near the optimum will not be changed. The tables presented could be used in flocks of any breed in which clean wool weight and reproduction rate were uncorrelated and to which approximately the same estimates of heritability, variances, and relative weights of lamb and wool could be applied.
The influence of various factors on survival rate to weaning of Merino lambs. I. Sex, strain, location, and age of ewe for single-born lambs
Authors: Lax J , Newton Turner H
Published: November 2004

The influence of sex, strain, location, and age of ewe on survival rate to weaning of single-born Merino lambs has been examined in two sets of data: the strain trial, involving five strains run without selection at each of three locations (Cunnamulla, Qld.; Armidale, on the northern tablelands of New South Wales; Deniliquin, in the Riverina area of New South Wales), with six age groups of ewes; and the same five strains later included in selection groups at Armidale with seven age groups of ewes. The strain trial at Armidale ran mainly on native, and the selection groups mainly on improved pastures. Female lambs had a higher survival rate than either castrated or entire males, the differences in lambs weaned per lamb born being 0.03 and 0.04 respectively. No strain differences could be regarded as statistically significant, and neither could the strain x location interaction in the strain trial. Mean survival rates for the strains ranged from 0.673 to 0.786 on the Armidale native and from 0.802 to 0.850 on the Armidale improved pasture, from 0.746 to 0.859 at Cunnamulla, and from 0.838 to 0.894 at Deniliquin. The strains did not rank consistently in the same order. Location had a marked effect on survival rate, the means being 0.744 for the native and 0.824 for the improved pasture at Armidale, 0.810 at Cunnamulla, and 0.868 at Deniliquin. Age of ewe had a marked influence in the poorest environment (Armidale native pasture), survival rate rising with age and later falling sharply. The effect was less marked in the intermediate environments (Armidale improved pasture and Cunnamulla) and negligible at Deniliquin. The patterns at Cunnamulla and Deniliquin are confirmed by data from other experiments on these stations. Survival rate is one component of number of lambs weaned. The other component, number of lambs born, has a higher mean value at Deniliquin than Cunnamulla, but shows a strong association with age of ewe in both environments. Number of lambs born responds rapidly to selection, but no information is yet available concerning the likely response in survival rate. If improvement in environment can raise the survival rate, particularly in the youngest and oldest ewes, then selection for number of lambs born, combined with improved environment, should lead to a marked rise in the number of lambs weaned.
Variations in the sulphur content of wool from Merino sheep on two semi-arid grasslands
Authors: Reis PJ , Williams OB
Published: November 2004

Seasonal variations in sulphur content and growth rate of wool were measured at intervals of 6 weeks over a period of 1 year on two groups, each of six Merino wethers, which grazed on two semi-arid grasslands. Each group consisted of three high-producers and three low-producers, selected on the basis of wool growth rate. There were substantial seasonal variations in sulphur content, which followed very closely the seasonal pattern of wool growth. Mean sulphur contents on the two grasslands ranged from 3.25 and 3.32% during December–April, to 3.67 and 3.79% respectively during July-October. Seasonal variations in sulphur content and growth rate of wool were related to the amount of edible forage available, and it was concluded that these seasonal variations were due mainly to variable nutrition. The range of sulphur contents was 2.93 to 3.92%, owing to seasonal nutritional variations and differences between sheep; annual mean sulphur contents of wool from individual sheep ranged from 3.22 to 3.84%. The annual mean sulphur content of the wool from high-producers (3.39%) was lower than that of wool from low-producers (3.66%). The seasonal variation in sulphur content also appeared to be greater in wool from high-producers than in wool from low-producers.
Flower initiation in relation to maturity in crop plants. III. The flowering response of early and late cereal varieties to Australian environments
Authors: Aitken Y
Published: November 2004

