Einfluß des Erstkalbealters auf Fruchtbarkeit und Leistung bei Milchkühen

Title of the paper: The influence of the age of first calving on fertility and Performance in dairy cows The influence of the age of first calving (respectively heifer conception age) on later fertility was investigated according to the lactation reports of 8 German herds (n = 4125), one US-American (n = 300) herd as well as to the annual average data of 206 Israeli herds. All the correlation coefficients were set nearly zero. The optimal sphare for the age of first calving regarding some milk performance characteristics is from 24–26 months. This can be infeired from the variance analyses from the comparisons among the groups. The analysis of 1032 heifer births showed a rising tendency in the frequency of dystocias in higher age of first calving.