Effects of oestradiol benzoate by injection at
CIDR(TM) insertion for the treatment of postpartum anovulatory anoestrus
in dairy cows
G.A. Verkerk, V.K. Taufa, S. Morgan, B.A. Clark and K. L. MacMillan
Dairying Research Corporation, Private Bag 3123, Hamilton
Proceedings of the New Zealand Society of Animal Production. 1998,
58: 82-84
The effect of an intramuscular (im) injection of oestradiol
benzoate (ODB) at insertion of an intravaginal progesterone-releasing
device (CIDRTM, InterAg, NZ) during hormonal treatment for postpartum
anoestrum in dairy cattle was investigated. Inclusion of injected ODB at
CIDRTM insertion in synchronisation programmes for cycling cows can
increase fertility, possibly by initiating an emergence of a new ovarian
follicle wave with resultant improved oocyte competence. A total of 882
cows, of mixed age and breed from 18 herds, were examined and diagnosed
as anoestrous during the week preceding each herd’s planned start of
mating. Cows were allocated randomly as controls or to receive 0.5 or 1
mg ODB (Oestradiol Benzoate Inj., Intervet, Netherlands) by im injection
at CIDRTM insertion. The device was removed after 7 days, and any cow
which was not observed in spontaneous oestrus within 48 h received 1 mg
ODB im (CIDIROLTM Injection, InterAg, NZ). Cows with an observed heat
within 12 days of CIDRTM removal were defined as responders, and returns
to service in the subsequent 30 days were recorded. There were no
significant differences between the control, 0.5 and 1 mg ODB treatments
for either the proportion responding (89.5%, 89.4% and 90.9%,
respectively) or returning (52.3%, 50.3% and 55.4%, respectively);
however the proportions of cows observed in spontaneous oestrus varied
by treatment (P<0.01; 28.5%, 22.9% and 17.2% for control, 0.5 and 1 mg
ODB treatments, respectively). Conception rates were not significantly
affected by treatment (35.9%, 42.5% and 43.2% for control, 0.5 and 1 mg
ODB treatments, respectively). Of cows which did not become pregnant to
the induced oestrus, 21.7%, 20.7% and 29.9% for control, 0.5 and 1 mg
ODB treatments respectively, returned to service with an interval of
more than 24 days. These observations suggest that an injection of ODB
at CIDRTM insertion may alter follicle wave patterns in cows with PPA,
but that this may not result in increased conception rate, and might be
detrimental to ovarian activity in a proportion of cows.
Keywords: NZSAPAB;
postpartum anoestrum; oestradiol benzoate; progesterone; cattle.
Last Updated 12-09-1998
