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Milkability and udder health in dairy cows 2. data analysis of the official progeny test on milkability in schleswig holstein west germany

Perez-Guzman, M.D.; Claus, J.; Junge, W.; Kalm, E.

Zuechtungskunde 58(2): 75-86

1986


Accession: 005902547

The analysis of the data supplied by the official progeny test on milkability in Schleswig-Holstein can be summarized as follows. If the average amount of milk per minute is corrected linearly and quadratically to the total amount of milk, differences between breeds and lactation numbers no longer occur. An additional consideration of the lactation day does not decrease the remainder error. For the Black and White breed the systematic effects of the "region" the "month of recording" and the interaction "control year .times. month" are to be considered at a breeding value estimation on milkability. With all three breeds the effect of the application of a milcoscope to determine the amount of milk has to be corrected in accordance with its breed specific value. If the average amount of milk per minute is used for selection on milkability, it has to be corrected linearly and quadratically on milk yield. It seems sensible for the selection on milkability to use the characteristics duration of milking and the duration of milking shortened by six minutes instead of the average amount of milk per minute, as they directly bear an economic impact. However, the connection between udder health and milkability here, too, has to allow for the udder health index dependent on the milk flow. The characteristics of duration of milking have to be corrected to the same systematic effects as the average amount of milk per minute. The correction on the day of lactation can be applied linearly. As breeding value estimation model for milkability a BLUP [best linear unbiased predictor]-model can be especially recommended for the Black and White breed, as a BLUP-model can take unevently filled effect classes better into account than the customary Contemporary Comparison. Its additional calculation requirements are low.

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