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Contents

  1. Top of page
  2. Contents
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Conflict of interest
  9. Author contributions
  10. References

The study evaluated the reproductive performance of primiparous sows submitted to post-cervical insemination (PCAI) compared with cervical artificial insemination (CAI). Difficulty with catheter introduction, the occurrence of bleeding or semen backflow during insemination, and volume and sperm cell backflow up to 60 min after insemination were also evaluated. Sows were homogenously distributed, according to body weight loss in lactation, lactation length, weaned piglets, weaning-to-oestrus interval and total born in previous farrowing, in two treatments: PCAI (n = 165) with 1.5 × 109 sperm cells in 45 ml (2.4 ± 0.04 doses per sow) and CAI (n = 165) with 3 × 109 sperm cells in 90 ml (2.5 ± 0.04 doses per sow). During PCAI, sows were inseminated in the absence of boars. Transabdominal real-time ultrasonography was performed at oestrus onset, immediately before the first insemination and at 24 h after last insemination. There was no difference (P > 0.05) between treatments in farrowing rate (91.5% × 89.1%) and litter size (12.5 × 11.9 piglets born, respectively for PCAI and CAI sows). Successful passage of the intrauterine catheter in all the inseminations was possible in 86.8% (165/190) of sows initially allocated to PCAI treatment. Difficulty of introducing the catheter in at least one insemination did not affect the reproductive performance of PCAI sows (P > 0.05). Bleeding during insemination did not affect (P > 0.05) the farrowing rate in both treatments, but litter size was reduced in CAI and PCAI sows (P ≤ 0.06). Percentage of spermatozoa present in backflow within 1 h after insemination was greater in CAI than PCAI sows (P < 0.01). More than 85% of primiparous sows can be successfully post-cervical inseminated with doses containing 1.5 × 109 sperm cells in the absence of the boar during insemination without impairing the reproductive performance.


Introduction

  1. Top of page
  2. Contents
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Conflict of interest
  9. Author contributions
  10. References

Post-cervical insemination (PCAI) is a technique that enables the reduction in total number of spermatozoa and volume of insemination dose. This technique allows the use of 1–2 × 109 (Watson and Behan 2002; Bennemann et al. 2004) or even 0.5 × 109 sperm cells/dose (Mezalira et al. 2005), extended in a lower volume, because the post-cervical semen deposition avoids a number of barriers to spermatic transport (Watson and Behan 2002). Thus, this method allows optimization of the use of genetically superior boars. Several studies were performed in multiparous sows comparing cervical insemination (CAI) with PCAI (Martinez et al. 2001; Watson and Behan 2002; Dallanora et al. 2004) or evaluating different numbers of sperm cells when using the PCAI technique (Bennemann et al. 2004; Mezalira et al. 2005).

Primiparous sows represent a large percentage (~20%) of females in a herd and their reproductive performance has a large impact on farm productivity. As the first reports of intrauterine deposition of insemination dose, using endoscopy (Martinez et al. 2001), flexible catheters (Martinez et al. 2002; Vazquez et al. 2003) and specific PCAI pipettes (Watson and Behan 2002; Roca et al. 2003; Bennemann et al. 2004; Mezalira et al. 2005), the success of introducing the catheter into the genital tract of multiparous sows has exceeded 90%. Nevertheless, the difficulty is greater in primiparous sows because there is medium or high difficulty when introducing the PCAI catheter in more than 45% of them (Diehl et al. 2006).

There is a lack of information concerning the reproductive results of PCAI in primiparous sows because only few trials have been performed involving this parity order, and not as a primary purpose (Rozeboom et al. 2004; Serret et al. 2005; Diehl et al. 2006). Most trials with PCAI involve multiparous (Watson and Behan 2002; Bennemann et al. 2004; Mezalira et al. 2005; Roberts and Bilkei 2005) or a low number of primiparous sows (Rozeboom et al. 2004; Serret et al. 2005; Diehl et al. 2006). Although PCAI, compared with CAI, does not compromise the reproductive performance of multiparous sows (Martinez et al. 2001; Watson and Behan 2002; Bennemann et al. 2004; Dallanora et al. 2004; Mezalira et al. 2005), some studies have reported unsatisfactory results with primiparous sows (Serret et al. 2005; Diehl et al. 2006). Available information is not conclusive about the possibility of performing PCAI in primiparous sows without impairing the reproductive performance, mainly due to the difficulty of carrying out the technique. Therefore, this study aims to evaluate the possibility of conducting PCAI in primiparous sows evaluating the difficulty of catheter insertion, the occurrence of semen backflow and bleeding as well as the reproductive performance compared with CAI.

