Longitudinal field study to assess sow level risk factors associated with stillborn piglets

Sow reproductive performance following artificial insemination with semen doses processed using Single Layer Centrifugation without antibiotics in the tropics

Single Layer Centrifugation (SLC) through a low density colloid offers an alternative solution to antibiotic use in boar semen extenders, with lower costs compared to high density colloids. The aim of this study was to explore the reproductive performance of sows when using SLC-prepared semen doses without antibiotics, employing low density Porcicoll to prepare semen doses for artificial insemination in a commercial swine herd in Thailand. Ejaculates were divided into two equal parts to create insemination doses, with each dose containing 3000 × 106 sperm/80 ml for intra-uterine insemination in individual sows. The sows were inseminated twice, with the interval between the two inseminations ranging from 8 to 16 h. The CONTROL group consisted of 206 semen doses treated with antibiotics, prepared for insemination in 103 sows, while the SLC group comprised 194 SLC-prepared semen doses without antibiotics for inseminating 97 sows. Fertility and fecundity traits, including non-return rate, conception rate, farrowing rate, and litter traits (i.e., the total number of piglets born per litter, number of piglets born alive per litter, number of stillborn piglets, and number of mummified fetuses), were compared between groups. Furthermore, data on piglet characteristics, including live-born and stillborn piglets (i.e., the prevalence of stillbirth (yes, no), birth weight, crown-rump length, body mass index (BMI), and ponderal index (PI)), were determined. No significant differences in non-return rate (75.7 % vs. 77.3 %), conception rate (73.8 % vs. 73.2 %), and farrowing rate (71.8 % vs. 73.2 %) were observed between the CONTROL and SLC groups, respectively (P > 0.05). Nevertheless, the total number of piglets born per litter in the SLC group was higher than in the CONTROL group (14.6 ± 0.9 vs. 12.3 ± 0.6, respectively, P = 0.049). Interestingly, the prevalence of stillbirth in the SLC group was lower than in the CONTROL group (6.2 % vs. 11.6 %, respectively, P < 0.001). Moreover, the newborn piglets in the SLC group exhibited higher birth weight and BMI compared to those in the CONTROL group (1.36 ± 0.03 vs. 1.26 ± 0.02 kg, P = 0.005, and 18.3 ± 0.3 vs. 17.3 ± 0.2 kg/m2, P = 0.003). In conclusion, employing sperm doses after SLC through a low density colloid in artificial insemination within a commercial breeding operation did not have a detrimental impact on either fertility or fecundity traits but showed potential benefits in increasing the total number of piglets born per litter. Moreover, improvements were observed in the birth weight and body indexes of piglets, and the percentage of stillbirths was reduced. Our findings introduce new possibilities for antibiotic alternatives in semen extenders to reduce the risk of antimicrobial resistance in the swine industry. Additionally, they provide compelling reproductive outcomes supporting the integration of SLC-prepared semen doses into artificial insemination practices.

Factors contributing to stillbirth in young hyper-prolific sows in a tropical free-farrowing system

The present study investigated factors associated with the incidence of stillbirth in young hyper-prolific sows within free farrowing systems in tropical environments. A total of 714 live-born and 54 stillborn piglets from 57 Landrace × Yorkshire sows, with an average parity of 2.7 ± 1.0 (range: 1 - 4), were comprehensively investigated. Reproductive variables of the sows, including gestation length, farrowing duration, the total number of piglets born per litter, and the birth order and status of each piglet, were recorded. Differences in the physiological characteristics of live-born and stillborn piglets, such as birth interval, cumulative birth interval, body weight at birth, crown-rump length, body mass index (BMI), ponderal index (PI), meconium staining score, and the percentage of piglets with a broken umbilical cord, were analysed. Piglets were divided into four groups based on the quartiles of birth order (Q1-Q4). On average, the duration of farrowing was 173.3 ± 85.9 min, and the total number of piglets born and number of piglets born alive-per litter were 14.1 ± 3.8 and 12.5 ± 3.5, respectively. The incidence of stillbirth was 6.7% (54/801 piglets). The higher percentages of stillbirths were detected in sows with large litter sizes (≥17 piglets, 10.9%) compared to those with small (≤13 piglets, 6.1%) and moderate (14 - 16 piglets, 2.8%) litter sizes (p < .001). The incidences of stillbirth in Q3 and Q4 of the litters were higher than in Q1 and Q2 (p < .001). Compared to live-born piglets, stillborn piglets had higher cumulative birth interval (103.0 ± 3.71 vs. 142.4 ± 9.35 min, p < .001), BMI (17.1 ± 0.15 vs. 18.4 ± 0.39 kg/m2, p = .002), PI (63.7 ± 0.59 vs. 70.8 ± 1.59 kg/m3, p < .001), meconium staining scores (1.78 ± 0.04 vs. 2.04 ± 0.10, p = .021), and the percentage of piglets born with a ruptured umbilical cord (45.2% vs. 66.0%, p = .004). An increase in the incidence of stillbirth was detected at 60, 120, 150, 180, and ≥ 210 min after the first piglet was born, compared to those born within the first 30 min of farrowing (p < .05). In conclusion, the study found that stillbirths in young, hyper-prolific sows were linked to several factors: large litter sizes (≥17 piglets per litter), prolonged cumulative birth intervals (142.4 min), elevated BMI of 18.4 kg/m2, high PI values of 70.8 kg/m3, increased meconium staining scores, and a higher occurrence of ruptured umbilical cords. To reduce the risk of stillbirth, particularly among piglets with high body indices born later in the birthing process, it is recommended to enhance farrowing supervision for young sows, starting at a cumulative birth interval of 60 min.

Effects of Bacillus subtilis supplementation on reproductive parameters during late gestation in multiparous sows

Background and Aim

Probiotics are used at different stages of gestation to promote reproductive performance in sows. This study investigated the effect of Bacillus subtilis QST 713 supplementation during late gestation in multiparous sows on different reproductive parameters.

Materials and Methods

On day 85 of gestation, 115 multiparous healthy Landrace Yorkshire sows were randomly assigned to two groups with equal parity numbers. The control group (58 sows) was fed with basal diets, and the probiotic group (57 sows) was fed with basal diets +1010 colony-forming unit (CFU) B. subtilis QST 713 from day 85 to parturition. Back fat thickness on days 85 and 110, number of total born, number of born alive, stillbirth and mummy rates, individual birth weight, litter birth weight, within-litter variation of piglet birth weight, and postpartum vaginal discharge duration were recorded and compared between the two groups.

Results

The number of total born, number born alive, back fat thickness of sows before farrowing, litter weight, within-litter variation of piglet birth weight, and postpartum vaginal discharge duration were similar in both groups (p > 0.05). Dietary supplementation with B. subtilis QST 713 decreased the stillbirth rate (3.96 vs. 6.39%, p = 0.046) and born dead rate (5.12 vs. 8.57%, p = 0.035) and increased the birth weight of piglets (1552.78 vs. 1506.15 g, p = 0.049).

Conclusion

Daily supplementation with 1010 CFU of B. subtilis QST 713 during late gestation in multiparous sows could increase reproductive performance by increasing birth weight and decreasing stillbirth rate.

Timing of dietary zinc additions during gestation for improved piglet survival

The objectives of this study were to determine a practical approach to feeding elevated dietary zinc (Zn) to gestating sows in a commercial setting and to confirm preweaning mortality could be reduced by feeding high Zn to sows during different periods of gestation. The study was conducted at a commercial sow farm in the upper Midwest. Mixed parity sows (n = 267) over three consecutive weekly farrowing groups (sows farrowing within 1 wk) were assigned randomly to one of the three dietary treatments within parity. Treatments consisted of: (1) control sows fed a corn-soybean meal diet containing 206 mg/kg total supplemental Zn supplied by zinc hydroxychloride; (2) breed-to-farrow: as control + 147 mg/kg supplemental Zn as ZnSO4 (353 mg/kg total supplemental Zn) fed from 5 d after breeding to farrowing; and (3) day 110-to-farrow: as control fed from breeding to farrowing + 4,079 mg/kg supplemental Zn as ZnSO4 (4,285 mg/kg total supplemental Zn) starting day 110 of gestation until farrowing. At farrowing, individual piglets were weighed and identified within 12 h of birth. Data were analyzed using PROC GLIMMIX of SAS and the model considered the fixed effect of dietary treatment and random effect of farrowing group. Dietary treatments did not affect number of total pigs born per litter. For breed-to-farrow sows, there was an increase in the percentage of pigs born alive compared to sows fed the control and day 110-to-farrow treatments (P < 0.001). The number of stillborn pigs expressed as a percentage of total litter size at birth decreased for breed-to-farrow sows (P < 0.001) compared with control or day 110-to-farrow sows. Mortality of low birth weight piglets from birth to weaning did not differ among dietary treatments (P = 0.305); however, a trend for decreasing post-natal mortality (P = 0.068) of normal birth weight pigs was observed for pigs born to sows fed elevated Zn 5 d before farrowing. In conclusion, feeding elevated Zn to sows throughout gestation increased the proportion of pigs born alive suggesting that elevated gestational Zn intake makes piglets more robust to endure the stresses of farrowing and decreases intrapartum mortality. Under the conditions of this study, elevated Zn intake of sows did not influence piglet post-natal survival. However, feeding high zinc throughout gestation may decrease piglet mortality during the parturition process.

