Potential economic benefit of intensification of beef production in Australian rangelands: an operational case study perspective.

In Australia, the development of rangelands has led to steady gains in pastoral productivity through more intensive and widespread land use (Stokes et al., 2006). Opportunities to benefit from intensification exist on large properties with relatively poor water and fencing infrastructure development, resulting in uneven utilisation of available forage (Ash et al.,2006). The objective of this study is to value expected economic gains from carrying out property improvements on a beef property located in Northern Australia.

The effect of earlier mating and improving fertility on greenhouse gas emissions intensity of beef production in northern Australian herds

Approximately 5% of Australian national greenhouse gas (GHG) emissions are derived from the northern beef industry. Improving the reproductive performance of cows has been identified as a key target for increasing profitability, and this higher efficiency is also likely to reduce the GHG emissions intensity of beef production. The effects of strategies to increase the fertility of breeding herds and earlier joining of heifers as yearlings were studied on two properties at Longreach and Boulia in western Queensland. The beef production, GHG emissions, emissions intensity and profitability were investigated and compared with typical management in the two regions. Overall weaning rates achieved on the two properties were 79% and 74% compared with typical herd weaning rates of 58% in both regions. Herds with high reproductive performance had GHG emissions intensities (t CO2-e t–1 liveweight sold) 28% and 22% lower than the typical herds at Longreach and Boulia, with most of the benefit from higher weaning rates. Farm gross margin analysis showed that it was more profitable, by $62 000 at Longreach and $38 000 at Boulia, to utilise higher reproductive performance to increase the amount of liveweight sold with the same number of adult equivalents compared with reducing the number of adult equivalents to maintain the same level of liveweight sold and claiming a carbon credit for lower farm emissions. These gains achieved at two case study properties which had different rainfall, country types, and property sizes suggest similar improvements can be made on-farm across the Mitchell Grass Downs bioregion of northern Australia.

Scrotal Circumference at Puberty and its Relationship to Testes Mass in Three Genotypes of Beef Cattle

Scrotal circumference (SC) is a simple, non-invasive measurement commonly used to evaluate bull breeding potential although its validity as a predictor of fertility is questionable (Holroyd, 1998). SC is highly heritable but varies with breed and animal factors such as condition, live weight and age. As an indicator of fertility, recommended SC values range broadly from 30cm to 38cm (Miller, 1992). It is assumed that SC accurately reflects testes mass (TM) which may be related to direct measures of fertility such as spermatogenesis (Entwistle, 1992). The SC measurements made here test the assumption that SC, used to estimate testes volume (TV), is directly related to TM. Miller (1992) reported a value of 261mm as the SC threshold for puberty. We have studied serial SC measurements so as to devise a more accurate means of using SC to determine puberty.

Weaning management of beef calves - practical guidelines for northern Australian

The ‘Weaning management of beef calves – practical guidelines for northern Australian beef producers‘ book or simply ‘the weaner book’ is a compilation of all the research, demonstration and practical knowledge available on weaning and weaner management in northern Australia. Most of this information has been available for some years, but it has not been collated in a single document that is practical and easy to understand. It has been difficult for property owners, managers and their staff to access. The end result of this project is an easy to read guide that has all the available information in one publication. Compiling this information has also highlighted areas where information is limited or non existent or where available information is not being implemented across the whole industry. This has been evaluated and included in recommendations for further research and or demonstration work.

Persistence of orally administered Megasphaera elsdenii and Ruminococcus bromii in the rumen of beef cattle fed a high grain (barley) diet

When cattle are fed grain, acidotic ruminal conditions and decreased efficiency in starch utilisation can result from the rapid production and accumulation of lactic acid in the rumen. The efficacy of drenching cattle with Megasphaera elsdenii and Ruminococcus bromii to improve animal performance was investigated. A feedlot trial was undertaken with 80 Bos indicus crossbred steers (initial liveweight 347.1 (s.d. 31.7) kg) in 10 pens in a randomised complete block design. An empty-pen-buffer was maintained between treated (inoculated) and untreated (control) groups to avoid transfer of inoculant bacteria to the control steers. Inoculated steers were orally drenched with M. elsdenii YE34 and R. bromii YE282, and populations increased rapidly over 3-14 days. The steers were fed for a total of 70 days with commercial, barley-based, feedlot rations. High growth rates (1.91 kg per day) were achieved throughout the experiment in both the inoculated and control steers. Intakes averaged 21.3 g dry matter (DM) per kg liveweight per day. There was probably no acidosis achieved in this trial following challenge (i.e. no change in pH occurred). There were no differences in any production or carcass measurements between the control and inoculated steers overall. However, the control group acquired dense ruminal populations of M. elsdenii by Day 14, while R. bromii populations established at high densities within the first 2 weeks but then declined and were undetectable by Day 50. R. bromii appears to be only transiently dominant, and once its dominance waned, it appeared that Ruminobacter spp. established in the rumen. Ruminobacter spp. became dominant between 14 and 28 days in all the steers examined and persisted through to the end of the study. These Ruminobacter spp. may be of future interest in the development of probiotics for grain-fed cattle.

