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Correlations were computed among averages of first lactation deviations from herdmate averages of groups of artificially sired daughters of the same Holstein bulls. The groups were constructed by specifying the time interval between animals in the different groups. Comparison of the actual correlations with the expected correlations suggests that environmental correlations are small or nil among artificially sired halfsibs in New York. The correlations between initial and later groups of 20 or 40 daughter records at different time intervals are so close to the expected correlations that there is no support for the view that accuracy of prediction in sire evaluation is being over-estimated due to failure to properly account for environmental correlations among contiguous half-sibs in artificial insemination.