Characterizing sow feed intake during lactation to explain litter and subsequent farrowing performance

Variation in feed intake results in nearly 20% of sows consuming less than the recommended lysine (Lys) intake for lactating sows. The Lys requirement for lactating sows is based on litter size and piglet average daily gain which influences milk production. Litter size continues to increase every year causing the need for routine reevaluation of nutrient requirements. If dietary inclusion levels are not continuously adjusted this can lead to inadequate daily Lys and energy intake and may negatively impact sow body condition and litter performance. The objective was to characterize the average daily feed intake (ADFI) of sows and define feed intake patterns and their effects on sow body weight, farrowing performance, litter performance, and subsequent farrowing performance. ADFI during lactation was recorded for 4,248 sows from 7 independent research studies. Data collection occurred from November 2021 through November 2023 at a commercial breed-to-wean facility in western Illinois. Each sow was categorized as: consistently low intake (< 5.5 kg/d) throughout the lactation (LLL); low intakes (< 5 kg/d) in the first week, then gradually increased throughout the rest of the lactation period (LHH); gradual increase in intake throughout lactation with no drop and a peak intake after day 10 of lactation (gradual); rapid increase in intake with no drop and the peak intake met before day 10 (rapid); a major drop in feed intake (> 1.6 kg decrease for ≥ 2 d) any time during lactation (MAJOR); minor drop (≤ 1.6 kg for ≥ 2 d; MINOR). Sows were also separated into low (quartile 1; ≤ 25%), average (quartile 2 through 3), or high feed intake (quartile 4; ≥ 75%) by parity (P1, P2, P3+). Sows in the LLL category were younger in parity, had the greatest preweaned mortality, weaned the lightest average pigs, and experienced the greatest loss in body weight percentage compared with sows in all other feed intake categories. Furthermore, sows in the LLL and LHH categories had one fewer subsequent pig born compared with sows in the other four categories. These data support historical findings that feed intake patterns directly contribute to current litter farrowing performance. Lactation intake patterns also influence subsequent farrowing performance. Identifying under-consuming sows that are likely Lys and energy deficient allows producers opportunities to promote consistent, adequate daily intakes to these groups and mitigate negative impacts on sow and litter performance.

Changes in Gut Microbiota Associated with Parity in Large White Sows

As one of the most critical economic traits, the litter performance of sows is influenced by their parity. Some studies have indicated a connection between the gut microbiota and the litter performance of animals. In this study, we examined litter performance in 1363 records of different parities of Large White sows. We observed a marked decline in TNB (Total Number Born) and NBH (Number of Healthy Born) We observed a marked decline in TNB (Total Number Born) and NBH (Number of Healthy Born) among sows with parity 7 or higher. To gain a deeper understanding of the potential role of gut microbiota in this phenomenon, we conducted 16S rRNA amplicon sequencing of fecal DNA from 263 Large White sows at different parities and compared the changes in their gut microbiota with increasing parity. The results revealed that in comparison to sows with a parity from one to six, sows with a parity of seven or higher exhibited decreased alpha diversity in their gut microbiota. There was an increased proportion of pathogenic bacteria (such as Enterobacteriaceae, Streptococcus, and Escherichia-Shigella) and a reduced proportion of SCFA-producing families (such as Ruminococcaceae), indicating signs of inflammatory aging. The decline in sow function may be one of the primary reasons for the reduction in their litter performance.

Statistical and machine learning approaches to describe factors affecting preweaning mortality of piglets

High preweaning mortality (PWM) rates for piglets are a significant concern for the worldwide pork industries, causing economic loss and well-being issues. This study focused on identifying the factors affecting PWM, overlays, and predicting PWM using historical production data with statistical and machine learning models. Data were collected from 1,982 litters from the U.S. Meat Animal Research Center, Nebraska, over the years 2016 to 2021. Sows were housed in a farrowing building with three rooms, each with 20 farrowing crates, and taken care of by well-trained animal caretakers. A generalized linear model was used to analyze the various sow, litter, environment, and piglet parameters on PWM. Then, different models (beta-regression and machine learning model: a random forest [RF]) were evaluated. Finally, the RF model was used to predict PWM and overlays for all listed contributing factors. On average, the mean birth weight was 1.44 kg, and the mean mortality was 16.1% where 5.55% was for stillbirths and 6.20% was contributed by overlays. No significant effect was found for seasonal and location variations on PWM. Significant differences were observed in the effects of litter lines on PWM (P < 0.05). Landrace-sired litters had a PWM of 16.26% (±0.13), whereas Yorkshire-sired litters had 15.91% (±0.13). PWM increased with higher parity orders (P < 0.05) due to larger litter sizes. The RF model provided the best fit for PWM prediction with a root mean squared errors of 2.28 and a correlation coefficient (r) of 0.89 between observed and predicted values. Features' importance from the RF model indicated that, PWM increased with the increase of litter size (mean decrease accuracy (MDA) = 93.17), decrease in mean birth weight (MDA = 22.72), increase in health diagnosis (MDA = 15.34), longer gestation length (MDA = 11.77), and at older parity (MDA = 10.86). However, in this study, the location of the farrowing crate, seasonal differences, and litter line turned out to be the least important predictors for PWM. For overlays, parity order was the highest importance predictor (MDA = 7.68) followed by litter size and mean birth weight. Considering the challenges to reducing the PWM in the larger litters produced in modern swine industry and the limited studies exploring multiple major contributing factors, this study provides valuable insights for breeding and production management, as well as further investigations on postural transitions and behavior analysis of sows during the lactation period.

Relationship between piglets' survivability and farrowing kinetics in hyper-prolific sows

BACKGROUND

Prolonged farrowing and more piglets born with low birth weight are undesirable consequences of genetic selection for increased litter size. The objective of the present observational study was to evaluate the relationship between piglets' survivability and farrowing kinetics in hyperprolific sows. A total of 58 sows of different parities and 1190 piglets were included. The entire farrowing process was monitored and the following parameters were recorded: inter-piglet birth interval, birth order, total born, live born, dead born, and mummified piglets, obstetric intervention, weight at birth and 24h, colostrum yield and intake.

RESULTS

The sows included in this study had on average 20.6 ± 0.6 total piglets born, of which 16.4 ± 0.6 were live born, 3.3 ± 0.4 were stillborn and 0.9 ± 0.2 were mummified piglets. The average farrowing duration and average birth interval were 411.3 ± 31.6 and 20.6 ± 1.7 min, respectively. Farrowing duration was positively associated (p < 0.05) with parity, number of stillborn and mummified piglets. Piglet mortality 24h after birth was negatively affected (p < 0.01) by birth weight and positively affected (p < 0.01) by cumulative birth interval. The last tercile of piglets born (birth order ≥ 17) had the highest (p < 0.01) inter-piglet birth interval (IPBI) (43.4 ± 4.17 min) compared to piglets born in the first (birth order between 2 and 7) (26.5 ± 3.8 min) and second (birth order between 8 and 16) terciles (21.9 ± 3.8 min). Cumulative birth interval, birth weight, occurrence of stillborn piglets and manual intervention were positively associated (p < 0.05) with IPBI. Piglet birth weight was also positively associated (p < 0.01) to individual colostrum intake. Piglets ingesting more colostrum had lower (p < 0.01) mortality from 24h after birth until weaning. Sow's parity and cumulative birth interval were positively associated with the presence of stillborn piglets (p = 0.02 and p < 0.01, respectively).

CONCLUSION

Reducing farrowing duration may be crucial to decrease stillbirth rate and neonatal mortality in hyperprolific sows. Moreover, special care must be provided to the lighter piglets within a litter to increase their colostrum intake and minimize piglet's mortality throughout lactation.

Review: Targeted nutrition in gestating sows: opportunities to enhance sow performance and piglet vitality

Birth weight is a key factor for piglet survival, and therefore, there is ongoing interest in how nutrition during gestation can influence birth weight. Interestingly, sows are generally fed one single diet throughout gestation. This paper reviews past attempts to increase foetal growth to term and discusses opportunities to target nutritional manipulations at specific windows of gestation where key developmental events occur. Birth weight limits chances to survive mainly in piglets with birth weight below 1 kg. These piglets represent around 16% of the population. Given the normal distribution of birth weight, the mean birth weight needs to be increased by at least 50-100 g to have a meaningful impact on this proportion of the population and on perinatal survival. Based on existing variation in reported mean birth weight across a number of studies, it is argued that it is unrealistic to expect an increase in mean birth weight of more than 100 g. Attempts in the past to increase birth weight have focussed on the last trimester of gestation, when foetal growth is accelerated. Increase in feed allowance or nutritional concepts that target placenta vascularisation have not been successful. It is argued that nutritional manipulations should rather focus on the middle of gestation, since in that period, placenta growth occurs and since placenta size limits the foetal size. Alternatively, nutritional manipulations can target placentation during the embryonic phase.

