Genetic and environmental dissection of short and long-term social aggression in pigs

It is common for pigs to engage in physical aggression when mixed into new social groups, in order to establish dominance relationships. Phenotyping aggression is time consuming, however skin lesions resulting from physical aggression are quick to record, are genetically correlated with aggressive behavioural traits, and have low to moderate heritability (0.19 to 0.43). Reducing aggression via selection on skin lesion traits would provide a socially acceptable, long-term solution to the problem. Barriers to implementing selection against skin lesions lie in the lack of understanding regarding the underlying genetic basis of aggression, and its relationship with other behaviour and production traits. This thesis has focused on dissecting the phenotypic and genetic relationship between skin lesions recorded 24 hours after mixing (SL24h), and either 3 or 5 weeks later (SL3wk/SL5wk, respectively), with aggression performed at mixing, and several production traits. Chapter 2 provided evidence of a potential trade-off between involvement in aggression upon first mixing, and receipt of aggressive attacks several weeks after mixing. In particular, animals that avoid aggression at mixing had the highest fresh skin lesion numbers at 3 weeks. This suggests that reciprocal fighting at mixing may be beneficial for long-term group social stability. It also suggests that it may be possible to phenotype the least aggressive individuals in a group using SL3wk. In Chapter 3, I quantified the magnitude of reduction in complex aggressive behavioural traits when using SL24h or SL3wk as selection criteria, to identify the optimum skin lesion trait for selection purposes. The results of Chapter 3 provided evidence that selection against anterior SL24h would result in the greatest genetic and phenotypic reduction in aggressive behaviour recorded at mixing. Although there is evidence that selection for increased SL3wk would reduce aggression at mixing, current understanding of aggressive behaviour under stable group conditions is insufficient to recommend using this trait for selection purposes. Chapter 4, presented genetic associations between skin lesion traits as a measure of short- and long-term aggression, and commonly used commercial performance measures: growth, feed intake, feed efficiency, and carcass traits. The results suggested that, genetically, animals that receive many lesions show improved performance compared to those with few lesions, except for anterior SL24h, which have been shown to be genetically positively correlated with the initiation of nonreciprocal attacks. The aim of Chapter 5, was to determine whether skin lesion traits are phenotypically or genetically associated with behavioural measures of fearfulness. As found in Chapter 4, there was some evidence of an association between SL5wk and the traits, however this was not the case for anterior SL24h. For the 6th and final Chapter, we used skin lesion data from 1,840 pigs to perform genome wide association studies (GWAS), which detected a single SNP significantly associated with SL5wk on a genome wide level, as well as several SNPs associated with both SL24h and SL5wk on a chromosome wide level

Ectopia cordis : a report of two cases in Cameroon

This article reports two cases of ectopia cordis in two children aged one day and twenty months respectively. A one day old newborn had complete thoracic ectopia cordis associated with an internal cardiac defect and severe thoracic and abdominal wall malformations. The centre does not have the facilities to manage complex congenital defects and prior to being transferred to a cardiac centre, the neonate died on the second day of admission. A 20-month old baby had partial ectopia of the heart and a defect in the abdominal wall. He had no major congenital cardiac defect and has remained clinically stable with no life threatening symptomspeer-reviewe

Genetic Parameters for Human-Directed Behavior and Intraspecific Social Aggression Traits in Growing Pigs

This study aimed to estimate heritabilities and genetic and phenotypic correlations for human-directed behavior and intraspecific social aggression traits in growing pigs, and to explore genetic and phenotypic correlations among them. Pigs (n = 2,314) were mixed into groups of 18 animals at 69 ± 5.2 d of age and skin lesions (SL) were counted 24 h (SL24h) and 5 weeks (SL5WK) post-mixing. Individual behavioral responses to isolation in a weighing crate (CRATE, 1 = pig performing exploratory behavior to 4 = pig performing serious, persistent attempts to escape) or when alone in an arena while a human directly approached them (IHAT) were assessed within 48 h post-mixing. During the IHAT, three separate scores were given for each pig based on the severity (0 = none to 3 = severe reaction) of their movement, vocalizations, and vigilance. Additionally, pigs were tested for behavioral responses to the presence of a single human observer walking in their home pen in a circular motion (WTP) within 1 and 4 weeks post-mixing recording pigs that followed, nosed or bit the observer. An animal model was used to estimate genetic parameters for all studied traits using the DMU software. Heritabilities (h2) for SL, CRATE and IHAT responses were low to moderate (0.17 to 0.29), with the greatest h2 estimated for speed of moving away from the approaching observer in the IHAT. Low but significant h2 were estimated for nosing (0.09) and biting (0.11) the observer at 4 weeks post-mixing in the WTP test. Positive high genetic correlations (rg) were observed between CRATE and IHAT responses (0.55 to 0.90), and within SL traits (0.60 to 0.94) while positive low to high rg were estimated within the WTP test (0.24 to 0.59) traits. Positive moderate rg were observed between CRATE and central and posterior SL24h. Genetic correlations between CRATE and IHAT test responses and WTP test traits were low, mostly negative (-0.21 to 0.05) and not significant. Low positive rg (0.06 to 0.24) were observed between SL and the WTP test traits except for the lack of rg between posterior SL24h and pigs biting or following the observer during both tests. Phenotypic correlations between CRATE and IHAT responses and SL or WTP test traits were mostly low and not significant. Under the conditions of this study, h2 estimates for all studied traits suggest they could be suitable as a method of phenotyping aggression and fear and/or boldness in pigs for genetic selection purposes. Additionally, there was evidence of genetic associations between aggression and fear indicators. These findings suggest applying selection pressure to reduce the accumulation of lesions is likely to make pigs more relaxed in a crate environment, but to alter the engagement with humans in other contexts that depends on the location of the lesions under selection