Material and Methods

  1. Top of page
  2. Contents
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Conflict of interest
  9. Author contributions
  10. References

All experimental procedures described in this experiment were conducted under experimental license (Project number 22979) from the Institutional Animal Care and Use Committee (COMPESQ-FAVET-UFRGS).

Local, animals and treatments

The work was carried out in a breeding herd with 6200 sows from February to May 2012, totalling 13 weeks of mating. The farm is located in the South of Brazil (Santa Catarina State) a region with subtropical climate, whose average ambient temperatures varied from 10 to 23°C. The average minimum and maximum temperatures ranged from 2 to 13°C and from 22 to 32°C, respectively.

Three hundred and sixty-two (362) Landrace X Large White primiparous sows (Agroceres PIC Camborough®, Patos de Minas, MG, Brazil) were used in this study. The first selection of females was made at farrowing and at weaning, excluding those with locomotor problems, body condition score (BCS) below 2.5, on a scale of 1 to 5 (Young et al. 2004) or any health problems. Sows were weighed within 24 h after farrowing and at weaning to evaluate weight loss during the lactation period.

Experimental design

After weaning, sows were homogenously paired according to weaning-to-oestrus interval, weight loss during lactation, number of weaned piglets and number of previous total born piglets. They were randomly allocated into two treatments: CAI – cervical artificial insemination with cervical deposition of semen doses (3 × 109 sperm cells) in the presence of a boar, using a disposable foam tip catheter for cervical fixation (Ponta de Espuma Bretanha®, Passo Fundo, Brazil) and PCAI with the intrauterine deposition of AI doses (1.5 × 109 sperm cells). In the PCAI treatment, a polypropylene catheter (Magaplus S® Magapor, Zaragoza, Spain) with an outside diameter of 4 mm and a length of 750 mm was inserted up to 200 mm beyond the disposable catheter of cervical fixation, allowing the post-cervical deposition of semen. A commercial lubricant for AI (Reprojelly – Minitüb GmbH, Tiefenbach, Germany) was used to insert the disposable foam tip catheter for cervical fixation. The PCAI method was performed in the absence of a boar in front of the sows based on the reduction in labour and on our personal experience, which has shown that the introduction of a PCAI catheter is facilitated in the absence of the boar.

Housing and feeding

During the previous lactation, sows were given a standard corn soybean lactation diet (18.5% CP, 1% lysine and 3,400 kcal ME) and, after weaning were fed twice daily (4.0 kg/d) with a standard corn soybean diet (14% CP, 0.65% lysine and 3,217 kcal ME). From insemination until 30 days of gestation, the sows were fed 2.4 kg/day. Between 31 to 90 days of gestation, they were fed according to their BCS and they received between 1.6 and 2.4 kg per day; from 91 to 109 days, they received 3.0 to 4.0 kg/day. From 110 days of gestation until farrowing, sows received no more than 2.0 kg/day. During gestation until 5 days before the estimated farrowing date, the sows were allocated in individual crates with a slatted floor and automatic feeders. Throughout the experiment, sows had ad libitum access to water.

Oestrus detection and artificial insemination

Oestrus detection was performed once a day (8:00 AM), and the sows had nose-to-nose contact with a mature teaser boar in association with back pressure test. Those exhibiting a standing reflex in association with the back pressure test were considered to be in oestrus, and first insemination was performed at oestrus onset. Inseminations were repeated at 24-h intervals during oestrus. No more than three semen doses per sow were used. At the moment of insemination, the following evaluations were performed: difficulty on catheter introduction was classified as either yes (catheter was introduced with some degree of difficult on the first attempt) or no (catheter was easily introduced). The occurrence of bleeding on catheter or vulva and backflow from vulva, during insemination, was also classified as yes or no.

