{"references": ["BERRY, D. P., HARRIS, B. L., WINKELMAN, A. M., MONTGOMERIE, W.: Phenotypic associations between traits other than production and longevity in New Zealand dairy cattle. Journal of Dairy Science, 88:2962\u20132974, 2005.", "BOETTCHER, P. J., JAIRATH, L. K., DEKKERS, J.C.M.: Comparison of methods for genetic evaluation of sires for survival of their daughters in the first three lactations. Journal of Dairy Science, 825:1034\u20131044, 1999.", "BOGDANOVI\u0106, V., \u0110EDOVI\u0106, R., PERI\u0160I\u0106, P., STANOJEVI\u0106, D., BESKOROVAJNI, R., PETROVI\u0106, M.D.: Karakteristike dugove\u010dnosti kao funkcionalne osobine mle\u010dnih krava. Radovi sa XXVI savetovanja agronoma, veterinara, tehnologa i agroekonomista Vol. 18. br. 3-4, str.23-33, Beograd, 2012.", "CARAVIELLO, D. Z., WEIGEL, K. A., GIANOLA, D.: Prediction of longevity breeding values for us holstein sires using survival analysis methodology. Journal of Dairy Science, 8710:3518\u20133525, 2004.", "CHIRINOS, Z., CARABA\u00d1O, M. J., HERN\u00c1NDEZ, D.:Genetic evaluation of length of productive life in the Spanish Holstein-Friesian population. Model validation and genetic parameters estimation. Livestock Science,106, 120\u2013131, 2007.", "DE VRIES, A., OLSON, J.D., PINEDO, P.J.: Reproductive risk factors for culling and productive life in large dairy herds in the eastern United States between 2001 and 2006. Journal of Dairy Science, 93: 613-623, 2010.", "DE VRIES, A.: Productive life of dairy cows in Florida. Department of Animal Sciences University of Florida, Gainesville, 2003.", "DUCROCQ,V.: An improved model for the French genetic evaluation of dairy bulls on length of productive life of their daughters. Animal Science, 80: 249-256, 2005.", "HADLEY, G. L., WOLF, C. A., HARSH, S. B.: Dairy cattle culling patterns, explanations, and implications. Journal of Dairy Science, 89: 2286-2296, 2006.", "HARE, E., NORMAN, H. D., WRIGHT, J. R.: Survival rates and productive herd life of dairy cattle in the United States. Journal of Dairy Science, 899:3713\u20133720, 2006.", "HARVEY, W.R. :Mixed model least squares and maximum livelihood computer program: User's guide for LSMLMW and MIXMDL, 1987.", "LOPEZ DE MATURANA, E., UGARTE, E., GONZALEZ-RECIO, O.: Impact of Calving Ease on Functional Longevity and Herd Amortization Costs in Basque Holsteins Using Survival Analysis. Journal of Dairy Science, 90:4451\u20134457, 2007.", "P\u00c1CHOV\u00c1, E., ZAVADILOV\u00c1, L., S\u00d6LKNER, J.: Genetic evaluation of the length of productive life in Holstein cattle in the Czech Republic. Czech J. Anim. Sci., 50, 493\u2013498, 2005.", "PRITCHARD, T., COFFEY, M., MRODE, R., WALL, E.: Understanding the genetics of survival in dairy cows. Journal of Dairy Science, 96: 3296-3309, 2013.", "SEWALEM, A., MIGLIOR, F., KISTEMAKER, G. J., SULLIVAN, P., VAN DOORMAAL, B. J.: Relationship Between Reproduction Traits and Functional Longevity in Canadian Dairy Cattle. Journal of Dairy Science, 91:1660\u20131668, 2008.", "TERAWAKI, Y., DUCROCQ, V.: Nongenetic effects and genetic parameters for length ofproductive life of Holstein cows in Hokkaido, Japan. Journal of Dairy Science, 92: 2144-2150, 2009.", "TSURUTA, S., MISZTAL, I., LAWLOR, T. J.: Changing Definition of Productive Life in US Holsteins: Effect on Genetic Correlations. Journal of Dairy Science, 88: 1156\u2013 1165, 2005.", "VAN RADEN, P. M., DEMATAWEWA, C. M. B., PEARSON, R. E., TOOKER. M. E.: Productive life including all lactations and longer lactations with diminishing credits. Journal of Dairy Science, 89: 3213-3220, 2006.", "VUKA\u0160INOVI\u0106, N., MOLL, J., KUNZI, N.: Analysis of productive life in Swiss Brown cattle. Journal of Dairy Science, 8010:2572\u20132579, 1997."]}

The objective of the research was to investigate the significance of the main systematic effects on productive life of high yielding Black-and-White dairy cows. The average length of productive life reached 1494.18��463.66 days Observed by genotypes, the mean values were as follows: 1377.35 days (>73% HF), 1477.47 days (58-73% HF) and 1627.71 days (<58% HF). Differences in length of productive life came as a result of highly significant (P���0.01) effect of the class of HF genes, bull sires and year of culling, whereas the reason for culling had no significant effect (P>0.05).