bluuebunny/crossref_metadata_2025 huggingface dataset:
Creatinine as an index substance for estimating the urinary excretion of nitrogen and potassium by grazing sheep
Authors: Langlands JP
Published: November 2004

The use of creatinine as an index of urinary nitrogen and potassium excretion of grazing sheep was examined in three experiments. Separate relationships between creatinine excretion and liveweight were derived for ewes and wethers in experiment 1. These equations were used in experiment 2 to predict the urinary nitrogen and potassium excretion of sheep maintained in metabolism cages from the nitrogen : creatinine and potassium : creatinine ratios in urine samples taken at 0900 and 1630 hours. These estimates were compared with the measured urinary nitrogen and potassium output. It was concluded that urinary nitrogen excretion of one sheep on one day could be estimated with a random error of ± 17% and potassium output with an error of ± 24%. Both estimates were subject to bias. In experiment 3, changes in the nitrogen : creatinine and potassium : creatinine ratios of six grazing wethers were measured; a diurnal trend in the nitrogen : creatinine ratio was observed. The reliability of two possible sampling procedures was examined and it was concluded that under grazing conditions the technique could only be used to detect large differences in urinary nitrogen and potassium excretion.
Distribution of Oesophagostomum columbianum larvae along the alimentary tract of the sheep
Authors: Dobson C
Published: November 2004

Linear distribution of the third-stage larvae of O. columbianum along the alimentary tract, and ectopic distribution within the organs of the body cavity, were investigated in sheep which were given first, second, and third infestations with 5000 larvae. Two types of nodule were recognized: (1) small gritty lesions, which predominated in the small intestine; (2) caseous nodules, mostly found in the large intestines. Linear distribution of the larvae was characterized by two peaks in numbers along the small intestine, the first immediately posterior to the common bile duct and the second at the ileocaecal valve. The origin of these peaks is discussed in relation to the exsheathment and subsequent behaviour of third-stage larvae and the flow of ingesta along the gut. Three peaks in larvae numbers were recognized in the large intestine; these are discussed in relation to the movements of ingesta. After second and third infestations the numbers of caseous nodules increased and those of ectopic migrations decreased. Also a third peak in the numbers of larvae invading the wall of the small intestine occurred at the beginning of the ileum. This is discussed in relation to the immunity reactions of the host. Of O. columbianum larvae, 75% were found to exsheath in the rumen after 12 hr; pH alone had little effect on exsheathment, except at a value of 6.5, which is equivalent to the pH of the ruminal contents when 10% of the larvae exsheathed after 8 hr. The effects of fresh bile on larval activity was also studied. These results are discussed in relation to the linear distribution of the larvae. It is suggested that after larvae have exsheathed, they respond specifically to environmental change by penetrating the gut wall. When the larvae penetrate into the body cavity, environmental changes are absent and the resultant larval migrations are completely random. It is also suggested that the final area in which the adult worm will settle depends on the part of the gut in which the larvae exsheathed and the area of the gut wall which the activated larvae penetrated. The distribution of caseous nodules is discussed in relation to the host specificity of O. columbianum.
Studies on the immunity of sheep to Oesophagostomum columbianum: The nature and fate of the globule leucocyte.
Authors: Dobson C
Published: November 2004

The histological, histochemical, and cytological relationships between the globule leucocyte, plasma cell, and Russell body cell were studied and it was concluded that they belonged to the same cell lineage. The histochemistry of the globules was studied. They were found to be made up of mucoprotein, which was shown to be a y-globulin. The presence of this substance is discussed in relation to the development of immunity to O. columbianum. A correlation was shown between the duration of infestation and multiple infestations, and the occurrence and numbers of the globule leucocyte. A relationship was demonstrated between the numbers of plasma cells, and globule leucocytes in the gut. The relationship between the distributions of larval lesions, adult worms, and globule leucocytes is discussed. It is concluded that globule leucocytes in a region are an indication that a strong immunological response has occurred, since their numbers were related to the numbers of larval lesions and particularly to the numbers of adult worms present in the gut. It is suggested that the presence of large numbers of globule leucocytes is an abnormal reaction by the host and indicates persistent antigenic stimulation or chronic stressing of the lymphoid tissue within the gut. This postulate is discussed in relation to the electrophoretic protein pattern of the serum and tissue proteins, the histochemistry of the plasma cell series of lymphoid cells, and the antibody levels in the serum and tissues.
Physiological and ecological studies on the oestrogenic isoflavones in subterranean clover (T. subterraneum L.) III. Effects of light
Authors: Rossiter RC , Beck AB
Published: November 2004

