Vle CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL.

OF INSEMINATION DATES IN PIGS

FIELD EXPERIMENTS ON THE PRECISE CONTROL

T.W, GROVES
Imperial Chemical Industries Limited,
Pharmaceuticals Division,
Alderley Park, Macclesfield, Cheshire, U.K.

It has been shown exverimentally (1), and under farm
conditions (2), that the drug methallibure® may be used to
synchronise oestrus cycles of mature gilts without affecting
their fertility or fecundity. More recently (3) it has been
demonstrated under controlled conditions that ovulation can
be induced to occur at 2 predictable time in gilts by treat-
ment with methallibure followed by pregnant mares serum (PMS)
and human chorionic gonadotrophin (HCG).

Imnroved conception rates and comparable embryo sur-
vival rates were obtained when artificial insemination was
aprlied in relation to the planned date of induced ovulation
comnared with those obtained when insemination was timed in
relation to the vhenomena of oestrus,

The results presented here describe the use of a tech-
nigue of ovulation control and fixed-day insemination in
gilts and dry sows, and examine the effects of avplying
similar principles of controlled breeding to the lactating
sow at weaning time,

MATERIALS AND METHODS

1, Gilts, and sows showing regular oestrus cycles (144
animals). Stock on commercial farms of the Large White
breed and crosses with Landrace, Essex and Welsh pigs,
were 2llocated to one of the two treatments, Individual
or group-feeding was employed,
(a) Methallibure (Group M), A premix containing 100
mgm of methallibure was added to the morning feed of 51
animals on 20 successive days, irrespective of the stage
of the reproductive cycle in each case,
(b) Methallibure + PMS + HCG (Group MPH). Ninety three
animals were treated with methallibure similarly; on the
following day (day 21) 750 i.,u., of PMS was given sub=-
cutaneously and 96 hours later (day 25) 500 i,u. HCG,
intramuscularly,.

(1) C. POLGE, 1965, Vet,Rec., 77 : 232,
(2) T.W, GROVES, 1967, Vet.Rec., 80 : 475,

(3) C. POLGE, B.,N. DAY & T.W. GROVES, 1968, In press.

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