The aim of this paper is to examine the impact of sowing structure on family farm competiveness using the model of family farm directed at the final production of fattened beef cattle in the conditions of unchanged estate size. Applying a partial budget analysis, it was examined whether the decision on buying alfalfa hay or mercantile maize on the market and changing the sowing structure was economically justified and under what conditions using additional procedure of sensitive analysis. Applying this approach, it was investigated to what extent that decision contributed to improving the family farm profitability. The results of the conducted research show that the decision on buying mercantile maize mainly contributes to improving competitiveness of family farms directed at the final production of fattened beef cattle compared with the decision on buying alfalfa hay. It is the consequence of the fact that buying mercantile maize on the market will enable sowing structure changes, that is, buying mercantile maize will make the area free, which according to some conservative estimations, can be used for the production of sufficient amounts of alfalfa and silage maize for fattening of additional 19 head, whereas buying alfalfa hay will make the area free, which can be used for production of sufficient amounts of mercantile and silage maize for fattening of additional 6 head. In addition, it is shown that more rational way of organising family farms directed at the final production of fattened beef cattle can additionally use available land resources and in that way increase profitability and improve competitiveness.