bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrigendum - Water content and water turnover in beef cattle
Authors: Springell PH
Published: November 2004

Twenty-four steers, comprising British (Hereford and Hereford x Shorthorn), Zebu (Africander), and Zebu cross (British x Brahman or Africander) breeds, were either maintained on pasture, or yarded and fed on diets of a low and a high nutritional value. Tritiated water was injected into the animals on five occasions at intervals of 3 months. The body water content and the water turnover rate were calculated, and some of the sources of variation defined. Observed differences in the water content are attributable to nutritional factors rather than to breed differences. The mean body water content ranged from 615 to 809 ml/kg fasting body weight, where the higher values were associated with a poor diet. The mean half-life of tritiated water was lower in summer (as low as 58 hr) than in winter (up to 128 hr) in grazing and well-fed yarded steers. On a poor diet, however, the half-life in yarded cattle remained high and almost constant throughout the year, dropping to below 100 hr on only a single occasion. Occasionally the half-life was breed dependent, but generally no significant differences between breeds could be found. While mean turnover rates of up to 7.1 ml kg-1 hr-1 were found in better-fed cattle in summer, the value in poorly fed animals was almost constant throughout the year at about 3.3 ml kg-1 hr-1. There was, however, a winter minimum in the well-fed yarded and grazing groups. The turnover rate was also influenced by breed only to a limited extent. The results are interpreted in the light of their possible significance in the adaptation to a tropical environment, and in relation to their value in predicting the body composition.
The effect of variety and environment of wheat on the volumes of test loaves moulded by hand and by machine
Authors: Balaam KB , Dettmann B , Moss HJ
Published: November 2004

The influence of dough-moulding techniques on the volumes of test loaves has been investigated. The effects of variety of wheat, locality of growth, and season have also been studied. Because of the strong influence of variety, locality, and seasonal conditions on the protein content of wheat and flour, and in turn the effect of protein level on loaf volume and baking quality, an analysis of covariance with protein content was performed. Where protein levels in the flour were high, hand-moulded loaves had greater volume than those moulded by machine, the reverse being the case where protein levels were low. Flours of Spica variety tended to be overrated and of Heron variety underrated by hand moulding relative to machine moulding but the manner of moulding did not affect the overall ranking of varieties. Variety, season, and locality each influenced volume even after allowing for the effect of protein level. Varieties should be evaluated over a range of environments because of variability from trial to trial.
Corrigendum - Response to selection in Australian Merino sheep. II. Estimates of phenotypic and genetic parameters for some production traits in Merino ewes and an analysis of the possible effects of selection on them
Authors: Brown GH , Turner HN
Published: November 2004

Estimates of heritabilities and of phenotypic and genetic correlations are given, based on extensive measurements on medium Peppin Merino ewes at 15–16 months of age. In general these substantiate results obtained by other workers and, in particular, confirm the high heritabilities of the traits measured. An effort has been made to try to detect possible changes in additive genetic variance for the trait under selection (clean wool weight). Estimates are obtained for data from animals at different stages of selection: (A) either unselected, or with little selection history, and (B and C) with varying amounts of selection. For stage A data the average estimated additive genetic variance was 0.31. There are problems involved in estimating from stage (B+C) data but an upper limit average value of 0.22 was obtained. Thus, although a decrease in additive genetic variance has occurred, its statistical significance is unknown and conclusions about the decrease must necessarily be tentative. In practically all cases the estimates of phenotypic and genetic correlations are of the same order of magnitude, and for the genetic correlations may be summarized as:

See PDFAll other combinations of traits have negligible genetic correlations (in the range –0.20 to + 0.2).
Resistance of cattle to cattle tick, Boophilus microplus. I. The development of resistance to experimental infestation
Authors: Hewetson RW , Nolan JV
Published: November 2004

The development of a resistance by cattle to artificial infestations with Boophilus microplus ticks is reported and the sequence of development discussed. There was a regression of adult female ticks becoming replete with infestation (regression y = 2399.41 – 574x ± 54) up to the fourth infestation. The weight of replete female ticks dropped from resistant cattle increased with infestation but this effect is confounded with the effects of climate. The day of modal drop of replete females increased with infestation, which indicated an effect of resistance on modal drop. Egg-laying was not affected by a developing resistance, but the fertility of eggs from female egg-laying ticks was. There was an increase in fertility of eggs laid after the second infestation.
Hornedness and polledness in sheep. VI. The inheritance of polledness in the Border Leicester
Authors: Dolling CHS
Published: November 2004

Polledness in the descendents of a Border Leicester ram has been shown to be due to the action of an autosomal dominant gene. Dominance is complete in the female and partially so in the male. As a result of matings between sheep containing this gene and sheep containing the gene P which results in polledness in the Merino, the Border Leicester gene has been shown to be either an allele of, or closely linked to, or identical with the gene P. The last interpretation is the simplest, and is accepted here.
The production and absorption of volatile fatty acids from the rumen of the sheep
Authors: Faichney GJ
Published: November 2004

