bluuebunny/crossref_metadata_2025 huggingface dataset:
Intake and digestion of mature Flinders grass (Iseilema spp.) by sheep and their response to the addition of urea and minerals
Authors: Stephenson RGA , Weston RH , Margan DE , Hogan JP
Published: November 2004

Studies were conducted of the voluntary feed consumption (VFC) and digestion by sheep offered mature Flinders grass hay containing, on a dry matter basis, 4.2% crude protein (CP), 71.8% cell wall constituents (CWC) and 12.6% total ash. The nutritive value of the hay was low, as indicated by the relatively low values for organic matter (OM) digestibility (40.9%), VFC (879 g OM/day) and CP digested in the intestines (5.8 g CP/100g feed OM intake). Digesta flows from the rumen and abomasum per unit OM intake, rumen and abomasal digesta pH, ammonia concentration in rumen liqour, and CP reaching the intestines relative to CP and digestible OM intakes were similar to values previously obtained with temperate grasses. Supplementation of the hay with urea increased VFC by 16%, and minerals in addition to the urea enhanced it by a further 6%. The supplements substantially increased OM and CWC digestibilities (by 16-17%) and CP digested in the intestines (DCPi) per unit hay intake (by 10%); these improvements could be attributed to changes in ruminal digestion. The higher levels of intake and digestion with the supplements were accompanied by increased concentrations of volatile fatty acids (VFA) in the rumen. It was calculated, by using the ad libitum feeding results, that the supplements of urea and minerals would have increased the intakes of digestible OM and DCPi by 44 and 36% respectively. However, with the supplements, DCPi per kg digestible OM remained low at 13.3 g. The data facilitate interpretation of previous animal production studies with Flinders grass hay and indicate that production may be limited by inadequate amino acids in the supplemented diet.
The availability of Trichostrongylid larvae to grazing sheep after seasonal contamination of pastures
Authors: Anderson N
Published: November 2004

Separate paddocks of improved pasture were contaminated at different rimes with worm eggs from grazing sheep with naturally acquired infections of the genera Ostertagia, Trichostrongylus and Nernatodirus. Worm counts from 'tracer' sheep on each paddock were used to estimate the availability of larvae for up to 9 months after contamination. Typical hot and dry weather prevailed during the summer months of 1970-71, and few Ostertagia and Trichostrongylus larvae were available on any paddocks. However, larvae of these species survived in faeces over summer and their availability increased to reach peak levels on all paddocks by 8 weeks after the onset of autumn rains. Infection persisted at moderate levels until midwinter. Rainfall in the summer months of 1971-72 exceeded the average by about 50% while in autumn it was reduced by a similar amount. Compared with the previous year, greater numbers of Ostertagia and Trichostrongylus spp. were available in summer on paddocks contaminated before and during summer, but fewer persisted through autumn and winter. In both years larvae from eggs deposited in late summer and autumn made the greatest contribution to worm burdens of 'tracer' sheep slaughtered in winter months. By mid-October, when mean maximum temperatures and evaporation rates were rising, the numbers of larvae decreased rapidly to low levels on all paddocks contaminated from late summer onwards. Availability of Nematodirus spp. was similar on all paddocks contaminated before or during summer. Peak numbers occurred in summer months of 1970-71, but not in 1971-72, and in both years a secondary peak was observed in March-April before the increase in availability of Ostertagia and Trichostrongylus spp. Some implications for the control of helminthiasis in sheep are discussed.
Studies on competition for sulfur between subterranean clover and annual ryegrass. II. Interrelation of nitrogen supply and soil temperature
Authors: Gilbert MA , Robson AD
Published: November 2004

The effects of soil temperature (7, 13, 19 and 25�C) end supplies of nitrogen and sulfur on growth and competition between subterranean clover ( Triticum subterraneum cv. Trikkala) and ryegrass (Lolium rigidum cv. Wimmera) were examined in a glasshouse experiment over a period of 62 days. Soil temperature influenced competition for sulfur in mixtures of species supplied with nitrogen fertilizer. When the sulfur supply was low, there was no competition between the species at temperatures of 7 and 13�C. However, at 19 and 25�C ryegrass suppressed the yield and sulfur content of subterranean clover. When sulfur was applied to the mixture, nitrogen application did not result in competition at any temperature. When nitrogen supply was low, the yield and sulfur content of ryegrass were poor compared with those of subterranean clover. However, this did not result in competition between the species at low or high levels of sulfur supply. In both species, yield and sulfur content increased, and sulfur concentration decreased with increasing soil temperature. Hence there were severe symptoms of sulfur deficiency in plants grown with added nitrogen at 19 and 25'C, and no symptoms in plants grown at lower temperatures. While both species had the same optimum temperature range for growth (between 19 and 25�C), ryegrass grew relatively better than subterranean clover at lower temperatures.
Effects of potassium and sodium application to soil on growth and cation accumulation of herbage
Authors: Mundy GN
Published: November 2004