Isoflavone levels in subterranean clover leaves were higher in 13 hr days of natural daylight than in 6 hr days, but length of photoperiod per se had no substantial effect on these levels. In the field, reduction of light intensity (by shading) to 40% daylight caused no decline in isoflavone levels compared with full daylight; even at 24% daylight the reduction in levels was ill defined. On the other hand, in young seedlings there was a marked fall in isoflavone content, especially in the unifoliate leaf, as light intensity fell from 950 to 320 f.c. However, appreciable isoflavone formation was found in dark-grown clover seedlings. Possible light reactions connected with the promotion of isoflavone synthesis are discussed. Changes in isoflavone levels resulting from variation in the natural light environment are unlikely to be sufficient to affect "clover disease".
The promotion of winter growth in pastures through growth substances and photoperiod
Authors: Arnold GW , Bennett D , Williams CN
Published: November 2004

The effects of growth substances and extended photoperiod on the growth rate of phalaris-annual grasses-subterranean clover pastures were studied at Canberra in the winter of 1964. Responses to applications of 4 and 20 g gibberellic acid (GA) per acre differed for June and July applications. All available data on GA responses on this pasture type were collated. Responses to GA increased with decreased growth rate of normal pasture. Thus a sixfold increase in growth rate was obtained when the normal growth rate was 2 lb dry matter/acre/day. Responses were independent of dose rate (from 1 to 105 g GA per acre) or time of application. Responses to GA were obtained subsequent to the first harvest. The length of time during which cumulative growth on GA-treated pastures exceeded that on normal pastures was related to the growth rate of the normal pastures. The response in growth to 4 g GA could be increased to the level of that obtained with 20 g GA by the addition of either 4 g naphthylacetic acid or 4 g kinetin. Phalaris showed greater response to GA than did annual grasses or subterranean clover. Extending the photoperiod to 16 hr gave a 40% increase in growth rate in winter. This was associated with earlier floral initiation whereas increases in growth rate induced by growth substances were not. These results are discussed in relation to increasing plant and animal productivity in year-round grazing systems.
Bioassay responses of ewes to legume swards. II. Uterine weight results from swards
Authors: Bennett D , Morley FHW , Axelsen A
Published: November 2004

Three years' results of sheep uterine weight bioassays on a range of clover swards are presented. Trifolium pratense L. (var. Grasslands Hamua Broad) and Trifolium subterraneum L. (var. Dinninup, Dwalganup, Tallarook, and Yarloop) showed high activity whenever they were green. Trifolium fragiferum L. (mixed+Palestine), Trifolium repens L. (var. Victorian Irrigation), and Trifolium subterraneum L. (var. Bacchus Marsh, Howard, Marrar, and a breeder's selection) showed variable activity; Medicago sativa L. (var. Hunter River), Medicago littoralis (Rhode), Trifolium alexandrinum L., Trifolium incarnatum L. (var. Dixie), and Trifolium repens L. (var. Grasslands Huia and Ladino) have not shown activity. Spraying two of the clovers with paraquat and dosing the sheep with cobalt sulphate had no effect on activity. There was a strong seasonal trend with highest activity in midwinter and lowest in mid spring. The relationships between chemical assay and bioassay results are discussed. There is reasonable evidence that the activity of Victorian Irrigation white clover is not related to any of the compounds being measured.
Rates of production of volatile fatty acids in the rumen. V. Evaluation of fodders in terms of volatile fatty acid produced in the rumen of the sheep
Authors: Gray FV , Weller RA , Pilgrim AF , Jones GB
Published: November 2004

l(a). Volatile fatty acid (VFA) production (moles/12 hr) by two sheep fed at 2-hourly intervals on a constant ration containing equal parts of wheaten hay and lucerne hay, showed no significant difference between the sheep or between day-time and night-time values. The precision with which production could be measured over a series of 12-hr periods is given. The quantities of VFA produced in the rumen on successive days varied considerably; the extent of this variation was similar to that occurring in the quantities of faeces passed. (b) Production remained much the same whether the sheep were fed at intervals of 1, 2, or 12 hr. (c) The energy of the VFA produced in the rumen was equivalent to about 54% of the digestible energy of the diet. 2. Similar amounts of VFA were produced from two different mixtures of wheaten hay and lucerne hay, and from lucerne hay alone. 3. A modification in the procedure for measuring VFA production was tested and found to be satisfactory. The necessary apparatus could be readily carried on the back of a freely moving sheep.
The reaction of calves to helminth infection under natural grazing conditions. II. Pathology of terminal disease
Authors: Elek P , Bremner KC , Durie PH
Published: November 2004

Calves raised worm-free were exposed to natural infection on unimproved pasture infected with Trichostrongylus axei, Haemonchus placei, Ostertagia ostertagia, Cooperia punctata and C. pectinata, and Oesophagostomum radiatum. Some calves received, in addition, experimental infections of O. radiatum and H. placei. All calves showed depressed body weight gains. Haematocrit, haemoglobin, and serum protein levels were reduced, returned to normal after 15–18 weeks' grazing in calves that survived, but continued to fall and reached lower levels in those that died. Calves killed in extremis showed emaciation, oedema, degenerated fat tissue, inflammatory and degenerative changes in the gastrointestinal tract, and atrophy of the lymphatic tissues and thymus. These symptoms are reminiscent of a "wasting syndrome".
Summer dormancy in Phalaris tuberosa
Authors: Hoen K
Published: November 2004

