Abstract
The aim of this study was to analyze the impact of reproductive management practices on fertility in primiparous and multiparous dairy cows and to identify the differences by parity. Data on reproductive performance and management of cows were gathered from 34 large commercial Holstein-Friesian dairy herds in Hungary. Individual data on 23 781 cows that calved in the studied herds in 2014 were collected from the national milk recording database and used to calculate the reproductive indices. Farm managers and veterinarians were interviewed in person from May 22 to November 6, 2015 using a questionnaire to collect information about reproductive management practices. The data were statistically analyzed by mixed-effects models. Our results showed that the use of a voluntary waiting period (VWP) was linked to a greater increase in calving-to-conception interval (CCI, P < 0.05) and a greater decline in the chance of pregnancy at 200 days in milk (P200, P < 0.001) in multiparous cows. Estrus synchronization was related to a larger reduction in days-to-first service (DFS, P < 0.001), breeding interval (IBI, P < 0.05), and CCI (P < 0.01) and a greater improvement in P200 (P < 0.001) in primiparous cows. Early pregnancy diagnosis and pregnancy recheck improved IBI (P < 0.01 for both practices), CCI (P < 0.01 and P < 0.001, respectively), and P200 (P < 0.001 for both practices) to a larger extent in primiparous than in multiparous cows. In conclusion, estrus synchronization, early pregnancy diagnosis, and pregnancy recheck led to a greater improvement in fertility in primiparous cows than in multiparous cows.
Résumé
L’objectif de la présente étude était d’analyser l’impact des pratiques de gestion de la reproduction sur la fertilité de vaches laitières primipares et multipares et d’identifier les différences par parité. Les données sur les performances de reproduction et la gestion des vaches ont été amassées auprès de 34 fermes laitières Holstein-Friesian commerciales importantes en Hongrie. Les données individuelles de 23 781 vaches ayant mise-bas en 2014 dans les troupeaux à l’étude ont été obtenues de la base de données nationale d’enregistrement de la production laitière et furent utilisées pour calculer les indices de reproduction. Les gérants de ferme et les vétérinaires ont été interviewés en personne entre le 22 mai et le 6 novembre 2015 à l’aide d’un questionnaire pour obtenir des informations sur les pratiques de gestion de la reproduction. Les données ont été analysées statistiquement par des modèles à effets mixtes. Nos résultats ont démontré que l’utilisation d’une période volontaire d’attente (VWP) était liée à une plus grande augmentation de l’intervalle vêlage-conception (CCI, P < 0,05) et à un plus grand déclin de la probabilité de gestation à 200 jours en lait (P200, P < 0,001) chez les vaches multipares. La synchronisation des oestrus était reliée à une plus grande réduction du nombre de jours avant la première saillie (DFS, P < 0,001), de l’intervalle de reproduction (P < 0,05), et de CCI (P < 0,01), et une meilleure amélioration du P200 (P < 0,001) chez les vaches primipares. Des diagnostics de gestation hâtifs et des vérifications de la gestation ont amélioré IBI (P < 0,01 pour ces deux pratiques), CCI (P < 0,01 et P < 0,001, respectivement), et P200 (P < 0,001 pour les deux pratiques) d’une manière plus importante chez les primipares que chez les multipares. En conclusion, la synchronisation des oestrus, les diagnostics de gestation hâtif, et la vérification de la gestation ont conduit à une plus grande amélioration de la fertilité chez les vaches primipares que chez les vaches pluripares.
(Traduit par Docteur Serge Messier)
Introduction
Reproductive performance has a huge impact on the productivity and profitability of a dairy herd. Fertility, in turn, is related to the parity of cows (1).
Primiparous cows often experience lower energy balance than their multiparous counterparts because, in addition to the energy and nutrient demand of lactation, they usually eat less and require energy for growth, which compromises their reproductive performance (2,3). As multiparous cows are more adaptable to reinitiating postpartum cyclicity, the interval from calving to first ovulation is longer in primiparous than in multiparous cows (4–6). While dystocia is more common in primiparous cows, multiparous cows are more likely to suffer from retained placenta and ovarian cysts, which extend the time to conception (1,7). Moreover, the likelihood of conception was 8% lower in cows in parity 3 and above compared to primiparous cows (1).
Certain physiological phenomena may directly influence the effectiveness of reproductive management practices. Pregnancy-associated glycoprotein (PAG) levels were higher in both milk and plasma samples from primiparous cows than in samples from multiparous cows. This can potentially affect the accuracy of a PAG test used for early pregnancy diagnosis (8,9). Response to hormonal synchronization differs by parity, as demonstrated in a meta-analysis comparing Double-Ovsynch and Presynch-Ovsynch. Borchardt et al (10) concluded that Double-Ovsynch was beneficial in terms of pregnancy per artificial insemination compared to Presynch-Ovsynch in primiparous, but not in multiparous cows. Astiz and Fargas (11) suggested that different hormonal synchronization protocols should be used in high-yielding dairy cows from different parities.
Parity-wise differences in the efficiency of reproduction management are increasingly being studied in dairy herds. Based on previous studies, we hypothesized that parity may affect the relationship between reproductive management and fertility parameters. The aim of this study was to analyze the relationship between reproductive management practices and fertility in primiparous and multiparous dairy cows.
Materials and methods
Data collection
The survey of reproductive management practices was carried out from May 22 to November 6, 2015 in a total of 34 large-scale Hungarian dairy herds. The inclusion criteria for the farms were as follows: computerized on-farm data recording; continuous participation in milk recording at least since January 1, 2014; herd size of more than 250 cows; and a willingness to provide data to the authors. Farm managers and veterinarians were interviewed during farm visits and a questionnaire was used to collect information about reproductive management practices. The farms were located in all regions of Hungary, where a continental climate consists of warm, dry summers and cold winters. Mean ± standard deviation (SD) size of the studied herds was 755 ± 470 cows (range: 291 to 2502 cows) and the 305-day milk yield of the herds amounted to 10 014 ± 965 kg (range: 8330 to 12 541 kg).
