bluuebunny/crossref_metadata_2025 huggingface dataset:
The genetic basis of growth, reproduction, and maternal environment in Romney ewes
Authors: Ch'ang TS , Rae AL
Published: November 2004

This paper is the first in a series of studies on the genetic variation and covariation in growth and reproductive characters of the New Zealand Romney sheep. The data used were obtained over a period of 11 years (1955-1965 inclusive) from a random-bred experimental flock maintained at Massey University, Palmerston North, New Zealand. Among the environmental factors studied, type of birth and rearing has a marked effect on liveweights measured at different times from weaning to the yearling stage. On average, the singles were about 9 lb heavier than the twins at weaning, or c. 17 % heavier in terms of the mean weaning weight. Presumably because of their pre-weaning growth handicap, the twins compared with the singles exhibited post-weaning compensatory growth. The age of the dam and of the individual moderately affected the weaning weight of the lamb. However, their effects on post-weaning liveweight characters over the hogget stage (from weaning to about 14 months) showed that the influence of age of dam remained undiminished whereas that of the individual tended to decrease with time from weaning. The number of times a ewe hogget comes into oestrus during the first autumn of her life (number of hogget oestruses) was unaffected by type of birth and rearing, moderately affected by age of the individual, but relatively strongly influenced by the age of dam effect. Some doubt existed as to whether the average difference in fertility (number of lambs born per ewe) between ewes themselves born as singles and twins (type of birth effect) could be regarded as environmental or as genetic in nature. The present results indicated that in the fertility data, type of birth effect contained a genetic component, and adjustment should not be made for difference in type of birth if the aim is to study genetic variation and covariation in fertility of the ewe. The estimates of heritability for the various characters were made. by using paternal half-sib correlation (method 1) and regression of daughter on dam (method 2). In general, good agreement existed between corresponding values of heritability obtained by different methods of analysis. The estimates of heritabilities by methods 1 and 2 were: weaning weight (December) 0.30 and 0.23; March liveweight, 0.45 and 0 35; June liveweight, 0.39 and 0.42; hogget liveweight (yearling in October), 0.51 and 0.46; number of hogget oestruses, 0.32 and 0.27; number of lambs born per ewe at the first lambing (2-year-old), 0.053 and 0.045; over the first two lambings, 0.121 and 0.111; over the first three lambings, 0.032 and 0.205. The results are discussed in relation to genetic improvement in the ewe's fertility by direct selection.
Nutrient cycling in grazed pastures. II. Further observations with [35S] gypsum
Authors: Till AR , May PF
Published: November 2004

The incorporation of sulphur-35 (35S) into the wool of sheep grazing radioactive pasture was measured in two successive experiments on the same site following application of [35S]gypsum. Equilibrium between the applied sulphur and sulphur present prior to the application was established at different rates with different rainfall. After 3 years the sulphur from the original gypsum application was still being turned over in the soil-plant-animal system, there had been no change in the total soil sulphur, and a large portion of soil sulphur did not enter the sulphur cycle. A diagram of a proposed sulphur cycle in grazed pasture is given, and the assumptions made are discussed.
Urea excretion in ruminants. II. Studies in sheep whose rumen contents were replaced with physiological saline
Authors: Thornton RF
Published: November 2004

Urea was infused intravenously into sheep whose rumen contents were removed and replaced with physiological saline. Despite large differences in plasma urea concentration the rate of nitrogen accumulation in the rumen, as urea plus ammonia, was similar at 6-7 mmoles/hr. The maximum concentration of nitrogen, as urea plus ammonia, was not influenced by plasma urea concentrations higher than 15-17 mg N/100 ml. Urinary urea excretion was positively related to plasma urea concentration but within any level of plasma urea concentration there was a close association between urine flow and urinary urea excretion.
Fertility of rams heated for 1, 2, 3, and 4 days
Authors: Rathore AK
Published: November 2004

Fertility in superovulated ewes, based on the fertilisation rate of ova 60-70hr after mating was significantly lower in ewes mated to rams heated for varying eriods and having semen containing varying and known prportions of abnormal spermatoza than in the ewes mated to unheated control rams having no abnormal forms in their semen.
The occurrence of Peanut Mottle virus in Queensland
Authors: Behncken GM
Published: November 2004

A disease causing a mottle in the leaves of peanuts (Arachis hypogaea L.) in the Mingaroy district of Queensland has been shown to be caused by a virus which appears to be indistinguishable from peanut mottle virus. This virus has not previously been reported in Australia. The virus was sap-transmissible to a range of plants, all but one of which were in the Leguminosae, but the only hosts in the field were peanut and garden pea (Pisum sativum L.). It was shown to be transmitted in a stylet-borne manner by five aphid species including Aphis craccirora Koch, which is the most common species found infesting peanuts. The virus was also seed-transmitted and probably spread to Australia in infected seed. The virus had a thermal inactivation point between 55 and 60�C and a dilution end-point between 10-3 and 10-4, and infectivity was lost within 48 hr of storage at 25�C. Partially purified virus preparations were obtained by clarification of sap by freezing and thawing and :he addition of activated charcoal followed by differential centrifugation An antiserum with an homologous> title of 1 : 64 was prepared but no serological relationships could be demonstrated between this virus and common bean mosaic or bean yellow mosaic viruses Flexuous rod-shaped particles with a normal length of 704 nm were seen in electron micrographs of virus preparations.
Rumen microbial protein synthesis in relation to energy supply: Diurnal variation with once-daily feeding
Authors: Walker DJ , Nader CJ
Published: November 2004