Experiments are reported in which sheep were given roughage diets or a high concentrate diet and the VFA absorbed from the rumen were estimated by an in vitro fermentation procedure. The VFA absorbed were compared with the digestible and metabolizable energy intakes of the sheep, determined in digestibility trials, for each diet. For a lucerne diet, a straw diet, and the high concentrate diet the proportions of the digested energy absorbed as VFA were 33.6, 42.4, and 33.2% respectively. On the lucerne diet, the difference between the mean molar proportions of the VFA absorbed and the mean molar proportions of the VFA in the rumen approached significance for acetic acid (P < 0.10) and was highly significant for butyric acid (P < 0.01). The differences were not significant for the other diets.
Some wool follicle and crimp parameters in fine-wool Tasmanian merinos
Authors: Nay T , Williams PA
Published: November 2004

Samples of wool and skin taken from the same animals were observed in finewool Tasmanian Merinos. It was found that highly crimped wool is produced by small follicles, follicle size being measured by the length of the chord or of the arc. It was also found that in animals on a high level of nutrition, high wool growth rate is associated with increases in both crimp chord and crimp depth. Whether the increase in wool growth rate brings about an increase in total crimp number per year is uncertain. The "pace-makers" of crimp size are the average wool fibres, which constitute the bulk of the staple. The longest and the shortest fibres conform to the average crimp chord by increasing or decreasing the crimp arc and amplitude respectively. A possibility that sebum may play a part in the cohesion of the crimp wave is discussed.
Cobalt distribution in several pasture species grown in culture solutions
Authors: Handreck KA , Riceman DS
Published: November 2004

Lucerne (Medicago sativa cv. Hunter River), subterranean clover (Trifolium subterraneum L. cv. Bacchus Marsh), prairie grass (Bromus catharticus Vahl), Phalaris tuberosa, and evening primrose (Oenothera sp.) were grown in culture solutions containing 60Co. The distribution of cobalt in the tops was determined with autoradiographs of pressed, rapidly dried plants and by measuring the total amounts of 60Co in pieces of fresh leaves dissected immediately after harvesting. Cobalt concentrations in the margins of lucerne, clover, and primrose leaves and at the base and extreme tip of the primrose and grass leaves were many times those found in other parts of the leaves. Cobalt accumulated at cut and cropped ends of leaves. Leaching removed up to 75% of the cobalt from dried leaves but none from fresh leaves. The concentration of cobalt in a given lucerne leaf reached a maximum soon after emergence and then declined rapidly as the leaf expanded.
Inheritance of congenital goitre due to a thyroid defection in Merino sheep
Authors: Mayo GME , Mulhern CJ
Published: November 2004

An analysis of data from 599 Merino sheep has provided clear evidence that a condition of goitre, existing on 26 properties spread throughout the more closely settled parts of South Australia, is simply inherited. It is suggested that the condition is due to the action of an autosomal recessive gene whose action shows high penetrance and variable expressivity, and is accompanied by manifold phenotypic effects themselves equally variable in expression. This suggestion accords well with biochemical studies of goitrous sheep taken from among this sample. This study is continuing.
Efficiency of conversion of food to wool. IV. Comparison of sheep selected for high clean wool weight with sheep from a random control group at three levels of dietary protein
Authors: Piper LR , Dolling CHS
Published: November 2004

An experiment is described in which ewes from a flock selected for a number of years for high clean wool weight per head (S) are compared with ewes from a random control flock (C) under ad libitum feeding of three diets differing in crude protein content but not in gross energy. Differences between the S and C groups were significant for clean wool weight (W), efficiency of conversion of gross energy to wool (W/I), fibre number per unit area of skin (N), and mean body weight (B), the S group having higher values for W, W/I, and N but being lighter in B. Differences between the means of ewes fed on the high and medium protein diets (H and M groups) and the means of those fed on the low protein diet (L group) were highly significant for Wand each of its physical and physiological components. The H and M groups had higher values for W, W/I, B, intake per unit body weight (I/B), fibre cross-sectional area (A), staple length (L), and smooth body surface area (S) but lower values for N. The mechanisms of these differences are discussed in relation to other published work. Differences between ewes fed on the H and M diets were significant for Wand W/I, the H groups having the higher value in each case. These responses are contrasted with those reported by other workers and the possible mechanisms are outlined. When differences between the S and C groups on the H and M diets were averaged and contrasted with the differences between them on the L diet, there were significant group x diet interactions in W and W/I and appreciable but not significant interactions in N, A, and L. Taking the value for the C group as 100 in each case, the values for the S group on the L, M, and H diets respectively were: W, 97, 125, 129;W/I, 92,129,132; N,129,110,111; A, 74,114,110; L, 92,109,110. The possible mechanisms for these changes in the differences between the S and C groups are discussed. The group x diet interaction was not significant for any character when the difference between S and C groups on the H diet was contrasted with the difference between them on the M diet, though there were slight increases in the differences in Wand W/I on the H diet.
Body water content and water turnover of tropical Bos taurus, Bos indicus, Bibos banteng, and Bos bubalus bubalis
Authors: Siebert BD , Macfarlane WV
Published: November 2004

