INVESTIGATIONS ON SOMATIC-CELL COUNT AND MILKABILITY OF DAIRY-COWS 2ND COMMUNICATION - GENETIC-PARAMETERS OF MILKABILITY TRAITS

The analysis of several milkability parameters and their relationships to milk yield and cell count was based on data of progeny test on milkability from 1988 to 1991. The most important environmental factors for milking time and average milk flow rate (DMG) were the measuring equipment for milk yield and the daily amount of milk. Heritabilities ranged from h(2) = 0.09 to h(2) = 0.25 for milking time and from h(2) = 0.15 to h(2) = 0.22 for DMG. Phenotypic correlations between milkability and cell count were of low magnitude. Genetic correlations between milking time and cell count ranged from r(g) = -0.10 to r(g) = -0.39, between DMG and cell count from r(g)= 0.32 and r(g) = 0.57. A selection for higher milk flow rate or decreasing milking time lead to an increasing cell count. Therefore, a very high milk flow rate is not desirable. Correlations between DMG and milk yield were positive. Thus, breeding for higher milk performance will lead to an increased milk flow rate.