Risk factors differ for viable and low viable crushed piglets in free farrowing pens

Newborn piglets have a high risk of being crushed by the sow, and this risk implies welfare and economic consequences. The aim of this study was to investigate the importance of differentiating between low viable (secondary crushing losses) and viable crushed (primary crushing losses) piglets for the evaluation of risk factors for crushing related to characteristics of the sow, the litter, and the environment. Eleven Swiss farmers recorded sows' production data (parity class, gestation length, numbers of live-born and stillborn piglets), data (age, sex, weight, cause of death, and signs of weakness) for every live-born piglet that died in the first week after birth (piglet loss), and ambient temperature. Piglet losses were assigned to five categorical events: piglet loss, subdivided into not crushed and crushed, the latter being further subdivided into low viable crushed and viable crushed. Piglets recorded by the farmer as crushed were assigned to the events low viable crushed and viable crushed based on the piglet's body weight and signs of weakness (diseases, malformations). Data of 9,543 live-born piglets from 740 litters were eventually used to statistically model the hazard of dying at any given time in the first week after birth due to one of these events (mixed-effects Cox model). Five potential risk factors were analyzed as co-variates: parity class, gestation length, number of live-born piglets, number of stillborn piglets, and daily number of hours with ambient temperature >30°C. We identified two risk factors for dying from the event viable crushed that were not identified as risk factors for low viable crushed, namely shorter gestation length and higher daily number of hours with ambient temperature  > 30°C. Vice-versa, we identified additional live-born piglets in the litter as risk factor for low viable crushed, but not for viable crushed. Our results show the importance of differentiating between low viable and viable crushed piglets for the interpretation of risk factors for crushing losses. Therefore, we suggest that for breeding purposes and in research, this differentiation should be made.

Characteristics of thermal images of the mammary gland and of performance in sows differing in health status and parity

Precision livestock farming can combine sensors and complex data to provide a simple score of meaningful productivity, pig welfare, and farm sustainability, which are the main drivers of modern pig production. Examples include using infrared thermography to monitor the temperature of sows to detect the early stages of the disease. To take account of these drivers, we assigned 697 hybrid (BHZP db. Viktoria) sows to four parity groups. In addition, by pooling clinical findings from every sow and their piglets, sows were classified into three groups for the annotation: healthy, clinically suspicious, and diseased. Besides, the udder was thermographed, and performance data were documented. Results showed that the piglets of diseased sows with eighth or higher parity had the lowest daily weight gain [healthy; 192 g ± 31.2, clinically suspicious; 191 g ± 31.3, diseased; 148 g ± 50.3 (p < 0.05)] and the highest number of stillborn piglets (healthy; 2.2 ± 2.39, clinically suspicious; 2.0 ± 1.62, diseased; 3.91 ± 4.93). Moreover, all diseased sows showed higher maximal skin temperatures by infrared thermography of the udder (p < 0.05). Thus, thermography coupled with Artificial Intelligence (AI) systems can help identify and orient the diagnosis of symptomatic animals to prompt adequate reaction at the earliest time.

CpG content in the Zika virus genome affects infection phenotypes in the adult brain and fetal lymph nodes

Increasing the number of CpG dinucleotides in RNA viral genomes, while preserving the original amino acid composition, leads to impaired infection which does not cause disease. Beneficially, impaired infection evokes antiviral host immune responses providing a cutting-edge vaccine approach. For example, we previously showed that CpG-enriched Zika virus variants cause attenuated infection phenotypes and protect against lethal challenge in mice. While CpG recoding is an emerging and promising vaccine approach, little is known about infection phenotypes caused by recoded viruses in vivo, particularly in non-rodent species. Here, we used well-established mouse and porcine models to study infection phenotypes of the CpG-enriched neurotropic and congenital virus—Zika virus, directly in the target tissues—the brain and placenta. Specifically, we used the uttermost challenge and directly injected mice intracerebrally to compare infection phenotypes caused by wild-type and two CpG-recoded Zika variants and model the scenario where vaccine strains breach the blood-brain barrier. Also, we directly injected porcine fetuses to compare in utero infection phenotypes and model the scenario where recoded vaccine strains breach the placental barrier. While overall infection kinetics were comparable between wild-type and recoded virus variants, we found convergent phenotypical differences characterized by reduced pathology in the mouse brain and reduced replication of CpG-enriched variants in fetal lymph nodes. Next, using next-generation sequencing for the whole virus genome, we compared the stability of de novo introduced CpG dinucleotides during prolonged virus infection in the brain and placenta. Most de novo introduced CpG dinucleotides were preserved in sequences of recoded Zika viruses showing the stability of vaccine variants. Altogether, our study emphasized further directions to fine-tune the CpG recoding vaccine approach for better safety and can inform future immunization strategies.

Altrenogest Supplementation during Early Pregnancy Improves Reproductive Outcome in Pigs

Progesterone plays an important role in initial conceptus development and in a successful pregnancy, but results related to progesterone or its analogues (altrenogest) supplementation in early pregnancy of pigs are conflicting. The present study evaluated the effects of altrenogest supplementation in sows during days 6 and 12 of pregnancy on reproductive performance. On day 6 of pregnancy, 301 females were allocated at random to one of the following treatments: CON (Control: non-supplemented females, n = 163) or ALT (females daily supplemented with 20 mg of altrenogest, orally, from day 6 to 12 of pregnancy, n = 138). Ovulation was considered as occurred at 48 h after the first estrus detection to standardize the first day of pregnancy. The supplementation increased the number of total piglets born (ALT: 17.3 ± 0.4; CON: 16.6 ± 0.4), piglets born alive (ALT: 15.6 ± 0.4; CON: 14.8 ± 0.3), and placenta weight (ALT: 4.2 ± 0.1; CON: 3.8 ± 0.1) and decreased the stillbirth rate (ALT: 5.9 ± 0.6; CON: 7.6 ± 0.6) and the number of piglets born weighing less than 800 g (ALT: 6.6 ± 0.6; CON: 8.0 ± 0.6), without impairment on farrowing rate. These results demonstrated that altrenogest supplementation on swine females between days 6 and 12 of pregnancy may be used to improve reproductive performance.

Effect of 1,25-Dihydroxyvitamin D3-Glycosides on the Farrowing Process and Piglet Vitality in a Free Farrowing System

Vitamin D improves the reproductive efficiency in animals. This study aimed to examine the effects of 1,25-dihydroxyvitamin D3-gylcosides (1,25-vitD) on the farrowing process in sows and the vitality of their piglets. In total, 100 sows were allocated into two groups at insemination (‘1,25-vitD’ and ‘negative control’). The 1,25-vitD group received 260−300 mg/sow/day 1,25-vitD in their feed during the gestation period. Backfat thickness, fecal score, and the farrowing process was evaluated. The piglets were categorized into live born or stillborn, and vitality was evaluated by assessing the umbilical cord and the meconium score. The number of total-born piglets in sows of ‘1,25-vitD’ was higher and the farrowing duration was shorter than in the negative control group without showing significance in the univariable analysis. In a linear multiple regression model including the variables ‘farrowing duration’, ‘total born piglets’ and ‘1,25-vitD’ differences became evident. We found that 1,25-vitD was associated with a reduced farrowing duration (p = 0.055). Moreover, significantly more mummies (p < 0.01) and short ruptured umbilical cords (p < 0.05) were observed in the 1,25-vitD group. This study showed an effect of 1,25-vitD on the farrowing process. However, more research is needed to better describe the mechanism of 1,25-vitD in detail.

Effects of Litter Size and Parity on Farrowing Duration of Landrace × Yorkshire Sows

Simple Summary

Litter size is an important economic trait in pigs. Improving the number born alive is an important breeding goal of the pig husbandry. A shorter farrowing duration is welcome for facilitating the management and sows’ health. Therefore, the aim of this study was to explore the effect of litter size and parity on farrowing duration, to determine whether a shorter length of farrowing duration could be considered as a breeding parameter in pig breeding. Our results showed the total number born had no significant relation with farrowing duration, but number of stillbirths increased with the prolongation of farrowing duration and decrease of live litter size if farrowing duration was longer than 240–300 min. Different parities sows had little difference in the same farrowing duration interval except for gilts. A shorter farrowing duration within 300 min might be considered in pig breeding without worrying about the decreasing of live litter size or the negative effect of parity.

