Calving performance in danish breeds of dual purpose cattle
Genetics Selection Evolution
Copenhagen (De.nmark) . Calving performance is discussed as one of the main factors of stillbirths in cattle. Data from 17 8 4 first calvings in two dual purpose Danish breeds of cattle (Red Danish and Black Pied Danish) were analysed. The data originate from the progeny testing stations, and calving performance was scored on a scale : Heritability for the scored calving performance was calculated in two different ways, the results ranging from 0 . 13 to 0 . 32 for Red Danish and from 0 . 10 to
... and from 0 . 10 to o.18 for Black Pied Danish. The phenotypic correlation between calving difficulty score and weight of calf was found to be between o.i8 and o.26 for both breeds. The size of the genetic correlations indicate that in the Red Danish breed the bigger heifers have the easiest calvings. For the Black Pied breed the smallest heifers have the easiest calvings. For both breeds the greater width of hips and thurls are followed by more difficult calvings. 1.958, Copenhagen (Denmark). As seen from the intervention prices, EEC attaches more and more importance to the milk protein and accordingly less importance to the butterfat. On this background is given an evaluation of the previous investigations regarding the genetic improvement of the cow's protein yield. It is concluded that if introducing protein registration this must be as a supplement to the present fat test, and that the most profitable alternative must be a limited and not too cost demanding registration. An investigation of the economic consequence in connection with the following 3 registration systems is carried out : registration among the potential bull dams, among the bull sire candidates, and among all first lactation cows. The last alternative turns out to be the most profitable Moreover investigations indicate that one protein test per every second or third of the present 13 fat tests per year is sufficient. Further the results indicate that a saving of 4 -6 D.Kr. per cow in costs when taking samples and laboratory analyses will justify a reduction in the number of both fat and protein tests.