The difference between early- and late-flowering characters in wheat, rye, barley, and oats has been studied by growing some Australian and overseas varieties in several field environments with mean temperatures ranging from 10 to 22°C, and mean photoperiod of 10½ to nearly 16 hr, together with vernalization and prolonged photoperiod. Similar genotypes were found in each of the four cereals. Early varieties all flowered at a low leaf number, which showed that the genotypes for early flower initiation in these varieties are almost or entirely insensitive to temperature and photoperiod. In consequence, varieties with such genotypes can be expected to flower early, even in tropical Australia. In contrast, the genotypes for lateness caused initiation at a higher leaf number, and more sensitivity to temperature and photoperiod, both before and after flower initiation. Contrary to the common assumption that very late varieties need a period of cold followed by long photoperiod for flower initiation, they were found to initiate both in summer (i.e, high temperature) and in winter (low photoperiod) at Melbourne. High temperatures (above 15°C), however, delayed initiation, which resulted in flowering at a higher leaf number than when the same varieties were grown at low temperatures. In addition, the young reproductive shoot died after initiation in a combination of high temperature and a 14–12 hr photoperiod, as happens when such varieties are springsown in temperate latitudes. Such a response also prevents flowering in tropical environments, where high temperatures are combined with a moderate photoperiod all the year round.
Variation in Phalaris tuberosa L.
Authors: Scurfield G , Biddiscombe EF
Published: November 2004

Variation in the performance, morphology, and nitrogen content of lines of Phalaris tubevosa introduced from the Mediterranean region and of the Australian commercial line was examined. Regional differences existed in culm height, date of anthesis, seed weight, and nitrogen content of tops, but not in chromosome number. Comparison of six lines, one each from Australia, Morocco, Algeria, Turkey, Israel, and Greece, grown at four different temperatures, established the high sensitivity of the Israeli line to high temperatures, and the vigour of the Israeli and Moroccan lines under low temperatures. The Algerian line showed some sensitivity to high temperatures also, but generally lines other than the Israeli responded similarly to increasing temperature. Regional differences in yield, apical dominance (reflected in tiller number and ratio wt. primary shoot/wt. tops), and leaf size and shape were obtained under each of four temperature regimes in a second experiment involving 55 lines. In a field experiment, herbage yields from a Moroccan, an Algerian, and an Israeli line were compared with that of the Australian line grown in swards with Trifolium subterraneum and cut at intervals over 1 year. Lines differed in their response, but the introduced lines were no better than the Australian line. The results are discussed in relation to the agronomic utilization of P. tuberosa, the possible geographical origin of the Australian line, and the question as to how far results from glasshouse experiments have predictive value in field experiments.
Silica metabolism of the Merino sheep
Authors: Nottle MC
Published: November 2004

Diets of wheat or oat grain with or without chaff, mixtures of all three, and a diet of chaff, oats, and bran with and without lucerne chaff were fed to sheep for the purpose of determining silica metabolism on diets approximating those in the field. These diets supplied from 0.08 to 16.6 g silica per day. Silica digestibilities and balances showed marked positive and negative values, which were considered to be due to variable retention in, or passage of particulate silica from, the rumen. The mean urinary silica excretion on wheat was 22 and 25 mg/day and oats 126 and 163 mg/day for two levels of feeding. Values for wheat plus chaff and oats plus chaff were respectively 190 and 224 mg/day and for mixed diets from 169 to 205 mg/day. No relationship between total urinary silica excretion and apparent absorption of silica was observed, but excretion seemed dependent on silica intake up to a level of about 8 g/day. Beyond this intake, urinary excretion plateaued at approximately 200 mg/day. Urine volumes on wheat grain diets were greater than on the corresponding oat grain diets, and these in turn were greater than on the mixed diets. The combined effects of urine volume and total excretion of silica resulted in urinary silica concentrations of 30 and 32 µg/ml on wheat grain diets, 255 and 336 µg/ml on oat grains, 266 µg/ml on wheat plus chaff, 419 µg/ml on oats plus chaff, and 421–728 µg/ml on mixed diets. A hyperbolic relationship between silica concentration and volume of urine, similar to one obtained in field studies, and also one between specific gravity and volume of urine were demonstrated. These findings are discussed in relation to the absorption and excretion of silica and the formation of siliceous urinary calculi.
Some effects of nutrition and heat stress on urea excretion by pregnant sheep
Authors: McC Graham N , Searle TW
Published: November 2004

