Assessment of Longevity and Lifetime Productivity of Local Cattle Breeds in Relation to International Breeds.

This study was based on data obtained from a total of 9518 cows belonging to seven cattle breeds: local breeds-Polish White-Backed (249), Polish Red (269), Polish Black-and-White (255), and Polish Red-and-White (290)-and international breeds-Polish Holstein-Friesian (5917), Jersey (940), and Simmental (1598). The breeds were characterised in terms of the following parameters: length of life, length of productive life, milking life, longevity index, percentage share of yield in the first 305-day lactation and first complete lactation in the lifetime yield, and functional longevity. Reasons for culling and the relationship between the length of life/productive life and milk performance parameters were determined as well. The analysis of the length of life and length of productive life in seven different cattle breeds kept in Poland unequivocally demonstrates that local breeds clearly stand out in this regard in comparison to international breeds. They may in the future constitute a valuable gene reservoir for improving longevity in other breeds. The length of life of Polish White-Backed and Polish Red cows was 2817 days and 3607 days, respectively, while that of Polish Holstein-Friesian and Jersey cows was only 2131 and 1956 days, respectively, and the most common cause of culling of cows in Poland (39.07%), irrespective of breed, was reproductive problems. The favourable results of parameters related to the longevity of the local breeds of Polish Red and White-Backed show that they can become a tool for improving the longevity of international breeds.