The turnover of water, measured in five types of cattle, was least in the banteng during winter. The greatest rates of water turnover (848 ml/l0.82/24 hr) were among Shorthorn cows during the desert summer when feed was plentiful. In the wet tropics, however, buffalo used more water than B. taurus Shorthorns, while the B. indicus types turned over significantly less water on the same pasture. There was an increase in body water content, and a reduction in body solids, in summer relative to winter in all cattle, while the water turnover rose with increasing temperature, humidity, and food supply. After drought, Shorthorn cattle gained 40% in body weight, while increasing body water by only 4.5% as they became fat. Shorthorn steers on improved Townsville lucerne pastures during the wet season contained 48% more solids but weighed only 11% more than cattle on native vegetation, turning over greater amounts of water.
Effect of progesterone and duration of pasture intake on cervical mucus response to phyto-oestrogens in sheep
Authors: Lindsay DR , Francis CM
Published: November 2004

Progesterone administered to ewes at the rate of 10 mg per day during grazing of an oestrogenically active sward of Trifolium subterraneum L. cv. Dinninup reduced the magnitude of cervical mucus response to the test pasture. Doses of 0.1 and I.0 mg of progesterone increased the magnitude and duration of the response. Cervical mucus responses to a strain of subterranean clover high in genistein (Northam A) were reduced when the ewes grazed on the test pasture for 8–10 days prior to bioassay. Reduction in response was significantly less on a strain high in formononetin (Dinninup). It was concluded that the rate of inactivation of genistein by the sheep is increased by a period of continuous ingestion.
The effect of potassium on the growth and chemical composition of some tropical and temperate pastrure legumes. II. Potassium, calcium, magnesium, sodium, nitrogen, phosphorus, and chloride
Authors: Andrew CS , Robins MF
Published: November 2004

Seven 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 were recorded. From the latter, data and discussion are presented for two groups of nutrients: cations (potassium, calcium, magnesium, and sodium) and nitrogen, phosphorus, and chloride. The multiple analyses permitted (a) an assessment of the effect of potassium chloride treatment on the above elements in the various plants, (b) a check of nutrient sufficiency at all levels of potassium treatment, and (c) the partial mineral characterization of those species. Species used were Phaseolus lathyroides, P. atropurpureus, Desrnodium intortum, D. uncinatum, Stylosanthes humilis, Lotononis bainesii, Centrosema pubescens, Medicago sativa, M. truncatula, Trifolium repens, and T. fragiferum. Within the cation group, potassium application had little effect on the plant potassium concentration at low treatment levels, despite large increases in growth; at medium to high application rates, potassium concentration increased in the plant tissue. Potassium treatment caused decreases in calcium, magnesium, and sodium in the plant tissue, but these effects were not general for all species. In P. lathyroides, P. atropurpureus, and M. sativa the effect of added potassium chloride on plant calcium was relatively small compared with that for the remaining species. In C. pubescens, M. truncatula, and T. fragiferum there was little to no effect of potassium chloride on magnesium concentration; in other species the uptake of magnesium was depressed. Sodium concentrations in D. intortum, D. uncinatum, and C. pubescens were not affected by potassium chloride additions; in other species there were substantial reductions. In both cases, magnesium and sodium, the species which did not show any interaction with potassium chloride were relatively low in magnesium and sodium respectively. There was little effect of treatment on total cation contents. Potassium chloride applications had no effect on plant nitrogen concentration but increased the concentration of chloride and decreased that of phosphorus; these effects, however, were also conditioned by species. The Desrnodium species were depressed in growth by high chloride.
Utilization of Zizyphus nummularia leaves by three breeds of sheep
Authors: Nath K , Malik NS , Singh ON
Published: November 2004

The chemical composition of Zizyphus nummularia leaves was determined, and their nutritive value studied by feeding them to 8-month-old ram lambs, three each of the Rambouillet, Rambouillet x Chokla, and Malpura breeds. Z. nummularia leaves contained 14% crude protein, 3% ether extract, 17% crude fibre, 56% nitrogen-free extract, 73% total carbohydrates, 10% total ash, 2.8% calcium, and 0.14% phosphorus. The dry matter intake of the lambs was 2.05 kg per 100 kg body weight. The palatability of the leaves was low and the animals lost weight. The average digestion coefficients of dry matter, organic matter, crude protein, ether extract, crude fibre, nitrogen-free extract, and total carbohydrates were 44, 54, 40, 28, 35, 64, and 57% respectively. The digestion coefficients of the nutrients did not differ between breeds except that for crude protein, which was higher in the Rambouillet (P < 0.05). The leaves contained 5.56 kg digestible crude protein and 49.7 kg total digestible nutrients per 100 kg dry matter. The nutritive ratio was 1 : 7.9. The leaves were quite nutritious, but palatability was low. Digestibility of protein was poor and urinary nitrogen excretion was low. Animals were in positive nitrogen balance, yet lost weight; possible causes for this are discussed. It is considered that Z. nummuluria leaves fed to growing lambs should be supplemented with other fodder. Protein and phosphorus supplements also seem desirable. Results indicate that wider investigations on factors limiting food intake, the role of supplements in improving the nutritional inadequacy of the diet, and ecological aspects of Zizyphus are necessary.
Relationships between body weight and some follicle and fleece characters in an Australian fine-wool Merino flock
Authors: Nay T , Hayman RH
Published: November 2004

