Effects of Two Different Methods of Teeth Grinding on Dental Injuries, Skin Lesions, Growth and Behaviour of Suckling Piglets Compared to a Non-Treated Control Group

Teeth grinding in suckling piglets is performed on many farms to protect the piglets' littermates and the sow's udder from injuries caused by the piglets' canines and third incisors. In this study, the effects of two teeth-grinding methods on the piglets' dental health and welfare were investigated. The piglets of a litter were evenly assigned to a treatment: one-third of littermates were ground with a roller grinding head (RG), one-third with a teacup grinding head (TCG), and one-third were not ground at all (CG). A random sample of 100 animals each from the RG and TCG treatment was examined for tooth injuries, i.e., dental pulp openings. Additionally, behavioural analysis was performed (n = 650 piglets), and skin lesions, growth and mortality were determined (n = 1565 piglets). TCG piglets had a lower risk (p < 0.001) of pulp opening than RG piglets (0.08 ± 0.31 vs. 2.67 ± 1.67 opened pulps per piglet). Mortality, growth, skin lesions and behaviour of piglets were not influenced by treatment (p > 0.05). This study showed that both teeth-grinding methods led to pulp openings. If teeth grinding cannot be avoided on a farm, using the teacup grinding head is recommended concerning animal health and welfare.

Investigation of supplementation with a combination of fermented bean dregs and wheat bran for improving the growth performance of the sow

To investigate the effect of dietary supplementation with a fermented mixture of bean dregs and wheat bran (FBW) on sow performance. FBW was given to sows during late gestation and lactation; in total, 24 sows were randomly assigned to 4 groups (control diet; 3% FBW diet; 6% FBW diet; 9% FBW diet, n = 6). The weight ratio of bean dregs (wet) to wheat bran was 4:6. Sows were fed different diets from 85 d of gestation until weaning. The results showed that supplementation with FBW increased average daily feed intake (ADFI) during lactation (p < 0.05). FBW supplementation also increased litter weight and milk yield (p < 0.05). The contents of Escherichia coli in the feces of the treatment groups were significantly reduced by FBW supplementation (p < 0.01). FBW supplementation significantly improved the fecal morphology (p < 0.05), alleviating sows' constipation. In conclusion, FBW could increase the ADFI, improve lactation and piglet litter weight in sows and reduce the pathogenic bacterial content in sow feces and constipation.

Effects of the Mean Weight of Uniform Litters on Sows and Offspring Performance

This study aimed to determine the effects of uniform litters of different mean birth weights on colostrum production of sows and piglets performance. The study involved 98 multiparous sows from a commercial lean genotype and their piglets. Simultaneous farrowing were supervised and the piglets were divided into experimental litters of 12 piglets each of heterogenous litters (HET, CV = 23.8%, n = 20), uniform light litters (ULL, CV = 9.8%, n = 27), uniform average litters (UAL, CV = 8.2%, n = 23) or uniform heavy litters (UHL, CV = 8.6%, n = 28) piglets and allowed to suckle. Piglets were re-weighed at 24 h and 21 d of life and deaths registered. Colostrum intake (CI) of the piglets and sow's colostrum yield (CY) was estimated using two prediction equations. Significant differences (p < 0.001) were observed in the CY of sows being higher in UHL, lower in ULL and intermediary in HET and UAL litters. CY was positively related to litter total weight at birth and litter weight gain in the first 24 h (p < 0.001). The CI differ between litter type being higher in UHL litters and lower in ULL litters. The coefficient of variation of CI in HET litters was higher than in uniform litters, regardless of their type. The mortality rate of piglets until 21 d was globally 9.6% and it was significantly higher in HET than in UAL (p = 0.033) and tended to be higher than in UHL litters (p = 0.052). No differences in piglet survival were observed between uniform litters. Results show the beneficial effect of uniformity in piglet survival and that the mean weight of uniform litter influences colostrum intake and piglet performance.

The impact of in vitro embryo production on placental and umbilical cord vascularization is minimized by the addition of reproductive fluids

Animals born from in-vitro-produced (IVP) embryos show changes in the placenta and umbilical cord vascularization. This study compares the placental and umbilical vascular morphometry in pigs (n = 19) born through artificial insemination (AI group) or after transfer of IVP embryos cultured with (RF-IVP group) or without (C-IVP group) reproductive fluids. The relationship between vascular parameters and animal growth during the first year of life was also analyzed. Samples were collected at birth, fixed, paraffin-embedded, cut in sections, stained, and photographed for vascular and morphometric analysis with ImageJ® and Slide Viewer®. The average daily weight gain was individually scored from birth to the first year of life. No differences were found in placental vascular morphometry among groups, except for the vascular area of small vessels (arterioles, venules, and small vessels) that was higher in the C-IVP group. Regarding the umbilical cord, the values for perimeter (AI: 26.40 ± 3.93 mm; IVP: 30.51 ± 4.74 mm), diameter (AI: 8.35 ± 1.01 mm; IVP: 10.26 ± 1.85 mm), area (AI: 43.18 ± 12.87; IVP: 56.61 ± 14.89 mm2), and Wharton's jelly area (AI: 36.86 ± 12.04 mm2; IVP 48.88 ± 12.80 mm2) were higher in IVP-derived than AI-derived animals, whereas arterial and venous morphometric data were similar between groups. A correlation study showed that placental and umbilical cord vascular phenotypes affect the further growth of pigs. In conclusion, assisted reproductive technologies impact small caliber vessels in the placenta and morphometric parameters in the umbilical cord. The addition of reproductive fluids in IVP-embryo contributes to reduce the differences with in vivo-derived animals.

Sow Nutrition, Uterine Contractions, and Placental Blood Flow during the Peri-Partum Period and Short-Term Effects on Offspring: A Review

The birth process is a crucial event for piglet survival. Along with increasing litter sizes, not only has the duration of parturition increased, but placental blood flow per piglet has reduced and placental area per piglet has become smaller, making these piglets more susceptible for hypoxia. Diminishing the risk of piglet hypoxia by either reducing the total duration of parturition or increasing fetal oxygenation may reduce the incidence of stillbirth and early post-partum mortality. This review discusses options to do so by nutritionally supporting the sow in the final pre-partum period, after discussing the role of uterine contractions and placental blood flow. Providing sufficient energy seems to be a logical first step, but also other nutrients needed for uterine contractions, such as calcium, or enhancing uterine blood flow by using nitrate seem promising. These nutrient requirements may depend on litter size.