Summer dormancy of field-grown plants of five strains of Phalaris tuberosa L. was investigated at various times during the summer by transferring them to trays with moist sand kept at room temperature (20–25°C). The rate of appearance of new shoots was used to measure differences in dormancy Levels. Differences between strains were significant in most experiments. They were largest in January, and decreased subsequently. The average level of dormancy was high in January, low in February, and increased again after mid February without reaching the original level. Development of new shoots was retarded by high temperatures. It is suggested that in the early stages dormancy is mainly a continuation of inhibition of bud growth by elongated tillers, whereas in the later part of summer, soil temperature and soil moisture are the main factors which control the development of new shoots.
Resistance of cattle to cattle tick, Boophilus microplus. II. The inheritance of resistance to experimental infestation
Authors: Hewetson RW
Published: November 2004

Fifty-nine quarter-bred Zebu steers sired by six half-bred Zebu bulls were exposed to four infestations of 40,000 larval ticks at 7–11 week intervals, followed in another 7 weeks by a paddock infestation. All developed a strong resistance to artificial infestations with cattle ticks by the third infestation. There was no sire difference at the first infestation and a zero heritability estimate for tick resistance. At the fourth infestation there was a heritability of 28%, which increased to 42% at the fifth infestation. Female tick weights, egg-laying ability of ticks. and viability of eggs laid appeared to be affected by sires. Heritabilities of these characters are discussed.
The significance of equol in relation to the oestrogenic responses in sheep ingesting clover with a high formononetin content
Authors: Shutt DA , Braden AWH
Published: November 2004

Equol (7,4'-dihydroxyisoflavan), a metabolite in sheep of the dietary isoflavone formononetin, was found to be oestrogenic in mice. By subcutaneous administration it had about one-quarter of the activity of genistein. Equol (35–68 µg/100 ml) was found in the peripheral blood of sheep 4–24 hr after first feeding with red clover (Trifolium pratense) pellets, and represented 9–68% of the "free" and 23–72% of the conjugated "phyto-oestrogens" in the plasma. In ewes grazing red clover, equol was found in the plasma (50 µg/100 ml) and in the uterine tissue (46 µg/uterus) and represented in both instances more than 70% of the extracted "phyto-oestrogen". It is concluded that equol is probably of major importance in relation to the oestrogenic activity found in sheep ingesting clover with a high formononetin content. In guinea-pigs, equol (32–71 µg/100 ml) was found in plasma samples 4–16 hr (day 3) after feeding with red clover pellets. Another probable metabolite of formononetin, referred to as metabolite "A" and tentatively identified as demethylated angolensin (2,4-dihydroxyphenyl-p-hydroxyphenylethylketone), was also noted in the plasma of sheep and guinea-pigs after ingesting red clover.
Studies on salt tolerance of sheep. VII. The tolerance of ewes and their lambs in pens for drinking waters of the types obtained from underground sources in Australia
Authors: Peirce AW
Published: November 2004

Groups of eight or 10 ewes were fed in pens on a ration of chaffed lucerne and wheaten hays and oats and were offered various solutions as drinking waters. In two experiments these comprised: (1) reservoir water (control group); (2) synthetic water containing salts in the proportions found in many underground waters in South and Western Australia ("chloride water") with a total salt concentration of 1.30%; or (3) synthetic water resembling the waters obtained in Queensland from the Great Artesian Basin ("bicarbonate water") with a total salt concentration of 0.50%. In a third experiment the total concentration of salts in the chloride water was only 1.00%, that of the bicarbonate water again being 0.50%. The ewes were mated, they lambed, and they reared their lambs on the experimental regime until the lambs were weaned at the age of approximately 10 weeks. The weaned lambs were continued on the treatment for a further 5 months, the total duration of each experiment being 13 months. The commencement dates of the experiments were separated by intervals of approximately 6 months; by this arrangement pregnant ewes, lactating ewes, and weaned lambs received, in at least one experiment, the saline waters during the months of high environmental temperatures, with the associated high water intakes. There was some indication in one experiment of a poorer reproductive performance by the ewes receiving either chloride (1.30% total salts) or bicarbonate water as compared with the control group. The intake of saline waters in all experiments was higher than that of reservoir water, the increases ranging from 20 to 50%. The body weight increases during early pregnancy of the ewes receiving saline waters were identical with those of the corresponding control groups. Significantly lower body weights, as compared with the control group, were observed at one period only in one group of treated lambs receiving chloride water with a concentration of 1.30% total salts. Reductions in the sodium, potassium, and chloride concentrations in the plasma occurred in some groups receiving saline water. No effect was observed on concentrations of calcium, while the effect on magnesium was variable. No adverse effects were observed on health, food consumption, or wool production of the ewes and lambs as a result of drinking any of the saline waters. It is suggested that under the conditions of the experiment, ewes and their lambs could tolerate drinking water of either the chloride type with 1.00% total salts or the bicarbonate type with 0.50*#37; total salts.
Undernutrition of the Merino sheep and its sequelae. II. The influence of finite periods of arrested growth on the subsequent wool growth, fleece development, and utilization of feed for wool production of lambs
Authors: Allden WG
Published: November 2004