Phenotypic correlations between body weight, follicle characters, and fleece characters have been investigated in a flock of 95 fine-wool non-Peppin Merino wethers, reared in the same locality under the same conditions. The results indicated that three follicle characters, follicle chord, follicle depth, and the index of follicle bending, were independent of body weight. It was found, in agreement with the results of other workers, that body weight was highly correlated with both greasy and clean wool weights (r = 0.53 and 0.51 respectively). It was also found that follicle characters were significantly correlated with most of the fleece characters which contribute to the clean fleece weight per unit area of skin. The correlation coefficient of wool weight per unit area of skin with follicle chord was 0.33, with follicle depth 0.28, and with follicle bending index –0.35. The follicle characters were also correlated with greasy and clean fleece weights. Crimp number per inch was predicted for individual animals by using as criterion the length of the follicle chord. A highly significant correlation coefficient of 0.67 was obtained between predicted and observed crimp number. The close relationship between crimp chord and follicle chord reported in previous work was confirmed. It is suggested that simultaneous selection for body weight and certain follicle characters may have an additive effect on the production of clean wool. It is also suggested that the genetic antagonism between clean wool weight and number of crimps per inch can be explained in anatomical terms.
Nodulation and nitrogen fixation by Vigna sinensis and Vicia atropurpurea: The influence of concentration, form, and site of application of combined nitrogen
Authors: Dart PJ , Wildon DC
Published: November 2004

Nitrogen fixation by Vigna sinesis nodulated effectively either by Rhizobium strain QA323 or by strain CB441 is little restricted by applications at sowing of ammonium nitrate up to 24 mg nitrogen per plant. The growth patterns of these two associations are differentially affected by nitrogen level, and are both considerably different from that of unnodulated plants given combined nitrogen. Nitrogen fixation by V. sinensis-strain SU318 may be stimulated by small doses of combined nitrogen at sowing, but for Vicia atvopurpurea all the combined nitrogen levels used in these experiments depressed fixation. Primary root nodulation of V. atropurpurea by the effective Rhizobium strain V27E and the ineffective strain NA6, and of V. sinensis by the effective Rhizobium strain SU318, is influenced by the form and amount of the nitrogen compound applied (ammonium nitrate, potassium nitrate, ammonium sulphate, or urea), and that of V. atropurpurea is also influenced by the Rhizobium strain. These forms of combined nitrogen restrict primary root nodulation on both hosts similarly except that urea has little effect on V. atuopurpurea. In both species many more nodules formed on the secondary roots than on the primary, but numbers of secondary root nodules are little affected by the combined nitrogen. Immersion of the first leaves of V. sinensis seedlings in solutions of combined nitrogen depressed nodulation, but urea slightly increased the dry weight of tops.
The effects of intravenous urea infusions on nitrogen metabolism in sheep
Authors: McIntyre KH , Williams VJ
Published: November 2004

The effects of intravenous infusions of measured amounts of urea solution into sheep, providing c. 5 g urea nitrogen per day, were studied in sheep on four rations differing in crude protein and readily available energy content. Nitrogen balances, water intakes, urea nitrogen excretions, and diurnal variations in plasma urea and rumen ammonia levels were compared over 8-day collection periods. When corn starch and dried molasses provided readily available energy in addition to crushed pure cellulose the retention of infused urea nitrogen was 50 % compared with 40 % with crushed pure cellulose. It is suggested that as nitrogen retention was similar to the increases in nitrogen balance, the nitrogen retained was first transported into the rumen, where it was synthesized to microbial protein. Thus corn starch, molasses, and crushed cellulose provided suitable energy levels for utilization of the extra nitrogen by the rumen micro-organisms. On a low protein, all roughage ration the nitrogen transferred into the rumen produced increased rumen ammonia levels and was subsequently reabsorbed and excreted in the urine.
Seasonal changes in growth and nodulation of perennial tropical pasture legumes in the field. II. Effects of controlled defoliation levels on nodulation of Desmodium uncinatum and Phaseolus atropurpureus
Authors: Whiteman PC
Published: November 2004