Prediction of mortality and conception rates of beef breeding cattle in northern Australia

In current simulation packages for the management of extensive beef-cattle enterprises, the relationships for the key biological rates (namely conception and mortality) are quite rudimentary. To better estimate these relationships, cohort-level data covering 17 100 cow-years from six sites across northern Australia were collated and analysed. Further validation data, from 7200 cow-years, were then used to test these relationships. Analytical problems included incomplete and non-standardised data, considerable levels of correlation among the 'independent' variables, and the close similarity of alternate possible models. In addition to formal statistical analyses of these data, the theoretical equations for predicting mortality and conception rates in the current simulation models were reviewed, and then reparameterised and recalibrated where appropriate. The final models explained up to 80% of the variation in the data. These are now proposed as more accurate and useful models to be used in the prediction of biological rates in simulation studies for northern Australia. © The State of Queensland (through the Department of Agriculture, Fisheries and Forestry) 2012. © CSIRO.

A universal equation to predict methane production of forage-fed cattle in Australia

The methods for estimating methane emissions from cattle as used in the Australian national inventory are based on older data that have now been superseded by a large amount of more recent data. Recent data suggested that the current inventory emissions estimates can be improved. To address this issue, a total of 1034 individual animal records of daily methane production (MP) was used to reassess the relationship between MP and each of dry matter intake (DMI) and gross energy intake (GEI). Data were restricted to trials conducted in the past 10 years using open-circuit respiration chambers, with cattle fed forage-based diets (forage >70%). Results from diets considered to inhibit methanogenesis were omitted from the dataset. Records were obtained from dairy cattle fed temperate forages (220 records), beef cattle fed temperate forages (680 records) and beef cattle fed tropical forages (133 records). Relationships were very similar for all three production categories and single relationships for MP on a DMI or GEI basis were proposed for national inventory purposes. These relationships were MP (g/day) = 20.7 (±0.28) × DMI (kg/day) (R2 = 0.92, P < 0.001) and MP (MJ/day) = 0.063 (±0.008) × GEI (MJ/day) (R2 = 0.93, P < 0.001). If the revised MP (g/day) approach is used to calculate Australia’s national inventory, it will reduce estimates of emissions of forage-fed cattle by 24%. Assuming a global warming potential of 25 for methane, this represents a 12.6 Mt CO2-e reduction in calculated annual emissions from Australian cattle.

Production of microalgal concentrates by flocculation and their assessment as aquaculture feeds

A novel technique was developed for the flocculation of marine microalgae commonly used in aquaculture. The process entailed an adjustment of pH of culture to between 10 and 10.6 using NaOH, followed by addition of a non-ionic polymer Magnafloc LT-25 to a final concentration of 0.5 mg L-1. The ensuing flocculate was harvested, and neutralised giving a final concentration factor of between 200- and 800-fold. This process was successfully applied to harvest cells of Chaetoceros calcitrans, C. muelleri, Thalassiosira pseudonana, Attheya septentrionalis, Nitzschia closterium, Skeletonema sp., Tetraselmis suecica and Rhodomonas salina, with efficiencies >=80%. The process was rapid, simple and inexpensive, and relatively cost neutral with increasing volume (cf. concentration by centrifugation). Harvested material was readily disaggregated to single cell suspensions by dilution in seawater and mild agitation. Microscopic examination of the cells showed them to be indistinguishable from corresponding non-flocculated cells. Chlorophyll analysis of concentrates prepared from cultures of Concentrates of T. pseudonana prepared using pH-induced flocculation gave better growth of juvenile Pacific oysters (Crassostrea gigas) than concentrates prepared by ferric flocculation, or centrifuged concentrates using a cream separator or laboratory centrifuge. In follow up experiments, concentrates prepared from 1000 L Chaetoceros muelleri cultures were effective as supplementary diets to improve the growth of juvenile C. gigas and the scallop Pecten fumatus reared under commercial conditions, though not as effective as the corresponding live algae. The experiments demonstrated a proof-of-concept for a commercial application of concentrates prepared by flocculation, especially for use at a remote nursery without on-site mass-algal culture facilities.

