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

THE EFFECT OF EXTERNAL STIMULI ON THE ONSET OF THE BREEDING SEASON |
OF WELSH MOUNTAIN EWES

H. Ll. WILLIAMS and Ll. S. WIGGAN **

Department of Animal Husbandry, Royal Veterinary College, Potters
Bar, Hertfordshire, England.

Records of incidence of mating and/or lambings in commercial hill
flocks give little indication of the onset of breeding activity.
The intentional delay in re-introducing the ram to the flock usually
results in an uniform rate of mating during the two week period
immediately following its entry (l). The limited available data for
this breed, derived from groups accustomed to the presence of the
rams, give the following mean dates of onset - day 288 - Oct 25 (2);
day 308 - Nov 4, day 287 - Oct 14, day 284 - Oct 11 (3). A
significantly earlier onset, day 249 - Sept 6, has been reported (4);
this was attributed to a combination of external stimuli applied on
day 197 - July 16.

The effect of the re-entry of the ram is well documented (5) (6)
(7) (8) (9). It has also been shown that stress, due mainly to
transportation, induced silent heats in some ewes (lO). Changes in
vaginal secretions of the ewe have been shown to be a reliable
indication of ovarian activity (11) (12) (4). An early onset to
cyclic activity has many advantages and therefore greater definition
is required of the relationships between the application of various
stimuli and the onset of the breeding season, particularly for breeds
originating and maintained in the higher latitudes.

MATERTALS & METHODS. 80 draft Welsh Mountain ewes were allocated
to six groups and subjected to one or a combination of three
treatments: T1 - TRANSPORTATION - 8-hour road Journey of 200 miles
from Corwen, North Wales to Potters Bar, Herts; T2 - HOUSING.

T3 - RE-ENTRY OF RAMS - Groups 1, 2 and 3 - harnessed vasectomised
Suffolk and Dorset Horn, Group 6 - entire Welsh Mountain.

The duration and sequency of treatments was as follows:

DAY
GROUP  NOS TRANS- DAY DAY RE-ENTRY DAY
PORTED  HOUSED OF RAMS SLAUGHTERED
1 24* 221 222 235 -
2 20 235 236 249
3 10 235 269 277
4 10 235 - - 243
5 18 " 235 u 242
6 8 & 235 235 242

* One died.

In Group 1, 2 and 3 vaginal smears were taken every three or four
days, starting on the day following arrival. The smears were
**present address: Bodles Agricultural Station, Jamaica, W.Indies.

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