Genetic trends in maternal and neonatal behaviors and their association with perinatal survival in French Large White swine

The Effect of Sow Maternal Behavior on the Growth of Piglets and a Genome-Wide Association Study

Sows' maternal behavior is important for improving piglet survival and growth; thus, breeding for good mothering sows is necessary for pig production. However, there is little research on the genetic mechanism of maternal behavior. In this study, a comparative analysis of piglets' growth traits between good and bad maternal behavior groups and a genome-wide association study (GWAS) was performed to elucidate the impact of sows' maternal behavior on piglet growth and identify candidate genes and markers of sow's maternal behaviors. Comparing the growth traits of piglets between good and bad sows' maternal behavior groups, the results showed that the growth traits of piglets from sows with good maternal behavior were better than those from sows with bad maternal behavior and especially for the multiparous sows group, this comparative difference was significant. For the intensive study of the genetic mechanisms of sows' maternal behavior, a total of 452 sows were genotyped using the Illumina Porcine 50K SNP Chip, and 4 traits, including biting piglets (BP), crushing piglets (CP), trampling piglets (TP) and screaming test (ST), were examined. Using a GWAS, 20 single nucleotide polymorphisms (SNPs) were found to be associated with these traits. Within 1 Mb upstream and downstream of the significant SNPs screened, 138 genes were obtained. After pathway enrichment and gene annotation, HIP1, FZD9 and HTR7 were identified as important candidate genes affecting sows' maternal behaviors. These findings preliminarily elucidate the genetic basis of sows' maternal behavior traits and provide candidate genes and markers for molecular breeding in pigs.

Vitality in Newborn Farm Animals: Adverse Factors, Physiological Responses, Pharmacological Therapies, and Physical Methods to Increase Neonate Vigor

Vitality is the vigor newborn animals exhibit during the first hours of life. It can be assessed by a numerical score, in which variables, such as heart rate, respiratory rate, mucous membranes' coloration, time the offspring took to stand up, and meconium staining, are monitored. Vitality can be affected by several factors, and therapies are used to increase it. This manuscript aims to review and analyze pharmacological and physical therapies used to increase vitality in newborn farm animals, as well as to understand the factors affecting this vitality, such as hypoxia, depletion of glycogen, birth weight, dystocia, neurodevelopment, hypothermia, and finally, the physiological mechanism to achieve thermostability. It has been concluded that assessing vitality immediately after birth is essential to determine the newborn's health and identify those that need medical intervention to minimize the deleterious effect of intrapartum asphyxia. Vitality assessment should be conducted by trained personnel and adequate equipment. Evaluating vitality could reduce long-term neonatal morbidity and mortality in domestic animals, even if it is sometimes difficult with the current organization of some farms. This review highlights the importance of increasing the number of stock people during the expected days of parturitions to reduce long-term neonatal morbidity and mortality, and thus, improve the farm's performance.

Analysis of image-based sow activity patterns reveals several associations with piglet survival and early growth

An activity pattern describes variations in activities over time. The objectives of this study are to automatically predict sow activity from computer vision over 11 days peripartum and estimate how sow behavior influences piglet's performance during early lactation. The analysis of video images used the convolutional neural network (CNN) YOLO for sow detection and posture classification of 21 Large White and 22 Meishan primiparous sows housed in individual farrowing pens. A longitudinal analysis and a clustering method were combined to identify groups of sows with a similar activity pattern. Traits under study are as follows: (i) the distribution of time spent daily in different postures and (ii) different activities while standing. Six postures were included along with three classes of standing activities, i.e., eating, drinking, and other, which can be in motion or not and root-pawing or not. They correspond to a postural budget and a standing-activity budget. Groups of sows with similar changes in their budget over the period (D-3 to D-1; D0 and D1-D7) were identified with the k-means clustering method. Next, behavioral traits (time spent daily in each posture, frequency of postural changes) were used as explanatory variables in the Cox proportional hazards model for survival and in the linear model for growth. Piglet survival was influenced by sow behavior on D-1 and during the period D1-D7. Piglets born from sows that were standing and doing an activity other than drinking and eating on D-1 had a 26% lower risk of dying than other piglets. Those born from sows that changed posture more frequently on D1-D7 had a 44% lower risk of dying. The number of postural changes, which illustrate sow restlessness, influenced piglet growth in the three periods. The average daily gain of piglets born from sows that were more restless on D1-D7 and that changed posture more frequently to hide their udder on D0 decreased by 22 and 45 g/d, respectively. Conversely, those born from sows that changed posture more frequently to hide their udder during the period of D1-D7 grew faster (+71 g/d) than the other piglets. Sow restlessness at different time periods influenced piglet performance.

