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dc.contributor.authorMcArthur, A. T. G.
dc.date.accessioned2010-11-08T00:04:37Z
dc.date.available2010-11-08T00:04:37Z
dc.date.issued1975
dc.identifier.urihttps://hdl.handle.net/10182/2767
dc.description.abstractThis study of the economics of animal replacement lies on the border of two well developed areas of knowledge. On the one hand it draws on the theory of animal breeding and on the other on replacement theory. Replacement theory in its turn lies on the borders of operations research and investment theory. As so often happens in the development of knowledge, some advance can be made by those working at the crossroads between two or more specialised areas. This has proved to be the case in the study of dynamic programming applied to animal replacement decisions. Decisions to replace animals are either voluntary or involuntary. Involuntary decisions are due to death or failure arising from a multitude of physical, physiological, and pathological causes. Voluntary decisions are usually made on the basis of the animal's age and also on the record of its past productive performance. The productivity of older animals tends to decline and the risks of death and failure tend to raise accounting for age being a factor in voluntary replacement decisions. Animals also vary in performance and there is usually a correlation between previous records and future production. Consequently farmers cull low producers and replace them with those with a higher expected productivity. Replacing low producers also implies that the genes of these animals make a smaller contribution to the genetic composition of the future population. Against these gains from voluntary replacement must be balanced the costs of replacement. A high replacement rate implies a lower efficiency because of the overhead costs of rearing replacements. The economic problem is to find the age and the critical level of previous performance that maximises the net gain from animals. Now the original purpose of dairy herd recording in New Zealand was to determine the butterfat content of individual cows and hence the total butterfat yield; the lowest producers, or "passengers," were to be replaced (Ward (1952) and Edey (1966)). Under the herd improvement plan of 1940, six consulting officers were appointed "... to assist dairy farmers in making better use of herd recording schemes." (New Zealand Dairy Board (1939)). Unfortunately there was little to guide consulting officers when helping farmers make culling decisions except the principle that cows should be replaced by those with a higher expected production. This principle did not take into consideration such economic factors as the net cost of replacement, the future profile of production of the existing cow, death and failure rates, and the economic cost of time. In the postwar era there was some scepticism expressed by farm improvement club advisers as to the economic value of spending money on herd testing (Du Faur (1955)). This challenge was answered by various studies (see particularly Searle (1961) which showed that the average dairy farmer using conventional culling procedures could get a positive economic return from herd testing. However, these studies did not indicate the best way of using herd recording information for replacement decisions nor was the method of economic evaluation particularly sophisticated. In New Zealand, the herd improvement associations record officially over 30 percent of the national herd at a total cost of approximately $lm annually. From the farmer's point of view the main purpose of recording is to provide objective information upon which to base culling decisions, yet almost no research has been done on how these decisions ought to be made. Recording sheep production is a much newer practice in New Zealand. Genetic gains are the main objective here, but sheep recording would receive an impetus if research showed how the information could be used for improving the replacement policy.en
dc.language.isoenen
dc.publisherLincoln College, University of Canterburyen
dc.rights.urihttps://researcharchive.lincoln.ac.nz/page/rights
dc.subjectanimal replacement decisionsen
dc.subjectdynamic programmingen
dc.subjectanimal breedingen
dc.subjectreplacement theoryen
dc.subjectagricultural economicsen
dc.subjectoptimal replacement policyen
dc.subjectstochastic dynamic programmingen
dc.titleDynamic programming applied to animal replacement decisionsen
dc.typeThesisen
thesis.degree.grantorUniversity of Canterburyen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen
lu.thesis.supervisorMcCarthy, Owen
lu.contributor.unitDepartment of Agricultural Management and Property Studiesen
dc.rights.accessRightsDigital thesis can be viewed by current staff and students of Lincoln University only. Print copy available for reading in Lincoln University Library. May be available through inter-library loan.en
dc.subject.anzsrc070201 Animal Breedingen
dc.subject.anzsrc070203 Animal Managementen
dc.subject.anzsrc0102 Applied Mathematicsen


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