{ "eprintid": "1871", "rev_number": "1", "eprint_status": "archive", "userid": "833", "dir": "disk0/00/00/18/71", "datestamp": "2003-11-05", "lastmod": "2009-08-20 14:21:23", "status_changed": "2009-08-20 14:21:23", "type": "journalp", "metadata_visibility": "show", "item_issues_count": "0", "doclang": "en", "projects": [ "da2b03" ], "fundingpart": "main", "refereed": "notyet", "budget": "0", "publicfulltext": "FALSE", "creators": [ { "name": { "family": "Nielsen", "given": "B.K.", "honourific": "Dr." }, "id": "" }, { "name": { "family": "Kristensen", "given": "A.R.", "honourific": "Dr." }, "id": "" }, { "name": { "family": "Thamsborg", "given": "S.M.", "honourific": "Professor" }, "id": "" } ], "title": "Optimal decisions in organic steer production - a model including winter feed level, grazing strategy and slaughtering policy", "ispublished": "unpub", "subjects": [ "1animalprod" ], "keywords": "compensatory growth; dairy bull calves; fattening; grazing; markov process; slaughtering", "abstract": "Organic steer production demand several decisions concerning grazing strategy, feeding level in the winter and factors as slaughter weight and length of the fattening period. The production system can be difficult to optimise, therefore the objective of this study was to develop a model to optimise the grazing strategy, feed level in winter and time of fattening and slaughter in organic steer production with regard to economic output at steer level. The steer model is a 4-level hierarchical Markov process with decisions defined at three levels. Decisions taken in the model include grazing strategy (permanent or ryegrass/clover pasture), feed level in winter (high and low), time for beginning of fattening (age 19-27 months) and time of slaughter (age 19-30 months). Overall optimal strategies at child level 1 with regard to economic output per produced steer were low feeding level in the winter period, grazing on permanent pastures in the first grazing season, whereas ryegrass/clover pastures gives the optimal net return per steer in the second and third grazing season. The optimal strategies from the model suggested that the effect of fattening in steer production might be overstated. It was concluded that the natural well-defined phases in organic steer production are well suited to be analysed by a multi-level hierarchic Markov processes.", "date": "2003", "date_type": "published", "publication": "Livestock Production Science", "referencetext": "Andersen, H. R., T. Kristensen, H. B. Bligaard, Thamsborg, S.M. 2002. Studeproduktion ved afgræsning af ferske enge. DJF Report No. 40 (Husbandry). Research Centre Foulum, Denmark Andersen, H. R., T. Kristensen, H. B. Bliggaard, Nielsen, B. 2003. Forskellige produktionssystemer for stude på kløvergræs. DJF Report (Husbandry). Research Centre Foulum, Denmark. In press. Anonym. 2002. Afregningspriser for uge 1-52/2001 for slagtekvæg efter klassificering (Danmark). Kødbranchens Fællesråd. Denmark. (www.meatboard.dk) Bowling, R.A., Riggs, J.K., Smith,G.C., Carpenter, Z.L.. Reddish, R.L., Butler, O.D. 1978. 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Influence of feeding level, grazing and finishing feeding on meat and eating quality of young bulls and the relationship between muscle fibre characteristics, fibre fragmentation and meat tenderness. Meat Science 54, 187-95. Wright, I.A., Russel, A.J.F., Hunter, E.A. 1986. The effect of winter food level on compensatory growth of weaned, suckled calves grazed at two sward heights. Anim. Prod. 43, 211-23. 1989. Compensatory growth in cattle grazing different vegetation types. Anim. Prod. 48, 43-50.", "full_text_status": "restricted", "documents": [ { "docid": "2370", "rev_number": "1", "eprintid": "1871", "pos": "1", "format": "source", "language": "en", "security": "validuser", "main": "optimal_decisions.doc", "files": [ { "filename": "optimal_decisions.doc", "filesize": "228352", "url": "http://orgprints.org/1871/1/optimal_decisions.doc" } ] } ] }