Pen Versus Crate: A Comparative Study on the Effects of Different Farrowing Systems on Farrowing Performance, Colostrum Yield and Piglet Preweaning Mortality in Sows under Tropical Conditions

The present study was performed to determine the farrowing performance of sows, newborn piglet characteristics, colostrum yield, milk yield and piglet preweaning mortality in a free-farrowing pen compared to a conventional farrowing crate system in a tropical environment. A total of 92 sows and 1344 piglets were included in the study. The sows were allocated by parity into two farrowing systems, either a free-farrowing pen (n = 54 sows and 805 piglets) or a crate (n = 38 sows and 539 piglets). Backfat thickness and loin muscle depth of sows at 109.0 ± 3.0 days of gestation were measured. Reproductive performance data including total number of piglets born (TB), number of piglets born alive (BA), percentage of stillborn piglets (SB) and percentage of mummified foetuses (MF) per litter, farrowing duration, piglet expulsion interval, time from onset of farrowing to the last placental expulsion, piglet preweaning mortality rate, percentage of piglets crushed by sows and number of piglets at weaning were analysed. In addition, piglet colostrum intake, colostrum yield, Brix index and milk yield of sows were evaluated. On average, TB, BA, farrowing duration, colostrum yield and milk yield during 3 to 10 and 10 to 17 days of lactation were 14.7 ± 2.8, 12.8 ± 3.1, 213.2 ± 142.2 min, 5.3 ± 1.4 kg, 8.6 ± 1.5 kg, and 10.4 ± 2.2 kg, respectively. Sows kept in the free-farrowing pen tended to produce more colostrum than crated sows (5.5 ± 0.2 vs. 4.9 ± 0.2 kg, p = 0.080). Piglets born in the free-farrowing pen had a higher colostrum intake than those in the crate system (437.0 ± 6.9 and 411.7 ± 8.3 g, p = 0.019). However, the piglet preweaning mortality rate (26.8 ± 2.9 vs. 17.0 ± 3.8, p = 0.045) and the proportion of piglets crushed by sows (13.1 ± 2.1 vs. 5.8 ± 2.7, p = 0.037) in the free-farrowing pen were higher than those in the crate system. Interestingly, in the free-farrowing pen, piglet preweaning mortality rate in sows with high backfat thickness was higher than that in sows with moderate (37.8 ± 5.1% vs. 21.6 ± 3.6%, p = 0.011) and low (21.0 ± 6.2%, p = 0.038) backfat thickness. Moreover, the incidence of crushing in sows with high backfat thickness was higher in the free-farrowing pen than in the crate system (17.6 ± 3.6 vs. 4.0 ± 5.7, p = 0.049), but this difference was not detected for sows with moderate and low backfat thickness (p > 0.05). Milk yield of sows during 3 to 10 days (8.6 ± 0.2 vs. 8.6 ± 2.3, p > 0.05) and 10 to 17 days (10.2 ± 0.3 vs. 10.4 ± 0.4, p > 0.05) did not differ between the two farrowing systems. In conclusion, piglets born in the free-farrowing pen had a higher colostrum intake than those in the crate system. However, the piglet preweaning mortality rate and the proportion of piglets crushed by sows in the free-farrowing pen were higher than in the crate system. Interestingly, a high proportion of piglet preweaning mortality in the free-farrowing system was detected only in sows with high backfat thickness before farrowing but not in those with low and moderate backfat thickness. Therefore, additional management in sows with high backfat thickness (>24 mm) before farrowing should be considered to avoid the crushing of piglets by sows.

Intrinsic challenges of neonatal adaptation in swine

Abstract. The losses of piglets in commercial pig farming remain at concerning levels and need to be addressed through the implementation of new sustainable breeding and management strategies. In fact, piglets are especially at risk in the first days of life. Both genetics and the farrowing process have been shown to impact piglet vitality. In addition, knowledge of the animal-intrinsic responses in adapting to extra-uterine life is particularly important but is scarcely described in the scientific literature. In this review, the three phases that constitute neonatal adaptation in the pig are systematically presented. The first phase of early adaptation involves primarily the development of cardiorespiratory function (within the first 10 min of life) as well as thermoregulatory processes and acid–base balance (up to 24 h of life). In the second phase, homeostasis is established, and organ maturation takes place (up to 14 d post natum). The final third phase aims at the development of neurological, immunological and muscular features (up to 28 d of life). The involvement of aggravating and ameliorating factors such as dystocia, low colostrum yield and heat supply is key to the development of strategies to reduce piglet losses and increase vitality. The insights are of particular value in addressing current concerns in pig farming and to further improve animal welfare in pig production across different management types.

Review: Improving the performance of neonatal piglets

Newborn piglets have a high incidence of preweaning mortality that is not only associated with low birth weights but also with the presence of intra-uterine growth-restricted (IUGR) piglets. Such IUGR piglets are commonly seen in litters from hyperprolific sows as a result of insufficient placental transfer of nutrients. Nutritional strategies can be used prior to and during gestation to enhance foetal development and can also be implemented in the transition period to reduce the duration of farrowing and increase colostrum yield. Recent findings showed that the energy status of sows at the onset of farrowing is crucial to diminish stillbirth rate. Newborn piglets often fail to consume enough colostrum to promote thermostability and subsequent growth, and this is particularly problematic in very large litters when there are fewer available teats than the number of suckling piglets. One injection of 75 IU of oxytocin approximately 14 h after farrowing can prolong the colostral phase, hence increasing the supply of immunoglobulins to piglets. Nevertheless, assistance must be provided to piglets after birth in order to increase their chance of survival. Various approaches can be used, such as: (1) optimising the farrowing environment, (2) supervising farrowing and assisting newborn piglets, (3) using cross-fostering techniques, (4) providing nurse sows, and 5) providing artificial milk. Although research advances have been made in developing feeding and management strategies for sows that increase performance of their newborn piglets, much work still remains to be done to ensure that maximal outcomes are achieved.

