The study aimed to estimate the effect of the time period of fattening on the weight efficiency of calves, as the study relied to achieve its objectives on the quantitative economic analysis in addition to the descriptive economic analysis. Through the preliminary data obtained from the paragraphs of the questionnaire form that was prepared and designed by the researcher specifically for the random sample that included (12) fields that included (645) local calves and included 20% of the research community. The research used mathematical methods to obtain the desired results from the research. The study dealt with a group of fields in the north of Nineveh Governorate during the productive year 2021. The results indicated that there is a direct relationship and positive between the fattening period and the daily and total weight rates to a certain extent because it is subject to the law of diminishing yields. As it was shown from the results that the maximum fattening period for fattening reaches (240) days and after this period the law of diminishing yields begins to work and the economic returns (profits) decrease. The researcher suggests not to sell and the marketing of fattened animals only after reaching 6 months (180) fattening days as a minimum and 8 months (240) fattening days as a maximum, taking into consideration the other economic factors and variables involved in the fattening process.

The research seeks to measure the technical, allocative and economic efficiency of the fields of breeding and fattening calves, and to determine the amount of resources that achieve the economic efficiency of the fields of specialized breeding and fattening calves, and then to estimate the surplus and deficit in both the quantity of concentrated, rough and green fodder, the value of veterinary medicines and the numbers of human labor force for one season. Technical efficiency according to the production function that the technical efficiency of the research sample fields reached an average of 90%, according to the cost function. The surplus percentage amounted to 47.8%, 3.77%, 16.14%, 3.03%, 55.64 and 61.05%, in the economic resources it amounted to each of the quantity of concentrated, rough and green fodder, the value of veterinary medicines and the number of human labor force for one season.