Five groups of Merino lambs were subjected to contrasting nutritional regimes during a preparatory period of 400 days. All animals were then restored to a normal diet and during the subsequent 27 months the sequelae to the experimental treatments were measured in terms of wool growth, fleece development, and the utilization of feed for wool production. The most rigorous treatment (growth arrested for 400 days at 15 kg weight) had as its sequel a less dense wool follicle population (adjusted to a standard body weight) and a reduced growth rate of wool during the early recovery period. Total fibre numbers and wool growth per unit of feed intake were also depressed but not significantly so. Fibre diameter, fibre weight, and the ratio of secondary to primary follicles were not affected. The less severe treatments (growth restrictions for 200 days (a) at 15 kg and (b) at 30 kg) influenced none of the parameters under study once a normal diet had been restored. It is concluded that only with extreme under nutrition from early in post-natal life is the wool-producing potential of young sheep likely to be impaired.
Birth weight, liveweight gain in early life, and subsequent gain in sheep and cattle
Authors: Wardrop ID
Published: November 2004

The relationships between birth weight, liveweight gain in early life, and subsequent gain of cattle and sheep grazing improved pastures were studied. In both species the correlations between liveweights at each age were highly significant. For female lambs, but not for males, birth weight was significantly correlated with the subsequent liveweight gain to 3 weeks, and this gain was significantly correlated with the subsequent gain to 17 weeks of age. These sex differences could be explained by the more variable growth rates of the female lambs. Ewe milk production and lamb milk intakes from birth to 3 weeks of age were significantly correlated with the liveweight gain over that period, but not with the subsequent gain. In cattle the correlation between birth weight and the liveweight gain to 6 weeks of age was non-significant. Gain from birth to 6 weeks was significantly correlated with gain between 6 and 36 weeks of age (weaning), but not with gain between 36 and 89 weeks (slaughter). The correlations between the gains, birth or 6 weeks to weaning, with the subsequent gains to slaughter were highly significant.
Response of plants to calcium concentration in solution culture
Authors: Loneragan JF , Snowball K , Simmons WJ
Published: November 2004

Calcium concentrations required in solution for growth of 30 grasses, cereals, legumes, and herbs were defined for a wide range of concentrations which were maintained constant in Bowing culture solutions of pH 5.7. Contrary to published results obtained with standard nutrient culture techniques, some legumes and herbs grew much better at low concentrations of calcium (2.5 and 10µM ) than many Gramineae. The minimal concentration required to produce maximum growth of plants and eliminate calcium deficiency symptoms varied widely (2.5–1000 µM) within each group; it varied over the same range for Gramineae as for legumes and herbs. At 100 µM all plants grew well without symptoms of calcium deficiency. Increasing the concentration to 1000 µM increased growth in only a few species. At concentrations < l µM , severe deficiency symptoms developed on the tops of all species. The growth of legumes and herbs was more quickly and more severely affected than that of Gramineae. The roots of many legumes and herbs also degenerated rapidly. In the same solutions the roots of all Gramineae appeared healthy for some time. However, the advantage of Gramineae in these solutions was transitory, since the high relative growth rate in their early growth stages fell rapidly. It is suggested that distinct processes dominate the plants' behaviour at each range of calcium concentrations. At extremely low concentrations (< l µM ) , to which legumes and herbs are more sensitive than Gramineae, the dominant process may involve ion exchange equilibria between calcium in the environment and in the cell walls or membranes. At higher concentrations (2.5–1000 µM), to which Gramineae are as sensitive as legumes and herbs, processes of absorption of calcium from solution and translocation to plant tops are probably dominant.
Comparative photoperiodic responses for several soya bean varieties of tropical and temperate origin
Authors: Byth DE
Published: November 2004

Two experiments involving the testing of a number of soya bean varieties under a range of different photoperiods showed that all varieties were capable of flowering under all photoperiods tested, and appeared to be facultative short-day genotypes. Differential varietal responses were not obtained for flowering time at photoperiods of less than 12 hr per day, but the tropical varieties Mamloxi and Avoyelles differed markedly from the temperate variety Bienville in the flowering pattern under longer photoperiods. Other plant characters responded similarly to flowering time. Possible relationships of such responses to latitude of introduction, field adaptation in southeastern Queensland, and screening of varietal accessions are discussed. Uniform frequency distributions of an F2 population were obtained for most characters and photoperiods, which indicated a relatively complex form of inheritance. Skewness of some distributions, particularly in the longer photoperiods, suggested that the spectrum of action of genes determining these traits varied with photoperiod. Deviations from mid-parent values indicated dominance of low number of days to flowering, short node length, and high node number. Plant height approached that of the low parent in short photoperiods and the high parent in longer photoperiods. Transgressive segregation occurred for most traits, particularly in the longer photoperiods, and evidence of substantial genetic control of differences in photoperiodic response between varieties was found.
The growth of the young coconut palm (Cocos nucifera L). II. The influence of nut size on seedling growth in three cultivars
Authors: Foale MA
Published: November 2004

