Australian Journal of Experimental Agriculture最新文献

{"title":"Diet quality and liveweight gain of steers grazing Leucaena–grass pasture estimated with faecal near infrared reflectance spectroscopy (F.NIRS)","authors":"R. Dixon, D. Coates","doi":"10.1071/EA08007","DOIUrl":"https://doi.org/10.1071/EA08007","url":null,"abstract":"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.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"835-842"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58800070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Putting Merino weaner management recommendations to the test","authors":"J. E. Edwards, R. Gould, K. J. Copping","doi":"10.1071/EA08003","DOIUrl":"https://doi.org/10.1071/EA08003","url":null,"abstract":"Merino weaner survival is poor under normal traditional management practices. Data from four trials conducted between 2001 and 2005 were used to assess the effectiveness of current industry recommendations to achieve 95% survival rates of Merino weaners. There was very little difference between 2001 and 2003 in survival of Merino weaners despite average weaning weight ranging from 20 to 24 kg between years. The recommended target weaning weight of 23 kg does not always appear to be a good predictor of survival. However, a target of 45% mature liveweight at pasture senescence achieved the industry recommendation of 95% weaner survival. Merino weaners were fed over the summer–autumn period to reach 40 kg liveweight by the time green feed became available. Weaner survival reached 93% compared with 89% survival to hogget shearing in weaners managed under normal growth paths. Furthermore, twice as many ewe weaners died in the traditional feeding program compared with the well fed ewe weaners. Differences in mortality between feeding levels in the wether weaners was less than that observed in the ewe weaners. Flock average growth rates were not useful indicators of weaner survival and there was no relationship between Merino ram estimated breeding values for weaning weight and the survival of the progeny.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"974-978"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58800215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Faecal near infrared reflectance spectroscopy estimates of diet quality and responses to nitrogen supplements by cattle grazing Bothriochloa pertusa pastures","authors":"D. Coates, R. Dixon","doi":"10.1071/EA08004","DOIUrl":"https://doi.org/10.1071/EA08004","url":null,"abstract":"A grazing experiment in the seasonally dry tropics of north Queensland examined the diet selected and the growth responses of Bos indicus steers to urea supplement over two dry seasons and one wet season, from August 2001 to January 2003. There were two groups of 10 steers (control and urea-supplemented) and each group comprised two age cohorts, A and B, of five steers each with an age difference of ~1 year. In June 2002, cohort A steers were replaced with steers 2 years younger (cohort C). The steers grazed Bothriochloa pertusa pastures on a low fertility Red Chromosol soil. The groups were switched between two adjoining paddocks at fortnightly intervals when they were weighed and faecal samples were collected for faecal near infrared reflectance spectroscopy (F.NIRS) estimates of diet quality and growth rate. Rainfall and diet quality followed the expected seasonal pattern, but the 2001–02 wet season was very short (November–January) with only 65% of the long-term average rainfall. There was no rain during the 2001 dry season (DS-1) from August to mid November, and no effective rain (17 mm) between February and December 2002. Non-grass (i.e. herbaceous dicot plants) made only a small contribution to the diet, averaging 13%. In DS-1 and in the dry season of 2002 (DS-2) diet crude protein (CP) averaged 2.5% and 2.9%, and DMD/CP (ratio of dry matter digestibility to CP) averaged 18.6 and 17.1, respectively. Liveweight (LW) loss in control steers during DS-1 averaged 32 kg. Urea supplement reduced LW loss by 18 kg (P < 0.001), but most of the benefit was lost during the following growing season. During the extended dry period in 2002, average LW losses of control steers were 85 and 47 kg in the older and younger cohorts, respectively, and supplementation with urea reduced weight losses by 53 and 31 kg, respectively (P < 0.001). F.NIRS predicted the cumulative LW of the unsupplemented steers in cohorts A and B with acceptable accuracy, the difference between the observed and predicted final LW being 6 kg for cohort A after 10 months, 12 kg for cohort B after 17 months, and 27 kg for cohort C after 7 months. The results demonstrated that F.NIRS can be effectively used to monitor dietary CP and DMD levels in grazing cattle, to help develop an understanding of cattle responses to urea supplement relative to the quality of the basal forage diet, and to provide useful decision support information for the nutritional management of grazing cattle.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"829-834"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA08004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58800307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development and integration of animal welfare standards into company quality assurance programs in the Australian livestock (meat) processing industry","authors":"M. K. Edge, J. L. Barnett","doi":"10.1071/EA08024","DOIUrl":"https://doi.org/10.1071/EA08024","url":null,"abstract":"A collaborative project between the Australian Meat Industry Council and the Animal Welfare Science Centre, a Centre partnered by the University of Melbourne, Department of Primary Industries (Victoria) and Monash University, that commenced in 2005, resulted in the development of a series of industry animal welfare standards designed to complement existing regulatory and commercial requirements. The project was the fourth in a series of similar projects conducted since 1998 for the poultry, pork and dairy industries, that was aimed at developing industry-wide animal welfare audit material. This concept was further developed to result in national industry animal welfare standards with accompanying audit material that could be integrated with existing industry, commercial and regulatory quality assurance documentation to demonstrate animal welfare practices. The resultant animal welfare standards were accompanied by additional implementation and reference information to enable integration and uptake within the industries and for the delivery of assurance on animal welfare to Governments, customers, trading partners and the consumer.