Reproductive health is a key determinant of profitability in dairy production due to directly influencing insemination frequency and veterinary costs. Reduced fertility often demands repeated inseminations, which increase reproductive expenses and the potential of early culling in cows that fail to conceive(Han et al., 2024);(Tadesse et al., 2022). Reproductive failure has significant financial consequences, as the loss of pregnancy in dairy cows results in costs between US1900, depending on the gestational stage at occurs because problems that happen before mating may harm oocyte fertilization and impair subsequent development to the morula stage(Ribeiro et al., 2016). Nevertheless, cows that have successfully conceived remain vulnerable to reproductive disorders that may compromise post-conception performance. Among reproductive disorders, abortion, retained placenta, and dystocia are particularly important due to their prevalence and economic impact. Abortion is defined as fetal death occurring between 42 and 260 days of gestation(Peter, 2000). This death occurrence frequently exerts negative impacts on post-abortion reproductive which the pregnancy is terminated(Cabrera, 2014);(Vries, 2006). This required for conception(Mahnani et al., 2021);(Wielen et al., 2025), as well as a higher tendency of premature culling(Wathes et al., 2020). Furthermore, each abortion in dairy cows is thought to cost between US1,866 in lost income. The magnitude of these losses varies according to the gestational stage and the age of the cow at the time of abortion, with the most considerable losses noted in late-term abortions of primiparous heifers experiencing their first pregnancy(Carrillo Parraguez et al., 2025).

Retained placenta is defined as the persistence of all or part of the fetal membranes beyond 12 hours postpartum(Dervishi & Ametaj, 2017);(Yazlık et al., 2019). (Mahnani et al., 2021) reported that retained placenta adversely affected dairy cow production and reproduction, resulting in milk yield losses of 282–295 kg per lactation, extended DO by 8–20, and economic losses ranging from US$ 350.4 to 481.2 per case. Dystocia is a reproductive disorder that causes difficulty for cows to give birth(Hossein-Zadeh, 2016). (Kim et al., 2016) found that dystocia in Friesian cows negatively affected performance by lengthening the service period, DO, and calving interval, reducing the conception rate, and raising the number of services per conception. Each case of dystocia is estimated to initiate economic losses ranging between US465.04, depending on the severity of the calving problem(McGuirk et al., 2007). Furthermore, the incidence of these disorders has been associated with ovarian recovery and diminished reproductive effectiveness in the ensuing breeding season.

A delayed return to ovarian activity following calving is a significant concern for prompt insemination after the voluntary waiting period in dairy cows(Early postpartum estrous characteristics: Unveiling their predictive potential for fertility in dairy cows, 2025). Decreased ovarian function hinders estrus detection, prolongs the interval to initial insemination, and lowers conception rates(Bruinjé et al., 2023). In addition to reproductive disorders that may occur during parturition, health interventions applied at calving have been associated with delayed postpartum ovulation(Carbonari et al., 2024);(Pinedo et al., 2020).

Parity influences reproductive performance after calving, and this influence is associated with the occurrence of reproductive disorders. However, most existing reports on parity and reproductive disorders are limited to prevalence-based observations. Previous studies have shown an increased risk of abortion and dystocia among primiparous cows, compared to multiparous cows(Amicis et al., 2018);(Hohnholz et al., 2019);(Yaqoob et al., 2016), while retained placenta cases were more prevalent in multiparous cows(Bonneville-Hébert et al., 2011);(Kamel et al., 2022). The impact of the disorders on future reproductive performance remains insufficiently explored, particularly with respect to the role of parity. Therefore, this study aimed to assess the effects of abortion, retained placenta, and dystocia on subsequent reproductive performance in Holstein-Friesian cows, and compare the effects between primiparous and multiparous groups. Extra focus was given to examining how parity and reproductive disorders interacted to influence fertility results, with the intention to strengthen more targeted management practices in dairy production systems.