Renal clearance of urea and creatinine were measured at mating time and near lambing time in three groups of seven sheep, the groups being given differing amounts of food. On each occasion the measurements were made at normal ambient temperature (20°C) and in a hot environment (35°). The ewes on the lowest feeding level were severely undernourished in late pregnancy. Urine flow and the composition of blood and urine were quite variable, with standard deviations equal to 10–20% of mean values. Renal clearance of urea was greater at the highest feeding level (29–41 ml/min) than at the other levels (19–26 ml/min). Heat stress caused it to increase by 6–12 ml/min at mating time but had no effect in advanced pregnancy. Actual excretion of urea varied similarly. Urea clearance was a relatively constant fraction of creatinine clearance (40–50%).– It is concluded that apparent nitrogen economy or urea conservation by the pregnant ewe subjected to heat stress or caloric undernutrition is not evident at the renal level. It is suggested rather, that nitrogenous moieties of oxidized protein may be re-utilized.
The effect of direction of shoot growth on fruitfulness and yield of sultana vines
Authors: May P
Published: November 2004

Experiments are described in which the effect of training sultana shoots vertically or horizontally was tested. Horizontal training of shoots caused reduction in fruitfulness in all cases, with the exception of one experiment with very vigorous young vines. Vertical growth tended to improve vigour, in which case fruitfulness was greater, but this effect decreased with increasing numbers of vertical canes per vine. Increased yield was obtained in one year out of three in a field trial where the shoots to be used as pruning wood were encouraged to grow vertically. It is concluded that increased fruitfulness will result from measures which improve the vigour of shoots, such as vertical training, preservation of the shoot tip, or prevention of early trailing of the shoot; and that shoots which have grown horizontally should be avoided as pruning canes.
Studies of face cover in the New Zealand Romney Marsh sheep. I. The relationships between face cover, wool blindness, and productive characters.
Authors: Cockrem F , Rae AL
Published: November 2004

Forty open-faced and 80 woolly-faced Romney sheep were selected from a flock of about 500 18-month-old ewes so as to represent extremes of face cover. Half the woolly-faced group were left wool-blind and the remainder were wigged at regular intervals. No differences in liveweight, fertility, or fleece weight resulted from the wigging treatment. Over the subsequent 5 years the open-faced sheep had 30% more live lambs and averaged 0.3 1b greater clean fleece weight annually than the wool-blind and wigged sheep. The open-faced ewes had the greater liveweight over the whole period. It was concluded that wool blindness was not the basic cause of the observed differences between open- and woolly-faced sheep.
Nutritional evaluation of meat meals for poultry. V. Effect of addition of antioxidants during and after processing on growth-promoting value of high and low qualtiy meat meals
Authors: Sathe S , McClymont GL
Published: November 2004

Two antioxidants, butylated hydroxytoluene and ethoxyquin, were added separately, at c. 0.01 % and 0.02% of the fat, to high and low quality meat meals either during or after processing. Samples with 0.02% ethoxyquin added, and without antioxidant, were then stored for 3,6, and 9 months at l°, room temperature (c. 20°), and 37°C. The growth of chicks on diets based on wheat, skim milk, minerals, vitamins (including tocopherol) and antibiotic, and fresh or stored meals was then studied. Only the addition of 0.02% ethoxyquin after processing to both high and low quality meals significantly increased growth rates (by about 7%), and only with the fresh samples. The other treatments were without effect. It was concluded that oxidation in the course of processing or autoxidation during storage are unlikely to be major determinants of the relative growth-promoting ability of meat meals.
Breeding creeping-rooted lucerne for the subtropics
Authors: Edye LA , Haydock KP
Published: November 2004