The effects of potassium (K) and sodium (Na) applications to soil on growth and cation accumulation of herbage were investigated in pot and field experiments. The application of K to K-deficient soil was more efficient at increasing growth than was the application of Na; however, at suboptimal K availability, yield was increased by Na application. Growth responses to Na were restricted when the soil contained insufficient K to satisfy the minimum K requirement of pasture plants. The Na concentration of herbage was markedly reduced by K applications, whereas Na had little effect on K uptake. It was found that an application of Na to soil containing a low level of Na raised the Na concentration of herbage sufficiently to satisfy animal needs. Both K and Na reduced the calcium (Ca) and magnesium (Mg) concentration of herbage, although Na was less inhibitive than an equivalent amount of K. The decline in Ca and Mg in plant tissue with increasing concentrations of soil K and Na was exponential and, as the decline approached the asymptotic concentration, further increases in soil K and Na had only a small effect on Ca and Mg uptake. The implications of these findings are discussed.
Effect of rhizobia and soil nitrate on the establishment and functioning of the soybean symbiosis in the field
Authors: Herridge DF , Roughley RJ , Brockwell J
Published: November 2004

The symbiosis of the root-nodules of Bragg soybean [Glycine max (L.) Merrill] and the relative dependence of the plants on symbiotic and soil sources of N were evaluated in an experiment conducted on a vertisol which was high in organic- and mineral-N, free of Rhizobium japonicum, and where poor nodulation was characteristic of inoculated, new sowings. Effective inoculant containing R. japonicum strain CB 1809 was sprayed into the seed bed at three rates of application (10-fold intervals). Increasing rates of inoculant led to greater numbers of rhizobia in the rhizosphere and in the soil, and to improved nodulation. Uninoculated plants did not nodulate. High soil NO-3 (30 �g N/g, top 30 cm) did not prevent prompt, abundant colonization of rhizospheres by the bacteria from the inoculant, but nodule initiation was delayed and nodule development was retarded until 42 days after sowing. There was an acceleration in nodule formation and development between 42 and 62 days which coincided with a depletion of NO-3 from the top 60 cm of the soil profile. Nodulated and unnodulated soybeans took up NO-3 at similar times and rates to a soil depth of 90 cm; only unnodulated plants utilized soil NO-3 below 90 cm. Vacuum-extracted stem (xylem) exudate was sampled from plants throughout growth and analysed for nitrogenous solutes. The proportion of ureide-N relative to total-solutes-N in xylem sap was used as an index of symbiotic N2-fixation. The initial increase in concentrations of ureides coincided with the period of accelerated nodule formation and development between 42 and 62 days. Thereafter, there was a progressive increase in ureide concentrations in nodulated plants, and the levels were related to rate of inoculation, extent of nodulation, and to the decline in concentrations of soil NO-3. Ureide concentrations in unnodulated plants remained low throughout. The quantities of NO-3-N and �-NH2- N in xylem sap were not related to nodulation. The differences between treatments in terms of whole-plant N and grain N were less than predicted from the symbiotic parameters. This indicated that soybeans compensated for symbiotic deficiencies by more efficient exploitation of soil N and/or by more efficient redistribution of vegetative N into grain N, and that nodulation and soil NO-3 were interactive and complementary in meeting the N requirements of the crop.
Diagnosis of copper deficiency in wheat by plant analysis
Authors: Robson AD , Loneragan JF , Gartrell JW , Snowball K
Published: November 2004

A glasshouse experiment was conducted to define critical concentrations of copper in young leaves of wheat and to investigate the effect of water stress after anthesis on the relationship between yield and copper concentrations in young leaves. The concentration of copper in the youngest fully emerged leaf was a sensitive and accurate indicator of the copper status of wheat. The critical concentration for copper in the youngest fully emerged leaf did not change with the age of the plant. Copper deficiency occurred whenever the concentration of copper in the youngest fully emerged leaf fell below 1.3 �g g-I (dry weight). Water stress after anthesis did not change the relationship between copper concentrations in young leaves and grain yield, although this stress markedly decreased grain yield. In the field there was considerable variability among plants given the same copper treatment in copper concentrations in young leaves. Nevertheless, whenever copper deficiency decreased growth, the average concentration of copper in the youngest fully emerged leaf was less than 1.3 �g g-1.
Identification of subterranean clover cultivars and their genetic relationships by isozyme analysis
Authors: Collins WJ , Rossiter RC , Haynes Y , Brown AHD , Marshall DR
Published: November 2004

Isozyme patterns for the 22 registered cultivars of Trifolium subterraneurn L. are described for 15 enzymes. The patterns discriminated among all cultivars except that Uniwager was isozymically identical with Geraldton, from which it was derived by deliberate mutation. The 17 cultivars which originally came from naturally occurring isolates, as well as Uniwager, appeared to be isozymically homogeneous, whereas three of the five bred cultivars (Nungarin, Esperance and Howard) were polymorphic for at least one locus. The cultivars indicated that T. subterraneum is highly polymorphic at isozyme loci. Excluding the complex esterase patterns, the species was polymorphic at 21 of 26 putative loci, with an average of 2.3 alleles detected per locus. Estimates of genetic distance between the cultivars stemming from natural isolates strongly supported the classification into three subspecies. In addition, the cultivar Woogenellup (syn Marrar) was well separated from all other cultivars of the subspecies subterraneum. Isozyme surveys should therefore provide critical evidence on the role such factors as introduction, natural selection, mutation and outcrossing have had in the origin of variation within subterranean clover in Australia.
Competition between wheat and two Emex species
Authors: Williams JD , Groves RH , Weiss PW , Nichols AO
Published: November 2004

