Title:Az ikerellések és holtellések előfordulása és hatása a főbb szaporodási mutatókra, és az általuk okozott gazdasági veszteség hazai nagy létszámú holstein-fríz tehenészetekben
Varga-Balogh, Orsolya Gabriella
SUMMARY Background: The importance of twinning and stillbirth is increasing due to their potential effect on production, reproductive performance, and profitability in large dairy herds.Objectives: The aim of our study was to quantify the effect of twinning and stillbirth on the main reproductive parameters, and to estimate the resulting eco-nomic loss.Materials and Methods: The data of 3660 calvings that occurred on five large-scale Hungarian Holstein-Friesian farms in 2016 and 2017 were analysed. Informa-tion about twin calvings, stillbirths and uterine treatments were gathered. The main reproductive indices (i.e. calving to conception interval – CCI, services per conception – SPC, and first service conception risk – CR1) were calculated based on cow-level data. Statistical analyses were performed by using linear and logistic regression, and Dunnett-test. Losses due to calf revenue, open days and excess semen use were taken into account in the economic estimations (1 EUR = 320 HUF).Results and Discussion: Overall, twinning and stillbirth occurred in 4.1 and 6.9% of the calving events. Twinning was more likely, whereas stillbirth was less likely to occur in multiparous cows (odds ratio: 4.18 and 0.64, p < 0.0001 and p = 0.0015, respectively). Following twin calving, CCI and SPC were increased by 12.8 days and by 2.8, respectively, whereas CR1 was reduced by 7.1 percentage points. The estimated loss due to twinning amounted to 50.4 EUR/case. The analysed reproductive param-eters were not impaired after stillbirth. Although, the reduction of calf number and the excess semen usage led to 112.5 EUR estimated loss per stillbirth case, on aver-age. Moreover, both twinning and stillbirth were significantly (p < 0.0001) associated with retained placenta (odds ratio: 2.22 and 1.23). The occurrence of inflammatory uterine diseases was not affected by stillbirth, however, it was significantly (p < 0.0001) reduced by twinning.