A lucerne-breeding programme was undertaken at Lawes, south-eastern Queensland, to transfer the creeping-rooted habit from Heinrichs's Canadian strains to subtropical lucerne varieties. Before intensive selection commenced, the inheritance and association of three characters, summer yield, winter yield, and the number of extra crowns originating as adventitious shoots from roots, were determined in the F2 and F3 generations. The F2 genotypic variances for summer yield, winter yield, and number of extra crowns were predominantly additive and were respectively 81, 53, and 54% of their phenotypic variances. The genotypic correlation coefficient for winter yield and number of extra crowns was negative ( rG = –0.18), consisting of a negative additive correlation rg = –0.55 and a positive non-additive correlation rs = 0.50. In the F3 generation the approximate genotypic correlation for these two characters was small and positive and composed of a nearly zero additive correlation and a high positive non-additive correlation. Simultaneous mass selection for summer yield, winter yield. and creeping-rootedness was undertaken in the F3 generation, and the combining ability variances and covariances for these characters were studied in the F4 generation. All three variables were positively associated in their general and specific effects, and the majority of families did not differ significantly from Hunter River in winter and summer yield. The seed production of ten F4 families was studied and it was found that eight families were significantly lower seed producers than Hunter River, their seed yields ranging from 20 to 47% of the mean for Hunter River. Covariance analysis showed seed yield and number of extra crowns to be negatively associated in the F4 generation. The changes in creeping-rootedness in the successive generations F1 to F5 were 2, 9, 34, 19, and 59% compared with a mean of 4% for Heinrichs's Canadian strains at Lawes. Creeping-rooted individuals survived better than non-creeping-rooted plants of similar genotype and better than Hunter River, particularly in the F4 generation, where the respective survival rates were 75, 27, and 23% 19 months after transplanting in the field
Pathological changes associated with Oesophagostomum columbianum infestations in sheep: Serum protein changes in relation to multiple infestation, intensity of infestation, and immunity
Authors: Dobson C
Published: November 2004

A relationship between size of infesting dose and multiple infestation and the total serum proteins was demonstrated. During primary infestations with low and medium-sized doses of infective larvae, the total serum proteins fell. After infestation with large larval doses or after multiple infestations the total serum proteins increased. Hypoalbuminaemia could be demonstrated after both primary and secondary infestations; also the animals given secondary infestation had failed to regain the level of serum albumin present before primary infestation. Both α- and ß1-globulins of sheep with either first or second infestation retained a level commensurate with, or decreased compared with, that in the control animals. These changes are discussed in relation to osmotic balance of the infected animal. The ß2-globulins increased during both primary and secondary infestations: however, the increase was greatest during the primary infestation. Increases in the y-globulin fraction also occurred but here the greatest increase occurred after secondary infestation. After primary infestation the y-globulin levels first fell and then increased as the infestation progressed. There was a correlation between the complement fixation, but not the passive haemagglutination, antibody titres and the increased serum ß2- and Y-globulin levels. However, the increased y-globulin levels after secondary infestation were too great to be solely accounted for by an immunological response.
Studies on the productivity of tropical pasture plants. I. Growth analysis, photosynthesis, and respiration of Hamil grass and Siratro in a controlled environment
Authors: Ludlow MM , Wilson GL
Published: November 2004

Hamil grass and Siratro were grown as single plants in pots in controlled environment cabinets at a temperature favouring high growth rates and with adequate water and mineral nutrients. Leaf areas and dry weights of plant parts were recorded in two experiments, to which some of the plants were common. In the first experiment, weekly samples until 4 weeks from sowing provided data for the calculation of relative growth rates, net assimilation rates, and leaf area ratios. The relative growth rate of Hamil grass was almost twice that of Siratro and appears to be the highest yet recorded for any plant. The higher growth rate for the grass resulted from a high net assimilation rate, although the leaf area ratio was lower. The second experiment used Watson and Hayashi's method, in which plants are kept in darkness for a varying number of days to separate net assimilation rate into photosynthetic and respiratory components. Data were collected at 2 and 4 weeks from sowing. The high net assimilation rate of the grass was shown to result from a higher photosynthetic rate, despite a much greater respiration rate than in the legume. The technique used for estimating photosynthesis and respiration is discussed in relation to some of the assumptions that it makes.
A quantitative study of the effects of gibberellic acid on the growth of Festuca arundinacea
Authors: Morgan DG
Published: November 2004