Reproductive data for individual cows were collected from the national milk recording database (Livestock Performance Testing Ltd., Gödöllő, Hungary). The data of 23 781 cows that calved from January 1 to December 31, 2014 on the farms were analyzed retrospectively. For each cow, data were gathered regarding herd, animal ID, date of birth, date and number of inseminations, results of pregnancy diagnoses, calving dates, parity, 305-day milk yields, and culling date. Data were managed in MS Excel 2013 (Microsoft Corporation, Redmond, Washington, USA).
Management practices and reproductive parameters analyzed
The definitions of the management practices studied, the respective number of farms, and the number of primiparous and multiparous cows are shown in Table I. As part of the questionnaire, farms were asked whether they use a voluntary waiting period (VWP), i.e., the period after calving when they do not inseminate cows, and the length of the VWP. In those herds that applied a VWP, its average length was 50.2 ± 11.3 d. Two categories were created based on the questionnaire: farms that applied a ≥ 50-day-long VWP (“≥ 50 d”) and those that applied a VWP of < 50 d or did not use VWP (“< 50 d”).
Table I.
Reproductive management practices studied and the corresponding number of herds and cows by parity (the total number of farms is 34, unless otherwise specified).
| Definition | Farms (n) | Primiparous cows (n) | Multiparous cows (n) |
|---|---|---|---|
| Voluntary waiting period (VWP) | |||
| ≥ 50 d | |||
| The length of VWP reported by the farm was ≥ 50 d | 19 | 5107 | 7758 |
| < 50 d | |||
| The length of VWP reported by the farm was < 50 d or the farm did not apply a VWP | 15 | 4239 | 6677 |
| Estrus detection aids | |||
| Yes | |||
| Estrus detection aids, e.g., pedometers, activity meters, tail chalk, were applied | 25 | 6585 | 10 386 |
| No | |||
| Visual observation was used to detect cows in estrus | 9 | 2761 | 4049 |
| Estrus synchronization | |||
| Yes | |||
| Hormonal synchronization protocols, e.g., Ovsynch, Cosynch, or Presynch-Ovsynch, were applied | 27 | 7589 | 11 901 |
| No | |||
| Hormonal synchronization was not applied | 7 | 1757 | 2534 |
| Early pregnancy diagnosis | |||
| Yes | |||
| Pregnancy was diagnosed by transrectal ultrasonography or pregnancy-associated glycoprotein (PAG) tests | 24 | 6982 | 10 897 |
| No | |||
| Pregnancy was diagnosed solely by rectal palpation | 10 | 2364 | 3538 |
| Reproductive ultrasonography | |||
| Yes | |||
| Transrectal ultrasound was used for pregnancy diagnosis and other reproductive examinations | 23 | 6545 | 10 214 |
| No | |||
| Transrectal ultrasound was not used in the herd | 11 | 2801 | 4221 |
| Pregnancy recheck | |||
| Yes | |||
| Pregnancy diagnosis before day 60 post-insemination was followed by a pregnancy recheck around day 60 | 18 | 5113 | 8511 |
| No | |||
| Pregnancy status was not rechecked within 60 d post-insemination | 16 | 4233 | 5924 |
| Frequency of pregnancy diagnosis (n = 33) | |||
| > Once a week | |||
| Pregnancy diagnosis was done more than once a week | 10 | 3101 | 4563 |
| Weekly | |||
| Pregnancy diagnosis was done once a week | 16 | 4501 | 7135 |
| < Once a week | |||
| Pregnancy was diagnosed less frequently than weekly | 7 | 1521 | 2346 |
Estrus detection was carried out in every herd, using either estrus detection aids, such as pedometers, activity meters, and tail chalk, or visual observation alone. A combination of hormonal synchronization and estrus detection was applied in 79.4% of the herds. The most widely adopted synchronization protocol was Ovsynch, which was used by 74.1% of the herds that applied synchronization. This involves giving injections of a gonadotropin-releasing hormone (GnRH), followed by prostaglandin F2alpha (PGF2α) 7 d later, a second injection of GnRH 48 to 56 h later, then insemination after 16 to 24 h. Cosynch, which was used by 18.5% of the herds, involves insemination at the time of the second injection of GnRH during the Ovsynch protocol. And finally, 14.8% of the herds used Presynch-Ovsynch, which involves 2 PGF2α injections 14 d apart, followed by an Ovsynch protocol 10 to 14 d later.
Analysis of pregnancy diagnosis policy included the application of early pregnancy diagnosis methods, such as transrectal ultrasonography or PAG tests, and the frequency of pregnancy diagnosis (Table I). The first pregnancy diagnosis was conducted 35.1 ± 8.5 d after insemination, on average. Both transrectal ultrasonography and PAG tests were used from days 28 to 30 onwards. Use of transrectal ultrasonography was analyzed separately because this technique can be used not only to diagnose pregnancy, but also to examine the ovaries and diagnose pathological conditions of the reproductive tract. The information gathered during the ultrasonographic examinations was used in the treatment of reproductive disorders in these herds. It was also evaluated whether early pregnancy diagnosis before day 60 after artificial insemination (AI), followed by a pregnancy recheck around day 60, was associated with better reproductive performance. Pregnancy status was rechecked 1.6 ± 0.8 times, on average, typically around day 60 after insemination and around dry-off. Cows in all herds were fed total mixed ration (TMR).
The relationship between parity and management practices and the following reproductive indices was analyzed: days to first service (DFS), breeding interval (IBI), calving-to-conception interval (CCI), first-service conception risk (CR1), and pregnancy at 200 days in milk (P200). Days to first service (n = 19 794) and IBI (n = 14 811) were calculated for the inseminated cows, whereas CCI (n = 15 707) was calculated for those cows that were diagnosed pregnant after the date of last insemination. First-service conception risk was quantified for cows with at least 1 insemination followed by a known pregnancy diagnosis outcome (n = 19 794). Cows that stayed in the herd at least until 200 days in milk (DIM) were included in the analysis of P200 (n = 19 134).