Additionally, during 7 weeks, four randomly selected pairs of sows were evaluated for backflow within 1 h after insemination. Semen backflow was collected using a human colostomy bag fixed around the vulva. From the initial 112 sows with colostomy bags, data of semen backflow were analysed in eighty-four sows (42 sows of each treatment) because 28 of them had spontaneous loss of bag, urinated or sat upon the colostomy bag, in at least one of their inseminations. Total backflow volume was measured and the number of spermatozoa was estimated by counting in an improved Neubauer® chamber (Karl Hecht GmbH & Co.KG, Sondheim/Rhön, Germany).

Semen collection and processing

Homospermic doses from six crossbred boars (Pietran × Duroc × Large White × Landrace, Agroceres PIC®) without previous problems in motility during in vitro storage or in sperm morphology were used. The entire ejaculate from each boar was collected twice a week, by the same operator, using the gloved-hand technique. The motility score of the ejaculate and sperm cell concentration were obtained using computer-assisted semen analysis (CASA) system (Sperm Vision® 3.7 Minitüb GmbH, Tiefenbach, Germany). Only ejaculates with more than 70% motility and morphological defects below 20% were used. Ejaculates were diluted with Beltsville Thawing Solution (BTS® Minitüb GmbH, Tiefenbach, Germany) and stored for a maximum of 72 h. Semen doses were prepared with 3 × 109 sperm cells in a total volume of 90 ml and 1.5 × 109 sperm cells in a total volume of 45 ml, for use in CAI and PCAI treatments, respectively. All insemination doses were produced in split samples, that is, doses employed for both treatments were produced from the same ejaculate. Semen doses with storage times of 0–24, 24–48 and 48–72 h were used for first, second and third inseminations, respectively. Overall, the average semen age was 24.6 ± 0.61 h, without difference (P > 0.05) between treatments.

Ultrasonography

Transabdominal ultrasonography, using a real-time ultrasound equipment with convex linear transducer of 5 MHz (Aloka® SSD 500, Aloka Co. Ltd, Tokyo, Japan), was performed at oestrus onset, immediately before the first insemination and at 24 h after the last insemination, with the objective of retrospectively confirming whether at least one insemination was performed within 24 h before ovulation (Soede et al. 1995). Ultrasonography also was used to perform pregnancy detection on days 21 to 23 after the first insemination.

Statistical analyses

Due to the impossibility of introducing the intrauterine catheter at first insemination in sows initially allocated to the PCAI treatment, 18 sows were excluded (9.5%; 18/190). Additionally, 7 sows (3.7%) were excluded due to the impossibility of introducing the intrauterine catheter at second (n = 5) or third (n = 2) insemination. These 7 sows were excluded with their respective pair, so 330 females (165 pairs) were included in the final analysis.

Statistical analyses were performed using the Statistical Analysis System version 9.2 (2005, SAS® Institute Inc., Cary, NC, USA). Variables including farrowing rate, percentage of sows with difficulty in introducing the catheter, presence of blood and presence of semen backflow at the time of insemination were analysed by chi-square test. Data regarding the total number of piglets born and percentage of volume and sperm backflow were subjected to analysis of variance using the MIXED procedure, with the inclusion of the fixed effect of treatment and random effect of boars and duos of sows. In the analysis of the total born piglets, the number of piglets born in the previous farrowing, the weaning-to-oestrus interval and the percentage of weight loss during lactation were kept in the model as covariates. Lactation length, number of weaned piglets, number of semen doses per oestrus and semen age were not significant as covariates. The treatment means were compared by t test. Percentages of stillborn piglets and mummified foetuses were analysed using the procedure NPAR1WAY, and treatments were compared with the Wilcoxon test. Farrowing rate and total number of piglets born were also analysed according to the classification of females in two classes of loss in semen backflow during 1 h after insemination: below 20% (Low) and above 20% (High). Differences with P ≤ 0.05 were considered statistically significant, and P-values between 0.06 and 0.10 were designated as a tendency. Throughout the text, numerical data are expressed as LSMeans ± SEM or percentages (pregnancy rate, farrowing rate).

