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This dissertation explores, how milkcattlebulls react on a starvation of nine days, wether there are differences between the reactions of bulls with different pedigree breeding values milk and wether there are correlations between metabolic values and pedigree breeding values milk.59 potential AI-bulls of Holstein-Frisian-race were deprived feeding for nine days to provoke metabolic reactions in the bulls during a phase of negative energy balance, which simulate the condition of a milkcow at maximum lactation. Important in this context is, that -except of one bullnoone of the bulls showed symptoms of illness during or after starvation.For evalution of the single experiments the blood values from day of ormal feeding, ninth day of starvation and second day of refeeding were taken into consideration. Sixth day of starvation was included at determination of repetition-coefficients.The blood of the bulls was tested of serumconcentrations of cholesterine, cortisol, GGT, GLDH, glucose, GOT, urea, insulin, protein and thyroxine.Within the nine days of starvation Cholesterine-, GOT-, glucose- and protein-concentrations arrose. Cortisol-, GLDH-, GOT-, urea-, insulin- and thyroxine-concentrations reduced during the starvation. During refeeding every parameter -except of cortisol- had the tendency to return to its first level.On every testday bulls with a higher pedigree breeding value milk had the tendency to have lower levels of cholesterine and GGT and higher levels of protein than bulls with a lower pedigree breeding value milk. On the day of normal feeding the bulls with a higher pedigree breeding value milk showed higher throxine-concentrations in blood than the other bulls.On ninth day of starvation bulls with higher pedigree breeding values milk had lower cortisol- and GLDH- and higher glucose- and ureaconcentrations in blood than the bulls with the lower pedigree breeding value. On second day of realimentation a higher urea-concentrations has prooved on bulls with a higher pedigree breeding value milk than bulls with a lower pedigree breeding value milk.Most of the times the correlations between pedigree breeding value milk and the concentrations of the blood parameters on the different days of the test correspond to the expectations. Cholesterine and GGT mainly correlate in a negative and protein always in a positive way with the pedigree breeding value milk. On the day of normal feeding the correlation between thyroxine and pedigree breeding value milk is without an exception positive. The correlation between glucose resp. urea and pedigree breeding value milk falls out weakly significant to significant positive in two of three tests on ninth day of starvation. Further more there is no correlation between cortisol- resp. GLDHconcentrations and pedigree breeding value milk. On second day of refeeding urea and pedigree breeding value milk correlate in two of three tests weakly significant resp. significant positive.Very reliable because of their high repetition-coefficients are cholesterine (6th and 9th day of starvation, 2nd day of realimentation), GGT (6th and 9th, day of starvation), GLDH (6th day of starvation), glucose (2nd day of realimentation), urea (day of normal feeding, (6th day of starvation, 2nd day of realimentation), insulin (day of normal feeding) and thyroxine (day of normal feeding, 6th day of starvation).As well the age of the bulls as the individual bull mainly has a high significant influence on the blood concentrations on the named testdays, except on glucose and insulin. On glucose and insulin only the individually component has a high significant influence.As a conclusion to this dissertation you can say, that cattle with a genetic disposition to high milkyield have bigger and faster mobilable energy-reserves than cattle with a genetic disposition to lower milkyield.But in this coherence is to consider, that the pedigree breeding value based on the parentsachievements are relative inexact compared to the breeding values based on daughters achievements.Therefore the results are to be proofed in a following research which includes the tests of the offsprings.Moreover the recommendation can be given to standardize this test to classify the efficiency of metabolism of potential Al-bulls in the way that all bulls will be in the same age.If these results could be attested and if the conditions given above for test-enforcement could be turned into reality, a model to criticize the genetic given metabolic stability in case of energetic deficiency at potential AI-bulls based on a starvation-test would be created so that a first selection as to milkyield and metabolic health of the female offsprings would be able to be done.