Disentangling Litter Size and Farrowing Duration Effects on Piglet Stillbirth, Acid-Base Blood Parameters and Pre-Weaning Mortality

The current study evaluated interactions between farrowing duration and litter size on the level of asphyxia, vitality, percentage of stillbirth, and pre-weaning mortality of piglets. Farrowing duration was measured in 159 crossbred gilts and sows (Yorkshire × Dutch Landrace). Litter size ranged between 12 and 21 piglets. Blood acid–base parameters in umbilical cord blood and vitality scores of piglets were determined immediately after birth. Number of piglets born alive and stillborn as well as individual piglet weights at birth were recorded. Pre-weaning mortality (excluding stillbirth) was determined throughout lactation. Litter size as well as farrowing duration were categorized to evaluate the interaction between the two. There tended to be an interaction between litter size and farrowing duration for pre-weaning mortality (p = 0.10). In small litters (12–15 piglets), a prolonged farrowing duration (>250 min) tended to increase pre-weaning mortality compared with a short (<150 min) and medium farrowing duration (150–250 min), while for large litters (19–21 piglets), a medium to long farrowing duration tended to decrease pre-weaning mortality. No other interactions between litter size and farrowing duration were found. Piglets within large litters showed a higher umbilical cord lactate level (p < 0.01), lower average vitality score (p = 0.01), and a higher stillborn percentage (p < 0.01) compared with piglets within medium size (16–18 piglets) and small litters. Each additional piglet born to a litter linearly decreased average piglet birth weight (17.6 g, p < 0.01), increased farrowing duration (11 min, p < 0.01), and increased stillbirth (0.5%, p = 0.04). A medium farrowing duration resulted in a lower stillborn percentage compared with a short or prolonged farrowing duration, suggesting that farrowing duration might have an optimum. When analyzed linearly, stillborn percentage increased with 1.85% per every 100 min (p < 0.01) of farrowing duration. It can be concluded that both litter size and farrowing duration affect stillborn percentage, but independent from each other. However, these two factors tended to interact regarding pre-weaning mortality, suggesting that setting a certain threshold for maximal farrowing duration should be taken with care, because this appears to depend on litter size.

Piglet Morphology: Indicators of Neonatal Viability?

The morphological measures, crown-to-rump length (CR), and abdominal circumference (AC) have been suggested to be as good, if not better, than birth weight for predicting piglet performance. We explored the relationships between CR and AC, and piglet weights at birth and 24 h, to investigate their predictive value for piglet survival. Piglet weight and AC at birth and 24 h, and CR at 24 h were recorded for 373 piglets born to 31 sows. Morphological measures were categorised into two levels for weight and three levels for AC and CR. Further, AC and CR groupings were concatenated to create a new variable (PigProp) to describe the proportionality of piglet morphology. Proportionate piglets had equal CR and AC levels, and disproportionate piglets had contrasting levels. Birth AC was a good predictor of colostrum intake (p < 0.001) when accounting for birth weight, but 24 h weight and PigProp were good indicators of actual colostrum intake (p < 0.001 for both). The significant interaction of colostrum and PigProp showed that within the smaller piglet groups, those who had greater than 200 g of colostrum had higher 24 h weight and survival (p < 0.001 both). As expected, as body weight and colostrum intake increased, so did weight change to d 21 (P = 0.03 and trend at p = 0.1, respectively). A similar pattern was seen with increasing PigProp group (p < 0.001); however, piglets from the disproportionate group 1,3 had the greatest observed weight change (5.15 ± 0.06 kg). Our data show morphological measures may be more predictive of piglet viability in terms of both performance and survival than weight and there may be subgroups that have higher than expected chances of survival.

Microorganisms in the reproductive system and probiotic's regulatory effects on reproductive health

The presence of microbial communities in the reproductive tract has been revealed, and this resident microbiota is involved in the maintenance of health. Intentional modulation via probiotics has been proposed as a possible strategy to enhance reproductive health and reduce the risk of diseases. The male seminal microbiota has been suggested as an important factor that influences a couple’s health, pregnancy outcomes, and offspring health. Probiotics have been reported to play a role in male fertility and to affect the health of mothers and offspring. While the female reproductive microbiota is more complicated and has been identified in both the upper and lower reproductive systems, they together contribute to health maintenance. Probiotics have shown regulatory effects on the female reproductive tract, thereby contributing to homeostasis of the tract and influencing the health of offspring. Further, through transmission of bacteria or through other indirect mechanisms, the parent’s reproductive microbiota and probiotic intervention influence infant gut colonization and immunity development, with potential health consequences. In vitro and in vivo studies have explored the mechanisms underlying the benefits of probiotic administration and intervention, and an array of positive results, such as modulation of microbiota composition, regulation of metabolism, promotion of the epithelial barrier, and improvement of immune function, have been observed. Herein, we review the state of the art in reproductive system microbiota and its role in health and reproduction, as well as the beneficial effects of probiotics on reproductive health and their contributions to the prevention of associated diseases.

