Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)


Supply relations underlie the surplus, price and income problems of American agriculture. Yet specific knowledge of supply relations is stilt small. This study is part of a larger investigation directed toward increased knowledge of output response or supply in agriculture. It is concerned with a particular category of farm commodities; namely, poultry products. The objective of the study is to quantitatively identify variables which have been important in the response of poultry output over time. But methodological purposes also are important for the study, and considerable emphasis is placed on comparison of: alternative models applicable to egg, broiler and turkey supply relations.

Technological change has been large in poultry production and evidently has had great effect on output. Hence, the first step in this study is that of quantifying technical change, as a substitute for time in the regression equations estimated. The number of eggs per layer, the broiler-feed conversion rate and the turkey-feed conversion rate are selected as the output-input ratios which best indicate the levels of technology for the three poultry products. In extracting the net change in technology, by eliminating the effects of certain market conditions, a logistic function is fitted to data for each type of poultry. The values obtained from the estimated logistic functions are called the technology index of egg production, broiler production and turkey production. Poultry supply models are constructed with these technology indexes incorporated as variables.



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