In a field experiment comparing the effects of varying levels of defoliation on the nodulation of two tropical legumes, D. intortum cv. Greenleaf and P. atropurpureus cv. Siratro, five treatments were imposed: (1) control, (2) cutting at 3 in., (3) removal of all leaves and petioles, (4) removal of half the leaves, taking the young leaves, (5) removal of half the leaves, taking the old leaves. The defoliation treatments were imposed twice, at plant age 73 and 103 days, and sampled twice, at 18 and 26 days, after each defoliation. The effects of defoliation were not evident for at least 18 days, but subsequently the nodule weight per plant was reduced by defoliation, the reduction being related to the severity of the initial defoliation. Cutting reduced both the nodule number and weight per nodule in both species. In P. atropurpureus removing all leaves had a similar effect to cutting. In the other defoliation treatments in both species, the weight per nodule declined even though the nodule number increased, and thus the nodule weight per plant increased or remained constant. This provided evidence that changes in nodule weight induced by defoliation were related to a loss of part of the original nodule population and initiation of new nodules.
Interrelationships of stocking rate and superphosphate rate on pasture as determinants of animal production. I. Continuously grazed old pasture land
Authors: Carter ED , Day HR
Published: November 2004

Merino wethers were grazed continuously on a predominantly annual pasture in the Mediterranean environment of South Australia to assess the animal and pasture responses to, and financial returns from, factorial combinations of stocking rate and superphosphate. Stocking rate and superphosphate both significantly influenced pasture production, pasture availability, percentage pasture utilization and consequent sheep body weight, wool production, and wool value. Neither main effect markedly influenced botanical composition. Significant interactions between stocking rate and superphosphate occurred in relation to sheep body weight on some occasions during the third year of the experiment, and in the case of wool per head, wool per acre, and value of wool per acre in the second and third years of the experiment. The results showed clearly that there was no economic justification for applying high levels of superphosphate to old pasture land unless the additional pasture production was utilized through an increased stocking rate. Only at the high stocking rate was there a significant correlation between pasture production and wool production. At this high stocking rate there was marked dependence on medium or high rates of application of superphosphate to ensure satisfactory levels of pasture production, pasture availability, wool production, sheep survival, and profitability.
Metabolism of pyrrolizidine alkaloids in the ovine rumen. I. Formation of 7-α-hydroxy-1-α-methyl-8-α pyrrolizidine from heliotrine and lasiocarpine
Authors: Lanigan GW , Smith LW
Published: November 2004

In vitro studies have demonstrated that the rate of metabolism of pyrrolizidine alkaloids in sheep's rumen fluid varies greatly. Fluids from sheep at pasture display much higher activity than do those from chaff-fed animals. Addition of dried Heliotropium europaeum to a chaff ration leads to a marked increase in the in vitro rate of alkaloid degradation by the rumen fluid but activity rapidly declines again when the H. europaeum is withdrawn. Thus a major factor limiting multiplication in the rumen of bacteria responsible for alkaloid breakdown appears to be lack of their specific substrates. N-oxides of pyrrolizidine alkaloids are rapidly reduced to tertiary bases in rumen fluid, even in samples from sheep not previously exposed to these substrates. The stimulation of the alkaloid-metabolizing system by vitamin B12 also varies greatly, both in whole rumen fluid and in fluids with activity reduced by removal of coarsely particulate matter. It is concluded that the B12 effect is not related to a specific requirement of the alkaloid-utilizing bacteria but to stimulation of other species which produce a metabolite essential for pyrrolizidine alkaloid metabolism.
The effects of increased nitrogen intakes on plasma urea nitrogen and rumen ammonia levels in sheep
Authors: McIntyre KH
Published: November 2004

A series of five roughage rations providing increasing amounts of nitrogen (6.8, 16.8, 23.5, 37.3, and 46.3 g/day) and some changes in dry matter intakes (720, 710, 704, 1056, and 1408 g/day) was offered to sheep. The first four rations were given hourly and the fifth ad libitum. Urine outputs, urine total nitrogen, urine urea nitrogen, and urea clearance values increased with nitrogen intakes. Water intakes were linearly related to dry matter intakes. Plasma urea nitrogen and rumen ammonia levels both increased linearly to about 30 mg/100 ml, but did not increase further on higher levels of nitrogen intake. At these levels of intake both plasma urea nitrogen and rumen ammonia levels were no longer related to urine nitrogen excretion rates. The results are discussed in relation to the role of the kidney tubules in nitrogen excretion in the sheep.
Shoot growth on lucerne plants cut at different heights
Authors: Leach GJ
Published: November 2004

Lucerne (Medicago sativa L.) plants grown to two stages of maturity were cut at 2, 5, or 10 cm above the crown. In addition, the leaf on the stubble and on basal shoots was either removed or retained. The change in the number and size of the regrowth shoots growing from different heights above the crown, and the total yield of dry matter, were observed for 4 weeks after cutting. Nearly all the regrowth shoots arose from very near to the crown, either on the crown itself or from within the first 2 cm above it, so that cutting at higher levels increased shoot numbers only slightly. Also most of the shoots arising from near the crown resumed extension growth earlier, and therefore grew larger, than the shoots arising from higher positions. In general the growth of shoots from one stubble segment was not influenced by whether segments were still present above. Increasing the cutting height above 2 cm consequently produced little effect on the yield of dry matter 2 and 4 weeks after cutting. Retaining stubble leaf and basal shoot leaf increased the shoot yield 2 and 4 weeks later, because the basal shoots resuming growth first grew larger than those on plants from which leaves were removed. The effect of retaining leaves was independent of the stage of maturity when the plants were cut and of the cutting height.
Physiological and ecological studies on the oestrogenic isoflavones in subterranean clover, (T. subterraneum L.) VIII. Phosphate supply in relation to temperature and to leaf development
Authors: Rossiter RC
Published: November 2004

