VIe CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. Il

A field trial on synchronisation of oestrus in gilts by admini-
stration of "Aimax" !ICI 33.828)

Dr. S.U.J.van Dieten
A.I.-Centre "De Kempen", Oerle, Netherlands.

One of the most serious problems in the application of artificial
insemination (a.i.) is the determination of the oestrus in order
to fix the exact time of insemination. Especially this is a
problem in gilts, because a constant checking for oestrus is
necessary; in sows the occurrence of the oestrus should be
watched from the fourth day after weaning.

The starting point for this research is: synchronisation of
oestrus in gilts may facilitate and improve the checking of their
being in oestrus, and in doing so the results of the A.I. may be
improved; for the pig-breeder needs to check for a limited number
of days only. The present papsr reports a field trial of
synchronisation of oestrus in gilts by administration of "Aimax"x
(ICI 33.828) and the effects on the reproduction. Because this

is a field trial, literature reference is made only to Gerrits
C.S. (1964), Groves (1967) and Polge (1964).

Materials and Methods

On 9 farms, a total number of 77 gilts were divided each time
into 2 groups, as uniform as possible (same litter). The gilts
were of the "Nederlands Landras" and from 6 - 10 months old with
an average weight of approximately 100 kg. "Aimax" had been
administered te one group, the other group was the control group,
In principle 1 mg "Aimax" per kg bodyweight was administered to
the treated group. The period of administration varied on the
farms from 17 to 22 days. In order to administer simply and yet
correctly, it was done as follows:

The drug was supplied as a premix in talcum powder.

One tablespoon of this premix contained 100 mg of the drug; this
is the daily dose for one gilt (average weight of 100 kg). The
premix was supplied in labelled tins containing exactly enough
compound for a 20-day treatment of 1 gilt. Each farmer was
supplied with as many tins as treated animals were in his group.
(The premix was added by the farmer to the morning food=ration
of the gilts).

For sach trial group and matching group all data were stated on
specially designed forms, such as identification, date of birth,
dose, initial and final date of administration, date and quality
of the heat, mating or a.i. and the results. As to the heat data
are stated on the standing-reflex, swelling of the vulva and the
secretion from the vulva. The trial was conducted completely
from the a.i.-centre and the farms were visited regularly (at
least once a week).

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