Statistical analyses
The associations of parity with the continuous variables, i.e., DFS, IBI, CCI, under different management practices were examined with linear mixed-effects models using the lme4 package in R (12). The continuous dependent variables were log-transformed to eliminate skewness of the data. The associations of parity with the dichotomous dependent variables, i.e., CR1, P200, under different reproductive management practices were analyzed with logistic regression, including mixed-effects using the lme4 package in R (12). In each mixed model, one of the reproductive indices was the outcome variable. Parity, a management practice, and the interaction between parity and the management practice were included as fixed explanatory variables. Herd was a random effect. Multiple comparisons within a given management practice, e.g., pregnancy diagnosis frequency, were carried out by Tukey’s post-hoc test, using the multcomp package in R (13). The associations between reproductive indices and management by parity were quantified by contrasts using the multcomp package in R (13). The statistical analyses were carried out in R version 3.4.0. (14).
Results
Reproductive performance and parity
In the overall population, mean (± SD) and median days to first service (DFS) were 75.6 d (± 35.8) and 68.0 d, respectively. Mean (± SD) and median breeding interval (IBI) were 42.8 d (± 24.9) and 37.3 d, respectively, whereas the mode of the IBI was 23 d. Mean (± SD) and median calving-to-conception interval (CCI) were 157.5 d (± 93.1) and 134.0 d. In the entire studied population, CR1 was 20.5%, whereas 59.6% of the cows were pregnant at 200 days in milk (DIM) in the herds.
In general, primiparous cows had a shorter breeding interval (42.2 versus 43.2 d, P < 0.001, Tables II and III), needed less time to conceive postpartum (152.3 versus 161.8 d, P < 0.001), conceived better for first service (24.8% versus 17.3%, P < 0.001, Table IV), and were more likely to be in calf at 200 DIM (65.2% versus 55.4%, P < 0.001) compared to multiparous cows. No differences between parities were found for time from calving to first insemination (75.7 versus 75.6 d, P > 0.05).
Table II.
Descriptive statistics of days to first service (DFS), breeding interval (IBI), and calving-to-conception interval (CCI) by voluntary waiting period (VWP), estrus detection, and hormonal synchronization and by parity.
| Days to first service | Breeding interval (d) | Calving-to-conception interval (d) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
||||||||||
| Primiparous | Multiparous | Primiparous | Multiparous | Primiparous | Multiparous | |||||||
|
|
|
|
|
|
|
|||||||
| Mean ± SD (Median) | n | Mean ± SD (Median) | n | Mean ± SD (Median) | n | Mean ± SD (Median) | n | Mean ± SD (Median) | n | Mean ± SD (Median) | n | |
| Voluntary waiting period (VWP) | ||||||||||||
| ≥ 50 d | 78.6 ± 37.1 (71) | 4642 | 79.5 ± 37.5 (71) | 6138 | 44.3 ± 27.5 (38) | 3355 | 46.3 ± 25.8 (40) | 4749 | 157.6 ± 96.7 (130) | 3979 | 172.3 ± 96.7 (150) | 4464 |
| < 50 d | 72.1 ± 35.3 (63) | 3742 | 71.0 ± 31.8 (64) | 5272 | 39.5 ± 24.3 (35) | 2687 | 39.6 ± 20.9 (35) | 4020 | 145.6 ± 91.0 (119) | 3188 | 150.4 ± 84.5 (130) | 4076 |
| Estrus detection aids | ||||||||||||
| Yes | 74.8 ± 35.1 (68) | 5931 | 75.4 ± 34.5 (69) | 8182 | 41.7 ± 25.9 (36) | 4308 | 42.9 ± 23.4 (38) | 6319 | 152.2 ± 95.1 (125) | 5094 | 163.1 ± 92.4 (141) | 6137 |
| No | 77.9 ± 39.6 (68) | 2453 | 76.1 ± 37.1 (67) | 3228 | 43.3 ± 27.1 (37) | 1734 | 44.1 ± 25.3 (38) | 2450 | 152.4 ± 92.6 (126) | 2073 | 158.5 ± 90.0 (138) | 2403 |
| Estrus synchronization | ||||||||||||
| Yes | 72.6 ± 32.8 (67) | 6803 | 73.5 ± 33.0 (67) | 9394 | 41.4 ± 24.3 (36) | 4962 | 42.9 ± 23.3 (38) | 7289 | 150.0 ± 92.9 (123) | 5909 | 160.8 ± 90.8 (139) | 7006 |
| No | 89.2 ± 47.0 (76) | 1581 | 85.4 ± 42.8 (74) | 2016 | 45.9 ± 33.6 (37) | 1080 | 44.9 ± 26.8 (39) | 1480 | 163.2 ± 100.0 (136) | 1258 | 166.6 ± 95.8 (144) | 1534 |
Table III.