Wheat was grown with either of the cereal weeds Emex australis or E. spinosa in two replacement series at different nitrogen levels to determine the relative competitiveness of the two weeds with wheat. Other planting combinations, including a three-species mixture, allowed comparison between the two Emex species with and without wheat. The two Emex species were more competitive with wheat at high levels of nitrogen than at low levels. E. australis was more competitive with wheat than E. spinosa, regardless of the growth index considered, at all but the highest nitrogen level. The results suggest that, where the two species co-exist, E. australis will suppress E. spinosa. The relative weediness of the two Emex species with wheat is discussed. We conclude that whilst the presence of E. spinosa seeds may reduce grain acceptability, the presence of E. australis plants may reduce wheat yields more than that of E. spinosa.
Physiology of growth and seed production in Lupinus angustifolius L. III. Effects of defoliation and lateral branch excision on dry matter and seed production at different growth temperatures
Authors: Downes RW , Gladstones JS
Published: November 2004

Plants of Lupinus angustifolius cv. Unicrop were raised at 27/22 or 21/16�C dayhight temperatures until flowering. They were then either grown on to maturity at these conditions or moved to the other regime. Branches were removed as they started to develop and leaves were removed at the start of flowering so that 0, 3, 6, 9, 12 upper leaves or all 21 leaves were retained. Conditions before flowering determined potential pod number. Defoliation treatments revealed that under favourably cool conditions all leaves contributed to seed yield but in treatments involving 27/22'C there was no seed yield response to more than about six leaves, emphasizing the significance of environmental conditions rather than current assimilate on pod set and other yield components. In another experiment, plants were raised to flowering at 27/22, 21/16 or 15/10�C before flowering, when all were moved to 21/16�C. Half the plants were allowed to develop branches and on the remainder branch buds were removed. Branch and stem growth appeared to provide severe competition for the development of the primary inflorescence. Though branching was much more pronounced in plants at 15/10�C before flowering than in other treatments, vegetative development exceeded reproductive investment and harvest index was low under these conditions. It was suggested that there appears to be a need to develop and evaluate unbranched or less-branched lupin genotypes.
The effect of spraying for buffalo fly (Haematobia irritans exigua) on infestations, growth rate and lesion development on Bos indicus × B. taurus cattle in the dry tropics of north Queensland
Authors: Holroyd RG , Hirst DJ , Merrifield AW , Toleman MA
Published: November 2004

The effect of spraying for buffalo fly (Haematobia irritans exigua) on infestations, growth rate and lesion development on Bos indicus x B. taurus steers (18 months old) and bullocks (30 months old) were studied in the dry tropics of North Queensland. There were four consecutive drafts commencing between July and September and terminating the following June-July. Half of the animals were sprayed with 200 g/l fenvalerate to control buffalo flies. Treated animals carried, at most, a few flies. The size of the fly populations on the untreated animals varied with the seasons, with the most flies being recorded during the wet season. Light coloured animals carried fewer flies than those with darker colours and bullocks carried more flies than steers. Except for steers in one dry season, repeatabilities of fly counts were significant (P < 0.01). In steers, treatment had no significant (P > 0.05) effect on growth over the four treatment periods, although there were significant effects of treatment on growth in some intermediate periods. Treatment significantly (P < 0.05) affected bullock growth in two of the four years. Significant (P < 0.05) positive correlations were found between fly counts and growth rate in two years. Few lesions were recorded on treated animals. Lesion prevalence and size on untreated animals were generally not associated with fly counts, coat colour or growth rate.
Effects of aluminium on nodulation and early growth of four tropical pasture legumes
Authors: Murphy HE , Edwards DG , Asher CJ
Published: November 2004

Effects of aluminium concentrations of 0, 12.5, 25, 50, 100 or 125 �M on the nodulation and growth of Centrosema pubescens cv. Belalto, Macroptilium lathyroides cv. Murray, Stylosanthes guianensis cv. Schofield and Stylosanthes guianensis cv. Oxley were studied in solution cultures maintained at pH 4.5. The strains of Rhizobium used were CB1923, CB756, CB756 and CB1650 respectively. Solutions containing >25 �M aluminium (Al) delayed the appearance of nodules and reduced the percentage of plants which nodulated and the number and dry weight of nodules produced by all four legumes. At 125 �M Al, the proportion of plants which nodulated ranked in the order M. lathyroides (42%) > C. pubescens (29%) > Schofield stylo (16%) > Oxley stylo (0%). However, there were no significant effects of Al on dry matter production in M. lathyroides or C. pubescens. In Schofield stylo 250 �M A1 caused a small but significant yield reduction. In Oxley stylo, the yield reduction was significant at 25 �M , but became large only at 125 �M. It is concluded that in M. lathyroides, C. pubescens, and possibly Schofield stylo, nodulation is more sensitive to aluminium toxicity than is host plant growth. In Oxley stylo, threshold concentrations were similar for significant effects of aluminium toxicity on nodulation and growth.
Effects of common stubble treatments and sowing sequences on scald disease (Rhynchosporium secalis) in barley crops
Authors: Mayfield AH , Clare BG
Published: November 2004

