A) Experiences obtained in gilts with functional an-

estrus:

91 gilts (German Landrace = GL) with anestrus or
weak and erratic estrous symptoms were injected with
2 ml of "I’and slaughtered 3 to 7 days later.

When slaughtered, 77.3 % had already shown inten-
sive heat symptoms. 22.7 % of the animals in heat
showed ripe follicles, against 22.8 % of animals not
yet in heat. In the former group 48 % had ovulated and
20 % showed already Corpora lutea (C.l.), against 20 %
with ovulation and 31.2 % with C.l. in the latter
group respectively.

B) Induction of a synchronized heat in sows and gilts

with functional anestrus after weaning:

172 anestrous gilts and sows which did not display
normal heat symptoms within 30 days after weaning were
treated with 2 ml of “I’i.m. Heat observations were
recorded from all animals, but only a total of 127
animals were served, 60 by A.I. and 67 by natural ma-
ting.

Heat presentations were recorded in 57 % of the
animals on day 3, in 73.9 % on day 3 and 4.

Conception rate after the first service was low:
31.7 % if A.I. was performed and 25.4 % if mating
occurred. After the third heat, 59 % of all these
animals with fertility problems became pregnant, with
an average litter size of 8.0 .

Similar or even better results than those given at
A) and B) were reported recently by Zerobin (1968),
using ‘I’ for the treatment of anestrus in SPF-gilts
and after weaning in SPF-sows.

&) Improved synchronization after weaning by simul-
taneous application of androgen—estrogens:

First experiment: 41 GL sows were treated with 2 ml
of "I"at the weaning date, 56 sows remained untreated
as controls.

80.5 % of the treated displaved heat at day 3 to 5,
49 % on day 4 (against 23 % of the controls).