This study investigated the effects of reproductive disorders on subsequent fertility in dairy cows, with parity considered as a contributing factor. Previous studies reported that abortion(Keshavarzi et al., 2020);(Wielen et al., 2025), dystocia(Hossein-Zadeh, 2016);(Kim et al., 2016), and retained placenta(Nyabinwa et al., 2020) were associated with poorer reproductive performance compared with healthy cows. However, in this study, not all reproductive performance parameters showed a decline. The differences in reproductive performance indicators (FSCR, PR, OPR, and S/C) between healthy and affected cows were not statistically significant (p>0.05). A numerical trend toward lower performance was observed in cows with reproductive disorders.

The results showed variation in pregnancy results between healthy and reproductive disorder cows over the observation period Table 1 Healthy cows had numerically superior reproductive performance, with multiparous FSCR of 0.28 (95% CI 0.19–0.40), primiparous PR of 0.68 (95% CI 0.52–0.80) and multiparous PR of 0.65 (95% CI 0.53–0.75), and primiparous OPR of 0.21 (95% CI 0.15–0.29) and multiparous OPR 0.21 (95% CI 0.16–0.28). Furthermore, the corresponding S/C were 2.35 in primiparous and 2.53 in multiparous healthy cows Table 2. The reproductive performance of healthy Holstein-Friesian cows at the study site was lower than previous reports, which showed higher fertility levels in the subjects raised in higher locations of Indonesia. The reports showed a CR of 47.3%(Syah et al., 2023), a PR of 68.7%(Susilawati et al., 2023), and S/C value of 1.47(Setyorini et al., 2022). The OPR in this study was relatively low, remaining below 65%(Kumaresan & Srivastava, 2022). The poor reproductive performance reported by the healthy group was probably due to the high temperature and humidity in the environment, which could cause heat stress(Asmarasari et al., 2023). Holstein-Friesian cows perform best when the temperature is between 13 and 25 °C and the relative humidity is 50 to 60%(Lim et al., 2021). The average daily temperature at the study site was between 22 and 25 °C, but the temperature throughout the midday might reach 38 °C, and the relative humidity tended to range from 67% to 94%. These conditions are known to lower the fertility of dairy cows by making sperm less viable, leading to difficulties with egg fertilization, slower embryo growth, and less intense estrus(Llamas-Luceño et al., 2020);(Rahman et al., 2018);(Reith & Hoy, 2018). Despite some level of acclimatization, these cows cannot be considered fully adapted to the high heat and humidity typical of the study area.

Reproductive performance is further compromised in cows with reproductive disorders by bacterial contamination and uterine infections that lead to endometritis and reduced embryo viability(Husnain et al., 2023). Bacterial toxins, particularly lipopolysaccharides (LPS), suppress pituitary LH secretion, inhibit dominant follicle growth, and impair ovulation(Opsomer et al., 2000);(Sheldon et al., 2002). Additionally, LPS directly disrupts steroidogenesis in ovarian follicular cells and reduces oocyte developmental competence, lowering embryo quality(Magata, 2020). The combination of uterine damage, hormonal disruption, and reduced oocyte quality contributes to lower conception rates and higher pregnancy failure risks in cows with a history of reproductive disorders compared with healthy subjects(LeBlanc et al., 2002).

Cows affected by reproductive disorders showed lower FSCR, PR, and OPR and higher S/C than healthy cows (all p>0.05), but DFS and DO were attained more rapidly. Abortion victims were inseminated 25.8 days before healthy cows, while those with dystocia and retained placenta were inseminated 10.3 and 6.4 days earlier, respectively (Figure 2). Consistent with the Kaplan–Meier plot, Table 2 shows the shortest mean DFS of 63.67 d (95% CI 48.49–78.84) in the abortion group of primiparous cows and 59.50 d (95% CI 48.12– 70.88) in multiparous types. Meanwhile, the healthy multiparous group had the longest mean DFS of 91.62 d (95% CI 83.81–99.43), and the tendency persisted for DO, adhering to the same pattern. Hazard-ratio (HR) analysis found diminished probabilities of conception in comparison to healthy cows for abortion (HR = 0.79; 95% CI 0.51–1.23; p = 0.29), retained placenta (HR = 0.80; 95% CI 0.57–1.13; p = 0.21), and dystocia (HR = 0.71; 95% CI 0.51–0.98; p = 0.04) Figure 3. The healthy multiparous group had the longest average number of DO, which was 183.59 days (95% CI 152.16–215.02), compared to the disorder groups (Table 2). These results show that HR and mean DO do not necessarily have to be the same. HR presents the chance of conception at any given time, and mean DO signifies the time required for half of the cows to conceive.

