Diet quality and liveweight gain of steers grazing Leucaena-grass pasture estimated with faecal near infrared reflectance spectroscopy (F.NIRS)

Three drafts of Bos indicus cross steers (initially 178-216 kg) grazed Leucaena-grass pasture [Leucaena leucocephala subspecies glabrata cv. Cunningham with green panic (Panicum maximum cv. trichoglume)] from late winter through to autumn during three consecutive years in the Burnett region of south-east Queensland. Measured daily weight gain (DWGActual) of the steers was generally 0.7-1.1 kg/day during the summer months. Estimated intakes of metabolisable energy and dry matter (DM) were calculated from feeding standards as the intakes required by the steers to grow at the DWGActual. Diet attributes were predicted from near infrared reflectance spectroscopy spectra of faeces (F.NIRS) using established calibration equations appropriate for northern Australian forages. Inclusion of some additional reference samples from cattle consuming Leucaena diets into F.NIRS calibrations based on grass and herbaceous legume-grass pastures improved prediction of the proportion of Leucaena in the diet. Mahalanobis distance values supported the hypothesis that the F.NIRS predictions of diet crude protein concentration and DM digestibility (DMD) were acceptable. F.NIRS indicated that the percentage of Leucaena in the diet varied widely (10-99%). Diet crude protein concentration and DMD were usually high, averaging 12.4 and 62%, respectively, and were related asymptotically to the percentage of Leucaena in the diet (R2 = 0.48 and 0.33, respectively). F.NIRS calibrations for DWG were not satisfactory to predict this variable from an individual faecal sample since the s.e. of prediction were 0.33-0.40 kg/day. Cumulative steer liveweight (LW) predicted from F.NIRS DWG calibrations, which had been previously developed with tropical grass and grass-herbaceous legume pastures, greatly overestimated the measured steer LW; therefore, these calibrations were not useful. Cumulative steer LW predicted from a modified F.NIRS DWG calibration, which included data from the present study, was strongly correlated (R2 = 0.95) with steer LW but overestimated LW by 19-31 kg after 8 months. Additional reference data are needed to develop robust F.NIRS calibrations to encompass the diversity of Leucaena pastures of northern Australia. In conclusion, the experiment demonstrated that F.NIRS could improve understanding of diet quality and nutrient intake of cattle grazing Leucaena-grass pasture, and the relationships between nutrient supply and cattle growth.

Seasonal changes in pasture quality and diet selection and their relationship with liveweight gain of steers grazing tropical grass and grass-legume pastures in northern Australia.

The variation in liveweight gain in grazing beef cattle as influenced by pasture type, season and year effects has important economic implications for mixed crop-livestock systems and the ability to better predict such variation would benefit beef producers by providing a guide for decision making. To identify key determinants of liveweight change of Brahman-cross steers grazing subtropical pastures, measurements of pasture quality and quantity, and diet quality in parallel with liveweight were made over two consecutive grazing seasons (48 and 46 weeks, respectively), on mixed Clitoria ternatea/grass, Stylosanthes seabrana/grass and grass swards (grass being a mixture of Bothriochloa insculpta cv. Bisset, Dichanthium sericeum and Panicum maximum var. trichoglume cv. Petrie). Steers grazing the legume-based pastures had the highest growth rate and gained between 64 and 142 kg more than those grazing the grass pastures in under 12 months. Using an exponential model, green leaf mass, green leaf %, adjusted green leaf % (adjusted for inedible woody legume stems), faecal near infrared reflectance spectroscopy predictions of diet crude protein and diet dry matter digestibility, accounted for 77, 74, 80, 63 and 60%, respectively, of the variation in daily weight gain when data were pooled across pasture types and grazing seasons. The standard error of the regressions indicated that 95% prediction intervals were large (+/- 0.42-0.64 kg/head.day) suggesting that derived regression relationships have limited practical application for accurately estimating growth rate. In this study, animal factors, especially compensatory growth effects, appeared to have a major influence on growth rate in relation to pasture and diet attributes. It was concluded that predictions of growth rate based only on pasture or diet attributes are unlikely to be accurate or reliable. Nevertheless, key pasture attributes such as green leaf mass and green leaf% provide a robust indication of what proportion of the potential growth rate of the grazing animals can be achieved.

The role of tillage, fertiliser and forage species in sustaining dairying based on crops in southern Queensland 2. Double-crop and summer sole-crop systems.