Results

  1. Top of page
  2. Contents
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Conflict of interest
  9. Author contributions
  10. References

Inseminated sows had on average 12.4 ± 0.16 total piglets born in the previous farrowing, 207.3 ± 0.92 kg of body weight at farrowing and 187.5 ± 0.97 kg at weaning. They lost 9.5 ± 0.23 % of body weight during 22.3 ± 0.08 days of lactation, weaned 10.3 ± 0.10 piglets and showed a weaning-to-oestrus interval of 4.6 ± 0.05 days. The numbers of inseminations were similar for CAI and PCAI treatments (Table 1; P > 0.05).

Table 1. Reproductive performance of primiparous sows submitted to cervical artificial insemination (CAI) or post-cervical artificial insemination (PCAI)
VariablesCAI (90 ml) (3 × 109 sperm cells)PCAI (45 ml) (1.5 × 109 sperm cells)P-value
  1. a

    Values presented as LS means ± standard error of mean.

  2. b

    Values presented as mean (median–maximum).

Number of AI dosesa2.5 ± 0.042.4 ± 0.040.675
Pregnancy rate, % (n/n)90.9 (150/165)93.3 (154/165)0.414
Farrowing rate, % (n/n)89.1 (147/165)91.5 (151/165)0.457
Total piglets borna11.9 ± 0.3312.5 ± 0.330.121
Stillborn piglets, %b4.4 (0–92.3)4.3 (0 – 42.9)0.699
Mummified foetuses, %b3.5 (0–69.2)2.3 (0 – 35.3)0.924

There was no difference (P > 0.05) in reproductive performance (pregnancy rate, farrowing rate and number of total born piglets) between CAI and PCAI treatments (Table 1).

In CAI sows, no difficulty or impossibility of introducing the catheter was observed. On the other hand, the successful passage of the PCAI catheter in all the inseminations was possible in 86.8% of sows (165/190). Difficulty in catheter insertion in one, two or three inseminations was observed in 30.3% (50/165), 20.6% (34/165) and 7.3% (12/165) of sows, respectively. The difficulty in catheter insertion in at least one insemination had no influence (P > 0.05) on farrowing rate or litter size (Table 2).

Table 2. Reproductive performance of primiparous sows submitted to cervical artificial insemination (CAI) or post-cervical artificial insemination (PCAI) according to the difficulty in the catheter insertion, and the occurrence of semen backflow or bleeding during insemination
 Farrowing rate, % (n/n)Litter Sizea
 NoYesP-valueNoYesP-value
  1. a

    Values presented as LSmeans ± standard error of mean.

  2. b

    Difficulty for catheter introduction was classified as either yes (catheter was introduced with some degree of difficult on the first attempt) or no (catheter was easily introduced). For PCAI sows, this effect was evaluated taking into account the difficulty in catheter insertion in at least one of the inseminations performed. CAI values are not shown because there was no difficulty to insert the catheter in this treatment.

  3. c

    The presence of bleeding of backflow during insemination in at least one of inseminations performed in each sow is being considered in this analysis.

Difficulty in catheter introductionb
PCAI94.2 (65/69)89.6 (86/96)0.29312.8 ± 0.4212.2 ± 0.360.298
Bleeding during inseminationc
CAI88.8 (143/161)100.0 (4/4)1.0012.1 ± 0.297.8 ± 1.720.015
PCAI90.5 (115/127)94.7 (36/38)0.52612.7 ± 0.3111.5 ± 0.550.059
Semen backflow during inseminationc
CAI86.7 (78/90)92.0 (69/75)0.27411.9 ± 0.4012.0 ± 0.420.868
PCAI92.9 (118/127)86.8 (33/38)0.31612.3 ± 0.3113.0 ± 0.590.307

