Midlands Integrative Biosciences Training Partnership (MIBTP) PhD CASE: Factors influencing the production of mycotoxins in grass silage and their effect on gut health and performance in dairy cows

Grass silage is the predominant forage fed to dairy cows in the UK. The aim when ensiling grass is to create an anaerobic environment to restrict proliferation of undesirable microbes, thereby maintaining the nutritive value over the winter-feeding period, and preventing spoilage. Factors such as the dry matter and sugar content of the grass, along with plant maturity and ensiling conditions can all affect the forage quality. Under adverse forage growing and ensiling conditions, or aerobic spoilage of clamps or bales at feed-out, fungal spoilage can be widespread. Under these conditions fungi can produce secondary compounds, including mycotoxins, which have been reported to occur in over 90% of the forage fed to cattle in temperate regions such as the UK, Ireland and Northern Europe. When present in the diet of cattle, mycotoxins and biologically active breakdown products can negatively affect gut function, health, fertility and production, and, in extreme cases, lead to death. Moreover, there is a risk that mycotoxins can be passed into the human food chain via the milk or meat.

Ruminants such as cattle rely on the activity of the microbes in the first stomach, or rumen, to digest feeds such as grass silage. Cattle can be more resistant to certain mycotoxins due to the activity of the rumen microbial community. However, most work has been undertaken on maize silage and few studies have been conducted on the mycotoxins commonly found in grass silage, or the subsequent effect of these compounds on the rumen microbiome. The ability of the rumen microbiome to efficiently digest forages is also dependent on a delicate balance of microbial species that can break down fibre and protein in the diet. An imbalance or shift in microbial population as a result of mycotoxins in grass silage may reduce digestive efficiency and indirectly impair health, milk performance and fertility.

Harper Adams University is one of the few centres in the UK that has the capability to carry out high impact research to investigate mycotoxin production in grass silage and subsequent effects on the rumen microbiome, rumen fermentation and immune response in dairy cows. These facilities allow us to ensile grass silage at multiple scales and under varying conditions to produce different levels of mycotoxins. Studies undertaken in vitro or in the animal can be undertaken to examine the ability of the microbiome to detoxify mycotoxins, and the uptake of biologically active compounds into milk. The rumen microbial community will be analysed using the current metagenomic and metabarcoding methodologies. Blood samples may be collected to examine the immune response to feeding forages with different mycotoxin loads, and strategies will be examined to mitigate and deactivate the effects of mycotoxins, such as the use of in-feed binder supplements. Mycotoxin analysis will be conducted by at a dedicated laboratory run by the industrial partner. 

Selection will be based on academic attainment, and research potential within the MIBTP Doctoral Training Partnership (DTP). However, international student numbers are capped at 30% by the funders (BBSRC).

Successful candidates will receive a yearly stipend (paid monthly in advance) set at the UKRI rate: for 2024/5 this will be £19,237. In addition, the industry partner will provide a £2000 per year uplift to the stipend.

Harper Adams University is unfortunately unable to offer a fee waiver for international students applying to the MIBTP programme. Evidence of funding will be required for international students to show they can cover the difference between the UK and international student fees for the full four years of the programme: for the 2024/5 academic year this amount is £10,890. However, scholarships may be available at the time of appointment to cover the difference between UK and International fees for the duration of the programme. 

Please note that in addition to the Harper Adams application form you will be required to complete an EDI form directly with MIBTP. 

Candidates are encouraged to contact Prof Liam Sinclair to discuss the project before applying if they wish to.