Rates of microbial protein synthesis and volatile fatty acid (VFA) production were measured in sheep rumen contents collected at 4-hr intervals after a single feed consisting of chaffed lucerne and wheaten hay. The protein synthesis rate observed was minimal at 4 hr after cessation of feeding, rising to a maximum 8 hr later. Protein synthesis in relation to energy supply (calculated from VFA production) was also minimal 4 hr after cessation of feeding, but did not reach a maximum until 16 hr later. Decreasing utilization of energy for protein synthesis was correlated with an increase in the polysaccharide content of the microbial cells, and a return of cellular polysaccharide levels to the pre-feeding values was accompanied by increased usage of energy for protein synthesis. The results are discussed in terms of alternative mechanisms for energy utilization at different times after feeding, and of overall microbial protein synthesis in relation to organic matter digested in the rumen.
Establishment and survival of pasture species from seeds sown on the soil surface
Authors: Dowling PM , Clements RJ , McWilliam JR
Published: November 2004

Some of the factors influencing the establishment and survival of temperate pasture species when sown on the soil surface were investigated. The following were the main findings from experiments conducted in the field and in a controlled environment. (1) Both the establishment and survival of seedlings sown by broadcasting on to non-arable land can be significantly improved by a prior treatment of the site with herbicide to reduce competition from existing vegetation. (2) Providing protection for seeds by retaining dead vegetative cover, or by creating some form of surface roughness, improves establishment as it reduces desiccation and provides a more favourable moisture environment in the vicinity of the seed. (3) Uptake of water by seeds resting on the soil surface is enhanced by absorbent lime or bentonite coatings, and increased germination results. (4) Failure of radicles to penetrate the soil following germination is an important factor limiting the establishment of legumes on exposed sites, and any restraint on the movement of germinating seeds under these conditions improves the penetration of the radicle. (5) Variation between species in their ability to establish on the surface suggests that the choice of more suitable species, and selection to improve their adaptation in this respect, could also contribute a great deal to the efficiency of aerial seeding.
Metabolism of intraruminally administered [4-14C]formononetic and [4-14C]biochanin a in sheep
Authors: Batterham TJ , Shutt DA , Hart NK , Braden AWH , Tweeddale HJ
Published: November 2004

Two ovariectomized ewes were given a single intraruminal dose of [4-14C]- labelled isoflavone and slaughtered 6 hr later. In the ewe given [4-14C]biochanin A, labelled genistein was detected in addition to labelled biochanin A in the blood plasma, urine, kidney, liver, bile, contents of the rumen, and those of the small intestine. p-Ethylphenol, which is almost certainly a metabolite of biochanin A, was present in the urine but not labelled, which indicates that it originates from ring B of the isoflavone molecule. In the ewe given [4-14C]formononetin, a similar distribution of the isoflavone and its demethylation product, daidzein, was found. In addition, labelled equol was found in the blood plasma and urine. Another labelled metabolite, identified as O-desmethyl angolensin (2,4-dihydroxyphenyl p-hydroxy-�-methylbenzyl ketone), was also found in the urine. In the urine from both ewes, there were also labelled light petroleuminsoluble acidic compounds but they were not identified.
Distance between food and water supply and its effect on drinking frequency, and food and water intake of Merino and Border Leicester sheep
Authors: Squires VR , Wilson AD
Published: November 2004

The walking and drinking behaviour of Merino and Border Leicester wethers was compared in summer 1968 when a diet containing 15 % sodium chloride was fed at points that were separated from the water supply by distances of up to 5.6 km. All sheep maintained two journeys daily to water until the distance between food and water reached 4.0 km. At this point Merino sheep drank three times every two days and at 4.8 km once a day. Border Leicesters drank twice daily until the distance reached 5.6 km, when they drank once daily. Food intake declined in both breeds as distance from water increased, but water intake was reduced only at the longer distances. When drinking once daily, water intakes were as much as 7 and 10 litres respectively for Merino and Border Leicester sheep. Walking distances reached a maximum of 13.6 and 17.6 km/day respectively for the Merinos and Border Leicesters. The average walking speed of the Merinos (2.51 km/hr) was greater than that of the Border Leicesters (2.06 km/hr). The implications for management of saltbush pastoral areas are discussed.
Chemical curing of annual pastures in Southern Australia for beef cattle and sheep
Authors: Pullman AL , Allden WG
Published: November 2004

