Relationships between production and fertility traits in first lactation and life time performances of Holstein cows under subtropical condition

The objective of this study was to determine the relationships between milk yield and calving interval in first lactation and breeding efficiency, herd life and length of productive life of 1 293 Holstein cows maintained at Ceylanpinar State Farm in Southeast Anatolia from 1990 to 2002. The least-squares means of first lactation milk yield, lactation length and calving interval were 5620.1 +/- 76.6 kg, 315.5 +/- 2.0 and 386.9 +/- 2.6 days. The values for breeding efficiency, herd life and length of productive life were 94.9%, 2095.9 +/- 34.7 and 1257.2 +/- 34.4 days. The year of first lactation had significant effect (P<0.05) on all traits except for calving interval and lactation length, and breeding efficiency was only affected by age at first insemination and age at first calving (P<0.05). Heritabilities were 0.27 +/- 0.08 for milk yield, 0.02 +/- 0.05 for lactation length, 0.06 +/- 0.05 for calving interval, 0.05 +/- 0.05 for breeding efficiency, 0.30 +/- 0.08 for herd life and 0.29 +/- 0.08 for length of productive life. Genetic and phenotypic correlations between different traits ranged from -0.49 to 0.99 and -0.37 to 0.99 respectively.