Genetic associations of novel behaviour traits derived from social network analysis with growth, feed efficiency, and carcass characteristics in pigs

Reducing harmful aggressive behaviour remains a major challenge in pig production. Social network analysis (SNA) showed the potential in providing novel behavioural traits that describe the direct and indirect role of individual pigs in pen-level aggression. Our objectives were to (1) estimate the genetic parameters of these SNA traits, and (2) quantify the genetic associations between the SNA traits and commonly used performance measures: growth, feed intake, feed efficiency, and carcass traits. The animals were video recorded for 24 h post-mixing. The observed fighting behaviour of each animal was used as input for the SNA. A Bayesian approach was performed to estimate the genetic parameters of SNA traits and their association with the performance traits. The heritability estimates for all SNA traits ranged from 0.01 to 0.35. The genetic correlations between SNA and performance traits were non-significant, except for weighted degree with hot carcass weight, and for both betweenness and closeness centrality with test daily gain, final body weight, and hot carcass weight. Our results suggest that SNA traits are amenable for selective breeding. Integrating these traits with other behaviour and performance traits may potentially help in building up future strategies for simultaneously improving welfare and performance in commercial pig farms

Pseudomonas Aeruginosa-Induced Bleb-Niche Formation in Epithelial Cells Is Independent of Actinomyosin Contraction and Enhanced by Loss of Cystic Fibrosis Transmembrane-Conductance Regulator Osmoregulatory Function

The opportunistic pathogen Pseudomonas aeruginosa can infect almost any site in the body but most often targets epithelial cell-lined tissues such as the airways, skin, and the cornea of the eye. A common predisposing factor is cystic fibrosis (CF), caused by defects in the cystic fibrosis transmembrane-conductance regulator (CFTR). Previously, we showed that when P. aeruginosa enters epithelial cells it replicates intracellularly and occupies plasma membrane blebs. This phenotype is dependent on the type 3 secretion system (T3SS) effector ExoS, shown by others to induce host cell apoptosis. Here, we examined mechanisms for P. aeruginosa-induced bleb formation, focusing on its relationship to apoptosis and the CFTR. The data showed that P. aeruginosa-induced blebbing in epithelial cells is independent of actin contraction and is inhibited by hyperosmotic media (400 to 600 mOsM), distinguishing bacterially induced blebs from apoptotic blebs. Cells with defective CFTR displayed enhanced bleb formation upon infection, as demonstrated using bronchial epithelial cells from a patient with cystic fibrosis and a CFTR inhibitor, CFTR(Inh)-172. The defect was found to be correctable either by incubation in hyperosmotic media or by complementation with CFTR (pGFP-CFTR), suggesting that the osmoregulatory function of CFTR counters P. aeruginosa-induced bleb-niche formation. Accordingly, and despite their reduced capacity for bacterial internalization, CFTR-deficient cells showed greater bacterial occupation of blebs and enhanced intracellular replication. Together, these data suggest that P. aeruginosa bleb niches are distinct from apoptotic blebs, are driven by osmotic forces countered by CFTR, and could provide a novel mechanism for bacterial persistence in the host. IMPORTANCE: Pseudomonas aeruginosa is an opportunistic pathogen problematic in hospitalized patients and those with cystic fibrosis (CF). Previously, we showed that P. aeruginosa can enter epithelial cells and replicate within them and traffics to the membrane blebs that it induces. This “bleb-niche” formation requires ExoS, previously shown to cause apoptosis. Here, we show that the driving force for bleb-niche formation is osmotic pressure, differentiating P. aeruginosa-induced blebs from apoptotic blebs. Either CFTR inhibition or CFTR mutation (as seen in people with CF) causes P. aeruginosa to make more bleb niches and provides an osmotic driving force for blebbing. CFTR inhibition also enhances bacterial occupation of blebs and intracellular replication. Since CFTR is targeted for removal from the plasma membrane when P. aeruginosa invades a healthy cell, these findings could relate to pathogenesis in both CF and healthy patient populations