Single plants of Festuca arundinacea (cv. S170) were treated with gibberellic acid (GA) and the sequence of effects on the growth of the whole plant and of various organs followed by means of growth analysis. The first effect of GA was to change the distribution of dry matter between shoot and root and between tillers within the shoot without affecting total plant weight. Shoot growth was increased and resulted in a larger amount of photosynthetic tissue with a higher net assimilation rate; total plant weight increased as a consequence of these effects. The significance of these results in interpreting previous work on the effects of GA on dry matter production in grasses and other plants is discussed.
Undernutrition of the Merino sheep and its sequelae. IV. Herbage consumption and utilization of feed for wool production followint growth restrictions imposed at two stages of early post-natal life in a Mediterranean environment
Authors: Allden WG
Published: November 2004

Merino lambs grazing sown pastures in the Mediterranean type environment of southern Australia were subjected to contrasting growth conditions (restricted or continuous) during two periods of early life (birth to 6 months of age and 6–12 months). Thereafter all groups received equal nutritional opportunity and the sequelae to these periods of retarded growth were examined in terms of herbage intake, utilization of feed for wool production, and body weight. During the 28-month recovery period those sheep which received a growth handicap in the first 6 months of life (pre-weaning treatment) did not reduce the weight margin of 6.6 kg held by their previously better-fed mates. They consumed significantly less herbage on an absolute basis, but after adjustment for differences in metabolic size (W0.75) the feed consumption of the two groups was similar. By contrast, sheep which were subjected to growth restrictions during the second 6 months of life (post-weaning treatment) rapidly reduced the weight advantage of 8.1 kg (P < 0.01) held by their well-fed companions at the beginning of the recovery period. This capacity to compensate for the effects of previous undernutrition was associated with a significantly greater feed intake/liveweight0.75 ratio. The effects of pre-weaning and post-weaning nutrition on body weight, feed intake, and wool production were independent and additive, no interactions being observed. Groups subjected to a growth restriction during early post-natal life produced significantly less wool during the first shearing following rehabilitation, but this effect was not sustained. Undernutrition during early life did not impair the efficiency of conversion of feed to wool; differences in wool production were almost wholly due to differences in intake. Wool growth appeared to be less sensitive than body weight to the after-effects of periods of undernutrition in early life.
Studies on the number of ewes joined per ram for flock matings under paddock conditions. II. The effect of mating on semen characteristics
Authors: Lightfoot RJ
Published: November 2004

Semen characteristics were studied prior to and during the paddock joining of rams to varying numbers of ewes in a series of three experiments. A marked fall in ejaculate volume, sperm density, and their product, total number of sperm per ejaculate to levels of c. 0.3 ml, 1.5 x l09 sperm/ml, and 0.45 x l09 total sperm respectively occurred during the first 4 days of joining. Although there were large differences in the number of ewes joined per ram (25 to 100) and consequently the number of ewes served per ram per day, the depression in these semen characteristics occurred to a similar extent in all rams during the first 2 weeks of mating. By examining the data for all collections throughout the joining period, however, highly significant negative correlations were obtained for ejaculate volume, sperm density, and total number of sperm per ejaculate in each case with the number of ewes served during the 4 days preceding semen collection. Increases in the proportion of abnormal sperm were found sporadically in the ejaculates of rams during joining. Rams 2½ years old produced significantly more sperm per ejaculate before, during, and after the 6 week joining period than rams 1½ years old.
Effects on reproduction of prolonged grazing of oestrogenic pastures by ewes
Authors: Fels HE , Neil HG
Published: November 2004

