| Summary: | This study uses modelling as a research method to provide insights that allow a better understanding of small-scale dairy farms in Mexico. Both biological and economical aspects are considered, in order to look for a possible approximation to the way resources are perceived and measured in these systems; and to improve the efficiency with which resources are utilised according to a given criterion of efficiency. The work proposes that the main elements of Mexican small-scale dairy systems are the crop production component and the herd. component. In order to represent these components and the basic interaction between them, four optimisation models were developed. Chapter 3 is a study of forage production on Mexican small-scale dairy farms utilising linear programming as an optimisation technique. In order to evaluate. the alternatives suggested by the model, a partial budget was utilised. Chapter 4 describes a nutritional model, again utilising linear programming, aimed at exploring the effects of different feeding strategies over the lactation. The nutritional requirements were calculated by considering milk production and live weight changes over the lactation to evaluate the impact of such strategies on cow performance. The two chapters reveal the importance of a knowledge of the lactation curve. Therefore in Chapter 5 the lactation curve of Mexican dairy cattle is studied comparing different equations that could represent the sequence more accuratately. In Chapter 6, a linear programme was developed that allows optimising the calving pattern and the lactating herd structure. A Markov Chain procedure was then used to simulate the dynamics of reproduction in the herd in order to identify the reproductive parameters that may ensure keeping such an optimal calving pattern. Chapter 7 integrates the outputs obtained by .~ the previous model through multi criteria programme modelling in which the basic elements of the crop production component, the nutrient requirements of the lactating herd over the year.and the optimal herd structure are brought together. And finally, all these chapters are discussed in Chapter 8 where the findings are compared with the objectives proposed, and possible further research is suggested, together with the practical implication for the small-scale dairy producers in Central Mexico.
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