In recently expanded first trifoliate leaves of the Dwalganup strain of subterranean clover, the relative difference for concentrations of formononetin at low and high phosphate supply levels was about the same at 12.5, 22.5, and 32.5�C. However, absolute differences were much less at the high temperature, where concentrations were also low. The concentrations of the other isoflavones, genistein and biochanin A, were much less affected by phosphate supply than was formononetin. Effects of phosphate on isoflavone concentrations were already evident at leaf emergence; and in phosphate-deficient leaves, concentrations of isoflavones - especially formononetin - increased during the later stages of leaf growth. Isoflavone production per leaf cell seems to be dependent on the supply of carbon substrates in the form of sugars and starch.
Fertility following synchronization of oestrus in the sheep with intravaginal sponges. II. Effect of dose of progestagen and rate of absorption
Authors: Robinson TJ
Published: November 2004

The effect on fertility of the amount of Cronolone (Searle) absorbed from intravaginal sponges and the method of artificial insemination was studied. A significant linear relationship exists between fertility and the amount absorbed in 16 days, over the range 1-10 mg. No such relationship can be demonstrated above this amount, and great variability and sensitivity to failure of fertility is shown at all dose levels. Insemination on a fixed time basis is superior to that on teasing. Of ewes inseminated on a time basis on the second or third day after withdrawal of sponges, 117 lambed of 237 treated (49.4%). Of ewes inseminated on detection of oestrus, 97 lambed of 196 in oestrus (49.5 %) of 249 treated (39 .O %).
The effects of grazing on the phosphorus requirement of an annual pasture
Authors: Ozanne PG , Howes KMW
Published: November 2004

The applied phosphorus requirement of a pasture sown to subterranean clover was measured with and without grazing. Under moderate grazing pressure, in the year of establishment, the pasture required about 50 % more phosphorus than when ungrazed. In the following season, at a higher stocking rate, the grazed areas needed twice as much phosphorus as the ungrazed to make 90% of their maximum growth. In both years this difference in requirement between stocked and unstocked treatments was present throughout the growing season. Increased phosphorus requirement under grazing is associated with the need for greater uptake of phosphorus under conditions where redistribution of absorbed phosphorus within the plant is prevented by defoliation. It does not appear to be due to effects of defoliation on root size. Nor does it depend on differential light interception or on changes in botanical composition.
Metabolism of pyrrolizidine alkaloids in the ovine rumen. III. The competitive relationship between Heliotrine metabolism and methanogenesis in the rumen fluid in vitro
Authors: Lanigan GW
Published: November 2004

Inclusion of up to 80% hydrogen in the gas phase markedly stimulated the in vitro metabolism of heliotrine in sheep rumen fluid. The maximal rate of heliotrine breakdown under these conditions was twice that obtained when cyanocobalamin was added and 10 times the rate in unsupplemented rumen fluid. A maximal rate of heliotrine metabolism equal to that in the presence of 80% hydrogen gas could be obtained with a pure carbon dioxide atmosphere if certain inhibitors of methanogenic bacteria were added to the rumen fluid. It is concluded that the heliotrine-metabolizing bacteria are normally at a disadvantage in competition with the methanogenic bacteria for metabolic hydrogen, and that inhibition of the latter organisms in vivo could provide a basis for development of effective prophylaxis in sheep at risk with Heliotropium europaeum in the field.
Digestion of pasture plants by sheep. V. Studies with subterranean and berseem clovers
Authors: Weston RH , Hogan JP
Published: November 2004

Subterranean and berseem clovers, harvested at early and late stages of maturity, were dried and offered to sheep ad libitum, or at about 90 % of ad libitum intake. Feed consumption and the times spent in ruminating and eating were measured when the forages were offered ad libitum and several aspects of digestion were studied at the restricted level of feeding. The effects of maturity on (i) forage chemical composition, (ii) nutrient digestibility, (iii) parameters relating to the movement of digesta through the stomach, (iv) ruminal volatile fatty acid production, (v) the molar proportions of individual amino acids in abomasal digesta and peripheral blood plasma, (vi) nitrogen balance, and (vii) the time and energy expenditure in ruminating and eating, were generally the same with these clovers as has been observed previously with grasses. Substantial amounts of nutrients were derived from forages harvested in the immature state, the consumption of which provided about 1200 g organic matter per day. It was calculated that under conditions of ad libitum feeding about 500 g of volatile fatty acids was produced in the rumen and 160-230 g of crude protein was digested in the intestines per day. High mean values for nitrogen balance were obtained with immature subterranean clover but the variation between sheep was large. The levels of amino acids in blood plasma were also exceptionally high with this diet. The data obtained on the digestion of immature clover forages were compared with those obtained previously with immature grass forages. The patterns of digestion were generally very similar for both types of forages and any differences observed could usually be ascribed to the higher feed intake with the clovers. The forages had similar capacities to furnish volatile fatty acids in the rumen and digested crude protein in the intestines. The calculated energy expenditure in eating and ruminating, however, was slightly lower for the clovers. The data were interpreted to indicate that if immature clovers are superior to immature grasses in promoting animal production, the superiority cannot be attributed to an inherent capacity of clovers to provide the animal with a more favourable balance of nutrients.
Inheritance of diazionon resistance in the Biarra strain of the cattle tick (Boophilus microplus) in Australia
Authors: Wilson JT , Stone BF , Wharton RH
Published: November 2004