Scald disease was absent in barley (Hordeurn vulgare L. cv. Clipper) grown in field plots where nonhosts of Rhynchosporiurn secalis had been grown successively, and from which living hosts of R. secalis had been absent for at least 18 months. In another field experiment, the burning or grazing of barley stubble containing R. secalis reduced the amount of scald disease of barley sown subsequently in the same plots, but only at early and not at later plant growth stages. Application of the fungicide maneb to burnt stubble gave no control additional to that given by burning. However, inoculation of field plots of barley at seedling emergence with differing amounts of R. secalis inoculum produced a corresponding range of levels of scald disease at both early and late growth stages.
Effect of treatment with sodium hydroxide on the feeding value of oat and rape straw for sheep
Authors: Coombe JB , Mulholland JG , Forrester RI
Published: November 2004

Oat and rape straws were treated with NaOH (70 and 40 g kg-1, respectively) by spraying with NaOH solutions (20 or 12.5% w/w), consolidating the sprayed straw into stacks, and storing under plastic. After storage for up to 60 weeks, in vitro digestibilities had been approximately doubled, although it appeared that the reaction was complete by 4 weeks. Potential digestibility of straw organic matter estimated by a polyester bag technique, was increased by c. 0.1 by NaOH treatment but the rate of digestion in the rumen was not changed. Following storage, treated and untreated straws were dried, ground, mixed with supplements and pelleted for feeding to sheep. Mixtures of treated or untreated oat straw, minerals, c. 3% urea and 0, 14, 28 or 42% starch were fed to mature wethers. The main effects of NaOH treatment of straw were to increase water intake, digestibilities of organic matter and cellulose, and rumen volatile fatty acid levels, and decrease rumen ammonia levels. Low intakes of NaOH-straw with no added starch were associated with high rumen pH (> 7.5 , probably due to unreacted alkali (equivalent to 23 g NaOH kg-1). Inclusion of starch, but not NaOH-straw treatment, improved dietary N utilization, although mean N balances were negative (- 5.5 to - 0.1 g day-1) on all diets. Feeding treated straw increased the amounts of Na eaten, and of Na and P apparently absorbed; the extra absorption was accounted for by increased urinary excretion so that retention was not increased. When diets of rape straw supplemented with urea and minerals were fed to 2-year-old wethers, NaOH treatment of straw increased intakes of food and water, organic matter digestibility, rumen volatile fatty acid concentration and N balance.
Effect of reference plant on estimation of nitrogen fixation by subterranean clover using 15N methods
Authors: Ledgard SF , Simpson JR , Freney JR , Bergersen FJ
Published: November 2004

Subterranean clover (Trifolium subterraneum L.) was grown in separate associations with annual ryegrass (Lolium rigidum Gaud.) and with phalaris (Phalaris aguatica L.) in reconstituted soil profiles (0-400 mm depth), and N2 fixation was measured by 15N isotope dilution and 15N natural abundance methods. In all experiments, two values were determined, viz. P, the percentage of clover nitrogen (N) iixed from atmospheric N2, and R, the ratio of N assimilated from added 15N-labelled N to N assimilated from indigenous soil N. Estimates of P that were negative were obtained for the clover/phalaris association, using 15N isotope dilution, during the first 16 days after 15N addition. This was due to the R value being higher for clover than for phalaris, which in turn was due to differences in their temporal pattern of growth interacting with a declining ISN enrichment of the plant-available soil N. The R values for clover and ryegrass, when grown together, were similar throughout the experiment, and estimates of P by 15N isotope dilution and natural 15N abundance were similar. The activity of plant roots in different soil layers was examined by injecting a solution of 15N-labelled nitrate at 50, 150 and 300 mm depths. Uptake of 15N was similar at all depths for phalaris and clover, whereas ryegrass assimilated a greater amount at 150 and 300 mrn. However, since the amounts of roots and indigenous plant-available soil N were small in the 100-400 mm zone relative to the 0-100 mm zone, the greater activity of ryegrass roots at depth had no significant effect on the estimates of P. In both plant associations, the estimates of P, by both of the 15N methods, increased with time, and were higher in the clover/ryegrass association than with clover/phalaris. Since this was associated with lower levels of inorganic soil N in the clover/ryegrass association, it must be recognized that the reference plant can induce real changes in P by influencing the soil N status, in the association, as well as causing erroneous estimates of P by the 15N isotope technique.
The use of 'bending' in multiple trait selection of Border Leicester - Merino synthetic populations
Authors: Gunawan B , James JW
Published: November 2004

The consistency of phenotypic and genetic parameters estimated for various body weight and wool characters in Border Leicester-Merino synthetic populations was investigated by calculating the eigenvalues of matrices of phenotypic covariances (P), genetic covariances (G), and the product of the inverse of the phenotypic with the genetic covariance matrix (P-1G). If these estimates were found to be inconsistent (non-positive definite), the bending technique was applied before genetic selection indices were calculated. In general, the P were positive definite, but the G or P-1G were always non-positive definite. The results suggest that P and G should always be checked carefully before genetic selection indices are calculated. The bending technique was quite effective in giving reasonable results for accuracy of selection.
The effects of genotype, age, pregnancy, lactation and rumen characteristics on voluntary intake of roughage diets by cattle
Authors: Hunter RA , Siebert BD
Published: November 2004

