Die komplette Dissertation im pdf-Format (220.271 Bytes):
The objective of this study was to examine the influence of negative energy
balance in dairy cows post partum on the LH release after a single GnRH
application. Also the development of body condition, body weight and milk
concentration of betahydroxybutyrate, Acetoacetat and phosphoenol pyruvate was
analyzed to evaluate a possible correlation with energy balance.
For 30 Holstein-Friesian cows daily dry matter intake, milk yield and weekly
body weight was monitored. Based on this data, the negative energy balance per
day was calculated for each cow as the difference between energy needed for
maintanence plus lactation and energy consumed. The cows were divided in four
Group 1 (n = 7): Cows treated with 500 µg GnRH (Fertagyl®) intramuscularly
when the most negative point of energy balance (nadir) was reached.
Group 2 (n = 6): Cows treated with the same dose of GnRH when about 30 % of
the individual value of nadir was already compensated.
Group3 (n = 10): Cows treated with the same dose of GnRH when about 60 % of
the individual value of nadir was compensated.
Controls (n = 7): Cows received a placebo (0,9% NaCl solution) on different
stages of negative energy balance.
All cows were either in interestrus or in anestrus, as determined by plasma
estradiol-17? levels at the time of treatment. All animals did not experience
any postpartum disorders. Blood samples were collected every 20 minutes
beginning one hour before and ending four hours after treatment. LH was
determined using enzyme linked immuno sorbant assay (ELISA).
Body condition and body weight was evaluated weekly. Ultrasonic measurements
of the backfat thickness were made over the area between the hook- and the pin
bone. Weekly milk samples were taken and analyzed for betahydroxybutyrate,
Acetoacetate and phosphoenol pyruvate.
The LH release of group 1 cows was significantly higher than in every other
group. Group 2 and 3 cows were showing no difference. In group 4 no changes in
LH concentration could be detected before and after placebo administration.
None of the metabolic parameters tested was significantly correlated with
energy balance. In this study no statement was made about the biological
quality of the released LH.
We conclude, that the sensitivity of the pituitary gland for GnRH is not
directly affected by the level of energy balance post partum. It is possible,
that the interval from calving to nadir (i.e. the slope of the negative energy
balance curve) has a higher influence of the sensitivity of the pituitary
gland than the absolute level of negative energy balance.
600 Technik, Medizin, angewandte Wissenschaften::630 Landwirtschaft::630 Landwirtschaft und verwandte Bereiche
Einfluß der negativen Energiebilanz bei Hochleistungskühen im Puerperium auf
die Sensibilität der Hypophyse für GnRH und auf die Veränderung
unterschiedlicher indirekter Stoffwechselparameter
Univ.-Prof. Dr. Wolfgang Heuwieser
Univ.-Prof. Dr. Elze
Energy balance in post partum dairy cows: Impacts of a single GnRH
administration on the pituitary reaction and on different metabolic indicators