Descriptive statistics of days to first service (DFS), breeding interval (IBI), and calving-to-conception interval (CCI) by pregnancy diagnosis policy and parity.
| Days to first service | Breeding interval (d) | Calving-to-conception interval (d) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
||||||||||
| Primiparous | Multiparous | Primiparous | Multiparous | Primiparous | Multiparous | |||||||
|
|
|
|
|
|
|
|||||||
| Mean ± SD (Median) | n | Mean ± SD (Median) | n | Mean ± SD (Median) | n | Mean ± SD (Median) | n | Mean ± SD (Median) | n | Mean ± SD (Median) | n | |
| Early pregnancy diagnosis | ||||||||||||
| Yes | 71.3 ± 31.4 (66) | 6264 | 72.1 ± 31.2 (67) | 8606 | 40.4 ± 23.1 (36) | 4567 | 42.2 ± 22.5 (37) | 6647 | 148.8 ± 93.0 (121) | 5479 | 159.6 ± 91.0 (137) | 6462 |
| No | 88.6 ± 46.1 (77) | 2120 | 86.2 ± 43.8 (75) | 2804 | 47.7 ± 33.6 (40) | 1475 | 46.6 ± 27.5 (40) | 2122 | 163.6 ± 97.8 (139) | 1688 | 168.9 ± 93.7 (149) | 2078 |
| Reproductive ultrasound | ||||||||||||
| Yes | 71.6 ± 31.9 (67) | 5886 | 71.8 ± 31.4 (67) | 8089 | 40.4 ± 23.1 (36) | 4339 | 42.4 ± 22.6 (38) | 6296 | 150.7 ± 93.7 (123) | 5163 | 160.9 ± 91.5 (139) | 6091 |
| No | 85.4 ± 44.0 (73) | 2498 | 84.9 ± 41.8 (74) | 3321 | 46.6 ± 32.4 (39) | 1703 | 45.4 ± 26.9 (39) | 2473 | 156.3 ± 96.2 (130) | 2004 | 164.2 ± 92.4 (143) | 2449 |
| Pregnancy recheck | ||||||||||||
| Yes | 73.5 ± 33.0 (67) | 4651 | 74.8 ± 33.6 (68) | 6821 | 41.6 ± 24.7 (37) | 3338 | 43.6 ± 23.9 | 5274 | 150.2 ± 95.3 (120) | 4039 | 162.5 ± 92.7 (140) | 5063 |
| No | 78.5 ± 40.2 (70) | 3733 | 76.8 ± 37.4 (69) | 4589 | 42.9 ± 28.0 (36) | 2704 | 42.7 ± 24.0 (37) | 3495 | 155.0 ± 93.2 (130) | 3128 | 160.9 ± 90.3 (140) | 3477 |
| Frequency of pregnancy diagnosis | ||||||||||||
| > Once a week | 80.7 ± 42.9 (71) | 2773 | 77.2 ± 40.8 (67) | 3528 | 43.2 ± 28.9 (37) | 2007 | 43.5 ± 26.3 (37) | 2745 | 157.9 ± 94.4 (133) | 2287 | 160.2 ± 91.1 (137) | 2532 |
| Weekly | 76.0 ± 32.8 (70) | 4025 | 78.3 ± 32.8 (71) | 5620 | 42.4 ± 25.8 (37) | 2805 | 43.8 ± 23.5 | 4144 | 147.7 ± 92.4 (120) | 3582 | 159.7 ± 90.4 (138) | 4344 |
| < Once a week | 63.7 ± 27.5 (57) | 1384 | 64.2 ± 27.1 (58) | 1958 | 40.1 ± 22.6 (36) | 1105 | 41.3 ± 20.2 (38) | 1639 | 156.7 ± 99.0 (128) | 1120 | 170.5 ± 96.0 (148) | 1412 |
Table IV.
Descriptive statistics of first-service conception risk (CR1) and pregnancy status at 200 days in milk (DIM) by reproductive management and parity.
| First service conception risk | Pregnant at 200 days in milk (P200) | |||||||
|---|---|---|---|---|---|---|---|---|
|
|
|
|||||||
| Primiparous | Multiparous | Primiparous | Multiparous | |||||
|
|
|
|
|
|||||
| % | n | % | n | % | n | % | n | |
| Voluntary waiting period (VWP) | ||||||||
| ≥ 50 d | 24.9 | 4642 | 16.6 | 6138 | 63.4 | 4580 | 49.8 | 5975 |
| < 50 d | 24.7 | 3742 | 18.2 | 5272 | 67.5 | 3634 | 62.2 | 4945 |
| Estrus detection aids | ||||||||
| Yes | 24.8 | 5931 | 17.1 | 8182 | 65.7 | 5806 | 55.1 | 7820 |
| No | 24.9 | 2453 | 18.0 | 3228 | 64.0 | 2408 | 56.2 | 3100 |
| Estrus synchronization | ||||||||
| Yes | 24.7 | 6803 | 16.7 | 9394 | 66.9 | 6649 | 55.7 | 8958 |
| No | 25.6 | 1581 | 20.2 | 2016 | 58.0 | 1565 | 54.0 | 1962 |
| Early pregnancy diagnosis | ||||||||
| Yes | 24.7 | 6264 | 16.9 | 8606 | 68.3 | 6084 | 57.2 | 8100 |
| No | 25.3 | 2120 | 18.7 | 2804 | 56.3 | 2130 | 50.2 | 2820 |
| Reproductive ultrasound | ||||||||
| Yes | 23.9 | 5886 | 16.4 | 8089 | 67.9 | 5727 | 56.8 | 7631 |
| No | 27.0 | 2498 | 19.5 | 3321 | 59.2 | 2487 | 52.2 | 3289 |
| Pregnancy recheck | ||||||||
| Yes | 25.6 | 4651 | 16.9 | 6821 | 67.0 | 4540 | 55.1 | 6484 |
| No | 23.9 | 3733 | 18.0 | 4589 | 63.1 | 3674 | 55.8 | 4436 |
| Frequency of pregnancy diagnosis | ||||||||
| > Once a week | 22.9 | 2773 | 16.0 | 3528 | 60.7 | 2750 | 52.3 | 3462 |
| Weekly | 28.4 | 4025 | 20.4 | 5620 | 69.9 | 3933 | 58.5 | 5303 |
| < Once a week | 17.1 | 1384 | 11.2 | 1958 | 60.5 | 1327 | 52.7 | 1840 |
Voluntary waiting period, estrus detection, and synchronization
In primiparous cows, the interval from calving to conception was 8.24% longer when VWP was ≥ 50 d compared with those animals that were subject to a shorter or no VWP (Table V). Similarly, in multiparous cows, the CCI was 14.56% longer when VWP was ≥ 50 d compared with those cows that were subject to a shorter or no VWP. In primiparous cows, the odds of pregnancy at 200 DIM was smaller when VWP was ≥ 50 d than < 50 d (OR = 0.834, Table VI). In multiparous cows, the difference between the VWP of ≥ 50 d and < 50 d was greater (OR = 0.603). The benefit of short or no VWP was, therefore, greater in multiparous cows than in primiparous cows in terms of both time to conception and probability of pregnancy at 200 DIM (P = 0.015 and P < 0.001).