Abstract

Litter size has increased and farrowing duration has also prolonged in recent years. The aim of this study was to analyze the effect of litter size and parity on farrowing duration (FAR) to estimate the possibility of selecting a short farrowing duration. We recorded 32,200 parturitions of 8420 Landrace × Yorkshire sows, determined farrowing duration, litter size, parity, gestation length. Results showed that total number of born (TNB) and parity obeyed a cubic (p = 0.0004, p = 0.004) relationship while number born alive (NBA) and number born dead (NBD) obeyed a linear (p = 0.0239, p = 0.0035) relationship with FAR. Gestation length obeyed a linear (p = 0.02) relationship with FAR. FAR of sows with stillbirth was longer than that of sows without stillbirth. Stillbirth rate increased rapidly from about 2% to 4%, especially when FAR was over 240 min. FAR gradually prolonged with the parities. FAR of 7th parity sows was longer than that of 1st~6th parity sows (p < 0.05), but different parity sows had little difference in the same FAR interval except for gilts. Results indicated it was possible and necessary to consider FAR into pig breeding without worrying about decreasing of live litter size or negative effect of parity if FAR was shorter than 300 min.

Stillbirth rates and their association with swine leucocyte antigen class II haplotypes in Microminipigs

OBJECTIVE

Microminipig (MMP) is a miniature pig with an extra small body size for experimental use. In the present study, the occurrence of stillbirths and their genetic association with swine leukocyte antigen (SLA) class II haplotypes were evaluated in a population of MMPs.

METHODS

The occurrences of stillbirth and genetic association with SLA class II haplotypes using 483 stillborn and 2,246 live piglets, and their parents were compared among the three groups of newborn piglet litters; an all stillborn (AS) group consisting of only stillborn piglet litters, a partial stillborn (PS) group consisting of stillborn and live piglet litters, and an all alive (AA) group consisting of only live piglet litters.

RESULTS

The incidence of stillborn piglets was 483/2,729 (17.7%). Distributions of litter sizes, numbers of stillborn piglets in a litter, parities, and gestation periods were distinct among the three groups. The frequencies of low resolution haplotype (Lr)-0.7 or Lr-0.23 were higher in the AS group than in the PS or AA groups. In sires, the frequency of Lr-0.7 associated with the AS group was significantly higher in the AS group than with the AA group. In dams, the frequency of Lr-0.23 was significantly higher in the AS group than in the PS or AA groups, whereas the frequency of Lr-0.7 was not significantly different.

CONCLUSION

The incidence of stillborn piglets in MMPs appears to be higher than those in other pig breeds. Several traits related with stillbirths such as the number of stillborn piglets and parities of the AS group were different from those of the PS and AA groups. Specific SLA class II haplotypes were associated significantly with a high incidence of stillbirths and could be used as genetic markers to adopt breeding strategies to lower the rate of stillbirth in MMPs.

Risk factors associated with dystocia in swine

Background and Aim:

Dystocia in swine can increase the stillbirth rate; however, its importance in pig-breeding systems has been underestimated. Until now, few studies have investigated dystocia and associated risk factors. Therefore, in this study, we aimed to evaluate the effects of various risk factors on dystocia in swine.

Materials and Methods:

Out of 5,557 piglets, we included 4,997 piglets in risk analysis study. The dependent variable was dystocia, which was recorded when a birth interval exceeded 45 min or when obstetric assistance was applied. The independent variables were parity, gestation length, litter size, birth order, gender, presence of a dead piglet, birthweight, crown rump length, body mass index, ponderal index, and oxytocin use. We used generalized linear mixed models to examine the associations between potential risk factors and dystocia at the piglet level.

Results:

A total of 6% of the piglets were born with a dystocia event, and 47.2% of the farrowing experienced at least one event. Dead piglets and piglets with a crown rump length of >31 cm were associated with an increased dystocia rate. This rate decreased from birth order 2 to 7, stabilized to 11, and then increased till the end of the fetal expulsion process.

Conclusion:

Dystocia is common in swine. Therefore, this condition should be carefully addressed by veterinarians and farrowing house personnel so that its adverse effect on welfare and productivity of sows and survivability of piglets can be reduced. Further studies investigating dystocia status and risk factors in different swine farrowing systems should be undertaken to provide more knowledge about this neglected condition.

Non-infectious risk factors for intrapartum stillbirth in a swine farm in the North of Vietnam

Background and Aims

Stillbirth causes considerable loss to the pig farming industry. Methods aimed at reducing stillbirth should base on the understanding of risk factors for intrapartum stillbirth because it accounts for 75% of all stillbirths. Unfortunately, few studies have differentiated between intrapartum and prepartum stillbirths leading to inadequate information about risk factors for sole intrapartum stillbirth. This study investigated risk factors for piglet's intrapartum stillbirth.

Materials and Methods

Data of 1527 piglets born from 103 sows in one herd were recorded. Generalized linear mixed models were used to determine the relationship between investigated risk factors and intrapartum stillbirth at the piglet level. The potential risk factors were parity, gestation length (GL), litter size (LS), birth order (BO), birth interval (BI), cumulative farrowing duration (CFD), gender, crown-rump length, birth weight (BW), body mass index, ponderal index (PI), and BW deviation.

Results

About 60% (60.2%, 62/103) litters had stillborn piglet(s), and the intrapartum stillbirth rate was 5.8% (89/1527). BW deviation (≤0.1 and >0.6 kg), LS >13, GL (<114 and >117 days), PI ≤54, and BO >10 were the most significant factors associated with increased intrapartum stillbirth. No effect of parity, sex, BI, and CFD on intrapartum stillbirth was detected.

Conclusion

These data stressed the importance of piglets' size and shape in the prediction of intrapartum stillbirth. Furthermore, large LS, high BO, short, and long GL were associated with increased intrapartum stillbirth. The results of this study suggest that procedures aimed at increasing litter homogeneity, optimizing piglets' size and shape, avoiding short and long gestation, and increasing supervision rate, especially at the second half, of the farrowing may reduce piglet's intrapartum stillbirth.

Observation of dose dependent intravaginal Prostaglandin E2 application in free farrowing sows during parturition - a pilot study

The duration of birth is an important factor influencing the survival of piglets and the health of sows. A prolonged parturition is usually treated with oxytocin, even though several undesirable side effects are described. Therefore, the aim of this study was to evaluate the safety and efficacy of Prostaglandin E2 (PGE2) of different concentrations as an intravaginal applied gel after the birth of the fourth piglet in sows. Twelve sows were randomly allocated to one of four treatment groups: Group I (control group) application of placebo gel; Group II application of 0.5 mg; Group III application of 1.0 mg PGE2; Group IV PGE2 application of 2.0 mg PGE2. Total duration of parturition (time between first piglet and last placenta), piglet interval before and after treatment and placenta expulsion duration (time between first and last placenta) were recorded, and each piglet was scored for meconium staining and vitality. Furthermore, stillborn piglets were categorized into ante-partum and intra-partum deaths.

A significant dose-dependent effect of PGE2 after the fourth piglet in a linear regression model with group I, II and III on the total duration of parturition and the placenta expulsion duration was detected. An increase of the PGE2 dosage from 0 to 1 mg significantly reduced the total duration of parturition (group I: 553.7 ± 114.2; group II:456 ± 167.9; group III: 284.7 ± 40.5; p-value: 0.02) and placenta expulsion duration (group I: 364 ± 120; group II: 289 ± 144.1; group III: 119 ± 46.13; p-value: 0.03). Although no further significant differences between the groups using ANCOVA and a linear regression model including all groups were detected, severe meconium staining in more than 10% of piglets was observed in group II and IV. Moreover, piglets of group IV showed oedematous and haemorrhagic umbilical cords, lethargy and anoxia after treatment, and intra-partum deaths were recorded.

The best outcome for the sows and piglets was achieved using the 1 mg PGE2 dosage, whereas the other dosages showed more negative side effects, impairing the health and welfare of the animals. The results of this study can be used for further studies with larger sample sizes.

Fetal mortality associated with backfat thickness at first mating and first farrowing of the primiparous sows raised in a commercial herd in Thailand

This study aimed to investigate the fetal mortality, including stillborn piglets (SB) and mummified fetuses (MM), in relation to backfat thickness both at first mating (MBF) and at first farrowing (FBF) in 200 primiparous sows accommodated in a commercial breeding herd in Thailand. Backfat thickness of all pigs was measured at P2 position using an A-mode ultrasonography. Based on MBF, the gilts were classified into four groups: MBF1 (≤12.0 mm), MBF2 (>12.0-15.0 mm), MBF3 (>15.0-18.0 mm), and MBF4 (>18.0 mm). According to FBF, the primiparous sows were categorized into four classes: FBF1 (≤15.0 mm), FBF2 (>15.0-18.0 mm), FBF3 (>18.0-21.0 mm), and FBF4 (>21.0 mm). At farrowing, 174 litters were examined for percentage of SB and MM. The results indicated that mean MBF and FBF were 16.7 ± 0.3 mm and 19.6 ± 0.3 mm, respectively. Based on MBF, the pigs in MBF1 significantly possessed higher percentage of MM (13.8 ± 4.5%) than others; meanwhile, SB percentage was not different among groups (P > 0.05). According to FBF, the pigs in FBF4 farrowed the highest percentage of SB (9.1 ± 3.2%) than others, whereas MM percentage was not different among classes (P > 0.05). In summary, backfat thickness of the gilts should be one of the parameters to pay more attention since it is related to fetal mortality of the primiparous sows. The farmers should monitor the backfat thickness not only at the first mating time, but also along the gestation period in order to minimize fetal mortality in the primiparous sows.