A desiccant herbicide (paraquat) was used to kill an annual pasture during the late spring months when the digestibility of the dry matter (DM) was 75%. The nutritive value of this standing herbage during the summer drought period was compared in field and pen studies with pasture allowed to mature naturally in the Mediterranean environment of South Australia. The herbicide treatment resulted in a significant reduction of standing herbage at the beginning of the summer period (5766 v. 2791 kg DM/ha). The DM digestibility by beef cattle of treated and untreated herbage was similar (52.4 v. 53.0% respectively). There was no difference between the paraquat-treated and the naturally matured pasture in the content or the apparent digestibility of organic matter, water-soluble carbohydrate, cellulose, or lignin; but nitrogen content, digestibility, and retention were significantly higher for paraquat-treated herbage. Rainfall between spraying and the beginning of the summer period was 140 mm. Indirect evidence from a separate study indicates that the fall in digestibility of the herbage after paraquat treatment was influenced by both rainfall and the spraying treatment. The productivity of beef cattle and sheep grazing the treated and untreated pastures during the dry summer confirmed the results of the digestibility studies, there being no difference between treatments in weight change or wool production. After the commencement of the autumn rainfall season the proportion of grass . on the sprayed area was greatly reduced, and the growth of cattle was significantly impaired. Thus the overall effect of the paraquat treatment was to reduce cattle growth.
The effect of formaldehyde-treated casein on the growth of ruminant lambs
Authors: Faichney GJ
Published: November 2004

Growth studies were made with two groups of 12 crossbred wether lambs given a diet containing 10% casein for 18 weeks from 9 weeks of age. The casein in the diet of one group was untreated but in the other was treated with formaldehyde. The group receiving the treated casein grew significantly faster and required significantly less food per unit of gain than did the lambs given untreated casein. There was no difference in the rate of wool growth. Although the digestibility of nitrogen was lower in the lambs given the treated casein, these lambs excreted less nitrogen in their urine and then nitrogen balances were higher than in the lambs given untreated casein. There appeared to be a lower proportion of fat and a higher proportion of protein in the body gain of the group receiving treated casein. The feeding of treated casein was also associated with an increase in the level of �-ammo nitrogen and a decrease in the level of urea nitrogen in the plasma.
Studies on ovine infertility in agricultural regions of Western Australia; Cervical mucus production by fertile and infertile ewes
Authors: Smith JF
Published: November 2004

The production of cervical mucus by fertile and infertile ewes was examined as part of a study on ovine infertility in the agricultural regions of Western Australia. Infertile ewes produced a greater weight of mucus than did fertile ewes at both a synchronized and a natural oestrus. Following ovariectomy, however, both groups of ewes showed similar responses to exogenous oestrogen. The data indicate that the increased weight of mucus is indicative of the secretion of a thinner, more watery mucus.
The determination and properties of the fibrous covering of the wheat grain
Authors: Moss HJ , Stenvert NL
Published: November 2004

The neutral detergent method of fibre determination effects a clean separation of the outer layers of the wheat grain from the endosperm. The fibre thus separated gives a good indication of the milling yield of soft wheats, but is useful only in conjunction with other tests in similar comparisons of hard wheats.
Temperature influences on the growth, digestibility, and carbohydrate compositions of two tropical grasses, Panicum maximum var Trichoglume and Setaria sphacelata, and two cultivars of the temperate grass Lolium perenne
Authors: Wilson JR , Ford CW
Published: November 2004

Two tropical grasses, Panicunl maximum var. trichoglume and Setaria spliacelata cv. Nandi were compared with two cultivars of Lolium perenne, S.24 and Kangaroo Valley, grown in controlled environment at day/night temperatures of 15.6/10, 21 .1/15.6,26.7/21.1, and 32.2/26.7�C. The plants were harvested when still vegetative. The tropical grasses grew faster than the L. perenne cultivars at all but the lowest temperatures, and had a generally higher relative water content. The in vitro dry matter digestibility of the L. pereiine cultivars appeared inherently higher than that of the tropical grasses, but for each species digestibility Mtas modified by the environment and was highest at the lower growth temperatures. The tropical grasses were lower in alcohol- and cold water-soluble sugars, and higher in starch and structural (cell wall) carbohydrates than the L. perenne cultivars. For all grasses, as temperature increased from 15.6/10 to 26.7/21.1�C the concentration of the structural carbohydrates increased whilst that of the total non-structural carbohydrates changed relatively little. A further increase in temperature to 32.2/26.7� resulted in a marked decline in the concentration of simple sugars and structural carbohydrates whilst polymeric sugars increased. At this latter temperature the starch content in Setaria and Panicurn increased to as high as 16 and 13% of dry weight respectively. The differences in digestibility appeared to be associated with the differences in the proportions of the different carbohydrate fractions.
Comparison of plasma phyto-oestrogen levels in sheep and cattle after feeding on fresh clover
Authors: Braden AWH , Thain RI , Shutt DA
Published: November 2004

Wethers and heifers were fed on freshly cut pasture (red clover, Mt. Barker or Tallarook subterranean clover, or ryegrass) and the blood plasma concentration of the phyto-oestrogens and their metabolites estimated 5 hr, 24 hr, and 6 days after the beginning of the feeding. The heifers were allowed to graze the pastures after the first day. On the basis of increase in teat length in the wethers, red clover and Tallarook were estimated to have equivalent oestrogenicity ; Mt. Barker was much less active. Qualitatively, the metabolism of formononetin and biochanin A appeared similar in the two species, but there was evidence that the rates of metabolism and of conjugation were faster in cattle than in sheep. The findings are discussed in relation to an infertility syndrome in dairy cattle.
The effect of phosphorus on the growth, chemical composition, and critical phosphorus percentages of some tropical pasture grasses
Authors: Andrew CS , Robins MF
Published: November 2004