Dairy farms located in the subtropical cereal belt of Australia rely on winter and summer cereal crops, rather than pastures, for their forage base. Crops are mostly established in tilled seedbeds and the system is vulnerable to fertility decline and water erosion, particularly over summer fallows. Field studies were conducted over 5 years on contrasting soil types, a Vertosol and Sodosol, in the 650-mm annual-rainfall zone to evaluate the benefits of a modified cropping program on forage productivity and the soil-resource base. Growing forage sorghum as a double-crop with oats increased total mean annual production over that of winter sole-crop systems by 40% and 100% on the Vertosol and Sodosol sites respectively. However, mean annual winter crop yield was halved and overall forage quality was lower. Ninety per cent of the variation in winter crop yield was attributable to fallow and in-crop rainfall. Replacing forage sorghum with the annual legume lablab reduced fertiliser nitrogen (N) requirements and increased forage N concentration, but reduced overall annual yield. Compared with sole-cropped oats, double-cropping reduced the risk of erosion by extending the duration of soil water deficits and increasing the time ground was under plant cover. When grown as a sole-crop, well fertilised forage sorghum achieved a mean annual cumulative yield of 9.64 and 6.05 t DM/ha on the Vertosol and Sodosol, respectively, being about twice that of sole-cropped oats. Forage sorghum established using zero-tillage practices and fertilised at 175 kg N/ha. crop achieved a significantly higher yield and forage N concentration than did the industry-standard forage sorghum (conventional tillage and 55 kg N/ha. crop) on the Vertosol but not on the Sodosol. On the Vertosol, mean annual yield increased from 5.65 to 9.64 t DM/ha (33 kg DM/kg N fertiliser applied above the base rate); the difference in the response between the two sites was attributed to soil type and fertiliser history. Changing both tillage practices and N-fertiliser rate had no affect on fallow water-storage efficiency but did improve fallow ground cover. When forage sorghum, grown as a sole crop, was replaced with lablab in 3 of the 5 years, overall forage N concentration increased significantly, and on the Vertosol, yield and soil nitrate-N reserves also increased significantly relative to industry-standard sorghum. All forage systems maintained or increased the concentration of soil nitrate-N (0-1.2-m soil layer) over the course of the study. Relative to sole-crop oats, alternative forage systems were generally beneficial to the concentration of surface-soil (0-0.1 m) organic carbon and systems that included sorghum showed most promise for increasing soil organic carbon concentration. We conclude that an emphasis on double-or summer sole-cropping rather than winter sole-cropping will advantage both farm productivity and the soil-resource base.

Handling of Two Tropical Australian Sharks to Improve Quality and to Identify the Cause of Tough Texture

Sharks caught in tropical Australian waters occasionally exhibit tough texture. Two species of Carcharinid shark, originally known as the sorrah shark (Carcharinus sorrah) and the black spot shark (Carcharinus tilstoni), compose the majority of the catch. Experiments were conducted to identify the cause of tough texture and to improve the overall quality of the catch. The possibility that a cold shock reaction may occur was investigated by observing the contraction of fillets under a range of temperature conditions before freezing. The effect of on-board handling practices were evaluated using frozen shark fillets, which had been stored prior to freezing in refrigerated seawater at different rigor stages, temperatures and times as trunks. Fillets were analyzed for nucleotides, lactate, thaw pH, sarcomere length and raw and cooked shear force values. The existence of thaw rigor was also investigated. There was little difference in the texture between the individual strips of a fillet exposed to different temperatures but there were significant differences between individual sharks. A cold shock reaction could not be demonstrated in these species. The main influences on texture were of biological origin. The species, sex and size were found to have significant links with texture of fillets. The quality of the fillets deteriorated quicker during the warmer season and were at their worst if the trunks were kept on deck till post-rigor or held in 15 degree C refrigerated seawater before freezing

Changes in sensory quality of sterile cantaloupe dice stored in controlled atmospheres.

Diced cantaloupe flesh that was microbiologically sterile was prepared in order to study the physiological deterioration of fruit when stored under a range of controlled atmospheres at 4.5°C. Sterile fruit pieces were prepared by boiling whole melons for 3 min, then dicing aseptically. Storage atmospheres were in continuous flow and contained from 0 to 26% CO2 and 3.5 to 17% O2. Sensory assessments were carried out by a highly trained panel at 14-day intervals. Products that were acceptable for up to 28 days were obtained when the following 3 treatments were used: 6% CO2 and 6% O2; 9.5% CO2 and 3.5% O2; and 15% CO2 and 6% O2. Overall, treatment with 0, 19.5 or 26% CO2 (irrespective of O2 concn.) caused significant deterioration in sensory properties.