The growth of three coconut cultivars of the tall type from germination up to 17 months of age was compared by growth analysis. These cultivars differ considerably in mean nut size. Within each cultivar a comparison was also made between the growth of seedlings from small, medium, and large nuts. There were considerable differences between cultivars in seedling growth up to 2 months but these differences did not persist. Similarly differences due to nut size within cultivars were recorded at early harvests but had disappeared by 6 months. Thus neither genotype nor nut size had any sustained effect on the plant size. Consumption of endosperm depended on seed size: evidently a lower, compensating net assimilation rate occurred in plants with large nuts to give a similar total supply of assimilate. This suggests that the potential supply of assimilate was not limiting the growth rate. Large nuts transfer dry matter from the endosperm more rapidly than do smaller nuts; hence under unfavourable conditions for photosynthesis, larger nuts may produce larger seedlings. It is suggested that any seedling selection should be done in a favourable nursery environment so that emphasis is placed on differences in seedling vigour due to genetic variation.
Undernutrition of the Merino sheep and its sequelae. III. The effect on lifetime productivity of growth restrictions imposed at two stages of early post-natal life in a Mediterranean environment
Authors: Allden WG
Published: November 2004

The growth of Merino lambs was retarded under field conditions at two stages during the first year of life, and for the 6 years following the removal of growth restrictions the residual effects of the treatments were measured in terms of body weight, body size, wool production, teeth development and wear, and mortalities.Growth during the recovery period differed according to previous treatment. The effects of retarded growth during the first 6 months of life (pre-weaning treatment) persisted for 56 months whereas undernutrition during the second 6 months of life (post-weaning treatment) lasted for only 11 months. Each effect was independent and additive. Generous feeding during the post-weaning period produced transitory benefits but did not compensate for poor nutrition during the suckling period. All groups ultimately attained normal adult weight and stature.Pre-weaning undernutrition had as its sequel a significant reduction in clean wool production (total 620 g) during the first 23 months of the recovery period; no residual effect of post-weaning undernutrition was detectable during the early part of the recovery period. However, comparisons of the total clean wool production of the treatment groups for the 6-year recovery period provided no evidence of significant differences other than those due to sex. Wethers produced 13% (2.74 kg) more clean wool than ewes and were 15% heavier in body weight. There were no differences between the groups in respect of mortalities. Retarded growth delayed the eruption of the permanent incisors by up to 16 weeks. Teeth losses were similar in all groups.
Variation in and correlations between yield and creeping-rootedness in lucerne
Authors: Bray RA
Published: November 2004

Two polycross populations, derived from selected creeping-rooted clones, were studied in two subtropical environments. The polycrosses were similar in percentage creeping-rootedness in both environments (38% and 39%) but the prostrate polycross contained more genetic variation for most yield characters. Further progress in breeding for yield should be possible, but exploitation of non-additive variation may be necessary. High positive genotypic correlations have been established between creeping-rootedness and yield at all times of the year, indicating successful selection in early generations. Very high positive genotypic correlations exist between yields at different times of the year, although environmental correlations are low. A combination of the best parental clones should give high-yielding persistent creeping-rooted varieties.
Plasma coumestrol levels in sheep following administration of synthetic coumestrol or ingestion of medic hay (Medicago littoralis)
Authors: Shutt DA , Braden AWH , Lindner HR
Published: November 2004

Administration of coumestrol to ovariectomized sheep by either intraruminal (i/r) infusion (350 mg/day) or intramuscular (i/m) injection (7.5-–25 mg/day) gave rise to mean plasma levels of 0.6-3.1 µg coumestrol per 100 ml and to near-maximal stimulation of uterine growth. In addition the plasma contained water-soluble conjugates of coumestrol, hydrolysable by molluscan ß-glucuronidase; this fraction was quantitatively more important, relative to 'free' coumestrol, following i/r infusion of coumestrol, but seemed less closely related to oestrogenic action than was "free" plasmacoumestrol. Feeding on a ration of medic hay (Medicago littoralis), supplying approximately 146 mg coumestrol and 124 mg 4´-methoxycoumestrol per day, gave rise to plasma levels of 0.5–0.7 µg "free" coumestrol and 1.2–4.0 µg conjugated coumestrol per 100 ml, and was associated with oestrogenomimetic changes in the composition of the cervical mucus. 4´-methoxycoumestrol was not detected in the plasma, which suggested that this compound had been converted to coumestrol by O-demethylation in the medic-fed sheep.
Brown rot of stone fruits on the Murrumbidgee Irrigation Areas. I. Aetiology of the disease in canning peaches
Authors: Kable PF
Published: November 2004

