Farm and cow factors and their interactions on the incidence of retained placenta in holstein dairy cows
Introduction
The process of parturition has been divided into three separate stages: 1) the dilation of the cervix, 2) the onset of myometrial contractions, and 3) the placement of the fetus for expulsion [25]. Given the importance of parturition, knowledge of factors around parturition and their economic importance are crucial issues in dairy farm management [11,31].
Retained placenta (RP) is one of the most common postpartum reproductive disorders. Since, this abnormality occurs during the transition period, it is also known as a metabolic disorder [10,20]. The fetal membranes are normally expelled within 8 h post-partum but are considered as retained if they are not expelled within 24 h of calf delivery. This is due to the failure of timely breakdown of the cotyledon-caruncle attachment [20].
The frequency of RP incidence varies across countries, herds and different parities within a herd. For instance, the incidence rate of RP in South Korea has been reported as 4.0–16.1% per calving [20], while in one study from the USA, 7.8% of dairy cows in different parity were affected by RP [18].
Based on the results from recent studies, many factors such as parity (Han and Kim, 2005), season of calving [17], dystocia, stillbirth, twinning [8] affect the incidence of RP. Moreover, the length of dry period [21], as well as pregnancy length [20] has been also associated with the incidence of RP. Higher milk yield [19] has also been associated with an increased the risk of RP. In addition to direct effect of above-mentioned factors, their interactions may also affect the incidence of RP in dairy cows.
The above studies have studied the factors influencing the incidence of RP in dairy cattle. However, thus far, most studies have examined only main effects without considering the interactions. Nevertheless, interactions play an important role in the study of factors affecting the incidence of disorders. Therefore, the objective of this study was to quantify the herd-cow level risk factors and their interactions on RP in Iranian Holstein cows. We used cow-herd level records collected from nine commercial dairy herds over an 8-year period.
Section snippets
Study herds
Data were collected from nine commercial dairy farms located in Isfahan province of Iran, for cows that calved between March 2011 and December 2018. Farms with herd size of >600 milking cows, and an accurate recording system were selected, with all farms under official performance and pedigree recording. All cows were raised in intensive production systems with free stall barns, fed a balanced total mixed ration, and milked 3 times per day. Although each herd had their own specific feeding and
Descriptive findings
Fig. 1 shows the eight-year trend of incidence of RP in primiparous, and multiparous cows as well as in all cows which calved during 2011–2018. In general, the incidence of RP in the studied herds had a decreasing trend that corresponded to a rate of −0.2% per year (Fig. 1). As shown in Fig. 1, the incidence of RP is higher in multiparous cows than in primiparous ones. During the study period, the incidence rate of RP reduced by 2.7%, and 1.5% for multiparous and primiparous cows, respectively.
Discussion
The average rate of RP incidence was 12.3% that varied from 9.0 to 15.4 across the studied herds. The incidence of RP for investigated herds showed a descending trend with a slope of −0.18 during 8-years study from 2011 to 2018. Dry period management in dairy cows is one of the effective factors on the occurrence of metabolic and reproductive diseases [32]. In the recent years, particular attentions have been paid to the use of fog lamps to reduce heat stress, density reduction and nutritional
Conclusion
The overall average of RP rate was 11.3% and declined between 2011 and 2018. Dystocia, twinning and stillbirth were identified as factors which had significant effects on the incidence of RP. The length of dry period and age at first calving (management factors) had significant effects on RP rate. Cows with extended dry period length (>75 d) and age at first calving (>28 months) had higher rate of RP. Furthermore, cows with a higher milk yield (>13,000 kg per lactation) had the highest risk for
Funding source
None.
CRediT authorship contribution statement
Abolfazl Mahnani: Conceptualization, Methodology, Software, Formal analysis, Investigation, Writing - original draft, Writing - review & editing, Project administration. Ali Sadeghi-Sefidmazgi: Conceptualization, Methodology, Software, Investigation, Validation, Formal analysis, Writing - review & editing, Supervision. Saeid Ansari-Mahyari: Validation, Supervision. Gholam-Reza Ghorbani: Validation, Supervision. Hamideh Keshavarzi: Methodology, Software, Validation, Formal analysis, Writing -
Acknowledgments
The authors of the article would like to thank the herd managers for collaborating and generously providing the information needed. Special thanks are extended to Peter Fennessy (AbacusBio Limited, Dunedin, New Zealand) for assistance in editing the manuscript.
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