Morphological and developmental comparisons of seven greens quality hybrid bermudagrass (Cynodon dactylon (L.)Pers.x C transvaalensis Burtt-Davy

Fine-textured hybrid bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] cultivars have been widely used for golf putting greens and lawn bowls greens in warm-climate areas for more than 40 years. During the past decade, the choice of cultivar for professional turfgrass managers has been expanded by a range of secondgeneration hybrid bermudagrasses, which differ from the first-generation cultivars ‘Tifgreen’ and ‘Tifdwarf ’ in their management requirements. In this paper, we present comparative morphological and developmental data for seven cultivars (Champion Dwarf, FloraDwarf, MS-Supreme, Novotek, Tifdwarf, TifEagle, Tifgreen) grown in spaced plant and sward experiments at Cleveland, Australia (27º32’S lat, 153º15’E long, 25 masl). The four ‘ultradwarf ’ cultivars (Champion Dwarf, MS-Supreme, FloraDwarf, TifEagle) showed slower vertical extension and produced fewer inflorescences than Tifdwarf, Tifgreen, and Novotek. However, in terms of the length of stolon internodes and their overall rate of lateral spread, Champion Dwarf, FloraDwarf, and TifEagle were comparable to Tifdwarf; MS-Supreme (with longer internodes) spread faster laterally, though slower than Tifgreen (which had the longest stolon internodes). In unmown swards, the four ultradwarfs produced shorter leaves than Tifgreen, Tifdwarf, and Novotek, but only Champion Dwarf produced significantly narrower leaves than Tifgreen, Tifdwarf, and Novotek, with TifEagle leaves also significantly narrower than those of Tifgreen and Novotek. Minimum threshold temperatures for growth were approximately 9° to 10°C (air temperature) and 15° to 16°C at 10 cm soil depth.

Evaluation of wood characteristics of tropical post-mid rotation plantation Eucalyptus cloeziana and E. pellita: Part (c) Wood quality and structural properties.

This study provides information about wood quality, structural properties, processing characterists and product suitability of wood harvested from fast-grown hardwood plantations. Wood quality attributes tested included density, extractive content, unit shrinkage, heartwood proportion and sapwood width. Structural properties tested included small clear and full section strength and stiffness, hardness, joint group, visual grade assessment and natural vibration-based grade assessment. The variation between the inner, intermediate and outer heartwood zones and the variation between provenances was also tested. Overall, the wood qualtiy attributes measured for 19 year-old E. cloeziana and 15 year-old E. pellita plantation material fall between those expected from the wood of mature, native forest trees and those found in younger plantation material of the same species.

Implementation costs of Agricultural Management Practices for Water Quality Improvement in the Great Barrier Reef Catchments. CSIRO: Water for Healthy Country National Research Flagship

Executive summary. In this report we analyse implementation costs and benefits for agricultural management practices, grouped into farming systems. In order to do so, we compare plot scale gross margins for the dominant agricultural production systems (sugarcane, grazing and banana cultivation) in the NRM regions Wet Tropics, Burdekin Dry Tropics and Mackay Whitsundays. Furthermore, where available, we present investment requirements for changing to improved farming systems. It must be noted that transaction costs are not captured within this project. For sugarcane, this economic analysis shows that there are expected benefits to sugarcane growers in the different regions through transitions to C and B class farming systems. Further transition to A-class farming systems can come at a cost, depending on the capital investment required and the length of the investment period. Obviously, the costs and benefits will vary for each individual grower and will depend on their starting point and individual property scenario therefore each circumstance needs to be carefully considered before making a change in management practice. In grazing, overall, reducing stocking rates comes at a cost (reduced benefits). However, when operating at low utilisation rates in wetter country, lowering stocking rates can potentially come at a benefit. With win-win potential, extension is preferred to assist farmer in changing management practices to improve their land condition. When reducing stocking rates comes at a cost, incentives may be applicable to support change among farmers. For banana cultivation, the results indicate that the transition to C and B class management practices is a worthwhile proposition from an economic perspective. For a change from B to A class farming systems however, it is not worthwhile from a financial perspective. This is largely due to the large capital investment associated with the change in irrigation system and negative impact in whole of farm gross margin. Overall, benefits will vary for each individual grower depending on their starting point and their individual property scenario. The results presented in this report are one possible set of figures to show the changes in profitability of a grower operating in different management classes. The results in this report are not prescriptive of every landholder. Landholders will have different costs and benefits from transitioning to improved practices, even if similar operations are practiced, hence it is recommended that landholders that are willing to change management undertake their own research and analysis into the expected costs and benefits for their own soil types and property circumstances.

