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Dairy production systems are complex and cannot be described by a single profit function. In a bio-economical model, relevant biological and economical aspects of the production system are described as a system of equations. These models describe the life cycle of a dairy cow, including inputs and outputs, as a function of biological traits and economic parameters. For the derivation of the economic values of Estonian Holstein dairy breed, a bio-economical model of a closed herd, which included the whole integrated production system was used. The total discounted profit for the herd was calculated as the difference between all revenues and costs that occurred during the whole life of animals born in the herd within one year and which were discounted to the birth year of these animals. Core elements of the program are modules describing the age distribution of the herd based on different possible fate of cows, the production level in each lactation and cost rations on a daily basis. Change of profit has been considered as a function of genetic change, not other changes of phenotype. Economic parameters reflect the marketing and management system in which genetic improvement will be expressed. Economic values for use in selection indexes were derived for milk-, fat- and protein production, length of productive life, calving interval and age at first breeding. Analysis of dairy production system with bio-economical model enables the breeders to find out revenues, costs and different parameters for dairy production system, and also to estimate milk production profit. Različni načini proizvodnje mleka so kompleksni in jih ni mogoče opisati z eno samo dobičkovno funkcijo. V bioekonomskem modelu opišemo relevantne biološke in ekonomske vidike s sistemom enačb. Ta model opisuje življenjski cikel krav, vključno z vlaganji in pridelki, kot funkcijo bioloških lastnosti in ekonomskih parametrov. Za izračun ekonomske vrednosti črede estonskega holstajnskega mlečnga goveda smo uporabili bio-ekonomski model zaprte črede, ki je upošteval tudi integrirani način proizvodnje. Celotni dobiček za čredo smo izračunali kot razliko med prihodki in stroški, ki so nastali v celotnem življenjskem obdobju živali, ki so bile rojene v populaciji v obdobju enega leta po korekciji na rojstno leto. Glavni elementi programa so moduli, ki opisujejo starostno strukturo črede, različne lastnosti živali, raven proizvodnje v posameznih laktacijah in dnevne stroške. Razlike v dobičku smo pojmovali kot razlike v genetski vrednosti živali. Ekonomski parametri odražajo tržne razmere in sistem upravljanja, v katerem se izraža genetski napredek. Ekonomske teže, ki smo jih uporabili v modelu temeljijo na proizvodnji mleka, masti in beljakovin, dolžini proizvodnega obdobja, dobi med telitvama in starosti ob pripustu. Analiza prireje mleka z bio-ekonomskim modelom omogoča rejcem oceno stroškov, prihodka in dobička od prireje mleka v različnih proizvodnih sistemih. |
