engleski

POSTPARTUM REPRODUCTIVE PERFORMANCE AND PREGNANCY RATE IN ISTRIAN JENNIES, AN ENDANGERED CROATIAN DONKEY BREED

Purpose of the work The present study was designed to describe the postpartum (PP) reproductive performance and average pregnancy rate of an Croatian endangered breed: the Istrian donkey.In recent years, the reproductive physiology of the donkey has attracted increasing attention of veterinary practitioners and researchers considering the farming relevance of this species and the risk of extinction that involves several donkey breeds. Unlike in the equine industry, the research focused the reproductive physiology of donkeys has attracted scientific attention only recently. Majority of breeders and even veterinarians treat jennets as mares, but there are both anatomical and cyclical differences seen in jennets compared to mares. For the horse, the average length of gestation is 335-345 days while in donkeys it is 360-375 days or more. Normal donkey foals have reportedly been born at 10 ½ months up to 14 months of gestation. The estrous cycle of jennets ranges from 23-30 days, whereas the mare has a slightly shorter cycle of 21-25 days. Additionally, jennets usually have a heat period that averages 6 till 9 days. Materials and used methods To this aim, 64 pluriparous jennies, kept in two simmilar, neighboring herds were monitored to define the foal-heat (FH) and the first and second PP estrus episodes (1st PPe and 2nd PPe) for two consecutive years. Pregnancy was also monitored to detect its outcome. Monitoring included daily teasing of postpartum jennies, ultrasound control of follicular growth and ovulation during estrus, pregnancy detection 30-45 days after mating and monitoring of delivery.Each herd consisted two jackasses (four in total) but they were kept separately and they were rotated between the herds. Mating was strictly performed under control.Pregnancy detection was performed using rectal examination and transrectal ultrasound examination.The normality of the data distribution was tested with the Shaprio–Wilks test. Comparisons were carried out using an ANOVA test and then, when necessary, with the Tukey post hoc test. The data were expressed as percentages when compared with the chi-square test. The differences were considered significant when P < 0.05 and highly significant when P < 0.01. Data are reported as mean and standard deviation. Outcomes The data indicate that jennies spontaneously returned cyclicity in approximately 14 days after delivery. Then heats repeated with a regular interval of approximately 22 days. Estrus length was 1 week in FH and the 2nd PPe and significantly shorter in the 1st PPe. Pregnancy rate (PR) was lower when natural mating occurred during the FH and 2nd PPe (approximately 54%) than during the 1st PPe (approximately 70% ; P < 0.01). Estrus-ovulation, and delivery-ovulation interval and follicle growth were similar in all animals observed. In addition, the higher PR (>80% ; P < 0.01) was recorded in jennies when the FH occurred after the first week PP and it dropped (<40%) in early FH animals (FH<7days). The PR was also affected by the season and by age: it significantly decreased during the autumn-winter season and in jennies older than the eighth year of age. during the autumn-winter season and in jennies older than the eighth year of age. Conclusions For the first time, the reproductive performance of PP donkeys were defined on a large number of Istrian jennies thus offering useful information to improve farm management with an immediate benefit to increase livestock production, esspecially for dairy herds. This aspect of management improvement might be particularly important if applied to an endangered breed such as Istrian donkeys. However, further research is needed to compare Istrian donkeys reproduction with simmilar, equally endengered donkey breeds. Bibliography 1. CARLUCCIO A, TOSI U, CONTRI A, DE AMICIS I, VERONESI MC. (2006) Corpus luteum sensitivity to PGF2a administration in the Martina Franca jenny. Vet Res Comm ; 30(Suppl. 1):171–3. 2. CARLUCCIO A, PANZANI S, CONTRI A, BRONZO V, ROBBE D, VERONESI MC (2013):Influence of season on testicular morphometry and semen characteristics in Martina Franca jackasses. Theriogenology ; 79: 502–7. 3. HAGSTROM D. J., (2004) Donkeys are different: An overviewe of reproductive variations from horses, Extension script of Faculty of veterinary medicine, University of Illinois, University press, Local Extension Council Cooperating 4. IVANKOVIĆ, A., KAVAR, T., CAPUT, P., MIOČ, B., PAVIĆ, V., DOVČ, P. (2002): Genetic diversity of three donkey populations in the Croatian coastal region. Animal Genetics, 33: 169-177. 5. KORABI, N., D. TADIĆ, S. KOLARIĆ, M. KOLARIĆ, D. 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istrian donkey; reproduction; fertility

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