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 Dietary Modified Bazhen on Reproductive Performance, Immunity, Breast Milk Microbes, and Metabolome Characterization of Sows

Bazhen is a classic prescription used for the prevention of qi and blood deficiency. The present study aimed to investigate the effects of dietary supplementation with modified Bazhen powder (MBP) on sows during lactation. Forty pure-bred Yorkshire sows on day 100 of gestation were randomly fed a standard diet supplemented with 20 g MBP per sow per day (MBP group) or without (control group) during -14 to 7 days relative to parturition. Results showed that the serum levels of interleukin 2 (IL-2), immunoglobulin A (IgA), and IgG were higher, whereas IL-10 level was lower in sows fed with MBP diet than in controls on day 7 postpartum. A significantly elevated proportion of serum CD4⁺ T cells and a slight increase in the ratio of CD4⁺ to CD8⁺ T cells in the MBP group were also observed. Furthermore, MBP supplementation improved gastrointestinal function of postpartum sows, evidenced by increased levels of motilin, gastrin, and nitric oxide. Ultra high-performance liquid chromatography combined with a quadrupole time of flight and tandem mass spectrometer identified a total of 21 absorbed milk components. 16S rRNA gene amplicon sequencing data revealed that the microbiota diversity of the colostrum and transitional milk in the MBP group was increased. At the genus level, relative abundances of Enterococcus and Anaerostipes were significantly lower in the MBP group on day 0 of lactation. Metabolomic analysis showed that 38 metabolites were upregulated, and 41 metabolites were downregulated in the transitional milk; 31 metabolites were upregulated and 8 metabolites were downregulated in the colostrum in response to MBP. Metabolic pathways, protein digestion and absorption, and biosynthesis of amino acids were enriched in the colostrum and transitional milk. Our findings provide new insights into the beneficial effects of MBP, highlighted by the changes to the microbiota and metabolomic profile of breast milk from sows fed with an MBP-supplemented diet. Thus, MBP should be considered as a potential dietary supplement for lactating sows in pork production.

Piglet Viability: A Review of Identification and Pre-Weaning Management Strategies

Simple Summary

Neonatal piglet viability is decreasing in concert with the selection for ever-greater numbers of piglets born per sow per year. Their survival depends on the early intervention and management strategies used by production staff. This paper will review current and novel methods used to identify these piglets, some of the factors affecting their viability, and management strategies commonly used within production systems to improve their survival.

Abstract

Increased attention on the effects of the global push for a larger litter size has focused on the increased occurrence of piglets with decreased viability, which have lighter birthweights and a reduced ability to thrive in early life. To improve their odds of survival, interventions must be timely and targeted. This requires the early identification of low-viability pigs and appropriate strategies to manage them. Using novel measures such as abdominal circumference and crown to the rump length in conjunction with birth weight may provide an improved protocol for the identification of those at most risk of preweaning mortality. Further, identifying these at-risk piglets allows interventions to increase their colostrum intake and heat provisions shortly following birth. The appropriate management of the pre- and post-partum sows will improve the chances of decreasing the number of piglets born with lower viability. However, this outcome is constrained by limitations in resources such as technology and staffing. If these challenges can be overcome, it will allow for greater control and increased effectiveness in the implementation of current and new management strategies.

Investigating pig survival in different production phases using genomic models

Pig survival is an economically important trait with relevant social welfare implications, thus standing out as an important selection criterion for the current pig farming system. We aimed to estimate (co)variance components for survival in different production phases in a crossbred pig population as well as to investigate the benefit of including genomic information through single-step genomic best linear unbiased prediction (ssGBLUP) on the prediction accuracy of survival traits compared with results from traditional BLUP. Individual survival records on, at most, 64,894 crossbred piglets were evaluated under two multi-trait threshold models. The first model included farrowing, lactation, and combined postweaning survival, whereas the second model included nursery and finishing survival. Direct and maternal breeding values were estimated using BLUP and ssGBLUP methods. Furthermore, prediction accuracy, bias, and dispersion were accessed using the linear regression validation method. Direct heritability estimates for survival in all studied phases were low (from 0.02 to 0.08). Survival in preweaning phases (farrowing and lactation) was controlled by the dam and piglet additive genetic effects, although the maternal side was more important. Postweaning phases (nursery, finishing, and the combination of both) showed the same or higher direct heritabilities compared with preweaning phases. The genetic correlations between survival traits within preweaning and postweaning phases were favorable and strong, but correlations between preweaning and postweaning phases were moderate. The prediction accuracy of survival traits was low, although it increased by including genomic information through ssGBLUP compared with the prediction accuracy from BLUP. Direct and maternal breeding values were similarly accurate with BLUP, but direct breeding values benefited more from genomic information. Overall, a slight increase in bias was observed when genomic information was included, whereas dispersion of breeding values was greatly reduced. Combined postweaning survival presented higher direct heritability than in the preweaning phases and the highest prediction accuracy among all evaluated production phases, therefore standing out as a candidate trait for improving survival. Survival is a complex trait with low heritability; however, important genetic gains can still be obtained, especially under a genomic prediction framework.

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.

Reproductive fluids, used for the in vitro production of pig embryos, result in healthy offspring and avoid aberrant placental expression of PEG3 and LUM

Background

In vitro embryo production (IVP) and embryo transfer (ET) are two very common assisted reproductive technologies (ART) in human and cattle. However, in pig, the combination of either procedures, or even their use separately, is still considered suboptimal due to the low efficiency of IVP plus the difficulty of performing ET in the long and contorted uterus of the sow. In addition, the potential impact of these two ART on the health of the offspring is unknown. We investigated here if the use of a modified IVP system, with natural reproductive fluids (RF) as supplements to the culture media, combined with a minimally invasive surgery to perform ET, affects the output of the own IVP system as well as the reproductive performance of the mother and placental molecular traits.

Results

The blastocyst rates obtained by both in vitro systems, conventional (C-IVP) and modified (RF-IVP), were similar. Pregnancy and farrowing rates were also similar. However, when compared to in vivo control (artificial insemination, AI), litter sizes of both IVP groups were lower, while placental efficiency was higher in AI than in RF-IVP. Gene expression studies revealed aberrant expression levels for PEG3 and LUM in placental tissue for C-IVP group when compared to AI, but not for RF-IVP group.

Conclusions

The use of reproductive fluids as additives for the culture media in pig IVP does not improve reproductive performance of recipient mothers but could mitigate the impact of artificial procedures in the offspring.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-020-00544-0.

