The effect of retained placenta on the reproductive performance and its economic losses in a Holstein dairy herd

The effect of retained placenta on the reproductive performance and its economic losses in a Holstein dairy herd

 E.R. Kamel¹, H. Ahmed¹, and F.M. Hassan²

¹Animal Wealth Development Department, Faculty of veterinary medicine, Benha University, Moshtohor, Toukh, Qalyubia, ²Animal Wealth Development Department, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt

eman.ramadan05@yahoo.com, 0000-0002-2523-9638

fardoseconomy@yahoo.com, 0000-0002-6799-8296

hayaa93mohamed@gmail.com, 0000-0001-8510-9088

Abstract

Retention of placenta (RP) is a failure of the fetal membrane to be expelled and remained from 8 to 48 hours, average 12 hours after parturition. There are a variety of risk factors for the occurrence of RP. So, the aim of this study was to quantify the relative risk of calving season, parity, and gestation length on the occurrence of RP, and assess the impact of RP on the subsequent reproductive parameters, and the economic losses. A data of 2940 purebred Holstein-Friesian cows were collected from reliable records of large commercial dairy farm, Sharkia governorate, Egypt. These cows calved during the period extended from January 2018 to December 2019. Cows that did not release the fetal membranes within the first 12 hours after calf expulsion were diagnosed with RP.Results of logistic regression analysis revealed that the important risk factors for the occurrence of RP were summer calving season and short gestation period. Odds ratio estimation for summer calving season compared to spring calving was 2.84. The probability of RP incidence in cows with shorter gestation period was 0.19 times more than cows with longer gestation length, and the total direct economic losses from RP was 47 $/cow.Finally, we can conclude that short gestation length and summer calving season are strongly correlated with the development of RP in dairy cows. Subsequently, the occurrence of RP significantly affects reproductive parameters resulting in economic losses in dairy herds.

Keywords: Retained placenta, Risk factors, Reproductive performance, Economic loss

تأثیر المشیمة المحتبسة على الأداء التناسلی، والخسائر الاقتصادیة الناتجة عنها فی قطیع أبقار الهولشتاین الحلاب

إیمان رمضانکامل1، هیاء أحمد1 و فردوس محمدحسن 2

1قسم تنمیة الثروة الحیوانیة، کلیة الطب البیطری، جامعة بنها، مشتهر، طوخ، القلیوبیة، 2قسم تنمیة الثروة الحیوانیة، کلیة الطب البیطری، جامعة الزقازیق، الزقازیق، مصر

الخلاصة

مرض احتباس المشیمة هو عدم خروج الأغشیة الجنینیة حیث تظل محتبسه لفترة تتراوح من ثمانیة ساعات إلى ثمانیة وأربعون ساعة بمتوسط 12 ساعة بعد الولادة، هذا ویعتبر مرض احتباس المشیمة من اهم الأمراض التی تتعرض لها أبقار الهولیشتاین، حیث أن هناک العدید من عوامل الخطر المسببة فی حدوث احتباس المشیمة، لذلک فأن الهدف من هذه الدراسة هو تحدید عوامل الخطر التی تؤثر علی حدوث مرض المشیمة المحتبسة لأبقار الهولشتاین مثل موسم الولادة، عدد الولادات، وطول مدة الحمل، ثم دراسة التأثیر الناتج عنها على الأداء التناسلی، وتقدیر الخسائر الاقتصادیة الناتجة عن احتباس المشیمة. تم تجمیع بیانات 2940 بقرة هولشتاین-فریزیان أصیلة من خلال سجلات موثوقة لمزارع حلاب فی محافظة الشرقیة بجمهوریة مصر العربیة، حیث تم تسجیل ولادات هذه الأبقار خلال الفترة الممتدة من ینایر 2018 إلى دیسمبر 2019. وتم تشخیص الأبقار التی لم تتخلص من أغشیة الجنین خلال الاثنی عشر ساعة الأولى بعد الولادة بأنها مشیمة محتبسة. تم تطبیق تحلیل الانحدار اللوجستی وبینت النتائج أن أهم عوامل الخطر المسببة لحدوث المشیمة المحتبسة هی موسم الولادة الصیفی وفترة الحمل القصیرة. حیث بلغ تقدیر نسبة الأرجحیة لموسم الولادة الصیفی 2.84 مقارنة بولادة الربیع. کان احتمال حدوث المشیمة المحتبسة فی الأبقار ذات فترة الحمل القصیرة 0.19 مرة أکثر من الأبقار ذات فترة الحمل الأطول، وبلغ إجمالی الخسائر الاقتصادیة المباشرة من المشیمة المحتبسة سبعة وأربعون دولار لکل بقرة مصابة. ختاماً، یمکننا أن نستنتج أن فترة الحمل القصیرة وموسم الولادة الصیفی یرتبطان ارتباطًا وثیقًا بتطور المشیمة المحتبسة فی الأبقار الحلاب، وبالتالی فإن احتباس المشیمة یؤثر بشکل کبیر على الصفات التناسلیة مما یؤدی إلى حدوث خسائر اقتصادیة فی قطعان الأبقار الحلاب.

