Characterization of plasma LH-profiles in superovulated dairy cows

THERIOGENOLOGY Characterizationof Plassnal&Profiles in SuperovulatedDairy Cows T.Greve, H. Callesen and P. Hyttel" Institutefor Animal Reproductionand Departmentof Anatomya 'IheRoyal Veterinaryand AgriculturalUniversity 13, Biilowsvej, DK-1870 dpnhagen V, DENMARK The preovulatoryLH-surge was monitored in 37 lactating Friesian cows injected to super-ovulate with a regimen of either 2500 IU pregnant mare's serum gonadotropin(IN%) with cloprostenol or 32 mg folliclestimulating hormone (FSH; administered twice daily over 4 days in descendingdoses) with cloprostenol. Blood samples were collectedevery 4 h from 18 h after the cloprostenol injection. The preovulatory LHsurge or peak occurred 42.bO.l h following the cloprostenolinjection. It was recorded sooner in PMSG- (40.95.4 h) than in FSH- treated animals (44.9212.1 h). The interval from the LH-peak to heat was variable, and the external signs of heat were not an accurate estimate of the occurrenceof the LH surge. Ahighproportion of animals (12 our of 37)developed abnormal LH profiles (no LH surge, moderate LH surge, premature or delayed occurrence) which had a detrimental effect on both ovulation and fertilizationrates. Most of these animals had concurrentdeviation in their progesterone profiles and PMSG-treated animals more frequently encounteredLH abnormalitiesthan the FSH-treatedcows (Table 1).

TE

6.1af1.2

2.8b:4.1

5.1a!5.2

7.6'!5.4

YE (X)

4.sar4.4 1711

0.7b!!.3 (251

3.1a!3.8 (54)

5.L?'+4.4 l.P,Z.3 (75) (391

FR

854

42b

73”

91d

3.3a+b:3.,

5ob

6.6'!5.2

7.4"S.l

i.O"d.3 115)

6.Za!3.8 1.5%.4 (84) (JO)

884

844

,.0a'b!3.9 6.1*;5.2

44b

3..8a+b,4.2 (621 cd

It is concluded that: (1) The superovulatorytreatment frequently interferes with the normal LH release and (2)a normal LHpattern is a prerequisitefor achievinga high proportionof transferableembryos.

JANUARY 1984VOL. 21 NO. 1

237