THE INFLUENCE OF BODY CONDITION SCORE ON RESPONSE OF EWES TO THE “RAM EFFECT”

إنجليزي. The effect of body condition score (BCS) of ewes on their fecundity is well documented. However, data for the infl uence of BCS on the response of ewes to the so called “ram effect” which synchronizing effect appeared from the 16th to 26th days after introduction of rams into fl ock are equivocal, and not enough. The aim of this study is to estimate the effect of body condition score on reaction of ewes to the ‘ram effect”. For this purpose there were carried out 6 experiments with fi ve different Bulgarian breeds, and the total number of 1407 sheep. Body condition score of ewes varied from 1.9 to 4.6 in different sheep and it was estimated using a scoring system based on a fi ve-point scale. Rams were introduced into sheep fl ock at the end of anoestrous season, in the second part of July and the fi rst part of August. The response in all 6 experiments and in all 5 breeds was similar with the typical two peaks of oestrus activity. Ewes responded with oestrus behaviour between 16th and 26th days after ram introduction into fl ocks were 30.2% of the total number of animals with BCS < 2.4

44.4% with BCS 2.4–2.9

64.3% with BCS 3 – 3.5

65.4% with BCS 3.6–4.0 and 52.7% with BCS > 4.0. The differences were signifi cant between sheep with BCS > 3.0 and < 3.0, between sheep with BCS < 2.4 and BCS 2.4–2.9. In conclusion, for maximal “ram effect” it is necessary for ewes to have BCS between 3 and 4. The good body condition is connected with better sexual functions in general. Synchronisation of oestrus of ewes by proper applying of the “ram effect” is effective, easy, cheap, clean and ethic method, which merit application in sheep farming.