The organophosphorus-resistant Biarra strain of the cattle tick, B. microplus, from southern Queensland was crossed reciprocally with a susceptible reference strain and the resistances of these parental strains to diazinon were compared with those of F1, test cross, and F2 larvae. The data obtained were in agreement with expectations for one inconlpletely dominant autosomal gene or several closely linked genes controlling resistance. The degree of dominance at LD50s ranged from +0.488 to . + 0.622. Homozygotes and heterozygotes were respectively 20-36 and 9.5-18 times as resistant to diazinon.
The estimation of milk intake and growth of beef calves in the field by using tritiated water
Authors: Yates NG , Macfarlane WV , Ellis R
Published: November 2004

The growth of Hereford, Friesian x Hereford, and Friesian x Shorthorn calves was studied under grazing conditions in the south-east of South Australia during the autumn period of minimal dry pasture. Measurements of body water content, water turnover, and body weight changes of calves were undertaken during an 8-week period after calving in February 1968. From these measurements, estimates were made of liveweight gain and the yield of body solids per unit of water turnover (milk intake). The subsequent development of the calves was also measured. The average birth weights of the three groups were not significantly different. The 8-week total of water intake (milk) was 405 � 14.3 1. in Shorthorn cross calves, 279 � 18.0 1. for Hereford cross, and 263 � 14.3 1. among the Herefords. Over the first 8 weeks body weight gain (g/24 hr) was highest in the Shorthorn cross calves and their body solids gain was 63 % greater than that of the Hereford cross calves but only 29 % greater than that of the Hereford calves. Water turnover (1.124 hr) of the Shorthorn cross calves was 45 % greater than that of the Hereford cross calves and 54% greater than that of the Hereford calves over the 8-week period. There was no significant difference between the three groups in body weight or solids gain per unit of milk intake (g/l), though the average conversion of milk to solids by Herefords was greater than that of the other breeds. The Shorthorn cows weighed less than the other groups after calving and their average relative and absolute loss of weight during lactation was greatest. The offspring of the Shorthorn cows had the highest water intake expressed as a function of the body weight0.75 of the cows. The water turnover of Shorthorn calves as a function of calf weight0.82 was also greater than that of the other calves. The correlations between body weight gain (g/24 hr) and water turnover (l./24 hr) and between body solids gain (g/24 hr) and water turnover (l./24 hr) were 0.815 (P < 0.001) and 0.632 (P < 0.01) respectively. The correlation between cow body weight loss and calf body weight gain was 0.481 (P < 0.05). A group of nine Friesian x Hereford calves studied for 11 weeks after calving in April 1969 on newly grown winter rainfall pasture 50 km north of Adelaide had both average water turnover (l./24 hr) and body weight gains (g/24 hr) substantially higher than those of any group in the previous year. The efficiency of conversion estimated as body solids gain and body weight gain per unit of water intake was, however, similar to those of the Hereford calves in 1968. The differences between the years are presumed to follow from differences in the amount of pasture available in the dry season, relative to pasture after the rains had come. Average body water content (TOH space) was 801 ml/kg body weight at the beginning of the measurements and gradually fell to 713 ml/kg at 11 weeks.
Growth and water metabolism of cows and progeny on fertilized and unfertilized tropical pastures
Authors: Siebert BD
Published: November 2004

Growth of Brahman x Shorthorn cows and their calves grazing unfertilized and fertilized pasture was studied in relation to body water content and water turnover; the main plant species in the pasture were spear grass (Heteropogon contortus) and Townsville stylo (Stylosanthes humilis). During the dry season, prior to the birth of calves, there was little difference in body weight or body composition between cows from the unfertilized and fertilized areas, despite the greater yield of pasture on the latter. The increase in body weight of both groups after the onset of the new season was due to expansion of the body water space. Body solids did not increase until c. 2 months later. The cattle from the fertilized pasture continued to increase in weight over the entire wet season at a significantly faster rate (P < 0.001) than those in the unfertilized pasture, and this latter group ceased growing a month before the end of the season. There was no significant difference in birth weight between the two groups of calves, although those from the fertilized pasture were significantly heavier at 2 weeks of age; during these 2 weeks they had received 45 % more milk, and until about 20 weeks they continued to grow more rapidly and turn over more water than the group from the unfertilized pasture. From 20 weeks the quality of the forage in the unfertilized pasture became superior, owing to the relatively high proportion of legume (Stylosanthes humilis), and the calves from the unfertilized pasture grew more rapidly until the end of the wet season. Plant nitrogen content was reflected in plasma urea nitrogen levels. The relationship between pasture quality and growth of cows and their calves is discussed.
Oestrous activity and lamb production in the New Zealand Romney ewe
Authors: Quinlivan TD , Martin CA
Published: November 2004