A cross-specific multiplicative binomial recursive model for the analysis of perinatal mortality in a diallel cross among three varieties of Iberian pig

Perinatal piglet mortality is an important factor in pig production from economic and animal welfare perspectives; however, the statistical analysis of mortality is difficult because of its categorical nature. Recent studies have suggested that a binomial model for the survival of each specific piglet with a logit approach is appropriate and that recursive relationships between traits are useful for taking into account non-genetic relationships with other traits. In this study, the recursive binomial model is expanded in two directions: (1) the recursive phenotypic dependence among traits is allowed to vary among groups of individuals or crosses, and (2) the binomial distribution is replaced by the multiplicative binomial distribution to account for over or underdispersion. In this study, five recursive multiplicative binomial models were used to obtain estimates of the Dickerson crossbreeding parameters in a diallel cross among three varieties of Iberian pigs [Entrepelado (EE), Torbiscal (TT), and Retinto (RR)]. Records (10,255) from 2110 sows were distributed as follows: EE (433 records, 100 sows), ER (2336, 527), ET (942, 177), RE (806, 196), RR (870, 175), RT (2450, 488), TE (193, 36), TR (1993, 359), and TT (232, 68). Average litter size [Total Number Born (TNB)] and number of stillborns (SB) were 8.46 ± 2.27 and 0.25 ± 0.72, respectively. The overdispersion was evident with all models. The model with the best fit included a linear recursive relationship between TNB and the logit of [Formula: see text] of the multiplicative binomial distribution, and it implies that piglet mortality increases with litter size. Estimates of direct effects showed small differences among populations. The analysis of maternal effects indicated that the dams whose mothers were EE had a larger SB, while dams with RR mothers reduced the probability of born dead. The posterior estimates of heterosis suggested a reduction in SB when the sow is crosbred. The multiplicative binomial distribution provides a useful alternative to the binomial distribution when there is overdispersion in the data. Recursive models can be used for modeling non-genetic relationships between traits, even if the phenotypic dependency between traits varies among environments or groups of individuals. Piglet perinatal mortality increased with TNB and is reduced by maternal heterosis.

Influence of different sow traits on the expulsion and characteristics of the placenta in a free farrowing system

The last phase of parturition is the detachment and expulsion of the placentas and should not exceed a duration of 4 h after the birth of the last piglet. At present, only a small amount of information is available about factors influencing the expulsion of the placenta, especially in sows accommodated in free farrowing systems. This study aimed at investigating the influence of sow traits on placenta expulsion in a free farrowing system in Switzerland. In this study, 48 crossbred sows were included and the following traits of the sows were investigated: Backfat thickness, birth induction with at least 116 days of gestation with prostaglandin F2α, placenta parts and weight, placental efficiency (quotient of litter weight and placental weight) and expulsion of the first placenta part in relation to the last piglet. In addition, the farrowing process and litter parameters were recorded. The piglet expulsion duration (260.3 ± 199.5 min) and placenta expulsion duration (388.7 ± 300.2 min) were positively correlated (p = 0.001). Sows that expelled the first placenta part simultaneously with the last piglet or even before the last piglet was born showed a significantly prolonged piglet expulsion duration in comparison to sows that expelled the first placenta part after the last piglet was born (305 ± 216 min vs. 139.0 ± 34.9 min; p < 0.01). Sows with 2-4 placenta parts had a significantly shorter farrowing (292.91 ± 117.92 min) and placenta expulsion duration (160.73 ± 104.00 min) than sows with 5-7 placenta parts (634.63 ± 330.79 min farrowing duration; 460.77 ± 337.32 min placenta expulsion duration) and sows with 8-10 placenta parts (599.00 ± 138.20 min farrowing duration; 438.43 ± 117.98 min placenta expulsion duration) (p < 0.01). Sows with placental efficiency <5 were characterized by a significantly higher number of liveborn piglets compared to sows with a placental efficiency ≥5 (17.1 ± 2.7 piglets vs. 13.6 ± 2.8 piglets; p = 0.002). This is the first study that evaluated the placental characteristics in a free farrowing system and compared it with specific sow traits. Especially, the expulsion of the first placenta and the number of placenta parts could be a reliable parameter to detect sows with obstetric problems and therefore enable improvement sow and piglet health.

Effect of intramuscular and intravaginal PGE-2 treatment compared to intramuscular oxytocin treatment in eutocic sows on the farrowing performance in a free farrowing system

A duration of parturition beyond 300 min negatively impacts the health of the sow and the survival of piglets during parturition. Hence, oxytocin is widely used to speed up the parturition. However, oxytocin's negative side effects raise the need of finding alternative treatments such as those already implemented in human medicine. The aim of this study was to evaluate the efficacy of Prostaglandin E2 (PGE2) applied intravaginally (PGE2-V) (1.0 mg) or intramuscularly (PGE2-M) (2.5 mg) to improve the parturition process after expulsion of the fourth piglet compared to a placebo (P-V), which was sterile intravaginal gel or intramuscular oxytocin application (OXY-M) (20 iu) in free farrowing systems.In total, 201 eutocic sows were examined after stratification by parity and random allocation into groups: 54 (P-V), 48 (OXY-M), 50 (PGE2-V), 49 (PGE2-M). Farrowing duration (time between first piglet and last piglet), piglet interval and placenta expulsion duration (time between first and last placenta) were recorded, and each piglet was scored for meconium staining and vitality. Furthermore, stillborn piglets were categorized into ante-partum and intra-partum deaths.Under the present conditions, neither administration of PGE2 nor oxytocin revealed a significant effect on the farrowing process or the vitality of the piglets when compared to untreated sows. Nonetheless, significant differences could be detected between PGE-2 and oxytocin treatments. The duration of farrowing was significantly shorter in oxytocin-treated sows (156 min) compared to sows treated intramuscularly with PGE2 (238 min). Furthermore, the placenta expulsion duration in the OXY-M group (130 min) significantly differed from PGE2-V (198 min) and PGE2-M group (218 min). Although these accelerations of parturition might be considered as a beneficial effect, routine treatment with uterotonic agents after birth of the fourth piglet in free farrowing eutocic sows cannot be recommended, because an overall benefit when compared to untreated sows was not approved.

Risk factors associated with stillbirth of piglets born from oxytocin-assisted parturitions

Aim:

The present study aimed to investigate the effects of different risk factors on stillbirth of piglets born from oxytocin-assisted parturitions.

Materials and Methods:

Data were collected from a total of 1121 piglets born from 74 Landrace x Yorkshire crossbred sows from a herd. Logistic regression models were used to determine the associations between stillbirth and different risk factors including parity (1, 2, 3-5, and 6-10), gestation length (GL) (112-113, 114-116, and 117-119 days), litter size, birth order (BO), sex, birth interval (BI), cumulative farrowing duration, birth weight (BW), crown rump length, BW deviation, body mass index, ponderal index (PI), and the use of oxytocin during expulsive stage of farrowing.

Results:

The incidence of stillbirth at litter level and stillbirth rate was 59.5% (44/74) and 8.1% (89/1094), respectively. The final multivariate logistic regression selected BO, BI, PI, GL, and parity as the five most significant risk factors for stillbirth. Increased BO and BI, GL <114 and >116 days, parity 6-10, and low PI increased the stillbirth rate in piglets.

Conclusion:

Several factors previously determined as risks for stillbirth in exogenous oxytocin-free parturitions also existed in exogenous oxytocin-assisted parturitions. One dose of oxytocin at fairly high BO did not increase stillbirth, whereas two doses of oxytocin were potentially associated with increased values.

Sow and piglet traits associated with piglet survival at birth and to weaning

AbstractUnderstanding the relationship between sow and piglet characteristics that are associated with stillborn rate and preweaning mortality is beneficial as litter size continues to increase. Two experiments were previously conducted to evaluate prefarrowing nutrition regimens on sow and litter characteristics. These two datasets (experiments 1 and 2) were then used to identify sow and piglet characteristics associated with stillborn rate and piglet survival to weaning. A total of 1,201 sows that gave birth to 19,168 pigs comprised the dataset. The following characteristics were used in multivariate logistic regression analysis for traits associated with stillborn rate or survival to weaning: parity, litter weight, mean piglet birth weight, sow backfat, and BW at day 113 of gestation, gestation length, farrowing duration, litter size, piglet birth order, farrowing assistance, pig to teat ratio, colostrum intake, and colostrum yield. Sows within each experiment (herd) were categorized into quartiles for each of the independent variables to quantify the relationship to stillborn rate or survival to weaning. Increased stillborn rate was associated (P < 0.01) with heavier litter weights, lighter piglet birth weights, and larger litters in both experiments. In experiment 1, increased stillborn rate was associated (P < 0.01) with longer farrowing duration. Increased stillborn rate was associated with sows with less backfat depth at day 113, older parity, or increased farrowing assistance in experiment 2. In both experiments, pigs born later in the birth order had an increased (P < 0.01) risk of being stillborn. In both experiments, heavier piglet birth weight, greater colostrum intake, and lower total born were associated (P < 0.01) with increased survival to weaning. In experiment 2, pigs born in the first 75% of the litter, or in a litter with lower pig to teat ratio were associated (P < 0.01) with increased survival to weaning. Although the stillborn rate was similar between experiments (6.5% vs. 6.6%), differences in the traits associated with stillborn rate between studies indicate that some associated traits may be herd dependent. However, improving piglet birth weight, placing an emphasis on assisting pigs born later in the birth order and increasing colostrum intake will increase piglet survival from birth to weaning.