Nine tropical pasture grasses were grown in pots of a phosphate-deficient solodic soil with varying additions of phosphate. Growth responses and chemical composition of the plant tops were recorded, and from these, critical percentages of phosphorus were established. All species responded to phosphate addition. Under the conditions of this experiment Melinus minutiflora was the most responsive species and Pennisetum clandestinum the least responsive. Critical percentages of phosphorus in the tops of Melinus minutiflora, Cenchrus ciliaris, Paspalum dilatatum, Panicum maximum, Chloris gayana, Sorghum almum, Setaria anceps, Digitaria decumbens and Pennisetum clandestinum sampled at the immediate pre-flowering stage of growth were 0.18, 0.25, 0.25, 0.20, 0.22, 0.20, 0.21, 0.16, and 0.22% respectively of the dry matter. Phosphate applications decreased the concentration of plant potassium, had no significant effect on calcium, increased magnesium in most species, and in four species increased sodium. The increases in magnesium and sodium are considered to result in part from reduced potassium uptake and the plant's ability to preserve cation balance. Three species, C. gayana, P. maximum and D. decumbens, had relatively high concentrations of sodium (58, 46, and 46% of total cations respectively). In contrast S. anceps had a relatively high concentration of potassium (56 % of total cations) and low sodium (7%). Phosphate applications decreased the concentration of nitrogen, and had little effect on chloride.
The association of Prunus ringspot, prune dwarf, and dark green sunken mottle viruses in the rosetting and decline disease of peach
Authors: Stubs LL , Smith PR
Published: November 2004

The symptoms of a rosetting and decline disease of peach are described. Prunus necrotic ringspot virus (PRSV), prune dwarf virus (PDV), and a virus which causes a dark green sunken mottle (DGSM) on peach leaves have been isolated from diseased trees. Combinations of these viruses interacted synergistically in peach seedlings, but with considerable variation in the degree of synergism. The most severe expression of rosetting resulted from the interaction of all three viruses. Interaction between PRSV and PDV usually caused recurrent rosetting. PRSV and PDV were transmitted through the seed of rosetted peaches, but the latter in only a low percentage of seeds (max. 6%) and then only in combination with PRSV, which was transmitted to a maximum of 35.7 %. There was no evidence for seed transmission of DGSM. A study of natural spread of rosetting in a commercial planting of Golden Queen peaches showed that rosetted trees increased from 0.8 to 56.1 %, a total of 265 in 472 trees, in 7 years. Seedlings grown in soil obtained from the root zone of infected trees did not become infected.
Prediction of in vivo dry matter, organic matter, and energy digestibilities of silage in in vitro digestion techniques
Authors: Brown GD , Radcliffe JC
Published: November 2004

Twenty experimental silages were made from seven pasture species at different stages of maturity. In vivo dry matter, organic matter, and energy digestibilities of the silages were determined at restricted and ad libitum intake levels on standardized pairs of Merino wethers. In vitro dry matter digestibility determinations were made on ground frozen silage and ground oven-dried silage with and without a correction for the loss of volatile compounds during drying. Corrected in vitro dry matter digestibilities of ground oven-dried silage for a 48 hr rumen liquor digestion time gave the most accurate prediction of in vivo dry matter (r = 0.88), organic matter (r = 0.86), and energy (r = 0.74) digestibilities for restricted intake levels. In vitro digestibilities of ground frozen silage more accurately predicted in vivo digestibilities than did in vitro digestibilities of ground oven-dried silage without the correction for volatile losses. In vivo dry matter and organic matter digestibilities were highly correlated (v = 0.97), but both were poorly correlated with in vivo energy digestibilities. In vitro digestion of ground oven-dried silage with a correction for the volatile compounds lost during drying is recommended as a suitable routine determination for predicting the in vivo digestibility of silage.
Comparative requirements of sulphur by cereals and legumes
Authors: Holford ICR
Published: November 2004

In a pot experiment on a black earth, wheat and oats were more sensitive to sulphur deficiency than lucerne and white clover, and they required more sulphur to achieve maximum dry matter production. On the other hand the cereals recovered a higher proportion of the applied sulphur from the soil, and they used absorbed sulphur more efficiently for dry matter production by the time their grain had reached maturity. It is suggested that the higher efficiency of the cereals was possibly due to the translocation of accumulated sulphate sulphur to the developing inflorescences, where it was used for further dry matter production. These factors could account at least partly for the tolerance of cereals to sulphur deficiency in the field.
Mid-season movement of 45Ca in apple trees
Authors: Millikan CR
Published: November 2004