Measuring birth weight and umbilical cord diameter at birth to predict subsequent performance in swine

In the swine industry, pre-weaning mortality, umbilical hernia incidence and pig market weight are a few contributing factors affecting profitability and welfare on farm. Therefore, the ability to reliably predict any of these outcomes is valuable to swine operations. Mortality during the pre-weaning phase, umbilical hernia incidence and poor-quality finisher pigs can represent a multi-million dollar loss and increase in welfare concerns to the producer. Consequently, the objective of this study was to evaluate whether birth weight (BW), umbilical cord diameter at birth (UCD), and the calculated umbilical diameter at birth to birth weight ratio (UCD:BW), are potential indicators of both placental efficiency and relative defect size in the abdominal musculature as well as reliable predictors of pre-weaning mortality, umbilical hernia incidence, and pig body weight at 150 d of age in a commercial facility. Mixed sex commercial piglets were followed through production. Four hundred sixty-five piglets were weighed within 1 h of birth, and the UCD was determined using digital calipers, these animals were followed through weaning. Three hundred eighty-five pigs of the 465 were followed through the post-wean phase in the nursery facility and checked for umbilical hernia incidence. Finally, of the 385 pigs, 177 pigs were assessed for umbilical hernia incidence and weighed a final time at the grower-finisher facility. All data were analyzed using PROC Logistic and PROC GLM procedures. The variables of UCD:BW and BW were significantly associated with the probability of increased pre-weaning mortality (P < 0.001). For example, piglets with a low UCD:BW, but an increased BW had the greatest survival rate. Umbilical diameter (UCD) was not significantly associated with pre-weaning mortality. Post-weaning mortality was not significantly affected by UCD:BW, BW, or UCD variables. Umbilical hernia incidence was not significantly affected by UCD:BW at the nursery phase or growing-finishing phase. Pig body weight at 150 d of age was significantly affected by UCD:BW, BW, and UCD variables (P < 0.001). For example, piglets that had a larger UCD weighed more at 150 d of age. In conclusion, measuring the calculated UCD:BW has the potential to be a novel tool for future research looking into the impacts of umbilical measurements as it relates to placental function, fetal development, piglet survivability and impacts on future performance of the animal.

HAI-1 regulates placental folds development by influencing trophoblast cell proliferation and invasion in pigs

Fetal development is critically dependent on the efficiency of the placenta. Porcine trophoblast cell proliferation and invasion have crucial roles in placental fold development, which is one of the essential events determining placental efficiency. The membrane serine proteinase inhibitor hepatocyte growth factor activator inhibitor-1 (HAI-1) can regulate cellular invasion and motility in different types of epithelial cells, including trophoblast cells in mice. This work used quantitative polymerase chain reaction (qPCR) and immunohistochemistry to compare the expression level and location of HAI-1 in the placenta on gestational days 26, 50, and 95 in Yorkshire and Meishan pigs. The role of HAI-1 in porcine trophoblast cell (PTr2) proliferation, invasion, and migration in vitro was investigated by analyzing the effects of HAI-1 gene silencing or overexpression. Polymorphism in the HAI-1gene was detected to determine associations between the genotype and piglet birth weight in 400 healthy pure-bred Yorkshire piglets. qPCR results showed that HAI-1 mRNA levels significantly increased (P < 0.01) between gestational days 26 and 50 and then decreased (P < 0.01) between days 50 and 95 in both Meishan and Yorkshire pigs. Immunohistochemical analysis showed that HAI-1 protein was strongly expressed by the high columnar trophoblast cells located at the top of the placental folds with low proliferative and invasion capacities. However, it was expressed at very low levels in cuboidal trophoblast cells located at the side and base of the placental folds with high proliferative and invasion capacities. In vitro experiments indicated that HAI-1 had the ability to reduce the proliferation, invasion and migration of trophoblast cells. In addition, one single-nucleotide polymorphism (SNP) of HAI-1 showed a significant association (P < 0.05) with piglet birth weight. These results revealed that HAI-1 could be a vital molecule in placental folds development by regulating trophoblast proliferation and invasion in pigs.

Caffeine administered to pregnant sows improves piglet vitality, gas exchange and body weight gain

Intra-partum asphyxia is the most common non-infectious etiology limiting the performance of neonate piglets. Previous studies indicate caffeine (orally and subcutaneously) reverses the effects of intra-partum asphyxia in neonate piglets. In this study, there was investigation of whether use of a novel therapeutic protocol for administering caffeine subcutaneously to pregnant sows would improve the newborn piglets' vitality, physio-metabolic profiles and body weight gain. Sows were randomly divided into two groups (n = 10 each). Caffeine or NaCl 0.9% was administered 2 days pre-farrowing. Physio-metabolic profiles were measured using blood from the anterior vena cava. The vitality of piglets was evaluated immediately after birth. Piglets (n = 180) were weighed at birth and on days 7, 14 and 21 of lactation. Caffeine positively affected the vitality of the piglets, as indicated by greater vitality scores than that for the control group (8.72 ± 0.12 compared with 7.28 ± 0.16, P < 0.001). Metabolic values were similar between groups, but pO₂ values were greater in the piglets with greater vitality scores treated with caffeine (19.10 ± 0.82 compared with 14.49 ± 1.42, P < 0.01), indicating increased respiratory rates. Body weight gain at day 21 was greater in the piglets treated with caffeine that had greater vitality scores than the control piglets having greater vitality scores (6.87 ± 0.18 compared with 6.52 ± 0.25 kg, P < 0.05). Caffeine administration before birth improves the vitality and respiratory capacity of piglets, increasing their adaptation to extra-uterine environment.