Taking into account all inseminations performed in PCAI group, the overall difficulty rate was 38.3% (154/402) without difference (P > 0.05) between first (36.4%; 60/165), second (36.6%; 59/161) and third (46.0%; 35/76) inseminations. However, difficulty rates for catheter introduction in second (50.8%–30/59 vs 28.4%–29/102) and third inseminations (66.7%–18/27 vs 34.7%–17/49) were higher in sows that had already shown difficulty in their first insemination. Also, sows with difficulty in their second insemination had a higher difficulty rate in third insemination (62.9%–22/35 vs 31.7%–13/41).

Fewer CAI sows (2.4%; 4/165) bled during insemination (P < 0.0001) compared with PCAI sows (23%; 28/165). The presence of blood at insemination did not influence (P > 0.05) farrowing rate in both CAI and PCAI sows, but it reduced (P = 0.01) or tended to reduce (P = 0.06) the total number of piglets born in both treatments (Table 2).

Taking into account all the inseminations performed in PCAI sows, there was a higher bleeding occurrence (15.6%–24/154 and 8.9%–22/248) or semen backflow (18.2%–28/154 and 7.7%–19/248) in inseminations with difficulty of introducing the catheter compared with inseminations without difficulty, respectively. When sows were considered, the difficulty for introducing the catheter in at least one insemination resulted in a higher percentage (P < 0.05) of sows with bleeding (29.2%–28/96 vs 14.5%–10/69).

More CAI sows (45.4%; 75/165) showed semen backflow during insemination (P < 0.0001) than PCAI sows (23%; 38/165). Farrowing rate and total born were not influenced (P > 0.05) by the presence of backflow during insemination in both treatments (Table 2).

Taking into account sows in which backflow was collected until 1 h after insemination, only one PCAI female had no volume in the colostomy bag. Great amplitude in the percentages of backflow volume and spermatozoa was observed in both treatments (31.7–89.7% and 0–99.6% for CAI and PCAI sows, respectively). There was no difference (P > 0.05) between treatments in the percentage of semen backflow volume (64.1% and 58.0% for CAI and PCAI sows, respectively). However, the percentage of spermatozoa in the backflow was higher (P < 0.01) in CAI than in PCAI treatment (33.4% × 23.1%).

Most females (93.3%; 308/330) received at least one insemination within the interval of 24 h before ovulation with only 11 sows of each treatment being inseminated out of the optimal interval. From the 22 sows that were inseminated outside the optimal interval, 19 sows ovulated 48 h (10 PCAI and 9 CAI sows) e 3 sows ovulated 72 h (1 PCAI and 2 CAI sows) after the last insemination. The number of doses for sows inseminated outside the optimal interval was similar to that of sows inseminated within the optimal interval (2.5 vs. 2.4 doses). Farrowing rate (90.9% vs. 90.0% and 81.8% vs. 92.2% for CAI and PCAI sows, respectively) and litter size (11.1 vs. 12.1 and 12.8 vs. 12.4 piglets in CAI and PCAI sows, respectively) were not affected (P > 0.05) by the insemination outside the optimal interval in both treatments.

Discussion

  1. Top of page
  2. Contents
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Conflict of interest
  9. Author contributions
  10. References

PCAI has been widely studied in multiparous sows (Martinez et al. 2001; Watson and Behan 2002; Vazquez et al. 2003; Bennemann et al. 2004; Mezalira et al. 2005; Roberts and Bilkei 2005), but primiparous sows were included in low numbers and in few trials (Rozeboom et al. 2004; Serret et al. 2005; Diehl et al. 2006). The present study is, to our knowledge, the first to use a large number of primiparous sows in which a group of variables that are risk factors for subsequent reproductive failure were controlled. Reproductive trials involving primiparous sows demand greater care in the experimental design because this parity is more affected than multiparous sows by weight loss during lactation (Thaker and Bilkei 2005), which can compromise the subsequent reproductive performance (Zak et al. 1997; Thaker and Bilkei 2005; Vinsky et al. 2006; Hoving et al. 2012). In addition to other factors (weaning-to-oestrus interval, the number of previous total born piglets and number of weaned piglets), weight loss during lactation was balanced between treatments to prevent a bias on the results.