Apple trees (cv. Granny Smith) were grown in sand or water cultures supplied with a complete nutrient solution. 45Ca added to this solution c. 11–14 weeks after full bloom became distributed throughout each tree. It moved preferentially into the interveinal tissues of the young rather than the old leaves of the terminal growth. The 45Ca concentration was highest in the petiole, midrib, and veins and comparable for both types of leaf in these tissues. In the tree trunk, leaders, and fruit spurs the 45Ca concentration was much higher in the bark than in the wood. Although the isotope entered the bark and leaves of the fruit spurs it was not detected in the flesh of the attached fruits. It occurred in low concentration in the pedicels of a few fruits. When supplied to trees 4–5 weeks after full bloom, 45Ca did enter the fruits, but its concentration was much less than in the bark of the fruit spurs. In such fruit the concentration of 45Ca was highest in the core towards the stem end, least in the flesh, and intermediate in the peel.
The digestion of safflower oil-casein particles protected against ruminal hydrogenation in sheep
Authors: Hogan JP , Connell PJ , Mills SC
Published: November 2004

Three sheep were offered lucerne hay either alone or with a supplement of safflower oil-casein particles protected from microbial digestion by treatment with formaldehyde. The supplement provided an additional 70 g of long chain fatty acids and 9 g nitrogen. It was estimated that, as a result of providing the supplement, additional nutrients derived from the small intestine included about 10 g of nitrogen and 60 g of long chain fatty acids. About 38 g of these fatty acids was absorbed in polyunsaturated form. With the basal diet, negligible amounts of polyunsaturated acids were absorbed from the small intestine. The addition of safflower oil-casein particles was associated with slight but significant increases in the flow of digesta from the abomasum but had no effect on the volume of water in the rumen or on the rates of flow from the rumen or terminal ileum. It was calculated that the supplemented diet provided, per unit of organic matter intake, about 30% more metabolizable energy, 38% more net energy, and 70% more amino acids than the basal diet.
The effect of total water supply, and frequency of application, upon lucerne. II.* Chemical composition
Authors: Snaydon RW
Published: November 2004

Total water supply, expressed as a proportion of class A pan evaporation (Epan), and frequency of water application were varied independently during summer. The phosphorus concentration in the shoots of lucerne increased by 35% when the total water supply was increased from 0.1 to 1.0Epan; the nitrogen concentration was not significantly affected. The in vitro digestibility of leaf and stem fractions decreased with increasing total water supply, and the proportion of highly digestible fractions (leaf and flower) also decreased, so that total shoot digestibility decreased from 65% at 0.24 Epan to 55% at 0.58 Epan. Frequency of water application had no significant effect upon phosphorus or nitrogen concentration or in vitro digestibility.

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*Part I, Aust. J. Agric. Res., 23: 239 (1972)
Digestion of two legumes and rumen bacterial growth in defaunated sheep
Authors: Lindsay JR , Hogan JP
Published: November 2004

Defaunated sheep offered lucerne hay or dried red clover were used to study digestion in the stomach of dietary organic matter, plant cell wall constituents, and plant cell contents. Digestion in that section of the tract was, for dietary organic matter, 50 % with lucerne and 60% with red clover, for plant cell contents 65–70% with both diets, and for plant cell wall constituents 30% with lucerne and 60 % with red clover. Estimates of growth of rumen bacteria in these sheep indicated that about 32 g of bacterial organic matter and 23 g of bacterial crude protein were synthesized in the rumen for each 100 g of plant organic matter digested. Comparisons of apparent digestion in the stomach and intestines were made between the defaunated sheep and the same sheep carrying a normal population of rumen microorganisms. Levels of rumen ammonia were lower in the absence of protozoa. However, only small differences were observed in the flow of digesta along the tract and in the apparent digestion of organic matter and nitrogen in both the stomach and intestines as a result of defamation. Hence it is suggested that data on the digestion of forages obtained with defaunated sheep can be applied to sheep with rumen protozoa.
Branched ears in wheat and yield determination
Authors: Rawson HM , Ruwali KN
Published: November 2004

Differentiation of the branched ear of a semidwarf mutant wheat is described for plants grown under irrigated field conditions, and compared with cultivars bearing simple ears. With a very high spikelet number per ear (more than SO), and few grains per spikelet (a maximum of three), the branched ear offers a radically different concept for yield production. Yields per unit area of the current branched material were not as high as for Kalyan Sona, India's premier variety, but did exceed those for Late Mexico 120. Better yields could be expected if the random sterility of spikelets within the branched ear, first apparent early in spikelet differentiation, were reduced. However, individual fertile ears filled up to 128 grains weighing 4.8 g in the better plants.
Effect of temperature on the phenology and grain yield of Sorghum bicolor
Authors: Downes RW
Published: November 2004

When grown under controlled high temperature conditions United States sorghum cultivars exhibited depressed grain yield in comparison with yield at moderate temperatures. High temperatures (day/night 33/28°C) between germination and initiation resulted in low grain yield. High temperatures at initiation and during the early phases of panicle development did not reduce floret production. In plants exposed to high temperatures before initiation, high temperatures late in the panicle development stage induced floret abortion, and even moderate temperatures after anthesis were associated with embryo abortion. The adverse effect of high night temperatures on grain yield is likely to be associated with inadequate assimilate availability to support dark respiration.
Evaluation of five Mediterranean annual pasture species during early growth
Authors: Smith RCG , Biddiscombe EF , Stern WR
Published: November 2004