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"1009-1013"},"PeriodicalIF":0.0,"publicationDate":"2008-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58801054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DairyMod and EcoMod: biophysical pasture-simulation models for Australia and New Zealand","authors":"I. R. Johnson, D. Chapman, V. Snow, R. Eckard, A. Parsons, M. G. Lambert, B. Cullen","doi":"10.1071/EA07133","DOIUrl":"https://doi.org/10.1071/EA07133","url":null,"abstract":"DairyMod and EcoMod, which are biophysical pasture-simulation models for Australian and New Zealand grazing systems, are described. Each model has a common underlying biophysical structure, with the main differences being in their available management options. The third model in this group is the SGS Pasture Model, which has been previously described, and these models are referred to collectively as ‘the model’. The model includes modules for pasture growth and utilisation by grazing animals, water and nutrient dynamics, animal physiology and production and a range of options for pasture management, irrigation and fertiliser application. Up to 100 independent paddocks can be defined to represent spatial variation within a notional farm. Paddocks can have different soil types, nutrient status, pasture species, fertiliser and irrigation management, but are subject to the same weather. Management options include commonly used rotational grazing management strategies and continuous grazing with fixed or variable stock numbers. A cutting regime simulates calculation of seasonal pasture growth rates. The focus of the present paper is on recent developments to the management routines and nutrient dynamics, including organic matter, inorganic nutrients, leaching and gaseous nitrogen losses, and greenhouse gases. Some model applications are presented and the role of the model in research projects is discussed.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"621-631"},"PeriodicalIF":0.0,"publicationDate":"2008-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07133","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58791593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water management as a future necessity in sheep feedlots","authors":"J. Pluske, A. Schlink","doi":"10.1071/EA06282","DOIUrl":"https://doi.org/10.1071/EA06282","url":null,"abstract":"Improving water management in rural towns such as Wagin, Western Australia, will decrease infrastructure damage caused by water and salinity and produce a ‘new water’ resource. The aim of this paper is to predict feedlot water demand using a bioeconomic model, H20Sheep, to determine if using such a ‘new water’ resource could be a viable option for this production system. Wagin (–33.3075 S, 117.3403 E), a township south-east of Perth, was chosen as the specific location for a sheep feedlot producing prime lambs. In this paper, the H20Sheep model was used to show how feedlot returns are influenced by the price of water, different feeding regimens and climate change. This was done by integrating feed and water intake of lambs, general feedlot water use and waste disposal. To show relative sensitivity of changing other model parameters that are not directly connected with water, changes in the purchase and sale price of lambs were also investigated. As might be expected, H20Sheep shows that returns from a sheep feedlot enterprise can be extremely sensitive to changes in lamb purchase (just over 7% increase will result in negative returns) and sale prices (a 4% decrease will generate a negative outcome). With respect to water, the findings indicate that, while increases in water use in the feedlot and price have to be greater than the increase in relative price of sheep, monitoring the biological parameters associated with water as well as water prices is still important both from a management and an economic perspective. Hence, if towns involved in the Rural Towns – Liquid Assets project, such as Wagin, decide to sell their water, the relevant policy makers should ensure that the sale price enables an effective water management system for the town and is also attractive to end-users such as feedlots.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"641-647"},"PeriodicalIF":0.0,"publicationDate":"2008-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA06282","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58788333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of biotin supplementation on hoof growth and integrity in long-fed F1 Wagyu/Black Angus feedlot steers of known genotype","authors":"R. J. Lawrence, R. Elliott, B. Norton, M. B. Thoefner, I. Loxton, G. Webber","doi":"10.1071/EA07010","DOIUrl":"https://doi.org/10.1071/EA07010","url":null,"abstract":"Biotin was supplemented at three levels (0, 10 and 20 mg/steer.day) to 108 F1 Wagyu/Black Angus steers of known genotype, which were fed a wheat-based ration, to evaluate the effect on hoof growth, wear and integrity within feedlot pens. One hundred and eight steers of known sire lines were assigned to three biotin treatments (0, 10 and 20 mg/steer.day) with each treatment replicated four times using an unfasted liveweight of 410.5kg (s.e. ± 2.27, s.d. ± 24.41). A subset of 36 steers was randomly selected for monitoring of hoof growth on seven occasions, over a period of 301 days. Front hooves from selected steers within turn-off group were collected at the abattoir and investigated for hoof integrity through claw lesions, white line width and dry matter of both white line and hoof. Hoof growth rates over time remained relatively consistent. In contrast, hoof wear rates increased (P 0.05) hoof growth or wear. Examination of collected hooves revealed lesions present on both lateral and medial claws. Biotin supplementation had no effect (P > 0.05) on lesion number, white line width of the lateral and medial claws, or hoof and white line dry matter of the medial claw. In contrast, Grandsire had an effect on total hoof length at measurement periods 0, 167, 251 and 301 (P < 0.05), and also on white line width of both lateral (P = 0.015) and medial (P = 0.002) claws. Rainfall and related increase in pen moisture weakened hoof integrity by increasing hoof moisture content and hoof wear. Genotype appears to play a role in hoof integrity.