SUMMARY

The growth increase in differing growing systems was analysed on the basis of the data obtained from the current researches. As the initial trial material, 400 of the 1-day-old broilers of the proveniance Hybro, were used. Fattening of the broilers lasted 49 days and was organised in two modes. Namely, one half of the trial broilers was reared in adequate conditions of an intensive production, while the other one was provided with outlets, i.e. a type of a half-intensive rearing system. The growth increase was analysed on the basis of the data obtained by measuring bordy mass of the trial broilers on the first, fourteenth and on every seventh clay until the end of fattening period. The results have shown the following:

• The average body mass of 1-day-old broilers of both trial groups was alike. That one of the 14-days-old broilers did not vary noticeably, eithr, with negligible statistical differences found. However, all the next growth increase check ups have shown significant or highly significant differences in the average body weight of the broilers studied. Thus, at the end of fattening period, the broilers of the intensive fattening had on the average 129 g higher average body weight compared to that in the broilers from the half-intensive fattening system.
• Intensively-reared broilers in all the check periods had a greater average daily growth increment compared to those reared semiintensively. Thus, in the period from 15th to 49th day of the growth, the average daily growth incerement of the broilers reared in the intensive mode, amounted to 44.51 g, while that of those reared semiintensively amounted to 40.74 g.

          Key words: broilers, growth increase, rearing system, body mass.