A maturity index in Brown Swiss and Simmental cattle defined as development of milk production EBV’s over parities

Schleppi and Bigler (2002) proposed an maturity index to characterize the increase in milk production trait EBV’s over the first three lactations (MI). We calculated this index and examined genetic trends, genetic variability and its correlation with other components in the aggregated genotype for Braunvieh and Fleckvieh cattle in Germany and Austria. The results showed that there is genetic variability in MI and that there was no genetic trend over the past 15 years. The correlations with other traits were generally low. An interestingly high correlation (0.58 and 0.61) was found with persistency. This indicates that cows with good persistency will also tend to show a strong increase in performance in later lactations. However, we cannot recommend MI as a selection criterion. Correlations with other traits are too low to justify the increase in generation interval that would be necessary in order to consider this trait in selection. MI might however be useful for production in low input systems such as organic farming.

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