The influence of planting density on the production of 'Goldfinger' (Musa spp., AAAB) in the subtropics

'Goldfinger', a tetraploid banana produced from the Fundación Hondureña de Investigación Agrícola (FHIA) breeding program, was released to the Australian industry in 1995. It was promoted as an apple-flavoured dessert banana with resistance to Fusarium wilt race 1 and subtropical race 4, as well as resistance to black and yellow Sigatoka (Mycosphaerella fijiensis and M. musicola, respectively). This study was initiated to provide agronomic information to the banana industry, which was under threat from Fusarium wilt, on a new cultivar which could replace 'Williams' (AAA, Cavendish subgroup) or 'Lady Finger' (AAB, Pome subgroup) in those areas affected by Fusarium wilt. Also few studies had reported on the production characteristics of the new tetraploid hybrids, especially from subtropical areas, and therefore two field sites, one a steep-land farm and the other a level, more productive site, were selected for planting density and spatial arrangement treatments. The optimum density in terms of commercial production, taking into account bunch weight, finger size, length of the production cycle, plant height and ease of management, was 1680 plants/ha on the steep-land site where plants were planted in single rows with 2.5 m × 2.5 m spacings. However on the level site a double-row triangular layout with inter-row distances of 4.5 m to allow vehicular access (1724 plants/ha) gave the best results. With this arrangement plants were in an alternate, triangular arrangement along a row and a spacing of 1.5 m between plants at the points of each triangle and between each block of triangles.

Effect of micro-propagation on the health status of strawberry planting material for commercial production of strawberry runners for Queensland

Plant tissue culture has been used for a number of years to produce micropropagated strawberry plants for planting into runner growing beds in the Stanthorpe (Queensland) and Bothwell (Tasmania) regions. This process has allowed the rapid release of new cultivars from the LAWS (Late Autumn, Winter, Spring) breeding program into the current runner production system. Micro-propagation in vitro allows plants to be produced during the autumn and winter months, when mother plants would normally be in a fruit production phase in the field in Queensland. The plants produced are of a high health status when they are planted. The subsequent arrival and build up of various diseases in the runner fields are closely monitored. Using tissue culture for the first generation reduces the time the plants spend in the field by twelve months, reducing disease incidence. To date, any disease outbreak has been successfully managed using early detection and rapid response methods.

Screening selected myrtaceous tree species for production of essential oils in northern Queensland

Trials to identify alternative cropping options to Melaleuca alternifolia for northern Queensland essential oil growers were established at Dimbulah and Innot Hot Springs in 2001. Seed sources of Asteromyrtus symphyocarpa (1,8-cineole form), Eucalyptus staigeriana (citral), Melaleuca cajuputi subsp. cajuputi (trans-nerolidol), M. ericifolia (d-linalool), M. quinquenervia (trans-nerolidol and viridiflorol forms) and M. viridiflora (methyl cinnamate) with potential to produce commercial foliar oils were evaluated. Information was gathered on their adaptability, growth and oil yields over 49 months and 52 months (two harvests) from planting at Dimbulah and Innot Hot Springs, respectively. Of the species and chemotypes evaluated, M. quinquenervia showed potential for commercial production of trans-nerolidol, a compound used in perfumery. It had a very high survival rate (96%) and yields could be expected to improve dramatically from the average 100 kg/ha per harvest achieved in these trials with further research into selection of seed source, control of insect damage and breeding for genetic improvement. M. cajuputi subsp. cajuputi gave a similar performance to M. quinquenervia. The rarity of the trans-nerolidol form of this species and remoteness of its natural occurrence are impediments to further planting and research. E. staigeriana, with second harvest yields of ~600 kg/ha, performed exceptionally well on both sites but potential for development is limited by the ready availability of competitively priced E. staigeriana oil produced in South America. Survival of M. ericifolia ranged from 62% to 82% at 32 months (second harvest) at Innot Hot Springs and was deemed a failure at Dimbulah with poor growth and low survival, raising a major question about the suitability of this species for cultivation in the seasonally dry tropics. Planting of this species on a wider scale in northern Queensland cannot be recommended until more is known about factors affecting its survival. A. symphyocarpa and M. viridiflora were too slow-growing to warrant further consideration as potential oil-producing species at this time.

Production of bacteriocins by Streptococcus bovis strains from Australian ruminants.

Aims: To examine the prevalence of bacteriocin production in Streptococcus bovis isolates from Australian ruminants and the feasibility of industrial production of bacteriocin. Methods and Results: Streptococcus bovis strains were tested for production of bacteriocin-like inhibitory substances (BLIS) by antagonism assay against Lactococcus lactis. BLIS production was associated with source animal location (i.e. proximity of other bacteriocin-positive source animals) rather than ruminant species/breed or diet. One bacteriocin showing strong inhibitory activity (Sb15) was isolated and examined. Protein sequence, stability and activity spectrum of this bovicin were very similar to bovicin HC5. Production could be increased through serial culturing, and increased productivity could be partially maintained during cold storage of cultures. Conclusions: BLIS production is geographically widely distributed in Eastern Australia, and it appears that the bacteriocin+ trait is maintained in animals at the same location. The HC5-like bacteriocin, originally identified in North America, is also found in Australia. Production of bacteriocin can be increased through serial culturing. Significance and Impact of the Study: The HC5-like bacteriocins appear to have a broad global distribution. Serial culturing may provide a route towards commercial manufacturing for use in industrial applications, and purified bacteriocin from S. bovis Sb15 could potentially be used to prevent food spoilage or as a feed additive to promote growth in ruminant species.