The effects of genotype, age and liveweight, pregnancy and lactation on the voluntary feed intake by cattle of roughage diets of different qualities were studied in a number of experiments. The diets ranged from poor quality (low-nitrogen, high-fibre) spear grass (Heteropogon contortus) hay on which intakes were low ( 1 1 g DM/kg liveweight (LW)) to good quality lucerne (Medicago sativa) hay (26 g DM/kg LW). On the poorest-quality diet, differences in intake between Bos taurus and Bos indicus were not significant. However, on the higher quality diets Herefords (Bos taurus) ate significantly (P < 0.05) more than Brahmans (Bos indicus). In addition, as the quality of the diet improved from speargrass through to lucerne, the breed difference in favour of the Herefords became progressively greater and the variability between animals progressively smaller as a proportion of intake. Another study showed that with increasing age and liveweight of steers, intake per unit body weight declined, the rate of decline being significantly (P < 0.05) greater on good-quality lucerne compared to a poor-quality speargrass diet. There was no significant difference between Aberdeen Angus (Bos taurus) and Brahman steers in the rate of decline of intake of each diet with increasing age and liveweight of the steers. Another experiment which measured intake of pregnant and lactating heifers showed that the amount of feed eaten by pregnant heifers increased with increasing liveweight in late pregnancy, with intake per unit liveweight remaining constant. Lactating cows ate 35% more on a liveweight basis than their nonpregnant, non-lactating counterparts. These results are discussed in relation to mechanisms which control intake of roughage diets in ruminants, especially those associated with energy metabolism.
Barley yellow dwarf viruses in, and aphids on, grasses (including cereals) in Tasmania
Authors: Guy PL , Johnstone GR , Morris DI
Published: November 2004

Samples of 2077 grasses and cereal plants representative of the Poaceae found in Tasmania were collected from a wide range of habitats throughout the State. Each sample was examined for infestation with aphids and then checked for infection with viruses causing barley yellow dwarf by both aphid transmission and serological tests. Aphid species found among the samples were Hyalopterus pruni, Rhopalosiphum maidis, R. padi and Sitobion fragariae. R. padi transmitted a vector non-specific type of barley yellow dwarf (PAV) and a vector specific type (RPV), either alone or together, while S. fragariae transmitted PAV alone and occasionally RPV when present in plants together with PAV. The other aphid species did not transmit. A total of 189 samples contained virus. Incidence was greatest in samples from the Bambusoideae subfamily (31%) and least in the Arundinoideae (4%). There was no difference in the level of infection between the native and introduced species that were represented. The Arundinoideae and Panicoideae were predominantly infected with RPV types, while the Pooideae, with the exception of Dactylis glomerata and Poa pratensis, were predominantly infected with PAV types. Many more infected plants contained both PAV and RPV (11.9%) than would have been expected had the two types of virus infected independently (2.5%). No infected plants were found among samples from 25 of the 56 species tested, and some of these may prove useful in breeding for resistance to barley yellow dwarf viruses.
Biological characterization of six Australian isolates of potato virus Y and their serological detection by ELISA
Authors: Heath R , Sward RJ , Moran JR , Mason AJ , Hallam ND
Published: November 2004

Six potato virus Y isolates from Victoria and Queensland were characterized on the basis of host plant reactions. Four isolates from potato produced symptoms in indicator plants and potato cultivars consistent with those caused by the PVYO group. Two isolates from tobacco produced necrotic symptoms on some tobacco cultivars characteristic of the PVYN group, but did not systemically infect potato cultivars and therefore could not be considered to belong to any of the previously described PVY strain groups. Despite the wide variation in their biological characteristics, an antiserum produced to one of the potato isolates was able to detect all six of the isolates when used in ELISA
Studies on the growth and carcass composition in Daldale wether lambs. 1. The effect of dietary energy concentration and pasture species
Authors: Soeparn o , Davies HL
Published: November 2004

