First Lactation Performance and Herd Life

Abstract

Records of artificially sired cows of five breeds having up to five or more lactations were divided into four groups according to first-lactation deviations from herd-mate average. The average deviation for each group in each of four succeeding lactations was greater than for the group which was below it in the first lactation. The fraction of cows having subsequent records was also greater for the groups highest in first-lactation deviations. The pattern was similar for all breeds. The Holstein results showed that more of the high producers (Group 1) in the first lactation had second records than the low producers (Group 4)—82 vs. 61%. More than twice as many had at least five records—32 vs. 15%. The high producers in the first lactation not only continued to outproduce their lower-producing first-lactation mates but also had a substantially longer herd life. These results do not substantiate the claim often made, that high producers in the first lactation burn themselves out and leave the herd at an early age. Actually, these cows appear to stay longer and produce more than their lower-producing first-lactation mates. © 1964, American Dairy Science Association. All rights reserved.