Early-life maternal deprivation affects the mother-offspring relationship in domestic pigs, as well as the neuroendocrine development and coping behavior of piglets

Early-life adversity may have programming effects on the psychological and physiological development of offspring. Domestic pigs (Sus scrofa) are an excellent model species for studying these effects because of their many physiological similarities to humans. Piglets from 10 sows were subjected to daily 2-h maternal deprivation on postnatal days (PND) 2–15 alone (DA) or in a group of littermates (DG). Control piglets (C) from 10 sows stayed with their mothers. Mother-offspring interaction, milk oxytocin, and cortisol were analyzed. An open-field/novel-object (OF/NO) test was performed with piglets on PNDs 16 and 40. Plasma cortisol and immune parameters were determined on PND 5 and 16. Two piglets from each group and sow were sacrificed on PND 20 and stress-related gene expression in the limbic system and prefrontal cortex (PFC), as well as splenic lymphocyte proliferative abilities, were examined. The milk cortisol of sows increased during the first separation of mother and offspring on the second day of lactation, whereas milk oxytocin did not change. The increase in cortisol by the OF/NO test on PND 16 was greater in C piglets than in DA and DG ones. DA piglets showed less agitated behavior than DG and C piglets in the OF/NO test at PND 16, but appeared more fearful. On PND 40, DA piglets showed more arousal than DG and C piglets in the OF/NO test. Neither plasma IgA nor N/L ratios in blood nor mitogen-induced proliferation of spleen lymphocytes were affected by deprivation. We found a higher mRNA expression of CRHR1 in the hypothalamus and a higher expression of MR in the hippocampus in DA piglets than in DG ones. The expression of GR, MR, and CRHR1 genes in the PFC was reduced by maternal deprivation, however, the expression of arginine vasopressin and oxytocin receptors was not affected. Repeated maternal deprivation induces sustained effects on stress reactivity and behavior of domestic piglets. Some of these effects were buffered by the presence of littermates. In addition, we found sex-specific differences in behavior and gene expression.

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.

Genetic aspects of piglet survival and related traits: a review

In livestock, mortality in general, and mortality of the young, is societal worries and is economically relevant for farm efficiency. Genetic change is cumulative; if it exists for survival of the young and genetic merit can be estimated with sufficient accuracy, it can help alleviate the pressure of mortality. Lack of survival is a moving target; livestock production is in continuous change and labor shortage is a given. There is now ample evidence of clear genetic variance and of models able to provide genomic predictions with enough accuracy for selection response. Underlying traits such as birth weight, uniformity in birth weight, gestation length, number of teats, and farrowing duration all show genetic variation and support selection for survival or, alternatively, be selected for on their own merit.

Parental Behaviour in Sows

Parental behaviour in sows begins with prepartum nest-building behaviour, which mainly consists of rooting, pawing, and foraging, to achieve a structure for farrowing and to nurse and protect the offspring. A hormonal background is linked to the onset and cessation of nest-building behaviour. The ambient farrowing environment that can adequately address the needs for nest-building behaviour thus plays an important role in good parental behaviour of the sows during and after farrowing. In addition to these environmental factors, here we also discuss other well-known intrinsic factors, such as heredity, parental experience, and litter size, affecting parental behaviour of the sows for successful farrowing and lactating performance.

Relationship between Fertility Traits and Kinematics in Clusters of Boar Ejaculates

Simple Summary

Swine reproduction efficiency is determined by the fertility potential of the sow and sperm quality. The objective of this study is to compare boar sperm motility and kinematic features to evaluate their relationships with reproductive success after artificial insemination (AI). In this study, the movement patterns of boar ejaculates were analyzed by a computer-assisted semen analysis (CASA)-Mot system, and the kinematic values of ejaculate clusters were assessed. The semen of the Pietrain boars showed more linear trajectory of the spermatozoa, while curvilinear velocity and oscillatory movement characterized the semen of the Duroc × Pietrain boars. The offspring of sows inseminated with Pietrain boars showed significantly lower number of stillbirths. In addition, ejaculate grouping into clusters did not have a predictive capacity on litter size variables. Nevertheless, the kinematic variables of the ejaculate may have a predictive, albeit reduced, capacity regarding litter size variables. The results of this study therefore open up possibilities for future assessments of fertility.

