SEXUAL ACTIVITY AND USЕ OF NON-HORMONAL METHODS FOR SYNCHRONIZАTION OF FERTILITY AND INCREASING LITTER SIZE OF EWES FROM THE ILE DE FRANCE BREED

Nikola Metodiev, Nikolay Todorov, Emilia Raicheva

Abstract: The aim of this study was to establish the presence of sexual activity of ewes from the Ile de France breed during the spring and the effect of different schemes of non-hormonal treatments for synchronization of fertilities and increasing litter size. The experiment was carried out with ewes raised in the Institute of Animal Sciences - Kostinbrod, in the period 20.04.2008 - 30.05.2008. The ewes were divided according to the schemes of non-hormonal treatments into three groups of equal age, body condition score (BCS) and fecundity from preceding years: group I - Salt-free - salt diet + acute flushing (n=23, BCS= 3.09), group II - acute flushing (n=21, BCS=3.18), control - no flushing (n=27, БCS=3.39). All groups were subjected to the ram effect but in different periods of time. Before and during the experiment, the ewes were raised in pasture and received 200 g concentrated mix daily per ewe, consisting of equal amounts of sunflower meal, barley and corn. The acute flushing of ewes from groups I and II consisted in a supplement of 300 g crisp soybean screenings in addition to the concentrated mix, with duration of 10 days before the onset of the breeding campaign. On the 11th day the teasers were introduced to all the experimental ewes. This day was Day 1 of the breeding campaign. The salt-freesalt diet of the first group was conducted parallel to acute flushing by the following scheme: 10 days salt-free regimen, followed by 7 days salt regimen (20 g salt per ewe per day) and free access to the salt-licks. The salt regimen was started 2 days before ram introduction. The rams were isolated from the ewes till the beginning of the breeding campaign. The following indexes were investigated: time of manifesting estrus (in days) after beginning of the breeding campaign, fertility (at first estrus) and litter size (fecundity). The presence of ewes with clinically manifested estrus during the experiment showed that the ewes were normally cycled during the investigated season of the year (spring). The applied scheme for estrus synchronization had a slight effect. A significant effect of flushing with soybean screenings on litter size (F=5.47*, P<0.05) was observed. A significantly higher litter size was obtained for the ewes that were flushed (200%) in comparison to controls (156%) (P<0.05).

Keywords: ewes; fecundity; Ile de France; non-hormonal methods; sexual activity

Date published: 2023-02-01