Dietary energy sources during late gestation and lactation of sows: effects on performance, glucolipid metabolism, oxidative status of sows, and their offspring1

In this study, the effects of maternal energy sources during late gestation and lactation on the performance, glucolipid metabolism, and oxidative status of sows and their offspring were investigated using a total of 75 (2 to 6 of parity) Landrace × Large White sows at day 85 of gestation under 3 different dietary treatments: SO diet (basal diet plus 3.0% and 5.0% soybean oil during late gestation and lactation, respectively), FO diet (basal diet plus 3.0%/5.0% fish oil during late gestation and lactation, respectively), and CS diet (basal diet plus 32%/42% corn starch during late gestation and lactation, respectively). All the 3 groups showed no obvious differences (P > 0.05) in the number of total piglets born, born alive, after cross-fostering, and at weaning, whereas the CS group exhibited a shorter farrowing duration (P < 0.05) and lower stillbirth rate (P < 0.05) when compared with the SO group. In addition, litter weight at birth was significantly higher in the CS group than in the SO or FO group (P < 0.05). Despite no notable differences in the ADG of suckling piglets among dietary treatments (P > 0.05), the CS group had greater feed intake than the SO group during the lactation period (P < 0.05). In neonatal piglets with normal birth weight (NBW, 1.3 to 1.5 kg), the CS group was lower than the SO group in the content of liver glycogen (P < 0.05) and the mRNA abundances of fatty acid synthase, acetyl-CoA carboxylase, fatty acid-binding protein 1, and acyl-CoA oxidase (P < 0.05). Interestingly, compared with the SO group, the FO group had a lower preweaning mortality rate (P < 0.05), but greater liver glycogen pools (P < 0.05) in neonatal piglets with low birth weight (LBW, <1.1 kg). Compared with the CS group, the FO group showed an increase in the plasma malondialdehyde levels (P < 0.05) of sows, as well as an increase of 8-hydroxy-deoxyguanosine (P < 0.05) and a decrease of ferric reducing ability of plasma (P < 0.05) in NBW piglets. Overall, the diet rich in starch decreased the stillbirth rate and increased the litter weight of neonatal piglets, the dietary supplementation with fish oil decreased preweaning mortality rate, and the diet with a low n6:n3 ratio increased the oxidative status of sows and their offspring.

Analysis of survey data of breeding herd for reproductive management practices in swine farms of Punjab

The present survey was performed to analyze standard operating procedures for swine development and fertility based on prevailing reproductive management practices among different swine farms of Punjab. The average farrowing rate, farrowing interval, weaning to estrus interval, weaning to conception interval and age at first breeding were 71.5±11.4%, 165.4±13.8 days, 8.3±2.1 days, 42.7±11.0 days and 8.1±1.3 months, respectively. Mean live litter size at birth and weaning were 9.9±3.6 and 8.1±3.3 piglets per farrowing, respectively. Most farmers (94.1%) kept pigs in loose housing system with a mixture of both stalls and pens, and used cement and brick as construction material for sties. Majority of farms (84.3%) functioned as farrow to wean with intensive production systems (75.5%). The labor to animal ratio of 1:50 was most common. Accurate and well maintained records were noticed at 66.7% farms. Start of boar exposure after weaning began within 1 day, occurring most often in morning, with exposure times varying from < 2–5 min/sow in 87.3% farms. Natural mating was allowed within minutes to hours after detection of estrus on 100% of farms. At all farms (100%), sows were allowed 􀁴1 chance for breeding after conception failure before culling. Summer infertility was observed on 56.9% of farms. Feeding method for lactating sows was divided between ad lib. and gradual daily increase of concentrate feed and kitchen waste. None of the farmer practiced docking in newborn piglets. These results suggest that reproductive management of farms in key areas related to weaning, breeding, gestation, feeding and health care could be a source of varying reproductive performance among swine.

The African strain of Zika virus causes more severe in utero infection than Asian strain in a porcine fetal transmission model

Studies in mice showed that African Zika virus (ZIKV) strains cause more damage in embryos. These studies, however, were limited to the mouse-adapted African MR766 strain or infection at early gestation. Here, we compared infection of Asian and African strains in the fetal pig model at midgestation. Both strains caused fetal infection. ZIKV was detected in placenta, amniotic membrane, amniotic fluid, fetal blood, and brain. The African strain produced more vigorous in utero infection as represented by more efficient virus transmission between siblings, and higher viral loads in fetal organs and membranes. Infection with both strains was associated with reduced fetal brain weight and increased number of placental CD163-positive cells, as well as elevated in utero interferon alpha and cortisol levels. This is the first large animal model study which demonstrated that African strain of ZIKV, with no passage history in experimental animals, can cause persistent infection in fetuses and fetal membranes at midgestation. Our studies also suggest that similar to Asian strains, ZIKV of African lineage might cause silent pathology which is difficult to identify in deceptively healthy fetuses. The findings emphasize the need for further studies to highlight the impact of ZIKV heterogeneity on infection outcomes during pregnancy.

Subclinical in utero Zika virus infection is associated with interferon alpha sequelae and sex-specific molecular brain pathology in asymptomatic porcine offspring

Zika virus (ZIKV) infection during human pregnancy may lead to severe fetal pathology and debilitating impairments in offspring. However, the majority of infections are subclinical and not associated with evident birth defects. Potentially detrimental life-long health outcomes in asymptomatic offspring evoke high concerns. Thus, animal models addressing sequelae in offspring may provide valuable information. To induce subclinical infection, we inoculated selected porcine fetuses at the mid-stage of development. Inoculation resulted in trans-fetal virus spread and persistent infection in the placenta and fetal membranes for two months. Offspring did not show congenital Zika syndrome (e.g., microcephaly, brain calcifications, congenital clubfoot, arthrogryposis, seizures) or other visible birth defects. However, a month after birth, a portion of offspring exhibited excessive interferon alpha (IFN-α) levels in blood plasma in a regular environment. Most affected offspring also showed dramatic IFN-α shutdown during social stress providing the first evidence for the cumulative impact of prenatal ZIKV exposure and postnatal environmental insult. Other eleven cytokines tested before and after stress were not altered suggesting the specific IFN-α pathology. While brains from offspring did not have histopathology, lesions, and ZIKV, the whole genome expression analysis of the prefrontal cortex revealed profound sex-specific transcriptional changes that most probably was the result of subclinical in utero infection. RNA-seq analysis in the placenta persistently infected with ZIKV provided independent support for the sex-specific pattern of in utero-acquired transcriptional responses. Collectively, our results provide strong evidence that two hallmarks of fetal ZIKV infection, altered type I IFN response and molecular brain pathology can persist after birth in offspring in the absence of congenital Zika syndrome.

A number of studies showed that Zika virus (ZIKV) can cause severe abnormalities in fetuses, e.g., brain lesions, and subsequently life-long developmental and cognitive impairment in children. However, the majority of infections in pregnant women are subclinical and are not associated with developmental abnormalities in fetuses and newborns. It is known that disruptions to the in utero environment during fetal development can program increased risks for disease in adulthood. For this reason, children affected in utero even by mild ZIKV infection can appear deceptively healthy at birth but develop immune dysfunction and brain abnormalities during postnatal development. Here, we used the porcine model of subclinical fetal ZIKV infection to determine health sequelae in offspring which did not show apparent signs of the disease. We demonstrated that subclinical fetal infection was associated with abnormal immunological responses in apparently healthy offspring under normal environmental conditions and during social stress. We also showed silent sex-specific brain pathology as represented by altered gene expression. Our study provides new insights into potential outcomes of subclinical in utero ZIKV infection. It also emphasizes that further attempts to better understand silent pathology and develop alleviative interventions in ZIKV-affected offspring should take into account interactions of host factors, like sex, and environmental insults, like social stress.

