1. The neonatal pig: developmental influences on vitality

Abstract

Newborn piglets are most vulnerable to postnatal stressors, such as competition for energy intake, crushing by the sow, and hypothermia, leading to the persistently high pre-weaning mortality rate that is currently seen in the industry. The present chapter describes the developmental and physiological factors that impact the vitality of neonatal piglets. Experiences in utero, such as placental blood flow and nutrient supply, are of great importance and can be influenced by external factors. Low birth weight constitutes a high risk for mortality and is exacerbated in piglets also showing intra-uterine growth retardation or hypoxia at birth. It has long been recognized that piglets are physiologically immature at birth. They have very low energy stores and poor immune protection. Some nutritional and hormonal treatments can be used to alleviate these problems, such as feeding fish oils or providing phytoestrogens to late-pregnant sows, yet no treatment has proved infallible. Piglets also have very little body fat and have a great surface to body mass ratio which makes them highly susceptible to hypothermia. The lower critical temperature of piglets is much higher than that of sows and this must be taken into account in the farrowing environment. Furthermore, intake of colostral immunoglobulins is essential for piglets to acquire systemic immunity, hence, any attempt to maximize this transfer should prove beneficial.

Invited review: strategic adoption of antibiotic-free pork production: the importance of a holistic approach

“…Care of the neonate is an awesome and complex responsibility. Even before it is born, the fetus suffers challenges to its vitality, including the possibility of intrauterine growth retardation during gestation and hypoxia during farrowing, combined with physiological immaturity at birth ( Farmer and Edwards, 2020 ). It is born with very limited energy reserves, which make it dependent on early and frequent consumption of its mother’s milk; poor thermoregulatory capability further compromises the pig’s survivability ( Villanueva-Garcia et al, 2020 ), a risk factor that is magnified by low and highly variable milk intake among piglets, since metabolism of feed generates critically important heat energy within the body.…”

“…Along with an immature immune system, the piglet’s dependence on immunoglobulins from the sow’s colostrum and milk for protection from pathogens cannot be overestimated. Low birthweight, which is more common with the hyper-prolificacy of the modern sow ( Beaulieu et al, 2010 ), compounds the newborn’s tenuous adaption to life outside the womb, the consequences of which are exacerbated by a slow birthing process which may lead to hypoxia ( Farmer and Edwards, 2020 ). These problems are magnified by a large surface area to body mass ratio, which encourages body heat loss.…”

“…Success in the care of neonatal pigs therefore begins before birth and is influenced by factors related to intrauterine growth retardation and placental quality ( Farmer and Edwards, 2020 ). Proper feeding of the sow to ensure adequate but not excessive energy and nutrient intake is essential.…”

A window of opportunity : Modulation of the porcine gut microbiota and immune system by feed additives in early life

“…Overall, our study illustrates that the pre-weaning period serves as a 'window of opportunity' to modulate the gut microbiota, barrier function, the immune system, and their interactions by dietary interventions such as EcN. In early life and around weaning, pigs are at risk of developing diseases that compromise animal health and welfare, with major economic consequences for the pig industry [253]. These periods are especially critical, since the gastrointestinal (GI) system and the immune system are not yet fully established [7,64].…”

“…As for Salmonellaspecific IgM, a significant decrease was observed in EcN-treated animals, but remarkably this decrease could already be observed before vaccination (Chapter 5, Figure 6). A possible explanation could be that Salmonella-specific antibodies were already transferred to piglets before vaccination through passive immunization during gestation, which could also explain the presence of Salmonella-specific IgM and IgG on day 14 [253,306]. Because we did not collect blood serum before EcN administration and did not monitor colostrum intake, it is impossible to determine whether these lower IgM levels are caused by EcN or whether there was already a discrepancy between the treatment groups at the beginning of the study.…”