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

 

ESTRUS INDUCTION IN SOWS WITH
DIETHYLSTILBESTROL

E. M. RIGOR, R. L. VILLAREAL AND H. P. ILAGAN
University of the Philippines College of Agriculture
College, Laguna, Philippines ‘

Injections of diethylstilbestrol (DES) in gilts
have been shown to induce heat (Dela Cerna, 1958)
and ovulation (Kidder et al. (1955). The present
study was undertaken to determine the effect of
various levels of DES and divided doses in the
induction of estrus in recently weaned sows.

MATERIALS AND METHODS. Two groups of crossbred sows
(Philippine pig x Landrace, F1 and Yorkshire x
Philippine pig x Landrace, Fp) were assigned at
random as they weaned their litters at 42 days
postpartum to 0, 1, 2 and 4 mg. of diethylstilbestrol
in o0il given intravenously. In a second experiment
two groups of crossbred sows (Fq1 and Fy) were as-
signed at random to 0, 2 mg. DES given as a single
injection and 2-1 mg. DES given in 2 injections at
weaning and a day thereafter. All sows were checked
for heat with a vasectomized boar until they exhibited
two successive heat periods. The data were analyzed
according to Steel and Torrie (196D).

RESULTS AND DISCUSSION. No significant differences
in litter size at birth, at weaning, average weight
per pig at weaning and weight of the sow were ob-
served between strains and among treatments in both
experiments. Highly significant (P €.01) differences
were noted between the control groups and the treated
groups, such that the sows given any of the three
dose levels of DES exhibited heat earlier after wean-
ing than the controls, Table 1. While the sows were
not bred when they exhibited induced heat,it is pro-
bable that the induced heat was accompanied by ovu-
lation, the interval from induced heat to second heat
being approximately the average of one estrual cycle
length.

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