Parturition and Its Relationship with Stillbirths and Asphyxiated Piglets

Simple Summary

Piglets that experience a long labour are more likely to die during birth or immediately following birth, or to grow slowly during life. This is because the longer the piglet experiences contractions during labour, blood supply and oxygen delivery to the brain will be impaired. Even before the first piglet in the litter is born, sows that will have a delayed labour can be identified. This means that the key to saving piglets that are at risk of death because of long labours lies in managing the sow before she gives birth.

Abstract

The transition from an intra- to extrauterine existence is extremely challenging for the pig. This is evidenced by the fact that conservative estimates place intrapartum piglet death at between 5% and 10%. The main cause of this loss is the parturition process itself, with a long farrowing duration resulting in reduced oxygenation to the piglet via uterine contractions stretching, and in some cases, causing rupture of the umbilical cord. Sows that experience a long expulsive stage of parturition are likely compromised before the birth of the first piglet, and so any strategy to reduce stillbirth should be applied before this. Even in piglets born alive, 15% to 20% will have suffered asphyxiation because of a long cumulative farrowing duration. These individuals are significantly disadvantaged with regards to behavioural progression, colostrum intake, growth and survival extending past the lactation phase, and so require more labour and resources than littermates in order to make them viable. Given these immediate and longer-term impacts, identifying ways to correctly manage the sow before parturition leading to a reduction in farrowing duration should be a priority in order to maximise piglet performance.

The Course of Parturition Affects Piglet Condition at Birth and Survival and Growth through the Nursery Phase

The aim of this study was to relate the course of parturition to the condition of piglets at birth, based on umbilical cord blood acid-base values, and relate the condition at birth to neonatal survival and performance up to 10 weeks of life. Data were collected from 37 spontaneous unassisted parturitions, and neonatal performance was based on observations of 516 piglets. Stillbirth rate increased from 2% in the first piglets, to 17% in piglets born 13th in the litter or later. This was aggravated in sows with longer than average stage II of parturition. Umbilical cord blood values also reflected the effect of birth order, with pH decreasing and lactate increasing in the course of parturition. Interestingly, sows that had a long expulsion stage of parturition also took longer to give birth to the first four piglets (r = 0.74), suggesting that sows with complicated parturition were already experiencing problems at the start of expulsion of piglets. Piglets with signs of asphyxia, based on umbilical blood lactate higher than 4.46 mmol/L, were slower to start suckling, had a higher risk of neonatal mortality, and had a slower growth rate over the first 10 weeks of life.

Zika Virus Causes Persistent Infection in Porcine Conceptuses and may Impair Health in Offspring

Outcomes of Zika virus (ZIKV) infection in pregnant women vary from the birth of asymptomatic offspring to abnormal development and severe brain lesions in fetuses and infants. There are concerns that offspring affected in utero and born without apparent symptoms may develop mental illnesses. Therefore, animal models are important to test interventions against in utero infection and health sequelae in symptomatic and likely more widespread asymptomatic offspring. To partially reproduce in utero infection in humans, we directly inoculated selected porcine conceptuses with ZIKV. Inoculation resulted in rapid trans-fetal infections, persistent infection in conceptuses, molecular pathology in fetal brains, fetal antibody and type I interferon responses. Offspring infected in utero showed ZIKV in their fetal membranes collected after birth. Some in utero affected piglets were small, depressed, had undersized brains, and showed seizures. Some piglets showed potentially increased activity. Our data suggest that porcine model of persistent in utero ZIKV infection has a strong potential for translational research and can be used to test therapeutic interventions in vivo.

Risk factors associated with the different categories of piglet perinatal mortality in French farms

We aimed to identify mortality patterns and to establish risk factors associated with different categories of piglet perinatal mortality in French farms. At farm level, the analyses were performed on data from 146 farms that experienced perinatal mortality problems. At piglet level, the analyses were performed on data from 155 farms (7761 piglets). All data were collected over a period of 10 years (2004-14) by a consulting company, using a non-probability sampling at farm level and a random sampling at sow level. Six main categories of mortality, determined by standardised necropsy procedure, represented 84.5% of all the perinatal deaths recorded. These six categories were, in order of significance: Death during farrowing, Non- viable, Early sepsis, Mummified, Crushing and Starvation. At farm level, the percentage of deaths due to starvation was positively correlated to the percentage of deaths due to crushing and the percentage of deaths during farrowing (r>0.30, P<0.05) .The percentage of deaths due to crushing was negatively correlated to the percentage of deaths due to early sepsis (r<-0.30, P<0.05) and positively correlated to the deaths due to acute disease (r>0.30, P<0.05). Patterns of perinatal mortality at farm level were identified using a principal component analysis. Based on these, the farms could be classified, using ascending hierarchical classification, into three different clusters, highlighting issues that underlie farm differences. Risk factors were compared at piglet level for the different categories of death. Compared to other categories of death, deaths during farrowing were significantly fewer during the night than during the day. Compared to other categories of death, the likelihood of non-viable piglets tended to be higher in summer than other seasons. A smaller number of deaths in the litter was also identified for the piglets classified as non-viable or mummified. For the six main categories of perinatal mortality, the piglets which died from a specific category tended to have more littermates which died from the same category. Parity and litter size also had more significant effects on certain categories of death compared to others. The study provides novel information on the risk factors associated with specific categories of piglet perinatal mortality. The classification of farms into the 3 different clusters could lead to a more targeted management of perinatal mortality on individual farms.

Sow-level risk factors for stillbirth of piglets in organic sow herds

In Danish organic pig production, one-third of total born piglets die before weaning, and stillbirth has previously crudely been estimated to account for 27% of the total preweaning mortality. The objective of this study was to evaluate season, litter size, parity and body condition of the sow as risk factors for stillbirth in nine commercial Danish organic pig herds. The study was conducted over a 1-year period, and the data included registrations on 5170 farrowings with 82 906 total born piglets. The average number of total born piglets per litter was 16.0, and the number of stillborn piglets per litter was 1.1. A significant effect of season was seen with an odds ratio for stillbirth of 1.15 during summer (May to August) compared with the remaining part of the year. A non-linear effect of litter size was seen where an increase in litter size from 11 to 16 resulted in an odds ratio of stillbirth of 1.11. An increase in litter size from 16 to 21 resulted in an odds ratio of stillbirth of 1.45. A significant interaction between body condition and parity was present. In first parity sows, an increase in body condition score from 2 (thin) to 3 (moderate) and from 3 to 4 (fat) increased the probability of stillbirth with an odds ratio of 1.23 and 1.36, respectively. In sows with parity above 4, an increase in body condition score from 2 to 3 and from 3 to 4 decreases the probability of stillbirth with an odds ratio of 0.68 and 0.79, respectively. In conclusion, increasing litter size and being born during the summer months of May to August were found to be risk factors for stillbirth. Furthermore, an interaction between body condition and parity showed that thin sows with parity above 4 had a substantially increased risk of stillbirth compared with normal and fat sows with parity above 4. In contrast, for parity 1 sows risk of stillbirth was increased in fat sows.

Postmortem findings in cloned and transgenic piglets dead before weaning

Important factors contributing to the well-known high mortality of piglets produced by SCNT are gross malformations of vital organs. The aim of the present retrospective study was to describe malformations found in cloned piglets, transgenic or not, dying or culled before weaning on Day 28. Large White (LW) embryos were transferred to 78 LW recipients, while 72 recipients received Göttingen embryos (67 transgenic and five not transgenic) and 56 received Yucatan embryos (43 transgenic and 13 not transgenic). Overall pregnancy rate was 76%, and there were more abortions in recipients with minipig embryos than in those with LW embryos (26% and 24% vs. 6%). Piglets (n = 815) were born from 128 sows with 6.5 ± 0.4 full-born piglets per litter. The overall rate of stillborn piglets was 21% of all born with the number of stillborn piglets ranging from one to nine in a litter. The mortality of the surviving piglets during the first month was 48%. Thus, altogether 58% of the full-born piglets died before weaning. In 87 of the 128 litters (68%), one to 12 of the piglets showed major or minor malformations. Malformations were found in 232 piglets (29.5% of all born). A single malformation was registered in 152 piglets, but several piglets showed two (n = 58) or more (n = 23) malformations (7.4% and 2.8% of all born, respectively). A significantly higher malformation rate was found in transgenic Göttingen and Yucatan piglets (32% and 46% of all born, respectively) than in nontransgenic LW (17%). There was a gender difference in the transgenic minipigs because male piglets had a higher rate of malformations (49.1%) than females (29.7%). The most common defects in the cloned piglets were in the digestive (12.2%), circulatory (9.4%), reproductive (11.3%), and musculoskeletal (9.1%) systems. Malformations of the musculoskeletal system were most frequent in Göttingen (16.3% vs. approximately 5.5% in the two other breeds), whereas abnormal cardiopulmonary systems were most frequent in Yucatan piglets (26.9% vs. 2.1% in LW and 5.3% in Göttingen). In conclusion, these results show that pig cloning results in a considerable loss of piglets and that many of these can be related to various malformations that all are also seen in noncloned piglets. Because approximately half of the cloned piglets still survive, even with eventual unknown minor malformations, use of pigs as models for human diseases is still realistic. However, continued efforts are needed to further reduce the level of malformations.

