Evaluation of milk composition and yield in active populations of Black-White and Red-White primiparous cows in Poland

Active populations of crossbreeds of Slack-White (BW) x HF and Red-White (RW) x HF primiparous cows were superior to pure-bred BW and RW peer groups in terms of milk yield and its composition during a period of 305 lactation days irrespective of the percentage that they had of HF genes: Both RW pure-breds and :crossbreeds had a slightly better protein to fat ratio (SBT) and a smaller difference between fat and protein milk content (RTB) when compared to BW and BW x HF populations: There was a smaller difference between fat and protein content (RTB) and more favourable protein to fat. ratio (SBT):amongst pure-breds of the Black and White breed compared to their HF pure-bred contemporaries.