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"615-620"},"PeriodicalIF":0.0,"publicationDate":"2008-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07010","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58790000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of surface applied glycine betaine on herbage production and quality of perennial ryegrass–white clover pastures","authors":"Julia M. Lee, K. Elborough, W. Catto, D. Donaghy, J. Roche","doi":"10.1071/EA07123","DOIUrl":"https://doi.org/10.1071/EA07123","url":null,"abstract":"Osmoprotectants have been reported to reduce the detrimental effects of various environmental stresses in many different plant species. However, there is little research available concerning pasture species. Two experiments were undertaken with the aim of quantifying the effect of surface applications of exogenous glycine betaine (GB) on herbage production and quality of perennial ryegrass (Lolium perenne L.)–white clover (Trifolium repens L.) pastures during periods of moisture stress and cold temperatures over 2 years. Pastures fertilised with GB were compared with unfertilised pastures and pastures fertilised with nitrogen (N). Rates of 0.5, 1.0 and 1.5 kg GB/ha.defoliation were applied in experiment 1 and 5 kg GB/ha.defoliation was applied in experiment 2. Surface applications of GB did not significantly affect herbage production relative to unfertilised pastures; herbage yields averaged 12 248 and 12 693 kg DM/ha over 11 months in experiment 1, and 7253 and 7177 kg DM/ha over 6 months during summer and autumn in experiment 2, for the unfertilised control and GB, respectively. During both experiments, herbage quality parameters were not affected by GB application, although the proportion of white clover in the sward between summer and winter during experiment 1 was greater (P < 0.01) in plots treated with GB than in untreated plots. Application of N fertiliser increased (P < 0.001) herbage production, but did not consistently affect herbage quality. The failure of surface applications of exogenous GB to improve the herbage production or quality of perennial ryegrass–white clover pastures suggests that it is not an appropriate method to enhance plant tolerance to environmental stress at the concentrations applied in these studies.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"687-694"},"PeriodicalIF":0.0,"publicationDate":"2008-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07123","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58791256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Notch pathway gene expression and wool follicle cell fates","authors":"C. Gordon‐Thomson, S. Botto, G. Cam, G. Moore","doi":"10.1071/EA07315","DOIUrl":"https://doi.org/10.1071/EA07315","url":null,"abstract":"The Notch family of genes has been implicated in specifying cell fates during hair follicle morphogenesis. We examined Notch gene expression during wool follicle formation, as an understanding of genes that influence cell distributions in the developing follicle is a prerequisite for devising molecular strategies to manipulate fibre characters and follicle density. We identified transcripts for the Notch1 receptor and one of its ligands, Jagged1, in fetal sheep skin by reverse transcriptase polymerase chain reaction. The sheep-specific cDNA sequences were used as templates to produce probes to investigate the expression patterns of Notch1 and Jagged1 in developing ovine fetal skin by in situ hybridisation. Notch1 and Jagged1 were detected in the epidermis and in a subpopulation of mesenchymal cells before follicle initiation. At day 70 during follicle initiation, transcripts were also detected in cells at the tip of the epidermal plug and in dermal condensates. By day 86, Notch1 and Jagged1 were detected in the distal cells of the epidermal downgrowths and epidermis and Notch1 was no longer detected in the mesenchyme and dermal condensates. After day 96, transcripts were absent from the epidermis, but localised to differentiating outer root sheath (ORS) cells. The distributions of transcripts implicate a Notch1-Jagged1 signal pathway in the fates of prospective ORS cells. The transient appearance of Notch1 in cells at the epidermal-mesenchymal junction during early follicle morphogenesis suggests that the receptor may be responsible for the specification of a cell subpopulation committed to a prepapilla fate at initiation.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"648-656"},"PeriodicalIF":0.0,"publicationDate":"2008-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07315","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58797292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estimating the residue transfer of pesticides in animal feedstuffs to livestock tissues, milk and eggs: a review","authors":"D. Maclachlan, R. Bhula","doi":"10.1071/EA07196","DOIUrl":"https://doi.org/10.1071/EA07196","url":null,"abstract":"The through chain approach to livestock production places increased emphasis on on-farm management systems for addressing pesticide residues. The current risk management paradigm assumes the user of animal feeds has the ability to assess, or at least profile, risks to trade in animal commodities associated with feeding livestock material containing residues of pesticides. The paper details some approaches that may be used by livestock producers, focusing on simple calculations, and summarises available information needed as inputs. Calculated factors for the transfer of pesticides from feed to animal commodities (transfer factors) are summarised for about 150 pesticides.","PeriodicalId":8636,"journal":{"name":"Australian Journal of Experimental Agriculture","volume":"48 1","pages":"589-598"},"PeriodicalIF":0.0,"publicationDate":"2008-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1071/EA07196","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"58793101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}