[Does selection for characteristics of the udder, teats, ease of milking and udder health offer any prospects of improvement of resistance to mastitis? (author's transl)].

Improvement of resistance to mastitis by indirect selection for udder traits, ease of milking and milk cell counts is discussed. --Selection for less pendulous udders with shorter teats is practised. Genetic variation in udder and teat measurements between and within sub-populations of Dutch Friesian (DF) and Meuse-Rhine-IJssel (MRY) cattle in first lactations is important (Table 1). --Selection for ease of milking based on an ease of milking test of progeny groups has been practised since 1962. An optimum peak flow of about 2.9 kg/minute is attained in the DF and MRY breeds (Graph 1). --A field trial in 1587 DF and 1139 MRY cows showed that culling for problems of udder health after three lactations (DF 10%, MRY 20% of the cows culled) is of more importance than culling for hard milking (DF 6%, MRY 4%) (results in 3.3). --There was no relationship between the incidence of clinical mastitis (DF 20%, MRY 22%) in the third and fourth lactations and the peak flow tested in the first lactation (Table 2). --There was a positive correlation between peak flow and lactation milk yield (DF r = 0.23, MRY r = 0.19) (Table 3). --The incidence of leaking milk just before milking is slightly lower in the DF breed than in the MRY breed and related to the peak flow (Table 4). --Milk cell counts tested in DF and MRY progeny groups in first lactations showed genetic variations (DF log cell count 2.43 sigma 0.32 h2 = 0.30). --Determining milk cell counts in progeny groups during the last part of the first lactation (when differences are more marked than during the first part of lactation) may provide a basis for indirect selection for resistance to mastitis (Graph 2). There are prospects of improvements of udder health by indirect selection for udder and teat conformation traits. Selection for ease of milking is of minor importance in this regard. Further research is required to show that selection for udder traits during first lactations, e.g. a small proportion of daughter in the classes showing high milk cell counts, may provide a basis for selection for a lower incidence of mastitis in the older cows.