Abstract

The aim was to determine the relationship between kinematic parameters of boar spermatozoa and fertility rates of sow, as well as to assess the effect of sperm clusters on the fertility capacity of the ejaculate. Semen samples were collected from 11 sexually mature boars. Samples were analyzed by an ISAS^®v1 CASA-Mot system for eight kinematic parameters. Ejaculate clusters were characterized using multivariate procedures, such as principal factors (PFs) analysis and clustering methods (the k-means model). Four different ejaculate clusters were identified from two kinematic PFs which involved linear trajectory and velocity. There were differences (p < 0.05) between the sperm kinematic variables by sire line. There was no statistical difference (p > 0.05) between dam lines and ejaculate clusters in fertility variables. The discriminant ability of the different kinematics of sperm variables to predict litter size fertility was analyzed using receiver operating characteristics (ROC) curve analysis. Curvilinear velocity (VCL), average path velocity (VAP), amplitude of lateral head displacement (ALH), and beat-cross frequency (BCF) showed significant, albeit limited, predictive capacity for litter size fertility variables (range: 0.55–0.58 area under curve, AUC). The kinematic analysis of the ejaculates in clusters did not have a predictive capacity for litter size variables.

Resilience Effects of SGK1 and TAP1 DNA Markers during PRRSV Outbreaks in Reproductive Sows

The porcine reproductive and respiratory syndrome virus (PRRSV) is a major infectious stressor that causes serious health problems and productivity drops. Based on previous genome-wide analyses, we selected SGK1 and TAP1 as candidate genes for resilience, and genotyped three mutations, including a 3'UTR variant SGK1_rs338508371 and two synonymous variants TAP1_rs1109026889 and TAP1_rs80928141 in 305 Landrace × Large White sows. All polymorphisms affected the reproductive performance in the outbreak, but not during the endemic phase, thereby indicating a potential use of these markers for resilience. Moreover, some genotypes were associated with a stable performance across PRRSV phases. Thus, in the outbreak, the SGK1_rs338508371 AA sows had less piglets born alive (p < 0.0001) and more stillborns (p < 0.05) while other sows were able to keep their productivity. During the outbreak, TAP1_rs80928141 GG sows had less piglets born alive (p < 0.05) and both TAP1 polymorphisms influenced the number of mummies in an additive manner (p < 0.05). Remarkably, TAP1_rs80928141 AA sows had around one mummy more than GG sows (p < 0.01). Resilience to PRRSV could be improved by including the SGK1 and TAP1 markers in crossbreeding and/or selection schemes, as they contribute to maintaining a stable number of piglets born alive and lost, particularly mummies, despite the outbreak.

Estimation of the effects of selection on French Large White sow and piglet performance during the suckling period

The effects of 21 yr of selection were estimated for sow and piglet performance during the suckling period in a French Large White (LW) pig population using frozen semen. Two experimental groups (EXP = L77 and L98) were produced by inseminating LW sows with either stored frozen semen from 17 LW boars born in 1977 (EXP = L77) or with fresh semen from 23 LW boars born in 1998 (EXP = L98). Seventy-four L77 and 89 L98 randomly chosen females were mated to 15 L77 and 15 L98, respectively, randomly chosen boars for 6 successive parities. They produced 2,796 L77 progeny (G77) and 3,529 L98 progeny (G98) piglets including stillbirths. To disentangle direct and maternal effects on piglet growth, a 2 × 2 factorial design was set by cross-fostering half-litters across genetic groups the day after farrowing, resulting in mixed G77/G98 litters nursed by either L77 or L98 sows. Piglet traits investigated included individual weight at birth (IWB), at 21 d of age (IW21d), and at weaning at 4 wk of age (IWW) and ADG from birth to 21 d of age (ADG21d) and from birth to weaning (ADGBW) as well as probability of stillbirth, probability of mortality on the first day after farrowing and from d 2 to weaning. Sow traits analyzed included weight before farrowing and at weaning, feed intake, milk production, colostrum, and milk composition. The variability of performance across genetic groups and litters was also investigated. The data were analyzed using generalized (piglet mortality) or linear mixed models (other traits). Results showed an increase in IWB (+240 ± 72 g in 21 yr for IWB adjusted for total number born), and a negative maternal genetic trend was observed on piglet growth during the suckling period (e.g., +33 ± 13 g/d in 21 yr for ADG21d, that is, 14% of the mean), whereas direct genetic effects remained unchanged. Piglets from L98 litters also had a 40% larger probability of being stillborn and a 28% larger probability of dying on d 1 and had a more heterogeneous IWB (358 vs. 336 g; < 0.001) and growth during the suckling period (60 vs. 56 g/d; < 0.001). Sows from L77 and L98 experimental groups did not differ in weight, feed intake, colostrum, and milk composition. These results give evidence of negative correlated effects of selection for piglet traits related to robustness. These adverse effects are at least partly of maternal origin.