Six-year-old ewes, the survivors of two experimental groups that had grazed from May to October through the 5 preceding years on mixed pastures containing an oestrogenic variety (Dwalganup) of subterranean clover ("clover" group) and oat crops ("oats" group), were mated 6 months after their last exposure to oestrogenic pasture and allocated for slaughter to observe the fertilization rate of eggs or the numbers of surviving embryos. In late April the clover and oats groups did not differ significantly in the proportion of eggs fertilized (13/15 eggs v. 11/11) but in May there was a highly significant difference (4/12 v. 14/17). The difference between late April and May in the clover group was significant and was associated with changes in the ratio of oestrous ewes to rams. The ratio of live embryos to eggs shed was much higher in the oats than in the clover group (56173 v. 8/39). After estimating how many of these eggs had been fertilized it was concluded that more fertilized eggs developed successfully in the oats than in the clover group (c. 56/65 v. 8/17). The data suggested that more "clover" embryos died during days 13–19 of pregnancy. Significantly more clover group ewes had obvious reproductive tract infections. These ewes did not show oestrus regularly though they may have ovulated more or less regularly. Other clover group ewes showed oestrus as regularly as oats group ewes. Clover group ewes had many more macroscopic endometrial cysts in their uteri and cervices, but within groups, numbers of cysts were not significantly associated with previous or current reproductive performance.
Relationships between Oesophagostomum columbianum infection and the nutritional status of sheep. II. Haematological changes
Authors: Bawden RJ
Published: November 2004

Young sheep maintained on a low protein ration showed significant reductions in haemoglobin concentration, packed cell volume, and number of circulating erythrocytes following infection with 1500 Oesophagostomum columbianum larvae. Similar infections of sheep maintained on a high protein ration had no significant effect on the various haematological values. The development of anaemia in the inadequately fed sheep was more severe in those animals which had been infected with five consecutive daily doses of 300 larvae than in those which had received 1500 larvae in a single dose. Little change was apparent throughout the experiment in the values for the mean corpuscular values of volume, haemoglobin, and haemoglobin concentration.
The effect of increased rectal temperature on nitrogen metabolism in Brahman cross and Shorthorn X Hereford steers fed on lucerne chaff
Authors: Vercoe JE
Published: November 2004

A study was made of the effect on nitrogen metabolism of increasing the rectal temperature of Brahman cross and British steers on controlled feed intake. When the rectal temperature of the British steers was 1.3 °C higher than that of the Brahman cross steers, they excreted 13.5 g urinary nitrogen per day more than the Brahman cross. When the Brahman cross steers had a rectal temperature 1.3 °C higher than the British, they excreted 8.7 g urinary nitrogen per day more than the British steers. At the same nitrogen intake there was no significant breed difference in the increase in urinary nitrogen per degree rise in rectal temperature. Increasing the rectal temperature had a small effect on appetite but did not affect the apparent nitrogen digestibility; the concentration of nitrogen in the faecal dry matter was higher under the heat treatment. The ambient temperature at which rectal temperatures were increased by 1.3 °C was about 31°C for the British steers and 45° for the Brahman cross steers. At the increased rectal temperature the Brahman cross steers drank significantly more water than the British steers although faecal and urinary water losses were similar.
Phosphorus changes during the leaching and decomposition of hayed-off pasture plants
Authors: Jones OL , Bromfield SM
Published: November 2004

Ground samples of hayed-off pasture plants were decomposed in the laboratory under continuously moist, and intermittently moist and dry, conditions. During the course of decomposition they were leached at different frequencies and the resulting changes in inorganic and organic phosphorus measured. The dissolution of superphosphate and its conversion to organic phosphorus were also studied under some of these conditions.Inorganic phosphate was readily leached from the samples when microbes were inhibited. Microbial activity, on the other hand, largely prevented the loss of inorganic phosphate by leaching from a phalaris sample over a period of 3 months. Intermittent drying increased the amount of phosphate leached from decomposing plants but the leaching frequencies examined had little effect. The percentage of the phosphorus leached from plants varied with the type of material. In all cases less than half was recovered as inorganic phosphate, even after decomposition and leaching for 6 months. When superphosphate granules were leached in the presence of decomposing plants the conversion of fertilizer phosphate to organic phosphorus was small, but the dissolution of phosphate was sometimes retarded. The recycling of phosphate in hayed-off pastures is discussed in the light of these results.
Sulphur metabolism in sheep. IV. The effect of a varied dietary sulphur content on some body fluid sulphate levels and on the utilization of urea-supplemented roughage by sheep
Authors: Bray AC , Hemsley JA
Published: November 2004