Similar reproductive results observed when comparing CAI and PCAI corroborate the results obtained with multiparous sows (Martinez et al. 2001; Watson and Behan 2002; Dallanora et al. 2004; Hernández-Caravaca et al. 2012). In contrast to our results, Serret et al. (2005) observed a reduced litter size in primiparous sows compared with a CAI group using 3.5 × 109 sperm cells, and even with the intrauterine deposition of 2 × 109 sperm cells. However, those results should be carefully interpreted, considering that only 6 to 11 primiparous sows were used for each PCAI treatment. Low sperm cell numbers usually affect the reproductive performance of sows that are conventionally inseminated (Watson and Behan 2002), as well as those submitted to intrauterine semen deposition. With the deposition of 1 × 109 sperm cells or less, there is a higher risk of the success of the intrauterine technique being compromised (Rozeboom et al. 2004) by factors such as boars (Mezalira et al. 2005), AI-ovulation interval or sperm viability (Bennemann et al. 2005). In the present study, the use of 1.5 × 109 sperm cells was considered safe for the post-cervical insemination of primiparous sows.

In several studies concerning intrauterine semen deposition, the success of introducing the catheter into the genital tract of multiparous sows is above 90% (Watson and Behan 2002; Roca et al. 2003; Bennemann et al. 2004; Mezalira et al. 2005). The inability to insert the catheter in 13% of the sows and the difficulty experienced, in at least one of the inseminations, in 30% of PCAI sows is consistent with the report of more than 45% of primiparous sows with medium and high difficulty of introducing the PCAI catheter (Diehl et al. 2006). These difficulties can be explained by the fact that primiparous sows have a less developed reproductive tract than multiparous sows (Willenburg et al. 2003). Other authors who also used primiparous sows have not commented on the difficulty of introducing the PCAI catheter (Rozeboom et al. 2004; Serret et al. 2005).

In multiparous sows, the presence of blood on the catheter tip at withdrawal or in backflow semen did not occur (Mezalira et al. 2005) or was seen in <10% of all sows or inseminations (Watson and Behan 2002; Bennemann et al. 2004, 2005; Dallanora et al. 2004; Rozeboom et al. 2004). In primiparous sows, due to their smaller reproductive tract, it is likely that traumatic injury and bleeding may happen more easily if force is used to insert the catheter beyond the point at which resistance is encountered (Watson and Behan 2002). This assumption was confirmed in the present study as bleeding occurrence was more common in inseminations with difficulty of catheter introduction. Besides parity order, worker experience and boar presence during post-cervical insemination, the catheter model can also affect the success of introducing the catheter and consequent bleeding occurrence. In a study with primiparous sows (Diehl et al. 2006), bleeding occurrence was dependent on the model of catheter used. One model had a vaginal disposable catheter that was not fixed in the cervix where an internal catheter with 4 mm of diameter was inserted for a post-cervical semen deposition, and the other model was a disposable commercial catheter of cervical fixation with the same internal catheter. The authors (Diehl et al. 2006) reported 32.5% and 12.8% of bleeding for the first and second model, respectively. Although Serret et al. (2005) inseminated 35 primiparous sows with the same catheter model of the present study, they observed a lower percentage of bleeding (5.7% vs 23%), showing that other factors than catheter model also influence on the difficulty of catheter introduction.

The reduction in litter size when blood is observed at the moment of PCAI is in agreement with previously reported detrimental effects on reproductive performance which were expressed by higher return to oestrus rate (Dallanora et al. 2004) or litter size reduction (Bennemann et al. 2005). Additionally, the reduced farrowing rate of primiparous sows submitted to PCAI by Diehl et al. (2006) is probably explained by the fact that one of the catheters used resulted in a high percentage of bleeding. However, reproductive performance is not always affected by bleeding during PCAI insemination (Bennemann et al. 2004; Rozeboom et al. 2004). This discrepancy can be due to the fact that bleeding amount can differ between studies or to the fact that the presence of blood was only evaluated during insemination in some trials (Bennemann et al. 2004; Rozeboom et al. 2004), whereas sows were inspected for the presence of blood up to 2 h after semen deposition in others (Dallanora et al. 2004; Bennemann et al. 2005). In the present study, although most PCAI sows with blood during insemination also showed blood in colostomy bag (87.5%; 7/8), approximately a quarter of those without blood during insemination also showed blood into the bag (26.5%; 9/34) within 1 h after insemination.