Thirty-two Daldale wether lambs were randomly allocated in groups of four and were grown from 23.3 � 0.4 kg liveweight until slaughter at a final full liveweight of 37.5 kg. Eight lambs were fed on a high energy diet (HE) ad libitum, eight lambs were given a low energy (LE) diet ad libitum, eight lambs grazed Trifolium repens L. (WC) pasture and eight others grazed Phalaris aquatica L. (PH) pasture. Those on the HE diet grew at 171 g/day, the lambs on the LE diet at 105 g/day, white clover lambs at 227 g/day and lambs on phalaris at 198 g/day. The HE lambs when compared with the LE, the grazed Trifolium repens L. (WC) pasture and eight others grazed Phalaris aquatica L. (PH) pasture. Those on the HE diet grew at 171 g/day, the lambs on the LE diet at 105 g/day, white clover lambs aat 227 g/day and lambs on phalaris at 198 g/day. The HE lambs when compared with the LE, the WC and the PH lambs, had significantly greater dressing percentage (54.7 compared with 48.8, 5 1.3 and 49.4 respectively), fat thickness over the 12th rib section (8.9 mm compared with 5.5, 5.6 and 4.8 mm), more omental fat ( + 15%, + 65%, and + 57%), kidney, perinephric and pelvic fat (+ 35%, + 85%, and + 54%), a greater amount of dissectable fat from the 9-10-11th rib (+ 15%, +30% and + 33%) and from the long leg (+ 16%, +34% and +40%), and a greater amount of carcass chemical fat (+ 19%, +27% and + 35%). No differences existed among the LE and the two pasture groups in carcass composition.Digestion of two diets (HE and LE) in the stomach and intestines was studied. The flow of digesta from the rumen was higher (+ 37%); the flow of digesta from the abomasum per unit of organic matter intake was higher (+ 47%) and the mean residence time of 51Cr-EDTA in the rumen was lower (-17%) for the LE diet than for the HE diet. There was a 23% higher concentration of acetic acid, and a 33% lower concentration of propionic acid, 6.5% less butyric acid and 30% less combined valeric acids.The greater amount of fat in the carcass of the sheep fed the high energy diet appears to be associated with the higher concentration of propionic acid in the ruminal volatile fatty acids and none of the other parameters of digestion. There may also have been a more eficient utilization of metabolizabe energy on the high energy diet.
Tolerance of wheat, barley, triticale and rye to manganese deficiency during seedling growth
Authors: Marcar NE , Graham RD
Published: November 2004

The manganese (Mn) efficiencies, i.e. tolerances to Mn deficiency, of wheat, barley, triticale and rye seedlings, were compared, with emphasis on genotypic variation within wheat. Plants were grown in small pots containing a Mn-deficient calcareous sand, with and without Mn addition, over a 4-week period at 15�C.Barley proved to be the most Mn-efficient cereal, having the highest dry matter production, Mn uptake and utilization efficiency. The high rate of Mn uptake for barley was strongly associated with greater lateral root development. The severe Mn deficiency of this soil precluded any significant Mn uptake by the other cereals. Differences in growth between wheat cultivars without added Mn were associated with differences in the Mn content of sown seeds.The results obtained from the screening of wheat-barley addition lines suggested that Mn-efficiency characters could be transferred from barley to wheat, since relative growth at Mn 0 was significantly greater for some of the addition lines than for wheat.
Feeding high energy supplements to pasture-fed dairy cows. Effects of stage of lactation and level of supplement
Authors: Stockdale CR , Callaghan A , Trigg TE
Published: November 2004

Five experiments were done in which stall-fed dairy cows were provided with a basal ration of pasture (6-7 kg DM) which was supplemented with varying amounts of a pelleted, high energy supplement (0-10 kg DM). Forty-seven cows at various stages of lactation were fed in this manner for up to 5 weeks. Responses to feeding the supplement depended on the stage of lactation at which the supplement was fed, and the amount of the supplement consumed. Marginal responses in milk production fell from 1.6 to 0.7 kg milk per kg supplement as lactation progressed, and as the level of feeding increased. Although responses in milk fat yield also decreased as lactation advanced, there was also a reduction in milk fat production when more than about 6 kg DM of supplement were fed. This was due to a severe depression in the fat content of the milk, which was found to be associated with intakes of diets with less than 250 g kg DM-1 neutral detergent fibre; diets with less than this level of fibre resulted in ratios of lipogenic to glucogenic volatile fatty acids in the rumen below 4:1. This occurred when the supplement constituted 0.4-0.5 of the diet on a dry matter basis. In addition, rumen ammonia levels were low when large amounts of supplement were fed. With all rumen characteristics, stage of lactation had no influence on values.
Effect of ingestion of hydrolysable tannins in Terminalia oblongata on digestion in sheep fed Stylosanthes hamata
Authors: McSweeney CS , Kennedy PM , John A
Published: November 2004

Effect of hydrolysable tannins in the browse tree Terminalia oblongalu (yellow-wood) on digestion of organic matter, fibre and nitrogen in the stomach and intestines, was studied in sheep fed a basal diet of the tropical legume Stylosanthes hamata (verano). These tannins are toxic to the liver and kidneys, but their effect on digestion is not known. Although two of the four sheep used showed signs of yellow-wood toxicity with an intake of 0.9 g tannin/kg body weight, there were no significant effects on OM, N and CWC digestion of verano in the alimentary tract as a whole. However, yellow-wood appeared to depress OM and CWC digestion in the stomach, but this was compensated for by greater intestinal digestion. The OM digestibility of verano in the whole tract was 0.59 of intake, with two-thirds due to digestion in the stomach. About 0.87 of the total N loss (0.68 of intake) in the gut occurred in the intestines, and microbial N production was 33 g/kg of verano OM digested in the stomach. Therefore intake of non-toxic levels of yellow-wood should not compromise digestion.
Ecology of the cattle tick (Boophilus microplus) in subtropical Australia. III. Modelling populations on different breeds of cattle
Authors: Bourne AS , Sutherst RW , Sutherland ID , Maywald GF , Stegeman DA
Published: November 2004

