SUMMARY
Researches were carried out on 3186 lactations obtained from Romanian Spotted cows raised in farms from Bihor County that were enrolled in official performance control scheme. According to the number of milking cows (farm size), farms were divided into three categories small (n=10 cows), middle (n=11 to 25 cows) and large (n>25 cows). The influence of the farm size on five selection indices (global, for milk, for fitness, for reproduction and for functionality) and eight estimated breeding values (milk yield, milk fat yield, milk protein yield, age at first calving, inseminations per gestation, calving ease, longevity and somatic cell count) was determined by using One-way ANOVA. Reference population had an average ME milk production of 6028 kg with 3.67% fat and 3.28% protein, calved for the first time at 29 months and 14 days, had an average calving interval of 389 days and days dry of 51 days. Generally, the farm size had a significant influence on selection indices (p<0.05). Selection indices and estimated breeding values were similar between small and middle farms. Global selection index and selection index for milk were significantly higher (p<0.05) in large farms compared to small and middle size farms, while selection indices for fitness, reproduction and functional were higher (p<0.05) in small and middle farms compared to large farms. Estimated breeding values differed among farms according to their size (p<0.05), being higher for milk yield and somatic cell count in large farms, while in small and middle farms, the values for reproduction and longevity were higher than in large farms.