Table V.
Differences in reproductive parameters between users and non-users of each management practice by parity based on mixed-effects models (%).
| Days to first service (DFS) | Breeding interval (IBI) | Calving-to-conception interval (CCI) | |||||||
|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
|||||||
| Primiparous | Multiparous | P-value | Primiparous | Multiparous | P-value | Primiparous | Multiparous | P-value | |
| Voluntary waiting period (VWP) | +9.02 | +11.97 | 0.113 | +12.15 | +16.92 | 0.062 | +8.24 | +14.56 | 0.015 |
| Estrus detection aids | −3.98 | −0.92 | 0.015 | −3.70 | −2.72 | 0.353 | −0.13 | +2.90 | 0.171 |
| Estrus synchronization | −18.61 | −13.93 | <0.001 | −9.80 | −4.45 | 0.026 | −8.09 | −3.48 | 0.005 |
| Early pregnancy diagnosis | −19.53 | −16.36 | <0.001 | −15.30 | −9.44 | 0.001 | −9.05 | −5.51 | 0.006 |
| Reproductive ultrasound | −16.16 | −15.43 | 0.159 | −13.30 | −6.61 | <0.001 | −3.58 | −2.01 | 0.123 |
| Pregnancy recheck | −6.37 | −2.60 | <0.001 | −3.03 | +2.11 | 0.002 | −3.10 | +0.99 | <0.001 |
| Frequency of pregnancy diagnosis | |||||||||
| > Once a week versus weekly | +6.18 | −1.40 | 0.983 | +1.89 | −0.68 | 0.999 | +6.91 | +0.31 | 0.905 |
| > Once a week versus < once a week | +26.69 | +20.25 | 0.084 | +7.73 | +5.33 | 0.596 | +0.77 | −6.04 | 0.867 |
| Weekly versus < once a week | +19.31 | +21.96 | 0.044 | +5.74 | +6.05 | 0.542 | −5.74 | −6.33 | 0.648 |
Within parity, the numbers indicate the difference between the users and non-users of a management practice, e.g., calving-to-conception interval was 9.05% and 5.51% shorter in primiparous and multiparous cows, respectively, when pregnancy was diagnosed early. P-values correspond to the difference in the responses to the given management practice between primiparous and multiparous cows. Significant differences, i.e., P < 0.05, are indicated in italics.
Table VI.
Odds ratio of conception (first-service conception risk) or pregnancy (pregnant at 200 days in milk) between the users and non-users of each management practice by parity based on the mixed-effects models.
| First-service conception risk | Pregnant at 200 days in milk (P200) | |||||
|---|---|---|---|---|---|---|
|
|
|
|||||
| Primiparous | Multiparous | P-value | Primiparous | Multiparous | P-value | |
| Voluntary waiting period (VWP) | 1.011 | 0.895 | 0.139 | 0.834 | 0.603 | < 0.001 |
| Estrus detection aids | 0.995 | 0.940 | 0.596 | 1.077 | 0.956 | 0.158 |
| Estrus synchronization | 0.953 | 0.792 | 0.071 | 1.464 | 1.071 | < 0.001 |
| Early pregnancy diagnosis | 0.969 | 0.884 | 0.327 | 1.672 | 1.326 | < 0.001 |
| Reproductive ultrasound | 0.849 | 0.810 | 0.579 | 1.458 | 1.204 | < 0.001 |
| Pregnancy recheck | 1.096 | 0.926 | 0.020 | 1.187 | 0.972 | < 0.001 |
| Frequency of pregnancy diagnosis | ||||||
| > Once a week versus weekly | 0.749 | 0.743 | 0.068 | 0.665 | 0.778 | 0.197 |
| > Once a week versus < once a week | 1.440 | 1.510 | 0.012 | 1.008 | 0.984 | 0.862 |
| Weekly versus < once a week | 1.923 | 2.032 | < 0.001 | 1.516 | 1.265 | 0.668 |
Within parity, the numbers indicate the odds ratio of conception or pregnancy between the users and non-users of a management practice, e.g., the odds of pregnancy at 200 days in milk (P200) was 1.464-fold greater in primiparous cows and 1.071-fold greater in multiparous cows when estrus synchronization was carried out. P-values correspond to the difference in the responses to the given management practice between primiparous and multiparous cows. Significant differences, i.e., P < 0.05, are indicated in italics.
The use of estrus detection aids was associated with a shorter time to first insemination in primiparous cows than in multiparous cows (P = 0.015, Table V). When estrus synchronization was used, the reduction in DFS (P < 0.001, Table V), IBI (P = 0.026), and CCI (P = 0.005) and the improvement in probability of pregnancy at 200 days in milk (P200) (P < 0.001, Table VI) were greater in primiparous cows than in multiparous cows.
Pregnancy diagnosis policy
When early pregnancy diagnosis was performed, the reduction in breeding interval (P = 0.001, Table V), CCI (P = 0.006), and the improvement in the probability of pregnancy at 200 days in milk (P < 0.001, Table VI) were greater in primiparous cows than in multiparous cows. The use of transrectal ultrasonography was associated with larger reduction in IBI and a greater improvement in P200 in primiparous cows than in multiparous cows (P < 0.001). When pregnancy status was rechecked in a herd, IBI (P = 0.002), CCI (P < 0.001), and P200 (P < 0.001) were slightly better in primiparous cows than in multiparous cows.
