This paper analyzes the productive and breeding performances of cattle from the Bălțată cu negru românească (BNR) and Bălțată românească (BR) breeds, exploited under a semi-intensive system in Iași county. The results highlight a clear quantitative superiority of the Bălțată cu negru românească breed, with an average production of 10,096.50 kg of milk/lactation, compared to 6,114.92 kg for the Bălțată românească breed. From a qualitative perspective, the Bălțată românească breed exhibits superior parameters, with an average of 4.23 % fat, 3.56 % protein, and a high casein content (30.94 g·L-1 milk), making it optimal for industrial processing. Performance is significantly conditioned by local mesoclimatic factors (temperatures of 10 - 11 °C and precipitation of 500 - 600 mm). During periods of thermal stress, the Bălțată cu negru românească breed records production decreases of up to 15 %, while Bălțată românească demonstrates superior biological resilience, with losses below 5 %. The analysis of breeding indices by lactation number reveals a major advantage for Bălțată cu negru românească in early lactations, with a peak total breeding value of + 47.84 in the second lactation. However, in late lactations (7 - 9), the differences between the breeds become minimal (- 0.07 to + 1.55), suggesting that adaptability to the local environment becomes the determining factor in the long term, narrowing the initial genetic gap.