The numbers of cattle ticks, Boophi1us microplus, were counted on cattle, with different Bos indicus (zebu) content in central and southern Queensland, from November 1977 to May 1982. Concurrently, measurements were made of the survival rates of parasitic stages of the tick and of the success of free-living stages in producing larval progeny. These measurements were related to the tick burdens on the cattle in order to test current understanding of the ecology of the tick.Tick numbers increased exponentially with decreasing Bos indicus content. Tick numbers built up very rapidly on the Bos taurus cattle and resulted in deaths early in the first season, so the herd was replaced with animals of 25% zebu content. The pure zebu animals carried an average of five ticks per animal per day in central Queensland and only one in southern Queensland. The 50% zebu herds carried 65 ticks per day in central Queensland and 1 l in southern Queensland, compared with 79 and 37 on the 25% zebu herds at the two locations. During their brief time in the experiment the B. taurus animals carried 465 and 302 ticks per day in central and southern Queensland respectively.The observed tick infestation levels were estimated to cause annual losses of liveweight gain of 1, 14 and 17 kg in zebu, 50% zebu and 25% zebu animals respectively in central Queensland. Comparative figures for southern Queensland were 0, 2 and 8 kg. Compensatory liveweight gain would have reduced these losses by up to 6 kg. These data relate to animals which were breeding most of the time and hence were less resistant than dry cattle. The results indicate that B. microplus has been reduced to a marginal problem on animals with 50% zebu genes in the region. It is therefore difficull to justify any control measures in southern areas, particularly when they could increase the risk of babesiosis. Owners of B. taurus cattle will continue to be at risk of major losses in productivity.Changes in the tick burden on the herd5 were explained mostly by changes in survival rates of parasitic ticks in central Queensland and by changes in availability of larvae on the pastures in southern Queensland.
Utilization of clover diets by sheep. 2. Intake, digestion and utilization of nitrogen and sulfur
Authors: Doyle PT , McLaren CE
Published: November 2004

Nine mature Merino wethers were fed three clover diets at 95% of previously measured intake under steady state conditions. The diets were mature subterranean clover (MSC), green subterranean clover (GSC) and persian clover (PC). The utilization of dietary N and S was studied for each feed.The ratios of digestible organic matter (DOM) to crude protein (CP) in the diets ranged from 3.9 to 5.5 : 1. The flow of microbial crude protein (MCP) from the abomasum was only 34 g day-1 in sheep given MSC compared to 77 g day-1 for GSC and 85 g day-1 for PC. However, the calculated efficiencies of MCP synthesis were 230-250 g MCP per kg OM apparently digested in the rumen for the three clovers. Despite the similar efficiencies of MCP synthesis, the ammonia-N (30 mg l-1) and sulfide-S (220 8g l-1) concentrations in the rumen of sheep fed MSC were low. The concentrations for the the other clovers were ammonia-N 90-110 mg l-1 and sulfide-S 730-1770 8g l-1. The amount of CP apparently digested in the intestines (DCPi) was only 31 g day-1 in sheep given MSC compared to 100 g day-1 and 81 g-1 in those fed GSC and PC, respectively. While this indicates that protein insufficiency in the tissues may have limited the intake of MSC, the DCPi values per unit of DOM intake were 150,210 and 150 g kg DOM-1 for MSC, GSC and PC, respectively. Sheep excreted more N and S (% of intake) in faeces when given MSC compared to GSC or PC.The sheep were in positive apparent balance for N and S when fed GSC or PC, but were mobilizing these nutrients from tissues at the low intakes of DOM, N and S with MSC. The wool growth rates and amounts of N and S incorporated into wool when MSC was fed were about half the other two feeds.These results are discussed in relation to other work on the utilization of N and S by sheep and likely effects of this on the intake of the feeds.
Fleece rot and body strike in Merino sheep. I. Evaluation of liability to fleece rot and body strike under experimental conditions
Authors: Raadsma HW , Gilmour AR , Paxton WJ
Published: November 2004

The conceptual model that variation in resistance of Merino sheep to fleece rot and body strike could be attributed to an underlying variable with a continuous normal distribution, termed 'liability', was examined in four experiments. A total of 640 young Merino sheep were exposed from 0 to 13 days to a simulated rainfall treatment to allow the development of fleece rot. The incidence of fleece rot ranged from 0% of sheep affected in unwetted control groups and increased up to 100% affected with increased exposure to wetting. Assuming binomial variation, the response in fleece rot and flystrike incidence was fitted on an underlying scale using generalized linear models. In the case of fleece rot severity, grades of exudative fleece rot were shown to fit an ordered categorical response model. The assessment, induction and liability of sheep to fleece rot were found to be highly repeatable in all three cases, indicating that liability to fleece rot could be accurately screened for using experimental induction. Fleece rot severity was found to be an accurate indicator of liability to body strike but not of other forms of flystrike. The possible mechanisms and factors contributing to the liability of sheep to fleece rot and body strike have been discussed, and moisture status of the fleece during the development of the two diseases was indicated as an essential common denominator.
Studies on alternative means of legume inoculation: microbiological and agronomic appraisals of commercial procedures for inoculating soybeans with Bradyrhizobium japonicum
Authors: Brockwell J , Gault RR , Herridge DF , Morthorpe LJ , Roughley RJ
Published: November 2004