Heritability of udder morphology and colostrum quality traits in swine

The heritability of udder quality traits, defined as morphology and colostrum IgG concentration at farrowing, was estimated together with the genetic and phenotypic correlations of these traits with other production and reproduction criteria. Udder morphology traits were recorded in 988 Meidam sows and colostrum samples were collected from 528 sows. Teat length, teat diameter (DIA), interteat distance within the same row (SAMER), and teat distance from the abdominal midline (AML) were recorded to the nearest millimeter. For each sow, a record was also made of udder development score (DEV), the proportion of teats oriented perpendicular to the udder, and the proportion of nonfunctional teats. Colostrum IgG concentration was estimated with a Brix refractometer. Heritability of udder morphology traits varied from high ( = 0.46 for teat length and = 0.56 for DIA) to moderate ( = 0.37 for SAMER, = 0.22 for AML, = 0.25 for DEV, = 0.3 for the proportion of nonfunctional teats, = 0.1 for the proportion of teats oriented perpendicular to the udder, and = 0.35 for colostrum IgG concentration). The SAMER was negatively genetically correlated with the number of stillborns (genetic correlation [] = -0.48) and positively genetically correlated with the number of piglets born alive ( = 0.69), with the opposite for the trait AML ( = -0.40 for number of piglets born alive and = 0.40 for stillborns). The highest genetic correlation with productive traits was estimated between AML and ADG during rearing ( = 0.42), although this had a negative phenotypic correlation (; -0.11). Teat length was also moderately correlated with ADG ( = 0.27). Backfat thickness at 100 kg was positively correlated with DIA and the total number of teats present in both rows ( = 0.28 and = 0.36, respectively) and negatively correlated only with DEV ( = -0.22). The same results were found for the phenotypic correlation between backfat thickness at end of test and the total number of teats present in both rows ( = 0.03). Udder quality traits can be included in the breeding goal and appropriately weighted with other important traits in the breeding objectives to enhance maternal performance.

Estimation of the effects of selection on French Large White reproductive performance using frozen semen

Genetic trends for male and female sexual development and components of litter size and weight at birth (LB) as well as traits related to sow lifetime productivity were estimated in a French Large White (LW) pig population using frozen semen. Two experimental groups (EXP = L77 and L98) were produced by inseminating LW sows with either stored frozen semen from 17 LW boars born in 1977 (EXP = L77) or with semen from 23 LW boars born in 1998 (EXP = L98). In each group, about 100 males were measured for testicular development and bulbo-urethral gland development, and 90 gilts were checked for puberty, among which about 50 gilts were measured for their first ovulation rate at puberty (ORP). The females were then mated to 15 randomly chosen males for each group for 6 successive parities and measured for total number born (TNB), number born alive (NBA), litter weight at birth (LWB), and interval from weaning to first estrus as well as ovulation rate at fertilization (ORF = ovulation rate of gestating sows) on a subset of litters. The data were analyzed using mixed linear models including the fixed effects of EXP, of finishing (sexual development traits) or farrowing group, and parity (LB traits); the random effects of birth litter (sexual development traits) or sow (LB traits); and, when relevant, age or BW as covariates. The homogeneity of residual variances across EXP was also tested. For each trait, the genetic trend was estimated as twice the difference between L98 and L77. Limited differences were observed for sexual development traits, except for ORF, which increased by 0.17 ± 0.06/yr. The residual SD of NBA (2.7 vs. 2.0; = 0.004) and LWB (3.1 vs. 2.5; = 0.03) were larger in L98 sows than in L77 sows. Positive trends were observed for all litter traits (0.22 ± 0.07 ova, 0.12 ± 0.04 piglet, 0.09 ± 0.04 piglet, and 0.23 ± 0.06 kg/yr for ORF, TNB, NBA, and LWB, respectively) but at the expense of a degradation of prenatal and farrowing survival. A negative trend was also observed for length of productive life (-8.9 ± 3.9 d/yr). These results suggest that gains in productivity were associated with a loss of robustness.

Brain Mass and Encephalization Quotients in the Domestic Industrial Pig (Sus scrofa)

In the present study we examined the brain of fetal, newborn, and adult pigs raised for meat production. The fresh and formalin-fixed weights of the brain have been recorded and used, together with body weight, to calculate the Encephalization Quotient (EQ). The weight of the cerebellum has been used to calculate the Cerebellar Quotient (CQ). The results have been discussed together with analogue data obtained in other terrestrial Cetartiodactyla (including the domestic bovine, sheep, goat, and camel), domesticated Carnivora, Proboscidata, and Primates. Our study, based on a relatively large experimental series, corrects former observations present in the literature based on smaller samples, and emphasizes that the domestic pig has a small brain relative to its body size (EQ = 0.38 for adults), possibly due to factors linked to the necessity of meat production and improved body weight. Comparison with other terrestrial Cetartiodactyla indicates a similar trend for all domesticated species.