Introduction

The reproductive efficiency of a herd is an essential component of dairy cattle profitability worldwide) 1(. A cow's reproductive success is assessed by factors such as age at first calving, calving interval, days open, and number of services per conception. Low fertility and poor reproductive efficiency have a detrimental effect on the potential milk production and the number of cow calves each year and are considered the primary cause of involuntary culling )2(. Several factors influence dairy cattle's reproductive efficiency such as feeding scheme, herd management and genital diseases (3). In the last two decades, several researches have been interested in studying the impact of diseases on reproductive performance in dairy cattle as they found that the reproductive success is substantially impaired by postpartum diseases (4). One of the most common disorders found in domestic animals after parturition is the retained placenta (RP). Retention of placenta is a failure of the fetal membrane to be expelled from 8 to 48 hours, average 12 hours following parturition (5); it is a serious condition that causes major economic losses and renders the animal sub fertile even after treatment and recovery. In dairy cows placenta retention may be the cause of serious economic losses to the farmers as cows with RP may have infection of bacteria and become ill and thus decrease the amount of milk production (6).The occurrence of RP is associated with several risk factors including parity, season of parturition (7), shortened gestation (8), nutritional imbalance, and metabolic disorders, especially milk fever. On top of that, the incidence rate of RP can range between 20 and 50% or even more after abnormal calving (e.g. twin pregnancy, abortion, caesarean section, fetotomy, forced extraction of the fetus, premature calving) and in herds infected with brucellosis (9). Hormonal factors such as creatine kinase can be used as an indicator for tissue damage in the retained placenta in cows (10) .Our first aim in this study was evaluation of the effects of some factors (calving season, parity number, and gestation length) on the incidence of retained placenta in a Holstein dairy herd by the use of a logistic regression analysis method. The second goal was to assess the impact of retained placenta on the subsequent reproductive performance and financial losses.

Materials and methods

Herd management

All farm animals were housed in a free-stall barn provided with water splashing systems (cooling system) that operate when the ambient temperature exceeds 30°C. The cows were machine-milked three times a day, with milk yield and composition recorded at each milking. The total mixed ration (TMR) was given twice a day for all animals, and determined based on the actual milk production and body condition score. The TMR was formulated to satisfy the optimized requirements of energy, protein, vitamins, and minerals. Monthly, TMR was sampled and analyzed using wet chemistry methods. The primary analysis of TMR includes crude protein 16.55%, net energy for lactation (Mcal/kg = 1.79), and neutral detergent fiber 24.74%. The main utilized forage is Alfalfa hay. All animals were regularly vaccinated against most common diseases. Cows were estimated in estrus by visual detection and/or abnormal movement reported by the pedometer, after that they were introduced to insemination 10 to 16 hours later. A commercial on-farm software program (AfiFarm version 4.1) was used to monitor the productive and reproductive data.

Data collection and evaluation of the risk factors for retained placenta

Data were collected from 2940 calving from a large commercial dairy farm, Sharkia governorate, Egypt, during the period extended from January 2018 to December 2019. Retained placenta (RP) was diagnosed when the placental membranes were visible at the vulva after 24 hours or longer post-partum or by vaginal examination (11). In order to determine which explanatory variable in dairy cow farm (Parity, calving season, and gestation length) influence the development of RP, binary logistic regression (BLR) was applied with the SPSS software statistical package version 25.0 (SPSS, Inc., Chicago, Ill, USA). RP is considered the outcome variable which has binary codes: Zero for normal healthy cows, and 1 for cows with RP. The incidence of retained placenta for each parity, season of calving, and gestation length is illustrated in Table 1.