In a typical season brown rot development in canning peaches on the Murrumbidgee Irrigation Areas was found to follow a basic pattern. There is little or no blossom blight or post-blossom infection. Infection of fruit is first seen in January and increases until harvest. Infections of fruit during the preharvest period are almost all initiated in injuries. Damage caused by larvae of the oriental fruit moth is the most important form of fruit injury. Infections of injured immature fruits may occur in dry weather and cannot be prevented by the application of fungicides. These injured rotting fruits produce inoculum which can start epiphytotics if rain falls when the fruit is ripe. Blighted blossoms are usually unimportant as inoculum sources at this stage, but they are important links in the infection chain since they can provide inoculum for the first infections of injured fruits. Dried fruit beetles were found to be vectors during the preharvest build-up of the disease, and there was some evidence that they may carry inoculum to blossoms in spring. Quiescent and latent fruit infections initiated in spring were noted, but they are thought to have little overall significance in the aetiology of the disease. Some infections occurring during the ripening period may exhibit latency. The implications of these findings for disease control and their relevance to brown rot aetiology in other, more humid fruit-growing areas are discussed.
A comparison of cattle tick control by pasture spelling, planned dipping, and tick-resistant cattle
Authors: Wharton RH , Harley KLS , Wilkinson PR , Utech KB , Kelley BM
Published: November 2004

Control of Boophilus microplus by pasture spelling, planned dipping, and simulated "conventional" control methods was compared in duplicate herds of British cattle, and by simulated "conventional" control methods in duplicate herds of Zebu x British and a single mixed herd of Zebu x British and British cattle. Herds under conventional control were treated with an acaricide (dipped) when the count of "standard" ticks (5 mm or more in length) on the right side averaged 20 or more per animal. Herds under pasture spelling grazed alternately in two adjacent paddocks; the summer spelling period was 3½ months, followed by spelling periods of 4½ months, and cattle were dipped on transfer between paddocks. Herds under planned dipping were dipped at 21-day intervals until few larvae remained on the pasture, this treatment being repeated when the count of standard ticks averaged more than 20 per animal. Observations over 2 years confirmed the results of an earlier experiment which showed that pasture spelling and planned dipping resulted in increased efficiency of tick control. Compared with British herds under conventional control which required dipping on 19 and 20 occasions, herds managed by pasture spelling were dipped only on seven occasions and showed a mean reduction of 81% in tick burden. Herds subjected to planned dipping required 18 treatments but the tick burden was reduced by 83%. The two Zebu x British herds required dipping on four and 10 occasions and showed a mean reduction in tick burden of 39% compared with British herds under conventional control. There was little improvement in tick control in the mixed herd of Zebu x British and British cattle. Assessment of the tick resistance status of the Zebu x British cattle by artificial infestation with known numbers of larvae showed that the survival to mature female ticks was 1.3 and 1.8% for the herds requiring four and 10 acaricidal treatments respectively in the wet tropics. In a similar assessment of the "resistant" Australian

lllawarra Shorthorn (AIS) cattle herds which required one treatment or none over a
tick season in southern Queensland (Wilkinson 1962) the survival was 4.4 and 5.2%
respectively. The mean survival of female ticks to maturity on individual Zebu x British
cattle was 1.4% (range 0.01–6.6%) compared with 8.1 % (0.2–27.4%%) for AIS cattle.
The relation between the passage of time and the secretion of milk in the ewe
Authors: Morag M
Published: November 2004

The rate of milk secretion during 4, 8, 12, 16, 20, and 24 hr intervals between milkings was estimated in 24 ewes. The intervals were applied in a double 6 x 6 Latin square in which the second square was a mirror image of the first. Intervals were repeated four times per treatment in each square. There were no intervening periods either between the four repetitions of any given interval or between different treatment intervals. Residual milk was removed by intravenous administration of oxytocin after every milking. The milking was carried out by machine, and the stripping by hand. The experiment lasted 28 days. The secretion rates of milk, water, total solids, solids not fat, and fat increased up to 12 hr and then declined. Both ascending and descending phases were significant. There was a significant increase in milk yield when a given interval was repeated (taken over all treatments). The secretion rates of milk and of all the measured constituents increased following milking intervals of 4–12 hr, and decreased after intervals longer than 12 hr. No significant differences were found between the respective rates of milk secretion by day and by night. The variation in an estimate of the rate of milk secretion became significantly smaller as the interval became longer. The oxytocin removal of residual milk was shown to have a strong galactopoietic effect.
Drought dormancy inAstrebla lappacea, Chloris acicularis, and Stipa aristiglumis
Authors: Whalley RDB , Davidson AA
Published: November 2004

Patterns of carbohydrate storage and utilization in Astrebta lappacea (Lindl.) Domin, Chloris acicularis Lindl., and Stipa aristiglumis F. Muell. during periods of moisture availability and stress were found to be similar to those in perennial grasses undergoing seasonal dormancy. It is suggested that the above species when stressed for moisture enter a state of dormancy physiologically similar to seasonal dormancy and that this drought dormancy is hormone-mediated.
Physiological and ecological studies on the oestrogenic isoflavones in subterranean clover (T. subterraneum L.) VII. Effects of nitrogen supply
Authors: Rossiter RC
Published: November 2004