Pasture factors causing differences in the liveweight gain of sheep stocked at 10 sheep ha-l on continuously grazed swards of five annual species were examined during autumn and early winter. Differences in liveweight gain were due to the availability of the pasture species for prehension by grazing sheep, and depended on the weight of pasture offered and also on the growth form of the grazed plants. Subterranean clover and the volunteer species, silver grass and erodium, rapidly assumed a prostrate form under continuous grazing, thereby restricting apparent intake. Wimmera ryegrass changed less in growth form in response to grazing and for this reason liveweight gain on ryegrass in autumn was better than on clover, silver grass, and erodium. These species differences were reflected in the "critical" weight of herbage required for sheep to maintain their liveweight. Critical weight was lowest in the erect-growing Wimmera ryegrass (c. 130 kg ha-l) and highest (635 kg ha-l) in the prostrate erodium.
The effect of root geometry on the yield of wheat growing on stored water
Authors: Passioura JB
Published: November 2004

It is suggested that, when wheat is growing predominantly on stored water, it is an advantage for the plants to have root systems of high hydraulic resistance, so that they will conserve water during early growth and thus have more water available while filling their grain. This paper describes pot experiments in which, with wheat growing entirely on stored water, an attempt was made to increase the resistance of the roots by forcing plants to rely entirely on one seminal root. The treatment was successful in that single-rooted plants did use substantially less water before anthesis than did normal plants, and they produced substantially greater grain yields. The conservation of water by the single-rooted plants appeared to be due to their having extraordinarily large pressure drops in the root xylem: calculations showed that the flow rate in the xylem reached 800 mm sec-1 with a concomitant pressure gradient greater than 0.1 bar mm-1. The corresponding values in the normal plants were much less, although still surprisingly high (250 mm sec-1 ; 0.03 bar mm-1). The xylem of the seminal roots is dominated by one large vessel whose diameter probably determines the hydraulic resistance. It may be possible to breed high root resistance into existing cultivars by breeding for smaller vessels.
The initial leaching of hayed-off pasture plants in relation to the recycling of phosphorus
Authors: Bromfield SM , Jones OL
Published: November 2004

Hayed-off phalaris and clover plants of various nitrogen and phosphorus contents were leached under a wide range of laboratory conditions designed to simulate various first rainfalls following haying off. Of the total phosphorus in ground plant material, 60–83% was water-soluble and most of it was inorganic. Continuous leaching equivalent to 24.4 cm rain was required to leach more than 90% of the water-soluble phosphorus from certain samples of whole plant material, but leaching rates equivalent to only 1.25 cm over 96 hr were quite effective and removed up to 62%. The percentage of phosphorus leached at low intensities over periods of up to 4 days varied with the plant sample. It depended largely on the rate and extent of microbial conversion of inorganic phosphorus to water-insoluble forms. The percentage of soluble phosphorus immobilized increased as the nitrogen/phosphorus ratio of the sample increased. Some of the inorganic phosphorus rendered insoluble by microbes reverted to soluble phosphorus following a mild drying treatment, but about half of the solubilized phosphorus was organic. The results are discussed in relation to the recycling of phosphorus in pastures.
Assessment of summer forage crops for sheep by the put-and-take grazing technique
Authors: Wheeler JL , Hedges DA
Published: November 2004

During three summers a sorghum-Sudan grass hybrid (Sorghum bicolor x S. sudanense) and S. almum were grown at three levels of nitrogen fertilizer (0, 84, or 168 kg N/ha) in a cool temperate environment at Armidale, N.S.W. A pearl millet (Pennisetum typhoides) was included in the experiment during one summer and Japanese millet (Echinochloa crus-galli var. frumentacea) in two summers. Differences in dry matter production were non-significant except in one summer when Japanese millet produced almost twice as much as the sorghums. The forages were grazed by young sheep on the put-and-take method. Carrying capacity as judged by this technique was high on all crops except pearl millet but average daily gains were low, the performance on S. almum being generally the poorest. Total production (expressed as metabolizable energy intake) was significantly higher for S. almum than for the hybrid or pearl millet in the first year but there were no significant differences thereafter. Pre-sowing application of anhydrous ammonia did not increase the dry matter available at the first grazing and tended to depress animal performance. Liveweight gain per hectare was significantly reduced by nitrogen in one of the three summers. Residual soil nitrogen subsequently assessed by an oat crop was substantial on plots that had received ammonia. Crop performance measures were computed in various ways and differences between them are discussed. It is tentatively concluded that, of the four crops, Japanese millet has the most potential for use by sheep in this environment.
Ovulation rate and survival of fertilized ova in Merino ewes selected for and against multiple births
Authors: Trounson AO , Moore NW
Published: November 2004