Table 1: Descriptive statistics of data of retained placenta in relation to some risk factors

Firstly, the association between the occurrence of retained placenta and the risk factors was tested by Chi-square. Secondly, a stepwise procedure of logistic regression analysis was applied to obtain the appropriate model with α= 0.05. The equation of logistic function according to (12) is: Logit (p) = Log (p/1-p)= β₀+β₁x_i1+β₂x_i2+β₃x_i3 + ε. Where; p: The chance of selecting a category of RP results, X₁, X₂, X₃: The explanatory variables (parity, season of calving, and gestation length). β₀: The intercept (constant), β₁, β₁, β₃: the regression coefficient of x. ε: error terms. The term p / (1-p) is the odds ratio; odds Ratio (OR) and their 95% confidence intervals (95% CI) were used as estimates to compare risk factors for RP in both normal healthy and RP groups and to evaluate the strength of the association between the disease and potential risk factors.

Evaluation of the effect of retained placenta on reproductive performance

Data on the subsequent days to first insemination (DFI), days open (DO), calving interval (CI), and number of services per conception (N/C) between the RP and the control healthy groups were recorded in the study, and then analyzed by Linear mixed model, using SPSS program after verifying normality and homogeneity of variance components between tested groups. The statistical significance level was selected at P-value < 0.05.

Assessment of direct economic losses of retained placenta

For estimating the direct economic losses due to RP, we gathered information on average daily milk yield before and after the disease, price of kilogram milk, reduction in milk yield during treatment period, number of days in treatment, discarded milk during treatment period, and cost of treatment. These measurements are represented for the following inputs as average values according to (13). Treatment cost include veterinarian fee, drug cost during the period of treatment. Total milk discarded = Amount of milk that discard X period of treatment. Cost of discarded milk = Total discarded milk X Kg milk price. Cost of loss in milk production = [(average daily milk yield before disease - average daily milk yield after disease) X days in milk] X Kg milk price.

Result

Risk factors for retained placenta

The results of Chi-square test (Table 2) showed the significant relationship between calving season (χ² =26.4, P-value < 0.001), gestation length (χ² = 8.92, P-value = 0.008) and occurrence of retained placenta. While, parity had no significant effect on retained placenta (χ² =1.98, P-value = 0.167). On the other hand, binary logistic regression analysis showed that summer calving season (odd ratio = 2.84, P-value = 0.041) and gestation length < 270 d (odd ratio = 0.19, P-value = 0.003) were the significant risk factors for the occurrence of retained placenta. While, other calving seasons, cow parity and gestation period of 271-280 d were not identified by the model (Table 3).

Table 2: The association between the occurrence of retained placenta and the risk factors by Chi-square value

Table 3: Risk factors for retained placenta analyzed by a stepwise selection procedure in logistic regression analysis

References were multiparous cow, spring season, and >280.

Impact of retained placenta on reproductive performance

Linear mixed model was applied to quantify the effect of retained placenta on reproductive parameters. The results revealed that there was a significant (P < 0.001) effect of RP on calving interval (CI), days open (DO), days to first insemination (DFI), and number of services per conception (N/C) than in the normal healthy cows (Table 4 and Figures 1,2).

Table 4: Linear mixed model for assessing the effect of retained placenta (RP) on reproductive parameters

Figure 1: Effect of RP on CI, DO, and DFI.

Figure 2: Frequency of number of services per conception in retained placenta group and control group.

Direct economic losses of retained placenta

The direct economic losses due to occurrence of RP are listed in table 5. The total direct economic loss from RP in the studied farm during the study period was estimated at 47 $/affected cow, including cost of loss in milk production 30.3 $/cow which considered the major loss, followed by treatment cost 9.5 $/cow, then discarded milk cost 7.2 $/cow.

Table 5: Direct Economic losses of retained placenta (N=628)

Discussion

The current study revealed that the overall incidence of RP was 21.4%, which were comparable to those of 17.8% and 18.3% reported by Markusfeld (14) ; Gaafar et al (7) and Rahawy (15), while was higher than the incidences of 6.6%; 7.8%,and 10% estimated by Bruun et al. (16) and Goff (17). The dispersion of RP incidences mentioned by different authors might be attributed to various factors, such as environment, breed, age, heredity, nutrition, immunity, and hormonal status.