In experiments with young plants of the Dwalganup strain of subterranean clover, nitrogen deficiency was associated with increased concentrations of isoflavones in the expanded leaves and cotyledons. In the first trifoliate leaves the concentration of total isoflavones (formononetin+genistein+ biochanin A) was approximately doubled at low nitrogen supply. Biochanin A was much less affected than the other two isoflavones. The increase in isoflavone contents of nitrogen-deficient leaves was associated with decreased protein synthesis, but not always with increased sugar contents. The supply of carbon substrates for isoflavone synthesis may depend on starch as well as sugar contents. Practical implications of the results are considered briefly.
The provision of selenium to sheep by means of heavy pellets
Authors: Kuchel RE , Buckley RA
Published: November 2004

Heavy pellets in which the source of selenium was calcium selenate, barium selenate, or elemental selenium have enhanced blood and tissue selenium levels for periods up to 12 months, when dosed singly to sheep grazing pastures of normal selenium status. The components of choice were finely divided metallic iron and elemental selenium possibly in the proportion of 20 : 1.
Relation between metabolizable and digestible energy in sheep and cattle
Authors: Graham N. McC.
Published: November 2004

Published data for a wide variety of foods given to sheep were analysed statistically in order to clarify the relationship between metabolizable and digestible energy. Metabolizable energy was not a constant fraction of digestible energy; values ranged from 70 to 85%, depending on level of feeding and digestibility. A linear equation described the relationship for most diets and all levels of feeding. A possible reason for differences between diets is mentioned. The equation is shown to be valid for cattle.
The ovarian response to pregnant mare serum (PMS) administered after intravaginal progestagen treatment of cyclic and anoestrous ewes
Authors: Holst PJ
Published: November 2004

PMS was administered at several dose levels (250, 500, 750, 1000, and 1250 nominal i.u.) to progestagen-treated cyclic and anoestrous ewes. Times of PMS administration were 24 hr prior to and at the time of removal of the intravaginal pessary. The time of administration of PMS significantly affected oestrous response and the time of onset of oestrus. The stage of the breeding season also affected the time of onset of oestrus. The number of ovulations, as measured by the number of corpora lutea, was affected by the stage of the breeding season and dose of PMS. The anoestrous ewes had a greater number of ovulations than the cyclic ewes, particularly al the higher dose levels of PMS.
Corrigendum – Liveweight gain, food intake, and eating rate in Brahman, Africander, and Shorthorn X Hereford cattle
Authors: Frisch JE , Vercoe JE
Published: November 2004

Food intake, liveweight gain, and eating rate were measured over 3 years on nine Brahman, nine Africander, and nine Shorthorn x Hereford male cattle offered lucerne hay ad libitum for 53–76 days. When intakes were adjusted for differences in liveweight, the Brahmans ate significantly less feed than the Africanders and Shorthorn x Herefords. Gain was correlated with intake but not with liveweight. When gains were adjusted for differences in intakes the Brahmans gained significantly more than Africanders or Shorthorn x Herefords. The greater gain of the Brahmans is apparently related to a lower maintenance requirement. The eating rate of animals was highly repeatable, and significantly correlated withvoluntary food intake (r = 0.61, P < 0.01) and liveweight gain (r = 0.63, P < 0.01)
Some factors influencing the germination and early seedling development of pasture plants
Authors: McWilliam JR , Clements RJ , Dowling PM
Published: November 2004

Some of the important environmental and plant factors influencing the germination and early seedling development of a number of temperate grasses and legumes have been investigated under controlled conditions. Significant differences were found between legumes and grasses in a number of characters which appear to be important for establishment under field conditions, including quantitative aspects of water absorption, rates of germination, and early root elongation. Ryegrass was superior to all other species in its ability to germinate under conditions of moisture stress. The lower limit for germination was from 4 to 6 bars below the limiting potential found for the other species, and thus may be one of the important factors contributing to the ease of establishment of this species in the field. The early onset of autotrophic growth in young seedlings, as judged by the utilization of external nutrients and the attainment of positive net photosynthesis, occurs within 5 days of imbibition under favourable conditions, well before the exhaustion of endogenous reserves. This highlights the need for adequate water, nutrients, and light during this early stage of seedling development. It also suggests that reserves available to the seedling are probably in excess of requirements under favourable conditions, and may be of potential value under adverse conditions. These results are discussed in relation to the definition of field problems, and to some likely breeding objectives to improve establishment.
The body composition and herbage utilization of grazing Merino and crossbred lambs during periods of growth and summer undernutrition
Authors: Allden WG
Published: November 2004

