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

based on the principles used in the treatment of gilts, It
was considered advisable to apply a preliminary seven-day
treatment with methallibure to inhibit any follicular
activity which might be out of phase with the follicular
maturation to be stimulated by PMS treatment, It had been
noted previously that the mean interval to oestrus was
significantly shorter after weaning than was the case in
cycling animals after methallibure treatment, Therefore to
maintain control over the time of ovulation it was decided
to shorten the interval between PMS and HCG to 72 hours in
the lactating sows, Because ovulation rates are higher in
weaned sows than in gilts the dose of PMS was raised to
1000 i,u.

Although the results of the experiments indicate very
satisfactory responses to the treatments used, controlled
experiments are required to establish the optimum dosage and
timing of methallibure and supplementary gonadotrophin treat=
ments in the newly weaned sow, All treatments using PMS
tended to increase litter-size, suggesting that a modifica=
tion of the techniques used might allow a significant
increase to be obtained,

Table I, Oestrus and fertility in treated pigs.

Group |No, of | Days to Farrowing Litter-
pigs oestrus inseminated
(Mean) During | During
3 days | 1 day

6e 25(a) 43(e)

 

 

5,28(b) 100(£)*

4,91(c) 40(g)
4,96(c) 38(g)
4,02(d) 60(h)
4,33(d) 100(n)*

 

Significantly ) (a) vs, (b), (c) vs, (d)
different (e) vss (£), (g) vs, (h)
P € 0,001

*Insemination on fixed=day,

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