Effect of feeding frequency and sow parity based on isocaloric intake during gestation on sow performance

The aim of this study was to investigate the effect of feeding frequency and sow parity based on same rate of maintenance energy intake during gestation on sow performance. One hundred and seventy-seven sows [Topigs Norsvin 70, Landrace × Large White, Topigs Norsvin USA, Burnsville, MN; parity 3.80 ± 0.16; initial BW = 211.34 ± 3.37 kg; backfat (BF) 13.57 ± 0.54 mm] were blocked by parity, balanced for BW, and randomly assigned to 1 of 3 treatments in a randomized complete block design. Treatments included sows fed corn-soybean meal-based diet 1× daily at 0730 h (control, T1), 2× daily [half ration at 0730 and 1530 h (T2)], or 3× daily [a third portion at 0730, 1130, and 1530 h (T3)], with daily feed quantity kept at 1.25 × maintenance energy intake [100 × (BW)0.75] kcal ME/d. Treatments were imposed from day 30 of gestation. Sows received on average 6,921, 7,129, and 7,399 kcal ME/d from days 30 to 60, days 61 to 90, days 91 to 109 of gestation, respectively. Feeding frequency during gestation had no effect on lactation ADFI (P > 0.10). Sows fed 3× daily during gestation had improved lactation G:F (P = 0.040) compared with sows fed 2× but similar to control sows (P = 0.338). Treatment did not alter BW or BW variations during gestation, lactation, or from days 30 to wean (P > 0.10). Sows fed 2× daily had tendency to gain BF from day 30 to day 109 of gestation (P = 0.053) but tended to lose BF during lactation (P = 0.091) relative to the control sows. Feeding frequency (2× and 3× daily) tended to increase the number of piglets weaned by 0.40 (P = 0.056) and 0.53 (P = 0.098) piglets, respectively, compared with control sows. Sows fed 2× daily during gestation had reduced number of stillborn relative to control sows (P = 0.035). From day 30 to wean, gilts had propensity to lose BF relative to P1+ (P = 0.094), but lost BF compared with P3+ and P6+ sows (P = 0.003). Parity P6+ sows had highest percentage of both 72 h and preweaning piglet mortality than P0, P1+, and P3+ sows (P < 0.05). In conclusion, parity (P6+) had greater lactation BW gain but higher mortalities relative to lower parity sows. Sows fed 2× daily tended to gain BF from days 30 to 109 of gestation and had reduced number of stillborn relative to control sows. It appears that increasing gestation sow feeding frequency from 1× daily to 2× and 3× daily may reduce the number of stillborn and increase litter size at weaning although most of the reproductive traits were not affected.

Invited review: Piglet survival: benefits of the immunocompetence

Piglet mortality has a negative impact on animal welfare and public acceptance. Moreover, the number of weaned piglets per sow mainly determines the profitability of piglet production. Increased litter sizes are associated with lower birth weights and piglet survival. Decreased survival rates and performance of piglets make the control of diseases and infections within pig production even more crucial. Consequently, selection for immunocompetence becomes an important key aspect within modern breeding programmes. However, the phenotypic recording of immune traits is difficult and expensive to realize within farm routines. Even though immune traits show genetic variability, only few examples exist on their respective suitability within a breeding programme and their relationships to economically important production traits. The analysis of immune traits for an evaluation of immunocompetence to gain a generally improved immune response is promising. Generally, in-depth knowledge of the genetic background of the immune system is needed to gain helpful insights about its possible incorporation into breeding programmes. Possible physiological drawbacks for enhanced immunocompetence must be considered with regards to the allocation theory and possible trade-offs between the immune system and performance. This review aims to discuss the relationships between the immunocompetence of the pig, piglet survival as well as the potential of these traits to be included into a breeding strategy for improved robustness.

Effects of maternal dietary nitrate supplementation during the perinatal period on piglet survival, body weight, and litter uniformity

The objective of this study was to evaluate effects of different dosages of dietary nitrate supplementation to sows from d 108 of gestation until d 5 of lactation on reproductive performance of sows and piglet performance from birth until weaning. Dietary nitrate supplementation leads to nitric oxide (NO) formation that can potentially increase blood flow to the fetuses (by the vasodilative effect of NO), leading to a decrease in the loss of potential viable piglets in the form of stillbirth and preweaning mortality. Three hundred and five gilts and sows were allocated to one of six diets from d 108 of gestation until d 5 of lactation, containing 0.00% (Control), 0.03%, 0.06%, 0.09%, 0.12%, or 0.15% of dietary nitrate. The source of nitrate used was calcium nitrate double salt. Calcium levels were kept the same among diets by using limestone. Gilts and sows were weighed and backfat was measured at arrival to the farrowing room (d 108 of gestation) and at weaning (d 27 of age). Data included number of piglets born alive, born dead, and weaned, as well as individual piglet weights at d 0, 72 h of age and weaning. Preweaning mortality was determined throughout lactation. Body weight d 0 (P = 0.04) as well as BW at 72 h of age (P < 0.01) increased linearly with increasing dosages of nitrate in the maternal diet. Litter uniformity (SD) at birth was not affected by maternal nitrate supplementation level (P > 0.10), but tended to be higher at 72 h of age in the control treatment than in all nitrate-supplemented treatments (P = 0.07), and SD decreased linearly (increased uniformity) at weaning with increasing dosages of nitrate (P = 0.05). BW at weaning (P > 0.05) and average daily gain of piglets during lactation (P > 0.05) were not affected by maternal nitrate supplementation. A tendency for a quadratic effect (P = 0.10) of the dosage of maternal dietary nitrate was found on preweaning mortality of piglets with the lowest level of mortality found at 0.09% to 0.12% of maternal nitrate supplementation. We conclude that the use of nitrate in the maternal diet of sows during the perinatal period might stimulate preweaning piglet vitality. Exact mode of action and optimal dose of nitrate still need to be elucidated.

Ethics in animal breeding

Ethical breeding involves the use of healthy animals true to their species in behaviour and physical appearance, and when applicable, showing a sustainable performance. The concerns for the species/breed are essential parts of the breeding goals, including preservation of genetic resources within the species/breed, and the health and welfare of the individual animal. Ethical and welfare considerations were often not prioritized in developing new breeds of production or companion animals. As a result, animal breeding practices are increasingly becoming part of the debate on animal welfare. In companion animals, breeding for curiosity or "cuteness" may be a goal in itself, although dogs are also bred for utility. In production animals, breeding focus is on performance, i.e., quantitative entities and financial income, rather than physical appearance. For instance, dairy cows are bred to be larger and to have higher milk yields, sows and ewes to produce more offspring, and horses are designed for riding, racing, and companionship. Overbreeding in relation to current demand of horses, cats, and dogs raises welfare issues due to abandonment or killing of horses and millions of cats and dogs every year. There is variable regulation of health requirements for breeding animals in different countries of the world. In many countries, consumers are becoming increasingly aware of animal welfare issues such as negative effects of certain production traits in farm animals, leading to decreased demand for their meat at a time where increased food production is becoming crucial. Amidst these dilemmas are the veterinarians. This paper deals with issues connected to traditional breeding as well as some of the breeding technologies, and includes food safety, ethics, and animal welfare.