Peppin Merino ewes selected for (T group) and against (0 group) multiple births over a number of generations were used in an experiment designed to study the effect of selection on ovulation rate, response to exogenous gonadotrophin (1300 i.u. pregnant mare serum gonadotrophin—PMSG), and their ability to support one or more embryos of their own or the other group. Fertilized eggs, collected following treatment of donors with PMSG, were transferred within and between groups at a rate of one and three per recipient. Recipients were not treated with PMSG. The mean ovulation rates of T and 0 recipients were 2.03 and 1.13, and the mean ovulatory response to PMSG of T ewes was almost 50 % greater than that of O ewes (4.76 v. 3.29 corpora lutea). The survival to birth of transferred eggs was affected by both the selection group of the egg and the selection group of the recipient, and by the number of eggs transferred. More O than T recipients lambed (77 % v. 45 %); and within O recipients, intergroup transfers were more successful than intragroup transfers (94 % v. 54% ewes lambed). A similar but not significant difference was observed in T group recipients (54% v. 38% lambed). Where three eggs were transferred, neither the selection group of the recipient nor that of the egg had any effect upon the incidence of multiple births. It is concluded that selection has operated primarily on ovulation rate, and there was some evidence of heterosis in intergroup transfers.
Nutritional evaluation of meat meals for poultry. VII.* Effect of processing temperature on total and biologically available amino acids
Authors: Kondos AC , McClymont GL
Published: November 2004

The effect on the protein quality of meat meals of processing them under commercial conditions in a continuous dry renderer at maximum temperatures ranging from 116 to 160°C for a running time of 115 min was studied. Although the total levels of amino acids were little affected by processing temperatures, the biological availability of all essential amino acids, as determined by the protozoan Tetrahymena pyriformis, was reduced as the processing temperature increased. At 140 and 160°C the availability of certain amino acids was reduced by 37-56%, lysine, histidine, and methionine being the most severely affected. The availability of essential amino acids in meals produced at temperatures from 121 to c. 138° was not significantly different. The growth-promoting ability of the meat meals for chickens was closely related to the availability of the essential amino acids.

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*Part VI, Aust. J. Agric. Res., 19: 171 (1968).
Potassium nutrition, ionic relations, and oxalic acid accumulation in three cultivars of Setaria sphacelata
Authors: Smith FW
Published: November 2004

The effects of potassium and nitrogen fertilization on growth, chemical composition, ionic relations, and oxalic acid levels in the Nandi, Kazungula, and Narok cultivars of Setaria sphacelata have been studied. Potassium response curves have been derived and their use in predicting 'critical potassium levels' in these grasses discussed. Cation-anion balances (total inorganic cation concentrationndash;total inorganic anion concentration) have been calculated and the effects of potassium and nitrogen fertilization on ionic relations are discussed. The Kazungula and Narok cultivars contained higher levels of the cations calcium, magnesium, sodium, and ammonium when grown under limiting potassium conditions than when supplied with adequate potassium. The Nandi cultivar was similarly affected but did not accumulate sodium. All plants with high levels of potassium in their tissues also contained high levels of nitrate when the nitrogen supply was adequate. The cation-anion balance increased with increasing potassium fertilization in all cultivars but there was an interaction between potassium fertilization and nitrogen fertilization. Potassium and nitrogen fertilization resulted in large increases in oxalic acid levels. It is shown that the amount of oxalic acid accumulated is related to the cation-anion balance.
Effects of defoliation on growth and carbon dioxide exchange of subterranean clover swards
Authors: Davidson JL , Birch JW
Published: November 2004

From 4 weeks after germination, three defoliation regimes – undisturbed, cut to 3 cm above ground every 4 weeks, or cut to 1.5 cm every week – were imposed on small swards of subterranean clover cv. Tallarook grown at constant 20´C and a 10 hr day length of 23,700 1x intensity. The treatments induced marked differences in morphology, growth, and survival. Within 16 weeks from sowing 50% of uncut plants had died compared with 5% under weekly defoliation. The rate of 35S uptake was consistently higher in uncut swards, which were estimated to have produced over 60% more dry matter than defoliated swards, yet yielded some 30% less because of high rates of death and decay within them. An optimum leaf area index (LAI) of 2.5–3 for net photosynthesis resulted from the rapid decomposition of dead tissues. Photosynthetic efficiency increased with age in uncut swards, and respiration rates over all treatments were linearly related to total plant weight. Plants adapted to weekly cutting by developing a prostrate network of stolons with a dense population of sites of leaf production which led to rapid canopy development following defoliation, and increasing rates of 35S uptake as time progressed. Five times as many leaves were harvested as from the uncut treatment and 70% of the herbage was leaf, compared with 25% in uncut swards. After 8 weeks of cutting, the photosynthetic rate of ground cover left following defoliation was about two-thirds of that achieved by complete leaf cover. The usual confounding of LAI with age, and different susceptibilities of dead tissues within low and high density populations to decompose rapidly, may explain previous conflicting reports of whether or not optimum LAIS for growth exist in clover swards.
Formaldehyde as a silage additive. I. The chemical composition and nutritive value of frozen lucerne, lucerne silage, and formaldehyde-treated lucerne silage
Authors: Brown DC , Valentine SC
Published: November 2004