A grazing study was undertaken (i) to determine the changes in body energy and body composition of Merino and Dorset Horn x Merino lambs during their first year of life with the object of assessing the nature of body tissue reserves during periods of summer undernutrition, and (ii) to examine the nutritional basis of growth differences between the two genotypes in terms of herbage intake and feed utilization for weight gain. The relations between body weight and (i) total body energy, (ii) body protein, (iii) body fat, and (iv) body water were of linear form and similar for both groups. Each 1 kg of wool-free body weight increment by the unfasted grazing animal was associated with the retention of 3.17 megacalories (mcal) of body energy, whereas on an empty body weight basis 1 kg gain was associated with the retention of 4.18 mcal. Empty body weight was no better a predictor of body energy than the unfasted wool-free body weight of the grazing sheep; by either method more than 97% of the variance in body energy could be accounted for by differences in body weight. Dorset Horn x Merino lambs were significantly heavier at birth (4 5 v. 3.5 kg). They grew more rapidly than the Merinos throughout the 300 day experiment although during the first 200 days relative growth rates were similar. The intake of digestible energy WE) of the two groups was estimated for 112 days from weaning at c. 7 weeks. During this period the crossbreds weighed 20-23 % more than the Merinos; they consumed 23 % more herbage at the beginning and 11 % more at the end (P < 0.01). The efficiency of energy retention was similar for both breeds, 42.5 % of metabolizable energy above the maintenance being stored as wool-free body energy. During the summer drought period the crossbreds used their feed more efficiently than the Merinos; they consumed up to 25 % less feed per kilogram weight and at the same time increased their weight advantage. Differences in body weight underestimated differences in body energy. Crossbreds weighed 30% more than the Merinos at the beginning of the summer drought period, and 36 % more at the end. Corresponding differences for body energy were 40 and 53 %. There was no evidence to suggest that prolonged periods of arrested growth influenced the composition of the body at a given weight.
Water economy and food intake of sheep when watered intermittently
Authors: Wilson AD
Published: November 2004

The water economy and food intake of medium-wool Merino, fine-wool Merino, and Border Leicester wethers were compared when water was made available only every 3 or 4 days. The comparisons were made on penned sheep with two diets at both low (max. 12�C) and high (max. 36�) temperatures. The Border Leicesters used more water than the two groups of Merinos (20-40%), but they also ate more food per unit of body weight (15-28%). In proportion to food intake, the Border Leicesters and medium-wool Merinos drank 6-20 % more water than the fine-wool Merinos. It was concluded that although economy of water use may assist survival when water is unavailable, it appeared to be inversely related to food intake and therefore of limited value in selecting sheep for arid climates. The Border Leicesters lost more water in their faeces than the Merinos, but similar amounts of water as urine. The volume of urine appeared to be related to the amounts of potassium and sodium excreted, since on the second to fourth day without water the concentration of potassium + sodium was maintained at 600-800 m-equiv./l while the nitrogen concentration varied from 0.9 to 2.4 g/100 ml. Nitrogen and potassium excretion in urine remained relatively constant from day to day, but sodium excretion varied from c. 20 m-equiv./day on the first one or two days without water to 100-120 m-equiv./day on the final one or two days.
Urea excretion in ruminants. III. The role of the hind-gut (caecum and colon)
Authors: Thornton RF , Bird PR , Somers M , Moir RJ
Published: November 2004

The transfer of endogenous nitrogen to the hind-gut digesta of sheep and its relationship with urinary nitrogen excretion were studied concurrently with the estimation of nitrogen balance and of dry matter digestibility in sheep fitted with a re-entrant ileal cannula. Infusion of glucose into the terminal ileum increased the excretion of faecal nitrogen by 1 g/day, while the urinary urea nitrogen excretion decreased by 1 g/day, relative to the respective control levels. Plasma urea nitrogen concentrations remained unchanged. When glucose was infused, the excretion of nitrogen in the faeces was higher than the amount of nitrogen passing the terminal ileum. It is suggested that endogenous urea nitrogen was transferred to the digesta of the hind-gut, where it was incorporated into microbial protein and subsequently excreted in the faeces. The transfer of urea from the blood to either of the fermentative areas of the gut tract is apparently the preferential pathway of urea excretion in ruminants.
The effects of different cultivars of subterranean clover (T. subterraneum L.) on sheep reproduction in the South-west of Western Australia
Authors: Davies HL , Rossiter RC , Maller R
Published: November 2004

The cultivars Dwalganup, Geraldton, Yarloop, Woogenellup, and Mt. Barker were each grazed continuously by Merino and Merino x Border Leicester ewes from April 1963 to November 1967. There was a progressive decline in the proportion of Merino ewes conceiving on the three high oestrogen cultivars Dwalganup, Geraldton, and Yarloop; crossbred ewes showed a decline on Dwalganup and Yarloop. For neither breed of sheep was the decline in conception rate significant on the two low oestrogen cultivars Woogenellup and Mt. Barker. The incidence of uterine prolapse was higher on the high oestrogen cultivars. The percentage lambs marked in 1967 was only 50% for the high oestrogen cultivars (excluding the crossbred ewes on Geraldton), compared with 93% for the low group. Conception rates were significantly related to the concentration of the isoflavone formononetin in the clover leaves.