Semen backflow, during or after cervical insemination, is a common event in swine. One advantage of the PCAI method could be the reduction or even the absence of sperm backflow during insemination, as observed in multiparous sows (Bennemann et al. 2004, 2005; Dallanora et al. 2004). The higher occurrence of semen backflow in primiparous sows submitted to post-cervical insemination is probably explained by the fact that the retention of fluid can be facilitated in multiparous sows due to the gravity and position of their larger uterus, as it is positioned in the peritoneal cavity (Willenburg et al. 2003). Indeed, Steverink et al. (1998) observed that of the sows with backflow during insemination, a larger proportion of primiparous sows tended to have more than 5 ml backflow compared with sows of parity ≥2. Another possibility is that boar absence during insemination could lead to an increase in semen backflow. The decision for the absence of the boar was based on the reduction in labour to maintain boar contact during insemination and on our personal experience, which has shown that the introduction of a PCAI catheter is facilitated in the absence of the boar. The difficulty with the introduction of the catheter probably occurs because boar presence stimulates oxytocin release and uterine contractions (Langendijk et al. 2003). On the other hand, these contractions can favourably affect the semen transport through the genital tract and reduce the volume of semen in backflow, as shown during the initial stage of cervical insemination in gilts exposed to boar presence (Willenburg et al. 2003).

The high variation observed in percentages of backflow volume and spermatozoa loss after insemination is in agreement with semen backflow evaluations performed in CAI (Steverink et al. 1998) or PCAI sows (Mezalira et al. 2005; Hernández-Caravaca et al. 2012). The fact that the PCAI led to less sperm cell backflow than CAI is in agreement with a previous report (Hernández-Caravaca et al. 2012) and can be an advantage of the PCAI procedure when the purpose is to use insemination protocols with doses containing a reduced number of sperm cells or protocols with a reduced number of inseminating doses.

In conclusion, the successful introduction of the intrauterine catheter is possible in a high percentage of primiparous sows (86.8%). Post-cervical artificial insemination (PCAI) with 1.5 × 109 sperm cells, without the presence of a boar during insemination, does not impair the reproductive performance of primiparous sows, allowing a widespread use of genetically superior boars. A gentle manipulation during the catheter introduction is important to prevent bleeding during insemination, which can compromise the reproductive performance of sows. Although this study was performed with a high number of primiparous sows, the widespread use of PCAI procedure warrants further validation of successful reproductive performance under less controlled commercial conditions.

Acknowledgements

  1. Top of page
  2. Contents
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Conflict of interest
  9. Author contributions
  10. References

We would like to thank Master Genética Animal, especially all staff from Master Carijos (Papanduva, Santa Catarina, Brazil), for their partnership and to Agroceres PIC and CNPq for their financial support of this project.

Author contributions

  1. Top of page
  2. Contents
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Conflict of interest
  9. Author contributions
  10. References

Pedro Ernesto Sbardella is the student (MSc level) responsible for this project. He was helped during the experimental trial by Diogo Luiz Fontana and Cristina Vicente Ferrari (MSc Students) and Rafael da Rosa Ulguim (PhD student). Prof. Mari Lourdes Bernardi provided help with the statistical analysis and draft of the paper. Prof. Fernando Pandolfo Bortolozzo is the advisor and Prof. Ivo Wentz is the co-advisor; they contributed to the design of the study and the draft of the paper.

References

  1. Top of page
  2. Contents
  3. Introduction
  4. Material and Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. Conflict of interest
  9. Author contributions
  10. References
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