Neurophysiological development of newborn pigs: effect of the sow

The objective of the present study was to determine the effect of sow parity on neonatal piglet health and vitality at birth. We evaluated 1505 neonate piglets, which were born of York–Landrace sows with the following parity distribution: primiparous (n = 202), second (n = 207), third (n = 211), fourth (n = 222), fifth (n = 225), sixth (n = 218) and seventh parity (n = 220). Piglets born to primiparous and seventh-parity sows had the lowest and highest birthweights respectively, and showed the most marked imbalances in blood gas exchanges, acid–base balance and energy profiles, as well as the highest percentage of severe meconium staining of the skin and the lowest vitality scores (P &lt; 0.05). In contrast, the neonates from the fourth-parity sows had the highest vitality scores, required less time to reach the mother’s teat, and had the highest percentage of adhered umbilical cords and newborns with dyspnoea, apnoea and abnormal heartbeat (P &lt; 0.05). The results of this study suggest that during eutocic farrowings, the sow’s parity number has the following effects on newborn piglets: reduced vigour and longer latencies to begin breathing, stand and take the teat. These effects are due to the presence of imbalances in gas exchanges, the acid–base balance and energy profiles that occurred when the mother was a primiparous or older sow. These signs indicate that the newborn piglet survived a process of intrapartum asphyxia.

Causes of preweaning mortality in organic outdoor sow herds

The aims of the current study were to identify the causes of preweaning piglet mortality and investigate the effect of season and parity on the proportions of mortality causes. The study was conducted in nine herds over a one-year period, and dead piglets were collected for necropsy once during each of the four seasons. In total, 2672 piglets were necropsied of which 60% were live-born but died post-partum (pp), 32% were stillborn and 8% were euthanised. Intra-partum deaths accounted for 88% of stillborn piglets. Eighty-one percent of necropsied live-born piglets died within four days pp. Half of these had a body weight of <1 kg at the time of death. Crushed and starved piglets accounted for 83% and 9% of mortalities until day four pp, respectively. Thirty-three percent of the crushed piglets (age zero to four days) had not suckled prior to death and the proportion of these piglets was lower in summer compared to the remaining part of the year (OR = 0.6, 95% CI [0.5;0.9]) and was higher for multiparous sows compared to first parity sows (OR = 1.7, 95% CI [1.1;2.6]). In conclusion, sow parity and season affected the proportion of crushed piglets before four days of age. Furthermore, the group of crushed piglets was heterogeneous and consisted of both heavy well-fed piglets and small piglets with empty stomachs. Thus, management implementations to lower mortality may differ depending on sow parity, season and individual piglet characteristics.

Multi-level mixed models for evaluating factors affecting the mortality and weaning weight of piglets in large-scale commercial farms in central China

This study investigated the factors affecting piglet mortality (square root of mortality, SQRM) and average weaning weight (AWW) in commercial farms in central China. Information on sow diets, management and climate from 2478 weaning batches completed in 16 pig farms was collected from 2009 to 2013. Multi-level mixed models, which included batch level (level 1) and farm level (level 2), were used to analyze the factors associated with SQRM and AWW. The mean values of SQRM and AWW were 2.52% (SD = 0.96) and 7.31 (SD = 0.77), respectively. Lactation sow diets supplemented with oregano essential oils (OEOs) decreased the SQRM (P < 0.05) and increased the AWW of piglets (P < 0.01). The SQRM was lower in period 2 (June to September, hot) than in period 1 (February to May, warm) and period 3 (October to January, cold; P < 0.05 and 0.001, respectively). The AWW was lower in periods 2 and 3 than in period 1 (P < 0.01). In conclusion, supplying OEOs to lactation diets can increase the weaning weight and reduce the mortality of piglets. The sources of variations in SQRM and AWW are of greater concern in the warm season than in the hot season.

Newborn traits associated with pre-weaning growth and survival in piglets

Objective

Piglet pre-weaning mortality is an important variable indicating the efficacy of farrowing management and animal well-being during lactation. The present study determined the association of newborn traits measured soon after birth with piglet pre-weaning mortality and growth.

Methods

In total, 805 piglets born from 57 multiparous sows were investigated. Their blood oxygen saturation, blood glucose and rectal temperature at 24 h after birth (RT24h) were monitored. Birth order, sex, skin color, integrity of the umbilical cord, attempts to stand and birth intervention were monitored. Piglets were weighed at day 0, 7, and 21 to evaluate average daily gain (ADG).

Results

Piglet pre-weaning mortality for lactation period was 12.6% and cumulative mortality during the first 7 days of age was 8.6%. A higher proportion of piglets with pale skin color died compared to piglets with normal skin color (26.7% vs 7.7%, p<0.001). A higher (p<0.001) proportion of piglets that attempted to stand after 5 min (38.5%) died compared to piglets that attempted to stand within 1 min (6.3%) after birth. Piglet body weight at birth (BW_B), blood glucose and the number of piglets born alive (BA) were correlated with ADG (p<0.05). Piglets with BW_B <1.30 kg had higher (p<0.001) mortality rate than piglets with BW_B≥1.80 kg (19.0% vs 3.3%) and piglets with BW_B 1.30 to 1.79 kg (4.0%). Piglet with RT24h <37.0°C had higher (p<0.001) mortality rate (86.2%) than piglets with RT24h >38.5°C (3.9%).

Conclusion

Low BW_B and low RT24h compromise piglet survival during the lactation period in the tropical conditions. Piglets in the litters with a high BA, low BW_B and low blood glucose have reduced ADG.

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.