Consistent with previous reports Echternkamp and Gregory, Nobre et al. and Mahnani et al. (18-20), they reported that retained placenta was found to be significantly associated with season of calving. The summer calving season is an important risk factor that has a substantial effect on the occurrence of RP over other seasons. The estimated odds ratio for the summer season indicated that cows calved in summer season are more susceptible to RP occurrence 2.84 times than those calved in spring season. The highest rate of RP in the summer season may be attributed to the influence of heat stress that prevents placenta expulsion (21); this result is in the same line with Fernandes et al. (22) and indirect contradiction with Berglund et al. (23) who found that the rate of RP was increased in winter season than other seasons due to the stillbirth, dystocia and twinning. Also, (19) documented that the rainy season raises the environmental challenge for animals and predisposes them to the incidence of RP. 

Our results revealed that the short gestation period (< 271 days) was also another significant risk factor related to the occurrence of RP. The estimated odds ratio for this significant effect was 0.19 which indicates the lower probability of RP incidence in cows with longer gestation period (> 280 days). The Previous reports Vieira-Neto et al. (24); Tolera and Wahid (25) on the association between gestation period and the occurrence of RP showed that the higher incidence of RP occurred with shorter gestation periods in Holstein cows. Notably, Hossein-Zadeh and Ardalan (26) indicated that shorter gestation length was an essential factor for the occurrence of RP in dairy cows in Iran. However, Han and Kim (27) observed that by increasing the gestation time, the incidence of RP increased. Gestation period is affected by many factors, such as genetic factors, sexing of calf, single or twin pregnancies, age of cow, and Silva et al. (28). Moreover, it has been documented that there could be a decrease in gestation duration due to animal exposure to heat stress over the last six weeks of the gestation period (29).

 It was found that cow parity did not influence the incidence of retained placenta. The non-significant effect of parity in this study is similar to Han and Kim (27), Silva et al. (28), Tao and Dahl (29) and Könyves et al. (30), but is on contrary to previous studies Mahnani et al. (20); Azad (31) and Sarder et al. (32) that reported a significant impact of parity on the incidence of RP in dairy farms. Grunert (33) observed that with increased number of parities, the loosening mechanism in the placentomes was occurred and subsequently developing the retention of placenta.

The effect of retained placenta on reproductive performance was analysed by linear mixed model which was in the same line with Mohammed, (34) who applied linear mixed model to determine the assoctiation between mastitis and reproductive performance. The current results found that RP had a negative effect on the reproductive measurements (CI, DO, DFI, and N/C) of dairy cows. These results were in agreement with previous report Gröhn and Rajala-Schultz (35); Maizon et al. (36); Seifi et al. (37), and Rahawy (15).However, Kaneko et al. (38) showed that RP does not have a significant effect on fertility. Fertility can be decreased by retained placenta in two ways: firstly, by a direct effect through an unknown mechanism and secondly by indirect effect through causing endometritis (27). The adverse effect of RP on dairy cow fertility results in indirect economic losses due to the risk of other peripartum diseases and impaired productive efficiency, i.e. prolongation of calving intervals and open days, decline in pregnancy rates, and increased risk of culling (39).

Higher incidences of RP lead to considerable economic losses as it has a detrimental impact on the health, productivity and fertility of the cow and thus its prevention and treatment are of economic and welfare significance. In the present results the majority of the direct economic losses of RP were represented in cost of loss in milk production, followed by treatment cost, then discarded milk cost due to drug residues and poor milk quality which is unfit for human consumption and therefore cannot be sold. This is in agreement with Bellows et al. (40) who found that costs of treatment of RP in Georgia herds were $0.03 per cow inventory in beef operations and $0.40 per cow inventory in dairy farms. Sheldon et al. (41) reported about 239 kg losses in milk in uniparous cows infected with RP.

Conclusion

In this study, we concluded that there is a significant relationship between calving seasons and gestation length and the incidence of retained placenta. So, we can depend on these explanatory variables as risk factors for diagnosing it in dairy farms. Retained placenta negatively affected reproductive measurements and resulted in substantial economic losses in dairy herds.

Acknowledgement

The authors wish to thank the owners of cattle herd at Sharkia governorate, Egypt, for allowing us to collect the data.

Conflicts of interest

There is no conflict of interest of this article to declare.