A diet composed of oaten hulls, urea, and mineral mixture was shown to be deficient in sulphur with respect to the nutrition of sheep. Sulphate supplements to the diet increased both crude fibre digestion and nitrogen and sulphur retention. They also increased the concentration of inorganic sulphate in the blood and the levels of total sulphur and total sulphate sulphur in the parotid saliva, but decreased blood urea nitrogen levels and the concentration of residual nitrogen and residual sulphur (protein fraction) in the parotid saliva. The effect of these concentration changes is discussed with particular reference to the feeding of sheep on low sulphur, low nitrogen forages.
Relationships between Oesophagostomum columbianum infection and the nutritional status of sheep. III. Serum and tissue protein changes
Authors: Bawden RJ
Published: November 2004

The infection of young sheep with 1500 infective Oesophagostomum columbianum larvae was associated with the development of hypoproteinaemia resulting basically from a hypoalbuminaemia. Hypogammaglobulinaemia and hyperbetaglobulinaemia also developed in the infected animals. The concentration of α-globulin in the serum was not affected by infection. The extent and duration of the pathological features in the serum protein concentrations varied with the plane of nutrition. More severe effects were noted in sheep which had been maintained on a low protein ration and which exhibited severe protein depletion of the liver, spleen, and thymus, than in animals on a high protein ration. Within the low protein group the most severe depressions in serum protein concentrations resulted from infection with small multiple doses of larvae compared with the same total number given in a single dose.
The effect of potassium on the growth and chemical composition of some tropical and temperate pasture legumes. I. Growth and critical percentages of potassuim
Authors: Andrew CS , Robins MF
Published: November 2004

Eight tropical and four temperate pasture legumes were grown in pots of a potassium-deficient soil, with varying additions of potassium chloride. Growth responses and chemical composition of the plant tops were recorded, and from these, critical percentages of potassium in the plant tops were established. All species responded in growth to potassium additions; however, there was practically no increase in plant potassium concentration over the low treatment range of potassium chloride. Medium to high rates of application increased plant potassium. Critical percentages of potassium in the tops of Phaseolus lathyroides, P. atropurpureus, Desmodium intortum, D. uncinatum, Stylosanthes humilis, Lotononis bainesii, Centrosema pubescens, Glycine javanica, Medicago sativa, M. truncatula, Trifolium repens, and T. fragiferum sampled at the immediate pre-flowering stage of growth were 0.75, 0.75, 0.80, 0.72, 0.60, 0.90?, 0.75, 0.80, 1.2, 1.0, 1.0, and 1.0% potassium respectively in the dry matter. In this work an absolute critical percentage has not been sought, but rather a working value for the rapid diagnosis of nutrient deficiency.
Host selection for effective Rhizobium trifolii by red clover and subterranean clover in the field
Authors: Robinson AC
Published: November 2004

Cultures of root-nodule bacteria, from the nodules of red clover and subterranean clover growing closely together in the field, were tested for comparative symbiotic ability (effectiveness) with both red clover and subterranean clover. It was found that test plants of either host species nodulated faster and more effectively when inoculated with cultures isolated from the homologous host growing in the field than did test plants inoculated with cultures isolated from the heterologous host. Because the hosts had originally been nodulated in the presence of the same field populations of Rhizobium trifolii, it is concluded that the host legume exerts a selective effect in accepting infections from a mixed population.