The magnitude of herd effect ranged from 19% to 21%, 13% to 16%, and 13% to 14% in the models of DFS, IBI, and CCI, respectively. In the models of CR1 and P200, the magnitude of herd effect ranged from 30% to 43% and 43% to 51%, respectively.
Discussion
Multiparous cows experienced larger improvement in time to conception postpartum when the voluntary waiting period (VWP) was short or not applied compared with primiparous cows. This suggests that not having a minimum waiting period of at least 50 d is better for multiparous cows. It should be noted, however, that days to first service (DFS) was remarkably higher than the VWP reported by the farm. Stangaferro et al (15) found that the median days to conception was 6 d shorter (85 versus 91 d) in the 60-day-long VWP group compared to the 88-day-long VWP group in primiparous cows and 28 d shorter (104 versus 132 d) in multiparous cows. Inchaisri et al (16) found that the economically optimal duration of the VWP was < 8 wk in 63% of the cows and that primiparous cows experienced lower losses when VWP was extended with a longer period compared with multiparous cows.
In our study, primiparous cows experienced a greater advantage than multiparous cows in terms of time to first insemination when estrus detection aids were used. The secondary signs of estrus, such as walking activity, decrease, while the primary sign of estrus, i.e., standing still, increases with higher parity (17,18). Several studies indicate that the performance of activity meters may be compromised by higher parity (3,19). Each additional lactation number decreased walking activity at estrus by 21.4% in a study conducted in northeastern Spain (20). In Israel, the average herd rate of undetected estrus in 2008 was higher in multiparous than in primiparous cows (38.9% versus 43.9%) (21). Based on activity data, inseminating multiparous cows once a day may yield acceptable results, however, primiparous cows should be scheduled for insemination at least twice a day to improve conception rates (22). It is possible that the lack of associations among the method of estrus detection, reproductive performance, and parity in our study could be attributed to the widespread use of hormonal synchronization programs.
The use of hormonal synchronization protocols was related to a greater advantage in terms of time to first insemination, breeding interval, time to conception, and probability of pregnancy at 200 days in milk (P200) in primiparous than in multiparous cows. This suggests that parity is associated with the response of the cow to the synchronization protocol. In a study evaluating differences between primiparous and multiparous cows after Ovsynch based on 6 trials, it was found that Ovsynch was more effective in primiparous animals (CR1: 37.9% versus 31.6%; P200: 81.8% versus 75.4%) (23). Machado et al (24) compared insemination only at completion of the Presynch-Ovsynch program with insemination after detected estrus during the Presynch-Ovsynch protocol. While no differences were found in the effectiveness of the 2 strategies in primiparous animals, inseminating at completion of the synchronization program yielded better CR1 (41.2% versus 35.3%) in multiparous cows. Compared to inseminating at spontaneous estrus, another study found that timed insemination after the Presynch-Ovsynch protocol substantially improved pregnancy rate in primiparous cows as opposed to multiparous cows (25).
The application of early pregnancy diagnosis methods was associated with larger improvement of the reproductive parameters in primiparous cows. However, the accuracy of pregnancy diagnosis by means of transrectal ultrasonography is not affected by age of the cow (26). The accuracy of PAG tests showed minor variations by parity according to the results in 519 cows (27). Although significant, the link between early pregnancy diagnosis and shorter days to first service (DFS) in our study is not biologically plausible. This apparent association may be attributable to other management factors, e.g., it is possible that cows subjected to early pregnancy diagnosis were more likely to be involved in a hormonal synchronization protocol, which was associated with shorter DFS.
Early pregnancy diagnosis followed by a pregnancy recheck was associated with a greater improvement in CCI and P200 in primiparous cows than in multiparous cows. Pregnancy recheck is done to identify when pregnancy loss has occurred after the early pregnancy diagnosis (28). Some studies found no effect of parity on pregnancy loss (29–31), while others found higher incidence of pregnancy wastage in multiparous cows than in primiparous cows (32–36). A study of 6396 cows from 4 dairy herds found that multiparous cows were almost twice as likely to lose pregnancy 30 to 58 d after insemination as their primiparous counterparts (36). The odds of pregnancy loss were 40% lower in primiparous cows than in cows in parity 3 and above based on data from 1001 pregnant cows in Korea (37).
In addition to reproductive management and parity, herd also played a role in determining fertility results. The magnitude of herd effect was comparable to that of reproductive management practices and parity of the cow. Our results are in agreement with a Canadian study, which found that the effect of reproductive management on fertility was different by farm (38).
In conclusion, estrus synchronization, early pregnancy diagnosis, and pregnancy recheck led to a greater improvement in fertility in primiparous cows than in their multiparous herdmates. Our study has shown that the relationship between reproductive management practices and fertility is different in primiparous and multiparous cows.
Acknowledgements
The authors thank the farm managers and veterinarians who took part in the survey for providing farm data and information. The Project was supported by the European Union and co-financed by the European Social Fund: (1) EFOP-3.6.1-16-2016-00024 ‘Innovations for Intelligent Specialisation on the University of Veterinary Science and the Faculty of Agricultural and Food Sciences of the Széchenyi István University Cooperation’; (2) EFOP-3.6.2-16-2017-00012 ‘Development of a product chain model for functional, healthy and safe foods from farm to fork based on a thematic research network’; and (3) EFOP-3.6.3-VEKOP-16-2017-00005 ‘Strengthening the scientific replacement by supporting the academic workshops and programs of students, developing a mentoring process’.