Formaldehyde-treated silages, frozen lucerne, and untreated silage were prepared from a lucerne stand and offered to Merino wethers. Formalin was applied at rates of 16.6, 24.9, and 33.1 g formaldehyde per 100 g crude protein. Formaldehyde-treated silages had significantly lower concentrations of ammonia nitrogen and total and individual organic acids than did untreated silage, and hence the ensiling fermentation was inhibited by formaldehyde. Formaldehyde treatment of lucerne partly protected plant proteins against microbial degradation during in vitro rumen liquor digestion and so reduced ammonia nitrogen concentrations in the supernatant. Ad libitum dry matter intakes and in vivo dry matter and nitrogen digestibilities were significantly lower for the treated silages than for frozen lucerne or untreated silage. The treatment of lucerne with formaldehyde at concentrations of 16.6 g formaldehyde per 100 g crude protein and above was not a suitable method of controlling the ensiling fermentation to increase the voluntary consumption of lucerne silage by sheep.
Trichostrongylid infections of sheep in a winter rainfall region. I. Epizootiological studies in the Western District of Victoria, 1966-67
Authors: Anderson N
Published: November 2004

Regular post-mortem counts from 'tracer' and flock sheep, together with faecal worm egg counts and plasma pepsinogen determinations, formed the basis of an epizootiological study of trichostrongylid infections of Merino sheep in the Western District of Victoria. Species from genera Trichostrongylus, Ostertagia and Nematodirus predominated in the worm counts; Haemonchus contortus was absent. Counts of Ostertagia and Trichostrongylus spp. from successive groups of 'tracer' sheep showed a pronounced seasonal distribution of available larvae in accordance with the temperature and humidity components of the prevailing weather. Mean worm counts ranging from 2000 to 32,000 per fortnight were recorded between May and October, whereas at other times the counts were consistently less than 500. When the availability of larvae was high, faecal worm egg counts of weaners and adult sheep were less than 150 epg. At this time the majority of the worms in the abomasum were early fourth stage larvae. Some weeks after availability had decreased to low levels, mean egg counts increased from 100 to values over 700 epg. It was concluded that the high levels of larval availability were derived from worm eggs deposited in the previous summer and autumn. Resistance to the establishment of worms was evident in both young and mature sheep. It was found that raised plasma pepsinogen levels, indicative of severe abomasal lesions, were closely related to the numbers of newly ingested larvae. Liveweights and fleece weights of weaners treated with 88 mg thiabendazole per kg every 14 days and those from untreated weaners did not differ significantly until the availability of larvae decreased to low levels, after which the treated sheep were heavier and produced 0.52 kg or 14.6% more wool per head.
Response of soya beans to planting date in south-eastern Queensland. I. Influence of photoperiod and temperature on phasic developmental patterns
Authors: Lawn RJ , Byth DE
Published: November 2004

Phenological development of a range of soya bean cultivars for a series of planting dates was studied at Redland Bay, Queensland. Responses in the duration of the phasic development patterns were related to the changes in day length and temperature regime during each phase. Genetic lateness of maturity among cultivars was associated with increasing sensitivity to photoperiod during all phases of development. The earliest-maturing cultivars were effectively day-neutral in the photoperiodic range of the test environment and exhibited significant response to photoperiod during the flowering phase only. In contrast, the pre-flowering, flowering, and post-flowering phases of later cultivars were considerably extended for those planting dates which involved the occurrence of these phases during the periods of longest day length. Late-maturing cultivars were sufficiently sensitive to photoperiod during the pre-flowering and flowering phases for the post-flowering phase to be delayed until the occurrence of short day lengths towards the end of the season. Temperature effects were apparent only in the absence of a strong photoperiodic response. Longer pre-flowering phases for early plantings of early-maturing cultivars were associated with lower daily temperatures early in the season. Similarly, extended post-flowering periods and delayed maturity for late plantings of late-maturing cultivars were associated with lower daily temperatures late in the season. It is suggested that the patterns of response described may be expected to recur in most environments for that range of cultivars which is capable of successful reproductive growth in each environment.
The effects of dung beetle activity on the numbers of parasitic gastrointestinal helminth larvae recovered from pasture samples
Authors: Bryan RP
Published: November 2004

Studies have been made of the effect of the dung beetle, Onthophagus gazella, on the release of strongyle larvae from cattle faeces onto pasture. A series of faecal pats containing parasitic nematode eggs was placed on pasture, and beetles were added to some pats to give three levels of beetle activity, viz. 100 g, 200-250 g, and 500 g of faeces per pair of beetles. These pats were duplicated on irrigated and non-irrigated pasture. In both cases the numbers of strongyle larvae migrating from pats attacked by dung beetles were significantly less than those migrating from control pats containing no dung beetles. Compared with larval recoveries from control pats, the percentage reduction in numbers of larvae migrating from pats on irrigated pasture was 50% for pats of 100 g faeces per pair of beetles, 48 % for pats of 200-250 g faeces per pair, and 84% for pats of 500 g of faeces per pair. The respective figures for pats on nonirrigated pasture were 76, 86, and 93 % reduction in larval numbers. The results indicated that strongyle larvae migrated from faecal material buried by dung beetles, provided soil moisture was adequate. More larvae were recovered from the pasture surrounding irrigated faecal pats attacked by beetles than from the non-irrigated pats. During warm dry weather, surface faecal debris remaining after beetlc attack appeared to be helminthologically sterile.