Are farmer assessed temperament, milking speed, and leakage genetically the same traits in automatic milking systems and traditional milking systems?

摘要

The aim was to investigate whether subjectivelyscored milking speed, temperament, and leakage aregenetically the same trait when measured in differentmilking systems. Data were provided by the NorwegianDairy Herd Recording System and included a totalof 260,731 first-parity Norwegian Red cows calvingbetween January 2009 and February 2019 and milkedeither in a traditional milking system (milking parloror pipeline) or by an automatic milking system (AMS).Genetic parameters were estimated and lower heritabilitiesand less genetic variation were found for the3 traits when measured in AMS herds. The heritabilityof temperament, leakage, and milking speed were0.05, 0.04, and 0.22, respectively, with data from AMSherds; and 0.09, 0.14, and 0.27, respectively, with datafrom cows milked in traditional milking systems. Thegenetic correlations between temperament and leakage(−0.19), between milking speed and leakage (−0.88),and between milking speed and temperament (0.30)in AMS were slightly stronger than between the correspondingtraits assessed in other milking systems(−0.15, −0.82, and 0.16, respectively). The geneticcorrelations between traits across milking systems werestrong: 0.98, 0.96, and 0.86 for milking speed, leakage,and temperament, respectively. Strong correlations indicatethat the traits were almost genetically similardespite being scored in different milking systems. Therank correlations among estimated sire breeding valueswere strong: 0.98 and 0.99 for milking speed andleakage, with little or no reranking of bull performanceacross milking systems. Temperament had the lowestgenetic correlation (0.86) and rank correlation (0.91)across milking systems. These data suggest that AMSfarmers evaluate temperament slightly differently fromfarmers using other milking systems or that differentaspects of temperament are important for farmers withAMS.