Effects of crossbreeding native Black-and-White and Red-and-White cattle with Holstein-Friesian cattle in Poland

Research was carried out on the active population of Black-and-White (BW) and Red-and-White (RW) I and heifers crossbred with Holstein Friesian cattle (HF), under milk performance control in Poland (1991-1999). It was observed that milk, fat and protein yield was related to the ratio of HF genes in the genotypes of the analysed cows and that these parameters increased in relation to the amount of HF genes that the animals possessed, The predominance off-IF genes in BW crossbreeds resulted in a higher fat yield whereas the content of protein in HF x BW cows and fat and protein content in HF x RW crossbreeds did not evidently correlate with an increased share of BF genes, Red-and-White cattle transformed into milk producers at a slower rate than did Black-and-White. After 25 years of using HF breed to improve local cattle populations the percentage of active cows with more than 50% of HF blood under performance testing in 1999 amounted in 56.0% within Black-and-White populations and to 34.8% within Red-and-White breed.