References
- 1.Gröhn YT, Rajala-Schultz PJ. Epidemiology of reproductive performance in dairy cows. Anim Reprod Sci. 2000;60–61:605–614. doi: 10.1016/s0378-4320(00)00085-3. [DOI] [PubMed] [Google Scholar]
- 2.Lucy MC. Reproductive loss in high-producing dairy cattle: Where will it end? J Dairy Sci. 2001;84:1277–1293. doi: 10.3168/jds.S0022-0302(01)70158-0. [DOI] [PubMed] [Google Scholar]
- 3.Walsh SW, Williams EJ, Evans AC. A review of the causes of poor fertility in high milk producing dairy cows. Anim Reprod Sci. 2011;123:127–138. doi: 10.1016/j.anireprosci.2010.12.001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Adrien ML, Mattiauda DA, Artegoitia V, et al. Nutritional regulation of body condition score at the initiation of the transition period in primiparous and multiparous dairy cows under grazing conditions: Milk production, resumption of post-partum ovarian cyclicity and metabolic parameters. Animal. 2012;6:292–299. doi: 10.1017/S175173111100142X. [DOI] [PubMed] [Google Scholar]
- 5.Saqib MN, Qureshi MS, Khan RU. Changes in postpartum metabolites and resumption of ovarian cyclicity in primiparous and multiparous dairy cows. Appl Biol Chem. 2018;61:107–111. [Google Scholar]
- 6.Zhang J, Deng LX, Zhang HL, et al. Effects of parity on uterine involution and resumption of ovarian activities in postpartum Chinese Holstein dairy cows. J Dairy Sci. 2010;93:1979–1986. doi: 10.3168/jds.2009-2626. [DOI] [PubMed] [Google Scholar]
- 7.Citek J, Nemeckova D, Stadnik L, Stupka R. Ovarian diseases in Holstein dairy cows, factors determining their occurrence and impact on reproduction traits and breeding costs. Indian J Anim Sci. 2017;87:810–813. [Google Scholar]
- 8.Ricci A, Carvalho PD, Amundson MC, Fourdraine RH, Vincenti L, Fricke PM. Factors associated with pregnancy-associated glycoprotein (PAG) levels in plasma and milk of Holstein cows during early pregnancy and their effect on the accuracy of pregnancy diagnosis. J Dairy Sci. 2015;98:2502–2514. doi: 10.3168/jds.2014-8974. [DOI] [PubMed] [Google Scholar]
- 9.Mercadante PM, Ribeiro ES, Risco C, Ealy AD. Associations between pregnancy-associated glycoproteins and pregnancy outcomes, milk yield, parity, and clinical diseases in high-producing dairy cows. J Dairy Sci. 2016;99:3031–3040. doi: 10.3168/jds.2015-10595. [DOI] [PubMed] [Google Scholar]
- 10.Borchardt S, Haimerl P, Pohl A, Heuwieser W. Evaluation of prostaglandin F2α versus prostaglandin F2α plus gonadotropin-releasing hormone as Presynch methods preceding an Ovsynch in lactating dairy cows: A meta-analysis. J Dairy Sci. 2017;100:4065–4077. doi: 10.3168/jds.2016-11956. [DOI] [PubMed] [Google Scholar]
- 11.Astiz S, Fargas O. Pregnancy per AI differences between primiparous and multiparous high-yield dairy cows after using Double Ovsynch or G6G synchronization protocols. Theriogenology. 2013;79:1065–1070. doi: 10.1016/j.theriogenology.2013.01.026. [DOI] [PubMed] [Google Scholar]
- 12.Bates DM, Machler M, Bolker BM, Walker SC. Fitting linear mixed-effects models using lme4. J Stat Softw. 2015;67:1–48. [Google Scholar]
- 13.Hothorn T, Bretz F, Westfall P, Heiberger RM. Simultaneous inference in general parametric models. Biometrical J. 2008;50:346–363. doi: 10.1002/bimj.200810425. [DOI] [PubMed] [Google Scholar]
- 14.The R Project for Statistical Computing. Vienna, Austria: 2017. [Last accessed March 29, 2019]. Available from: https://www.r-project.org/ [Google Scholar]
- 15.Stangaferro ML, Wijma RW, Masello M, Thomas MJ, Giordano JO. Extending the duration of the voluntary waiting period from 60 to 88 days in cows that received timed artificial insemination after the Double-Ovsynch protocol affected the reproductive performance, herd exit dynamics, and lactation performance of dairy cows. J Dairy Sci. 2018;101:1–19. doi: 10.3168/jds.2017-13046. [DOI] [PubMed] [Google Scholar]
- 16.Inchaisri C, Jorritsma R, Vos PL, van der Weijden GC, Hogeveen H. Analysis of the economically optimal voluntary waiting period for first insemination. J Dairy Sci. 2011;94:3811–3823. doi: 10.3168/jds.2010-3790. [DOI] [PubMed] [Google Scholar]
- 17.Roelofs J, López-Gatius F, Hunter RH, van Eerdenburg FJ, Hanzen Ch. When is a cow in estrus? Clinical and practical aspects. Theriogenology. 2010;74:327–344. doi: 10.1016/j.theriogenology.2010.02.016. [DOI] [PubMed] [Google Scholar]
- 18.Madureira AM, Silper BF, Burnett TA, et al. Factors affecting expression of estrus measured by activity monitors and conception risk of lactating dairy cows. J Dairy Sci. 2015;98:7003–7014. doi: 10.3168/jds.2015-9672. [DOI] [PubMed] [Google Scholar]
- 19.Yániz JL, Santolaria P, Giribet A, López-Gatius F. Factors affecting walking activity at estrus during postpartum period and subsequent fertility in dairy cows. Theriogenology. 2006;66:1943–1950. doi: 10.1016/j.theriogenology.2006.05.013. [DOI] [PubMed] [Google Scholar]
