Incidence of Different Types of Dystocia in Different Seasons of the Year and Parities in Iranian Holstein Dairy Cows

Dystocia (DYS) is an important problem in Holstein cattle and imposes important economic losses on cattle producers. The etiologies and types of DYS are various and different factors can influence its incidence. In the present study, incidence of different types of dystocia was investigated in different seasons and parities in Holstein cows. One hundred and eighty two primiand multiparous cows with DYS were included in the study. The results showed significantly more calf births in anterior presentation to first-calf heifers compared to those born to cows in parities 2–3 or ≥ 4 (P≤0.05). There was no significant difference in the number of calves born in anterior presentation between cows in parities 2–3 and those in parities ≥4 (P>0.05). Also, significantly more dystocia cases were encountered in first-calf heifers compared with those in cows in parities 2–3 or ≥4 (P≤0.05) but there was no significant difference in this regard between the cows in parities 2–3 and those in parities ≥4 (P>0.05). In addition, the results revealed that DYS due to foetopelvic disproportion (FPD) mostly affected the primiparous cows and that the multiparous cows were mostly affected by dystocia due to twin birth (TB), uterine inertia (UI) and uterine torsion (UT). Moreover, the results showed that significantly most DYS cases occurred during winter compared with spring, summer or autumn (P≤0.05), of which the majority was due to FPD. On the other hand, the least DYS cases were observed in summer months, of which the majority was again due to FPD. Finally, there was no significant difference in the overall incidence of dystocia between spring, summer and autumn (P>0.05).