LIFETIME PRODUCTION PERFORMANCE OF HOLSTEIN-FRIESIAN COWS

Na uzorku populacije holstein-friesian pasmine društvenog sektora Slavonije i Baranje ustanovili smo duliinu produktivnog vijeka od 3,89 godina i 3,13 završenih laktacija u prosjeku, te nEpovoljaan indeks iskoristenja od 57,28. U starosnoj strukturi izlučenih krava visok je postotak mladih grla čiji postojeći genetski potencijal za visoku proizvodnju mlijeka nije u potpunosti došao do izražaja zbog prijevremenog izlučenja iz uzgoja. Za razliku od starosti pri prvom teljenju, količina mlijeka u prvoj laktaciji značajno utječe na ukupnu količinu proizvedenog mljeka toku života, što znači da se selekcijom za mliječnost u prvoj laktaciji može očekivati veća mliječnost u kasnijim laktacijama, ali ne i duži produktivni vijek.This study included 981 lactation records of 312 daughters of Holstein-Friesian sires from state farms of Slavonija and Baranja. The average age at first calving was 28\u279 months and the age at culling was 76.3 months (6.27 years). The average length of production life, number of lactations, total milk yield and total fat yield were 3.89 years, 3.14 lactations,22,335 kg and 813 kg, respectively. The index of exploatation expressing the relative length of production life was 57.28. The relations between the age at first calving and lifetime performances were negative and statistically insignificant, except for the index of exploatation (r= -0-198**). The correlations between milk production in the first lactation and total milk yield, milk per day of production life and per day of life were positive and significant (0.157*, 0,498**, 0,355**, respectively). It was evident that with selection for high milk yield in the first lactation, more milk yield can be expected in later life, but not a longer production life