- 20.López-Gatius F, Santolaria P, Mundet I, Yániz JL. Walking activity at estrus and subsequent fertility in dairy cows. Theriogenology. 2005;63:1419–1429. doi: 10.1016/j.theriogenology.2004.07.007. [DOI] [PubMed] [Google Scholar]
- 21.Galon N. The use of pedometry for estrus detection in dairy cows in Israel. J Reprod Develop. 2010;56:S48–S52. doi: 10.1262/jrd.1056s48. [DOI] [PubMed] [Google Scholar]
- 22.LeRoy CNS, Walton JS, LeBlanc SJ. Estrous detection intensity and accuracy and optimal timing of insemination with automated activity monitors for dairy cows. J Dairy Sci. 2018;101:1638–1647. doi: 10.3168/jds.2017-13505. [DOI] [PubMed] [Google Scholar]
- 23.Tenhagen BA, Surholt R, Wittke M, Vogel C, Drillich M, Heuwieser W. Use of Ovsynch in dairy herds — Differences between primiparous and multiparous cows. Anim Reprod Sci. 2004;80:1–11. doi: 10.1016/j.anireprosci.2003.08.009. [DOI] [PubMed] [Google Scholar]
- 24.Machado VS, Neves R, Lima FS, Bicalho RC. The effect of Presynch-Ovsynch protocol with or without estrus detection on reproductive performance by parity, and the long-term effect of these different management strategies on milk production, reproduction, health and survivability of dairy cows. Theriogenology. 2017;93:84–92. doi: 10.1016/j.theriogenology.2017.01.041. [DOI] [PubMed] [Google Scholar]
- 25.El-Tarabany MS, El-Tarabany AA, Roushdy EM. Impact of parity on the efficiency of ovulation synchronization protocols in Holstein cows. Theriogenology. 2016;86:2230–2237. doi: 10.1016/j.theriogenology.2016.07.016. [DOI] [PubMed] [Google Scholar]
- 26.Szenci O, Gyulai G, Nagy P, Kovács L, Varga J, Taverne MA. Effect of uterus position relative to the pelvic inlet on the accuracy of early bovine pregnancy diagnosis by means of ultrasonography. Vet Q. 1995;17:37–39. doi: 10.1080/01652176.1995.9694528. [DOI] [PubMed] [Google Scholar]
- 27.Dufour S, Durocher J, Dubuc J, Dendukuri N, Hassan S, Buczinski S. Bayesian estimation of sensitivity and specificity of a milk pregnancy-associated glycoprotein-based ELISA and of transrectal ultrasonographic exam for diagnosis of pregnancy at 28–45 days following breeding in dairy cows. Prev Vet Med. 2017;140:122–133. doi: 10.1016/j.prevetmed.2017.03.008. [DOI] [PubMed] [Google Scholar]
- 28.Santos JE, Thatcher WW, Chebel RC, Cerri RL, Galvão KN. The effect of embryonic death rates in cattle on the efficacy of estrus synchronization programs. Anim Reprod Sci. 2004;82–83:513–535. doi: 10.1016/j.anireprosci.2004.04.015. [DOI] [PubMed] [Google Scholar]
- 29.Starbuck MJ, Dailey RA, Inskeep EK. Factors affecting retention of early pregnancy in dairy cattle. Anim Reprod Sci. 2004;84:27–39. doi: 10.1016/j.anireprosci.2003.12.009. [DOI] [PubMed] [Google Scholar]
- 30.Chebel RC, Santos JE, Reynolds JP, Cerri RL, Juchem SO, Overton M. Factors affecting conception rate after artificial insemination and pregnancy loss in lactating dairy cows. Anim Reprod Sci. 2004;84:239–255. doi: 10.1016/j.anireprosci.2003.12.012. [DOI] [PubMed] [Google Scholar]
- 31.Labérnia J, López-Gatius F, Santolaria P, López-Béjar M, Rutllant J. Influence of management factors on pregnancy attrition in dairy cattle. Theriogenology. 1996;45:1247–1253. doi: 10.1016/0093-691x(96)00079-9. [DOI] [PubMed] [Google Scholar]
- 32.Alnimer MA, Ababneh MM. Effect of estrus expression prior to ovulation synchronization protocols on reproductive efficiency of lactating dairy cow. Livest Sci. 2014;163:172–180. [Google Scholar]
- 33.Bonneville-Hébert A, Bouchard E, Du Tremblay D, Lefebvre R. Effect of reproductive disorders and parity on repeat breeder status and culling of dairy cows in Quebec. Can J Vet Res. 2011;75:147–151. [PMC free article] [PubMed] [Google Scholar]
- 34.Gábor G, Kastelic JP, Abonyi-Tóth Z, Gábor P, Endrődi T, Balogh OG. Pregnancy loss in dairy cattle: Relationship of ultrasound, blood pregnancy-specific protein B, progesterone and production variables. Reprod Domest Anim. 2016;51:467–473. doi: 10.1111/rda.12703. [DOI] [PubMed] [Google Scholar]
- 35.Keshavarzi H, Sadeghi-Sefidmazgi A, Kristensen AR, Stygar AH. Abortion studies in Iranian dairy herds: I. Risk factors for abortion. Livest Sci. 2017;195:45–52. [Google Scholar]
- 36.Santos JE, Rutigliano HM, Sá Filho MF. Risk factors for resumption of postpartum estrous cycles and embryonic survival in lactating dairy cows. Anim Reprod Sci. 2009;110:207–221. doi: 10.1016/j.anireprosci.2008.01.014. [DOI] [PubMed] [Google Scholar]
- 37.Lee JI, Kim IH. Pregnancy loss in dairy cows: The contributing factors, the effects on reproductive performance and the economic impact. J Vet Sci. 2007;8:283–288. doi: 10.4142/jvs.2007.8.3.283. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 38.Neves RC, Leslie KE, Walton JS, LeBlanc SJ. Reproductive performance with an automated activity monitoring system versus a synchronized breeding program. J Dairy Sci. 2012;95:5683–5693. doi: 10.3168/jds.2011-5264. [DOI] [PubMed] [Google Scholar]