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.

Probiotic Bacillus amyloliquefaciens Strain H57 Improves the Performance of Pregnant and Lactating Ewes Fed a Diet Based on Palm Kernel Meal

Probiotic supplements are single or mixed strain cultures of live microorganisms that benefit the host by improving the properties of the indigenous microflora (Seo et al 2010). In a pilot study at the University of Queensland, Norton et al (2008) found that Bacillus amyloliquefaciens Strain H57 (H57), primarily investigated as an inoculum to make high-quality hay, improved feed intake and nitrogen utilisation over several weeks in pregnant ewes. The purpose of the following study was to further challenge the potential of H57 -to show it survives the steam-pelleting process, and that it improves the performance of ewes fed pellets based on an agro-industrial by-product with a reputation for poor palatability, palm kernel meal (PKM), (McNeill 2013). Thirty-two first-parity White Dorper ewes (day 37 of pregnancy, mean liveweight = 47.3 kg, mean age = 15 months) were inducted into individual pens in the animal house at the University of Queensland, Gatton. They were adjusted onto PKM-based pellets (g/kg drymatter (DM): PKM, 408; sorghum, 430; chick pea hulls, 103; minerals and vitamins; Crude protein, 128; ME: 11.1MJ/kg DM) until day 89 of pregnancy and thereafter fed a predominately pelleted diet incorporating with or without H57 spores (10 9 colony forming units (cfu)/kg pellet, as fed), plus 100g/ewe/day oaten chaff, until day 7 of lactation. From day 7 to 20 of lactation the pelleted component of the diet was steadily reduced to be replaced by a 50:50 mix of lucerne: oaten chaff, fed ad libitum, plus 100g/ewe/day of ground sorghum grain with or without H57 (10 9 cfu/ewe/day). The period of adjustment in pregnancy (day 37-89) extended beyond expectations due to some evidence of mild ruminal acidosis after some initially high intakes that were followed by low intakes. During that time the diet was modified, in an attempt to improve palatability, by the addition of oaten chaff and the removal of an acidifying agent (NH4Cl) that was added initially to reduce the risk of urinary calculi. Eight ewes were removed due to inappetence, leaving 24 ewes to start the trial at day 90 of pregnancy. From day 90 of pregnancy until day 63 of lactation, liveweights of the ewes and their lambs were determined weekly and at parturition. Feed intakes of the ewes were determined weekly. Once lambing began, 1 ewe was removed as it gave birth to twin lambs (whereas the rest gave birth to a single lamb), 4 due to the loss of their lambs (2 to dystocia), and 1 due to copper toxicity. The PKM pellets were suspected to be the cause of the copper toxicity and so were removed in early lactation. Hence, the final statistical analysis using STATISTICA 8 (Repeated measures ANOVA for feed intake, One-way ANOVA for liveweight change and birth weight) was completed on 23 ewes for the pregnancy period (n = 11 fed H57; n = 12 control), and 18 ewes or lambs for the lactation period (n = 8 fed H57; n = 10 control). From day 90 of pregnancy until parturition the H57 supplemented ewes ate 17 more DM (g/day: 1041 vs 889, sed = 42.4, P = 0.04) and gained more liveweight (g/day: 193 vs 24.0, sed = 25.4, P = 0.0002), but produced lambs with a similar birthweight (kg: 4.18 vs 3.99, sed = 0.19, P = 0.54). Over the 63 days of lactation the H57 ewes ate similar amounts of DM but grew slower than the control ewes (g/day: 1.5 vs 97.0, sed = 21.7, P = 0.012). The lambs of the H57 ewes grew faster than those of the control ewes for the first 21 days of lactation (g/day: 356 vs 265, sed = 16.5, P = 0.006). These data support the findings of Norton et al (2008) and Kritas et al (2006) that certain Bacillus spp. supplements can improve the performance of pregnant and lactating ewes. In the current study we particularly highlighted the capacity of H57 to stimulate immature ewes to continue to grow maternal tissue through pregnancy, possibly through an enhanced appetite, which appeared then to stimulate a greater capacity to partition nutrients to their lambs through milk, at least for the first few weeks of lactation, a critical time for optimising lamb survival. To conclude, H57 can survive the steam pelleting process to improve feed intake and maternal liveweight gain in late pregnancy, and performance in early lactation, of first-parity ewes fed a diet based on PKM.

