Efekat polne sezone na rezultate laparoskopskog osemenjavanja Ille de france rase ovaca u intezivnom sistemu držanja

Abstract

This paper presents results of the study conducted in order to investigate influence of the season on laparoscopic artificial insemination (LAI) success of Il de France sheep (approximately 90% of yearling ewes) on a 2 000 sheep farm in intensive rearing. Our work was based on weekly synchronization of 60 – 120 sheep, when the corrector rams were introduced 5 days following LAI in order to detect a new estral cycle. Ultrasound diagnostic of pregnancy was performed 45- 60 days following insemination when it was possible, according to the fetus size and accompanying structures, to determine undoubtedly if the pregnancy was achieved by LAI or mating with ram. All non - gravid sheep were synchronized again and subjected to LAI. This approach was used because by natural mating a conception rate in yearling ewes was only 40% monthly. Synchronization was performed by commercial intra - vaginal device (Synchropart ® 30 mg, CEVA, France) during 14 days and by 600-700 IU of pregnant mare serum gonadotropin (PMSG, Folligon®, Intervet International B.V. Holland). We have analyzed period of the sexual peak activity (LAI from 16th of July to 10th of September 2018) with total of 890 inseminations in comparison to period of lower sexual activity (LAI from 26thof December to 14th of March 2019, 714 inseminations). In the sexual activity peak a conception rate by LAI was 72.92% (649 ewes) and 15.10 % by rams (98 ewes). A total conception rate was 83.93% (747 ewes) while 16.07% remained non-pregnant. Out of the season, a conception rate by LAI was 71.86% (483 ewes) and 27 ewes became pregnant when mated by ram (4.04%). A total conception rate was 77.17% (551 ewes) and 34.11 sheep remained nonpregnant (163 ewes).Technique of LAI is acceptable measure in the intensive sheep farming. It is particularly recommended for the yearling ewes category because of the unpredictable first estrus occurence in out-of-season breeding.