The association between immunoglobulin G in sow colostrum and piglet plasma

Colostrum provides newborn piglets with energy and passive immunity and is essential for survival of the piglets. The plasma concentration of immunoglobulin G (IgG) in piglets is dependent on several factors, most importantly the concentration of IgG in sow colostrum (colostrum IgG). The main aims of this study were to investigate the variation in concentration of colostrum IgG between herds and the individual sows within herd and to investigate factors associated with plasma IgG concentrations in piglets (piglet IgG). From 4 herds (A to D), 876 piglets from 62 sows were included in the study. Colostrum was sampled from sows immediately after expulsion of the first piglet and before the first suckling (t1), midway through farrowing (just after the sixth piglet was born; t2), and after the last piglet was born (t3). At d 1, 0.5 mL blood from piglets was collected in tubes containing EDTA, and IgG concentrations were analyzed. Mean colostrum IgG concentration across all herds was 53.9 g/L. Herd A had mean colostrum IgG of 38.3 g/L, whereas the other 3 herds (B,C, and D) had mean colostrum IgG of 47.4, 60.4, and 67.8 g/L, respectively. Colostrum IgG at t1, t2, and t3 across all herds was 56.2, 53.7, and 42.5 g/L, respectively. Mean concentration of piglet IgG across all samplings was 21.7 g/L. Multilevel linear regression analysis was performed with piglet IgG (g/L) as outcome. In this model, the herd effect accounted for 9% of the total variance and 34% of the variance resided at sow level. Piglet IgG was associated with herd, birth order (), body mass index (BMI) > 17 (kg/m), and colostrum IgG at t1 (g/L) with an overall -value < 0.01. Herd D had the highest predicted mean level of piglet IgG. The main model predicted that piglet IgG decreased linearly by 0.4 g/L with each piglet born ( < 0.01). The model also predicted an increase by 0.1 g/L for each gram per liter extra colostrum IgG in colostrum ( = 0.03). Piglets with a BMI above 17 kg/m had a greater piglet IgG (+4.5 g/L) than those with a BMI at 17 kg/m or below ( < 0.01). Concentrations of colostrum IgG varied largely between herds and between sows. The largest variation of piglet IgG was mainly on the piglet level, supporting the complex nature of IgG production and uptake. However, the strong association between colostrum IgG and piglet IgG shows that increased IgG level in colostrum will improve the levels of IgG in piglets and potentially increase survival of the piglets.

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.

Placental accommodations for transport and metabolism during intra-uterine crowding in pigs

Litter size and birth weights are limited by uterine capacity, defined as the ability of the uterus to maintain the appropriate development of some number of conceptuses. Uterine capacity is the result of the combined effects of uterine, placental and embryo/fetal function. The number of living conceptuses that the uterus is capable of supporting is greater during early gestation compared to later gestation. Plots of log fetal weight versus log placental weight also indicate that fetal weights are less sensitive to reduced placental weight (and therefore reduced intrauterine space) in early gestation compared to late gestation. However, even in late gestation, mechanisms still exist that maintain fetal growth when the size of the placenta is reduced. One such mechanism is likely to be improved development of the folded placental-epithelial/maternal-epithelial bilayer. Fold depth, and therefore the maternal fetal interactive surface, increases as gestation advances and is greater in placenta from small fetuses. On the fetal side of the placenta, the epithelial bilayer is embedded in stromal tissue. Glycosaminoglycans are major components of stroma, including hyaluronan and heparan sulfate. Hyaluronidases and heparanases are present within placental tissues, and likely play roles in modification of stromal components to facilitate fold development. Glycosaminoglycans are polymers of forms of glucose (glucosamine, glucuronic acid, iduronic acid) suggesting that glycosaminoglycan synthesis may compete with the glucose needs of the developing fetus. Pig conceptuses are fructogenic, such that a substantial portion of glucose transferred from mother to fetus is converted to fructose. Fructose is an intermediate product in the synthesis of glucosamine from glucose, and glucosamine is linked to regulation of trophoblast cell proliferation through regulation of mTOR. These findings suggest a link between glucose, fructose, glucosamine synthesis, GAG production, and placental morphogenesis, but the details of these interactions remain unclear. In addition, recent placental epithelial transcriptome analysis identified several glucose, amino acid, lipid, vitamin, mineral and hormone transporter mechanisms within the placenta. Further elucidation of mechanisms of placental morphogenesis and solute transport could provide clues to improving nutrient transport to the pig fetus, potentially increasing litter size and piglet birth weights.

Invited review: the preterm pig as a model in pediatric gastroenterology

At birth, the newborn mammal undergoes a transition from a sterile uterine environment with a constant nutrient supply, to a microbe-rich environment with intermittent oral intake of complex milk nutrients via the gastrointestinal tract (GIT). These functional challenges partly explain the relatively high morbidity and mortality of neonates. Preterm birth interrupts prenatal organ maturation, including that of the GIT, and increases disease risk. Exemplary is necrotizing enterocolitis (NEC), which is associated closely with GIT immaturity, enteral feeding, and bacterial colonization. Infants with NEC may require resection of the necrotic parts of the intestine, leading to short bowel syndrome (SBS), characterized by reduced digestive capacity, fluid loss, and dependency on parenteral nutrition. This review presents the preterm pig as a translational model in pediatric gastroenterology that has provided new insights into important pediatric diseases such as NEC and SBS. We describe protocols for delivery, care, and handling of preterm pigs, and show how the immature GIT responds to delivery method and different nutritional and therapeutic interventions. The preterm pig may also provide a sensitive model for postnatal adaptation of weak term piglets showing high mortality. Attributes of the preterm pig model include close similarities with preterm infants in body size, organ development, and many clinical features, thereby providing a translational advantage relative to rodent models of GIT immaturity. On the other hand, the need for a sow surgical facility, a piglet intensive care unit, and clinically trained personnel may limit widespread use of preterm pigs. Studies on organ adaptation in preterm pigs help to identify the physiological basis of neonatal survival for hypersensitive newborns and aid in defining the optimal diet and rearing conditions during the critical neonatal period.