Effects of zinc oxide on the pig gut microbiome and performance
Prof H M Miller
No more applications being accepted
Funded PhD Project (UK Students Only)
A critical period in the life of the pig is immediately post weaning as the piglet switches abruptly from a predominantly liquid milk diet, supplied by the sow, to a predominantly plant based diet, supplied by feed, and hence undergoes rapid complimentary changes in gut structure, function and microbiome. During this period piglets characteristically fail to maintain their feed intake, lose weight and are susceptible to diarrhoea, often caused by enterotoxigenic Escherichia coli (ETEC) K88. Therefore improving piglet performance during this period has both economic and welfare benefits. Currently the main control measure used in the absence of growth promoting antibiotics to control and minimise diarrhoea is the inclusion of pharmacological levels of zinc oxide (ZnO) in piglet diets during the first 14 days after weaning.. When given a choice between un-supplemented feeds and feeds supplemented with ZnO piglets choose the latter (Reynolds et al. 2011), indicating that ZnO operates via its effects on intestinal health rather than by providing an immediately more palatable feed source, however the mechanism of action of ZnO remains elusive.
In earlier work using microarrays and quantitative real time PCR we identified lower transcript abundance for a number of genes associated with innate immune response and inflammation from the jejunum of pigs that had received ZnO in their diets compared to their non-ZnO fed contemporaries (Sargeant et al., 2010a). This work was then confirmed in vitro using intestinal porcine epithelial cells (IPEC J2; Sargeant et al., 2010b).However ZnO is thought to act primarily via antimicrobial effects hence feeding ZnO modifies the changes in the microbial composition of the piglet gut occurring during the critical post weaning period. Whilst it is generally considered that a healthy gut has a high ratio of lactobacilli to coliforms, in pigs receiving ZnO this ratio is reversed. Using next-generation sequencing it is possible to gain a better understanding of the changes to the gut microbiome which occur in pigs at weaning and how these are affected by feeding ZnO-supplemented diets. A recent study of the human gut has found that diet rapidly and reproducibly altered the microbiome and established links with bacterial species that cause disease. It also identified that foodborne microbes in the diet can actively colonise the gut. This and similar studies in human give us confidence that a metagenomic analysis of the pig gut will establish similar dietary links that can be manipulated by changing feed and farming practise to improve pig health and performance (David et al., 2014).
The broad objective of this project is to develop a robust framework for studying the gut microbiome of pigs using next-generation metagenomic sequencing. The specific aims are to (i) establish a faecal sampling regime that provides a reliable measure of the gut microbiome of individual pigs, (ii) identify the extent to which ZnO diets produces changes in the faecal microbiome profile at the level of phyla, species and genes, and (iii) investigate the level of correlation between faecal microbiome profiles and pig performance.
A better understanding of the link between ZnO diets, the pig gut microbiome and pig performance, will help us to design better feeds and feeding management for young pigs during the critical post weaning period weaning and may enable us to develop alternatives to ZnO.
KTN BBSRC industrial CASE studentship. The successful applicant will spend a minimum of 3 months during the PhD working with the industrial partner. In addition up to 8 days specialist training will be provided by KTN during the studentship.
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