Evaluating the role of extension in helping to improve water quality in the Great Barrier Reef

From 2012-2014 the Queensland Government delivered an extension project to help sugarcane growers adopt best management practices to reduce pollutant loss to the Great Barrier Reef. Coutts J&R were engaged to measure progress towards the project's engagement, capacity gain and practice change targets. The monitoring and evaluation program comprised a database, post-workshop evaluations and grower and advisor surveys. Coutts J&R conducted an independent phone survey with 97 growers, a subset of the 900 growers engaged in extension activities. Of those surveyed 64% stated they had made practice changes. There was higher (74%) adoption by growers engaged in one-on-one extension than those growers only involved in group-based activities (36%). Overall, the project reported 41% (+/-10%, 95% confidence) of growers engaged made a practice change. The structured monitoring and evaluation program, including independent surveys, was essential to quantify practice change and demonstrate the effectiveness of extension in contributing to water quality improvement.

Modified atmosphere packaging effects on the postharvest quality of papaya fruit

Export of Fijian papaya (Carica papaya) fruit to destinations such as New Zealand has increased significantly over the last several years. Shipment by sea rather than air is the preferred method, given the capacity for larger volumes and reductions in cost. Long shipping times, however, can compromise fruit quality, although the use of modified atmosphere packaging (MAP) may provide a viable solution for extending fruit storage life. In a collaborative ACIAR project, Australian and Fijian researchers investigated the potential of using MAP to extend storage life of a Fijian papaya ('Fiji Red') fruit based on simulated sea transport conditions. Fruit were packed in one of three MAP environments within cartons, consisting of either a (1) Low Density Polyethylene (LDPE) bag with 10 g of KMnO4, (2) Polyamide Film (PF) bag with macro-perforations or (3) without a bag (control fruit). Fruit were held for 1, 2 or 3 weeks at 10°C before being unpacked, ripened and assessed for quality. On day 6 after outturn, fruit with the highest overall quality were those held in LDPE bags. LDPE fruit generally coloured up faster at outturn than PF or control fruit, had less overall moisture loss and scored high in flavour. Headspace carbon dioxide and oxygen concentrations within the LDPE bags were also near recommended levels for maintaining optimum storage-life quality. The LDPE bag provided the most suitable conditions for long term storage of fresh papaya fruit and is therefore the recommended MAP type for use with sea freight export out of Fiji.

Production responses of reproducing ewes to a by-product-based diet inoculated with the probiotic Bacillus amyloliquefaciens strain H57

The potential application of the spore-forming probiotic Bacillus amyloliquefaciens strain H57 (H57) as a novel probiotic for ruminants was evaluated in reproducing ewes. Performance responses were determined by delivering H57 in a pelleted diet based mainly on palm kernel meal (PKM) and sorghum grain. PKM is an agro-industrial by-product with a reputation for poor palatability and the availability of the starch in sorghum grain can be limited in ruminants. The hypothesis was that H57 improves the feeding value of a relatively low quality concentrate diet. Twenty-four first-parity white Dorper ewes were fed PKM-based pellets manufactured with or without H57 (109 cfu/kg pellet) in late pregnancy. During this phase of late pregnancy, the H57 ewes ate 17% more dry matter (1019 vs 874 g/day, P = 0.03), gained more weight (194 vs 30 g/day, P = 0.008) and retained more nitrogen (6.13 vs 3.34 g/day, P = 0.01), but produced lambs with a similar birthweight (4.1 vs 4.2 kg, P = 0.73). Rumen fluid collected from H57 ewes in late pregnancy had higher pH (7.1 vs 6.8, P = 0.07), acetate : propionate ratio (3.4 vs 2.7, P = 0.04), lower ammonia (69 vs 147 mmol/L, P = 0.001) and total volatile fatty acid concentrations (40 vs 61 mg/L, P = 0.02). The digestibility of dry matter, organic matter and fibre were similar between the two groups. The lambs of the H57 ewes grew faster than those of the Control ewes for the first 21 days of lactation (349 vs 272 g/day, P = 0.03), but not thereafter. H57 can improve feed intake and maternal liveweight gain in late pregnancy of first-parity ewes fed a diet based on PKM.