Funder and dates: Scottish Government (RESAS RD 2.3.1.) and Government of Costa Rica, 2016-2019
Ruminants are responsible for a large proportion (between 6-8-%) of the anthropogenic methane emissions. Reducing the contribution of the cattle sector to methane emissions is an important measure to mitigate greenhouse gas (GHG) emissions. Previous research has shown that hormones released in response to stress can have deleterious effects on the balance of the microbiota present in the gut which can last long after stress hormone levels have returned to normal. Therefore these changes may have important consequences for ruminal fermentation and digestibility, leading to suboptimal use of nutrients and increased methane emissions. The body of knowledge is very limited in relation to the interactions between stress physiology, methanogenic microbiota and down-stream effects on environmental sustainability. This project aims to understand the mechanisms by which stress impacts feed efficiency and methane emissions in beef cattle which could inform future strategies to improve the economic and environmental sustainability of beef production as well as benefitting animal welfare. The work will occur in two phases. In phase 1 a synthetic glucocorticoid will be administered to fattening beef cattle to simulate the peripheral effects of an endocrine stress response on the ruminal microbiota. In phase 2, a commercially relevant chronic stress scenario will be applied to a different population of animals to examine how the combined behavioural and physiological stress responses of the host affect the rumen and subsequently feed efficiency and methane emissions.