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 mil kability from 1988 to 1991. The most important environmental factors f or milking time and average milk flow rate (DMG) were the measuring eq uipment for milk yield and the daily amount of milk. Heritabilities ra nged 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 milkabili ty 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 selectio n for higher milk flow rate or decreasing milking time lead to an incr easing cell count. Therefore, a very high milk flow rate is not desira ble. Correlations between DMG and milk yield were positive. Thus, bree ding for higher milk performance will lead to an increased milk flow r ate.