An experiment is described in which the effects of time of mating within the breeding season, farms, and ewe age on patterns of oestrous activity and other reproductive parameters in the New Zealand Romney ewe were examined. The following results were obtained: (i) The patterns of oestrus on each of five farms situated at varying altitudes, over nine 17 day periods of mating from January to June, followed that of a sigmoid curve (P < 0.001). The patterns of oestrous activity on farms 4 and 5 (situated at 1500 and 2000 ft), when compared with the three lower properties, were characterized by a later onset, a shorter period of peak activity, and an earlier decline in the proportion of ewes in oestrus (P < 0.001). The proportion of ewes 1.5 years old which exhibited oestrus was less than in the other three age groups studied: 1.5 years 53.2%, 2.5 years 57.7%, 3.5 years 56.3%, 4.5 years 58.1% (P < 0.01). (ii) The proportion of ewes which returned to service was lower the later the mating (P < 0.001). The incidence of barrenness in ewes which had failed to return to a single service and were therefore considered pregnant increased linearly with time of mating (P < 0.001). (iii) Of the ewes in oestrus, 78.8 % lambed to a single service. There was a significant linear increase in the proportion of ewes lambing to those in oestrus with time of mating (P < 0.001). Further, less ewes lambed to a single service on farms 4 and 5 than on farms 1, 2, and 3 (P < 0.01). (iv) There were significant differences in total and live lamb production with time of mating (0.01 > P > 0.001), between farms (P < 0,001), and between ewe ages (P < 0.001). Multiple births reached a peak at mid-season. Interactions of time of mating with ewe age for multiple births, and with farms for live lamb production, were also significant (P < 0.01). (v) The incidence of perinatal losses to 3 days after birth showed a highly significant difference between farms (P < 0.001). There was also a mid-season rise in lamb losses (P < 0.001) and this accounted for a non-seasonal peak period in live lamb production measured as a ratio either to ewes lambing or to ewes in oestrus. (vi) The performance of maiden ewes (1.5 years) was lower than that of the other three age groups for proportions in oestrus, multiple births, and the ratios of live lambs to both ewes lambing and ewes in oestrus. No significant differences were demonstrated in returns to service, in barren ewes, or in the proportion of dead to total lambs born for this age group.
The effect of urea in the diet of the early-weaned calf on weight gain, nitrogen and sulphur balance, and plasma urea and free amino acid concentrations
Authors: Leibholz J , Naylor RW
Published: November 2004

Experiments were conducted with 40 male Friesian calves between 5 and 11 weeks of age. The control diet contained meat meal as the sole protein supplement to grain, and this was replaced by urea to supply 20.1, 39.2, or 55.6% of the dietary nitrogen. The growth rate of the calves, when corrected for digestible dry matter intake, was significantly lower when urea supplied 55.6 % of the dietary nitrogen than when it supplied 0, 20.1, or 39.2% of the dietary nitrogen. The retention of nitrogen and sulphur was lower in the calves given 55.6% of the dietary nitrogen as urea, but the ratio of nitrogen to sulphur retained was constant for all diets. There was a positive correlation between dietary urea nitrogen intake and urea nitrogen concentration in the blood plasma. The urea nitrogen and a-amino nitrogen concentration in the blood plasma was greater in calves at 2 weeks of age than at 11 weeks of age. The concentrations of free glycine, valine, leucine, ornithine, lysine, and histidine in the blood plasma were significantly lower in the calves given the higher levels of urea in the diet.
Thermal status of sheep at pasture in western New South Wales
Authors: Brown GD
Published: November 2004

The thermal status of three unrestrained rams at pasture was studied for a period of 5 days during March in central western New South Wales. A temperature telemetry system was used to measure rectal temperatures, skin surface and subcutaneous temperatures on the mid back, and subcutaneous temperatures of the scrotum of each ram. Rectal temperatures of 40�C and above were recorded for all rams on each day, the highest recorded being 41 9 4 and 41.6�. Rectal temperatures in excess of 40� were also recorded for extended periods between 6.00 p.m. and midnight. Although respiratory frequencies increased with the increase in environmental heat load during the day, no obvious signs of extreme heat stress were noted at these elevated rectal temperatures, whereas sheep exposed to high heat loads in indoor experiments consistently exhibit heat stress at similar rectal temperatures. Rectal temperatures were generally higher and more variable than those reported by other workers for penned sheep in either indoor or outdoor environments. Subcutaneous scrota1 temperatures were usually lower than those which might be expected to induce sterility. Variations in the temperatures measured have been related to the thermal environment and patterns of behaviour of the sheep.