Post-mortem findings and piglet mortality in relation to strategic use of straw at farrowing

Piglet survival is the outcome of complex interactions between the sow, the piglet and their environment. In order to facilitate nest-building and to provide a suitable environment for the newborn piglets, a strategic method to supply loose housed sows with large quantities of straw at farrowing has been developed by Swedish piglet-producing farmers. The objectives of this cohort study were to use post-mortem findings to assess the causes of death and to quantify the effect of a large quantity of straw provided before farrowing compared to limited small daily amounts on stillbirths, post-mortem findings in piglets dying within 5 days after birth and the pre-weaning mortality. On each of four commercial piglet-producing farms in South-West Sweden, one batch of sows was studied during two consecutive lactations. At inclusion, sows were randomly assigned to two treatment groups, and sows remaining in the batch during the next lactation switched treatment group. In the STRAW group (n=181 litters) sows were provided with 15-20 kg of chopped straw 2 days prior to the calculated date of farrowing. Sows in the CONTROL group (n=182 litters) received 0.5-1 kg of chopped straw on a daily basis plus about 2 kg for nest-building when the stockperson judged the sow to be about to farrow. After onset of farrowing, additionally 1-2 kg was given. Post-mortem examination was performed in all piglets that died within 5 days after birth (n=798). The three major post-mortem findings were starvation (34%) crushing by the sow (28%), and enteritis (24%). In conclusion, strategic use of large quantities of straw reduced the number of stillborn piglets per litter by 27% (p=0.007). Under the conditions studied, the pre-weaning mortality of liveborn piglets was not affected by treatment; however, the distribution of post-mortem findings differed with fewer piglets dying due to starvation and more due to crushing and enteritis in STRAW litters.

Case-control study evaluating the sow's risk factors associated with stillbirth piglets in Midwestern in Brazil

Reproductive failure in swine herds is often difficult to diagnose and is important to swine production. The present study aims to identify the potential risk factors (infectious/noninfectious) for stillborn piglets in two commercial swine farms situated in midwestern region of Brazil. The potential risk factors were included in a multivariable logistic model, and the dependent variable was defined as the presence of at least one stillborn piglet in a given litter (yes or no). In the best fit model, two variables from the multivariable analysis, total litter size (p = 0.01), and average birth weight (p = 0.03) were significantly associated with the presence of stillborn piglets at the farms examined in this study. Porcine circovirus type 2 (PCV2) was detected in 29.1 % of the litters. Neither parvovirus (PPV) nor leptospirosis infections were identified in this study, suggesting that they have a minor impact on reproductive disease.

Invited review: piglet mortality: management solutions

Preweaning mortality varies greatly among herds and this is partly attributed to differences in farrowing house management. In this review, we describe the various management strategies than can be adopted to decrease mortality and critically examine the evidence that exists to support their use. First, we consider which management procedures are effective against specific causes of death: intrapartum stillbirth, hypothermia, starvation, disease, crushing, and savaging. The most effective techniques include intervention to assist dystocic sows, measures to prevent and treat sow hypogalactia, good farrowing house hygiene, providing newborn piglets with a warm microenvironment, early fostering of supernumerary piglets, methods that assist small and weak piglets to breathe and obtain colostrum, and intervention to prevent deaths from crushing and savaging. The provision of nest-building material and modifications to the pen to assist the sow when lying down may also be beneficial, but the evidence is less clear. Because most deaths occur around the time of farrowing and during the first few days of life, the periparturient period is a particularly important time for management interventions intended to reduce piglet mortality. A number of procedures require a stockperson to be present during and immediately after farrowing. Second, we consider the benefits of farrowing supervision for preweaning mortality in general, focusing particularly on methods for the treatment of dystocia and programs of piglet care that combine multiple procedures. Third, we discuss the need for good stockmanship if farrowing supervision is to be effective. Stockmanship refers not only to technical skills but also to the manner in which sows are handled because this influences their fearfulness of humans. We conclude that piglet survival can be improved by a range of management procedures, many of which occur in the perinatal period and require the supervision of farrowing by trained staff. Although this incurs additional labor costs, there is some evidence that this can be economically offset by improved piglet survival.

Non-infectious factors associated with stillbirth in pigs: a review

The main objective of this review is to provide current information regarding non-infectious risk factors associated with stillborn piglets. These factors can be roughly categorized as genetic, maternal, piglet and environmental factors, but also interactions exist between several factors. An understanding of this multifactorial problem should help practitioners and farmers implementing a more effective farrowing management to obtain a high reproductive efficiency. From the papers studied in this review, it can be concluded that litter size, parity, sow's body condition and farrowing supervision/birth assistance seems to be the most relevant risk factors associated with stillborn piglets.

Piglet mortality: the impact of induction of farrowing using prostaglandins and oxytocin

Induction is usually carried out by administering prostaglandins (prostaglandin F2α or a synthetic analogue). Other hormones, most commonly oxytocin, may also be given. The primary objective is to increase the synchrony of farrowing. This facilitates farrowing supervision, early fostering and 'all in, all out' management of the farrowing house, all of which have the potential to decrease piglet mortality. However, there are also risks, including decreased piglet viability when farrowing is induced too early and an increased probability of dystocia associated with oxytocin use. What are the effects of induction procedures on mortality in pigs? With respect to prostaglandins, studies show that the date of induction and the level of supervision provided are important factors affecting piglet mortality. We recommend administering prostaglandins no earlier than 2d before the expected farrowing date for the herd. Some studies have reported that prostaglandin induction decreases stillbirth and live-born mortality and this is probably due to increased farrowing supervision. The incidence of postpartum dysgalactia syndrome is also decreased in herds with a high prevalence of this condition. Inconsistent effects on the progress of farrowing are reported following the routine administration of oxytocin 20-24h after prostaglandin. Although there is generally no effect on stillbirth rate, dystocia may increase. Earlier administration of low doses may decrease stillbirths, but this requires further research. Carbetocin, a long-acting analogue of oxytocin, is a possible alternative. We recommend that prostaglandin induction be used in conjunction with skilled farrowing supervision to decrease piglet mortality.

Genetic parameters and phenotypic trends in the mean and variability of number of stillborn piglets and changes in their relationships with litter size and gestation length

This study examined changes in genetic and phenotypic factors affecting stillborn piglets (SB). Over 15 years, 76 851 litter records were available from Large White (LW), Landrace (LR) and Duroc (DU) sows to investigate SB. The analyses focussed on trends over time in SB and the changes in the number of SB per litter, in factors associated with SB and in genetic parameters for SB. Breed differences were identified with DU producing more SB than the white breeds (mean of 1.46 ± 0.02 vs 1.11 ± 0.01 and 1.07 ± 0.01). However, maximum differences between levels of each factor were 0.73 and 0.65 SB for parity and herd, respectively. Over the 15 years studied, SB had increased by 0.2 piglets accompanied by an increase in the total numbers of piglets born per litter (TB) of ~0.5 piglets. This increase in SB was driven by higher occurrence of more than two SB within a single litter. The effect of TB on SB changed over time with solutions of 0.127 ± 0.002 and 0.150 ± 0.002 SB/TB in 1996 and 2010, respectively. Heritability estimates for SB ranged from 0.06 ± 0.01 to 0.09 ± 0.01 for alternative models and time periods. The unfavourable genetic correlation between SB and TB of 0.46 ± 0.03 based on all data available was slightly lower using only data from the first 5 years (0.38 ± 0.07) versus using data from the last 5 years (0.46 ± 0.06). However, this increase in phenotypic and genetic associations between SB and TB over time may be larger in populations that have observed a larger increase in TB.

Anaemia in the sow: a cohort study to assess factors with an impact on haemoglobin concentration, and the influence of haemoglobin concentration on the reproductive performance

The aim of this study was to conduct a descriptive study of haemoglobin concentration found on high-prolificacy sows, to study the relationship between the concentration of haemoglobin and body reserves, and to determine whether anaemia is a risk factor for reproductive performance. A cohort of 308 sows from seven farms was followed from the last third of gestation to the confirmation of the following gestation. Haemoglobin concentration was assessed at four stages of the reproductive cycle: seven and four weeks before farrowing, a few days and three weeks after farrowing. Backfat thickness (BFT) was measured at parturition. The results were analysed using linear mixed-effect models. The mean haemoglobin concentration was 108.4 g/l. The mean modellised haemoglobin concentration of parity 1 sows with a BFT of 16 mm, sampled seven weeks before farrowing, was 118 g/l. Haemoglobin concentration of sows of parity 6 or higher was 8.0 g/l lower than those of parity 1 sows (95% confidence interval -11.0 to -5.1). Haemoglobin concentration is lower in sows with a lower BFT, whatever parity rank. There is no evidence of a relation between haemoglobin concentration and the number of total born, stillborn or number of piglets alive at three weeks and the next breeding performance.