Development and manipulation of the piglet intestinal microbiota

Abstract

Piglet pre-weaning mortality is a major industry issue and one area that has not been explored is the role of the gastrointestinal tract (GIT) microbiota. The first microbial colonisers are the greatest determinants of health. However, little is known about the initial colonisers and the degree to which external factors influence GIT microbiota development within the piglet. Research reported in this thesis outlines GIT microbiota development and evaluates different methods for influencing the GIT microbiota and its effect on piglet growth and survival. Chapter 1.2 and 2 provide literature reviews in pigs, outlining the gap in knowledge surrounding the pre-weaning period and the use of faecal microbiota transplantation (FMT). Chapter 3 identified the presence of bacteria within the spiral colon of stillborn piglets demonstrating colonisation prior to birth and outlined the first colonisers in piglets that had or had not sucked. This study provides evidence surrounding the importance of the immediate post-natal environment. Chapter 4 focussed on the impact of pen environment and sow parity on microbial colonisation. Sow parity was assessed due to the differences between multiparous and primiparous sow progeny. This experiment found that the removal of faeces from the pen for the first 10 days of life increased piglet growth and survival to weaning, while the addition of multiparous sow faeces to a primiparous sow pen had no effect on the piglets. Chapter 5 assessed the effect of feeding a phytogenic additive (PA) to sows and found that the PA was successful in altering the microbiota of sows and this change influenced the piglets reared and persisted to at least two weeks post weaning. Sows fed PAs throughout gestation gave birth to more piglet’s; however, this did not translate to more piglets born alive. Additionally, these sows tended to have a reduced wean to service interval. Currently no therapeutic alternatives to antibiotics exist for piglets, therefore, the evaluation of an alternative was assessed in Chapters 6 and 7. FMT has demonstrated success in the treatment of Clostridium difficile infections in humans, however there is limited research assessing its use in pigs in an industry appropriate manner. Chapter 6 was a proof-of-concept study that evaluated the use of a single FMT in 7-day-old antibiotic treated piglets. FMT at a young age was ineffective, however, requirements for optimisation in young pigs were gained and the key bacterial communities associated with age throughout lactation were identified. Chapter 7 evaluated the use of FMT post weaning and is the first study to demonstrate that a single FMT dose can elicit a change within piglets. Collectively, the findings of this thesis present a comprehensive evaluation of microbial colonisation within the piglet prior to weaning, methods for altering piglet microbial colonisation via the sow and environment, and information surrounding the potential application of FMT on farm. This research has enabled the identification of possible industry applicable practices and interventions to enable optimal microbial colonisation within sows and piglets for the improvement of pig health and productivity.