The phenomenon explained above can be attributed to the more rigorous post-disorder treatments administered to cows with reproductive problems, including antibiotics, multivitamins, and supportive care, which may have expedited reproductive recovery. Healthy cows in smallholder systems generally did not receive specialist postpartum treatment, initiating more vulnerability to negative energy balance (NEB) originating from increased energy requirements during peak lactation. (Walsh et al., 2011) asserted that the described condition prevented ovarian recovery in healthy cows. Cows with the experience of abortion(Wielen et al., 2025), dystocia(Roche et al., 2023), or retained placenta(Mahnani et al., 2021) typically had less milk production, leading to a less severe NEB, which promoted earlier estrus and ovulation(Butler, 2003). This phenomenon clarifies why cows with reproductive abnormalities have earlier DFS and DO, despite possessing lower total conception rates. Intra-group variation might have played a role because a few cows conceived rapidly, reducing the mean DO, and others did not conceive during the 500day observation period, leading to diminished herd reproductive values. Effective postpartum treatment is essential for expediting reproductive recovery in dairy cows. Numerous studies show that using targeted antibiotics for reproductive disorders significantly enhances conception rates and reduces the calving-toconception interval(Denis-Robichaud & Dubuc, 2015);(Menta et al., 2024). Vitamin supplementation during the transition phase has shown efficacy in enhancing uterine function, facilitating a more rapid return to estrus cyclicity(Moghimi-Kandelousi et al., 2020);(Morrison et al., 2018). The combination of targeted antibiotic treatment, multivitamin supplementation, and adequate postpartum nutritional support can be considered the most effective strategy for enhancing reproductive recovery following parturition.

Parity showed no observable effects across all results in the collected dataset. In logistic GLMs for the binary endpoints (FSCR, PR, OPR), the primiparous– multiparous comparison produced p>0.05 for all parameters Table 1. Similarly, in two-way ANOVA (GLM) for the continuous endpoints (DFS, DO, S/C), the main effects of parity were non-significant (all p > 0.05; Table 2). These results were consistent with previous reports, such as(Tadesse et al., 2022), who observed no parity effects on conception odds in multivariable logistic models. Similarly,(Nan et al., 2023) detected no meaningful differences in continuous reproductive measures across parity groups. The evidence shows that parity, as assessed in this study, is not a major determinant of fertility performance. Primiparous and multiparous cows have broadly identical probabilities of conceiving following reproductive disorders.

Table 2 shows a wide CI for cows with a history of abortion, which may reflect the limited sample size in this subgroup (n primiparous = 18, and n multiparous = 32). A limited sample size increases uncertainty in the estimates, reflected in wider CI, less stable OD, and reduced Statistical power to detect moderate effects(Button et al., 2013);(Zeng et al., 2022). As a result, results related to the abortion subgroup should be interpreted cautiously(Rafati et al., 2010). Greater precision would likely be achieved through studies with larger samples or by combining data across herds.

Reproductive disorders, including abortion, dystocia, and retained placenta, were generally not connected to a significant reduction in reproductive performance in Holstein-Friesian cows. DFS and DO sometimes showed faster postpartum recovery in reproductively challenged cows than in healthy animals, potentially associated with differences in milk yield or management practices. The lack of a clear parity-related effect confirms the primacy of preventive measures, timely clinical intervention, and control of environmental stressors for sustaining reproductive performance across the herd.

Although post-disorder pregnancy metrics (FSCR, PR, OPR) showed no statistically significant connection to reproductive problems, affected animals numerically underperformed their healthy counterparts. The control group maintained a better mean S/C than cows suffering from reproductive issues. Despite the diminished conception-related metrics, cows with reproductive abnormalities had reduced DFS and DO, potentially due to the postpartum interventions implemented following the onset of the disorders. There was a lack of statistical significance in the observed effects, and the numerical patterns still suggested possible biological relevance, showing the necessity of efficient postpartum management to enhance reproductive success in smallholder dairy production systems.