Four commercial procedures for inoculating soybean (Glycine max [L.] Merr.) with Bradyrhizobium japonicum were compared at three sites in New South Wales. Three procedures involved applying inoculant to the seed shortly before sowing (seed inoculation) as a slurry in water or gum arabic adhesive or by sprinkling inoculant on the seed in the seed box of the planter. In the fourth, inoculant was suspended in water and sprayed directly into the seed bed alongside and beneath the seed (liquid inoculation).With seed inoculation substantial losses of viability of inocula (94%-99.95%) occurred between inoculation and sowing. Some of the loss was attributable to separation of inoculant and seed, as it passed through the machinery; no such loss of viability occurred with liquid inoculation. Colonization of the rhizosphere relative to the numbers of rhizobia delivered into the seed bed was poorer with liquid inoculation than with the slurry treatments. This was attributed to the uniform distribution of rhizobia applied as liquid inoculant in the seed bed, in contrast to the concentration of rhizobia applied as slurries in the vicinity of each seed. Slurry treatments generally promoted earlier nodulation than liquid inoculation, but as the crops aged, the differences disappeared and were not reflected in seed yield or seed nitrogen. Application of inoculant to seed in the seed box, although better than an uninoculated control, was consistently inferior to the other inoculation procedures.Given favourable environmental conditions both at sowing and afterwards, slurry inoculation and liquid inoculation were equally likely to initiate a successful symbiosis. Slurry inoculation may be superior when there is limited soil moisture after sowing, whereas liquid inoculation may be better when seed is sown into relatively dry soil with good moisture beneath.
The effect of alfalfa mosaic virus on productivity of annual barrel medic, Medicago truncatula
Authors: Dall DJ , Randles JW , Francki RIB
Published: November 2004

Alfalfa mosaic virus (AMV) infection of the annual barrel medic, Medicago truncatula, has been shown to cause significant reductions in growth and productivity in field and pot trials. The degree of reduction was dependent on the medic cultivar and the virus isolate. In some experiments herbage production was reduced by more than 50%. Although infection did not appear to be associated with significant changes in root growth, root nodulation of infected plants was about one-third less than that of healthy plants. Two AMV isolates showed different effects on seed production. Infection with one virus isolate was associated with a 15-30% decrease in seed production, and the virus was detected in more than 2% of seed from the infected plants, whereas the other isolate failed to reduce seed yield and did not appear to infect any seeds.
Effect of phosphorus supply on three perennial Stylosanthes species in tropical Australia. I. Vegetative and reproductive growth
Authors: Gilbert MA , Edwards DG , Jones RK , Shaw KA
Published: November 2004

Three perennial Stylosanthes species (S. scabra cv. Seca, S.guianenis cv. Schofield and S. viscosu CPI 34904) were grown on a soil of low acid-extractable (0.005 M H2SO4) P status (4 mg/kg) and supplied with either 0 (P0) or 50 kg P/ha (P50) to test their ability to grow under phosphorus-deficient conditions. Plants were grown in the field for two years (1978 and 1979), during which time dry matter yields of standing plant shoots, leaves, stems, inflorescence, podded seed and litter were recorded regularly.Perennial stylo, but especially Seca, grew well and produced high seed yields under conditions of low soil phosphorus. Based on their growth rates during the second wet season, tolerance to low phosphorus conditions decreased as follows: Seca> Schofield >CPI 34904. Two factors favouring Seca were its ability to allocate much of its dry matter to stem and its high yield of fine roots. Positive effects of phosphorus application occurred with leaf, stem, inflorescence, seed and litter yields, but were generally similar for the three species. There were large differences in dry matter distribution between species and little effect of applied phosphorus. Features were the high percentage of stem in Seca, and of inflorescence and seed in CPI 34904.
Estimation of gestational age in Merino ewes by ultrasound measurement of fetal head size
Authors: Kelly RW , Newnham JP
Published: November 2004

Ultrasound measurements of fetal head length (occipito-snout diameter) and width (biparietal diameter) were made at 2-week intervals from about day 45 of pregnancy onwards in 3-6 year old Merino ewes bearing a single fetus, and at 1 week intervals from about day 36 to 86 of pregnancy in 4-5 year old Merino ewes bearing twin fetuses. The single-bearing ewes maintained liveweight (47 kg) during the study. The twin-bearing ewes (47 kg on day 30) were fed either to maintain weight or at 0.3 of this rate until about day 96 of pregnancy. A sample of ewes from both studies were slaughtered on days 92-94 of pregnancy, and comparable measurements taken. There were no significant effects of sex of the fetus, or undernutrition of the twin-bearing ewes on the head dimensions, except for effects (P<0.05) of feeding treatment on head length of the twins at about day 51, day 86 and day 92. The magnitude of these differences was small ( < 2 mm), equivalent to about 2 days' growth. Fetal head measurements were similar for single and twin fetuses up to about 80 days gestation. It was concluded that the most accurate prediction of gestational age was provided by head length of the fetus, with 95% confidence limits ranging from �2 days at about day 40 of pregnancy to �4 days at day 80 of pregnancy. A single linear prediction equation would be the most appropriate to use under field conditions. Verification of these relationships is recommended to check for differences that may exist between equipment, operators and breeds of sheep.