Canada_IPAP: Impact of alternative nutrition management on AMR burden, transmission and trends in dairy cattle.

Antimicrobial resistance (AMR) is the ability of microorganisms to resist antimicrobial treatments. It is an urgent global public health threat with a direct impact on human and animal health. AMR carries a heavy economic burden due to higher costs of treatments and reduced productivity caused by sickness. Misuse and overuse of antimicrobials are the main drivers in the development of drug-resistant pathogens, including in livestock production. In dairy cattle, antibiotics important in treating pathogens in humans such as penicillin, cephalosporin and tetracycline are also used extensively to treat mastitis.

Furthermore, AMR associated bacteria in livestock can be shed and disseminated to humans via direct contact, or through contact with the environment such as soil, water and faecal material, or through cross-contamination during food processing through a process known as horizontal gene transfer. Recent research has shown that diet has important effects on the presence and types of antimicrobial resistance genes (ARGs) present in dairy cows. The shedding and dissemination of ARGs by dairy cows has also been attributed to stress response of gastrointestinal tract microorganisms in relation to diet, and infection by harmful bacteria.

This is an important finding as feeding management and dietary change are crucial for metabolic adaptation especially in the transition dairy cows. The transition period in dairy cows is the time between 3 weeks before calving to 3 weeks after calving. This period is critical for the health, fertility, and productivity of dairy cows as cows go through drastic metabolic and changes which render them extremely vulnerable to diseases. Therefore, their diet and energy intake during this period is important to boost their immunity and prevent high incidences of infectious diseases which may lead to increased antibiotic use and thus increased resistance.

It is clear that nutritional changes provide the largest opportunities for improving health, reducing antibiotic usage and reducing AMR in dairy cattle. And so, to ameliorate the problem of AMR whilst bosting animal health, the use of non-antibiotic feed supplementation is gaining traction in the dairy industry. However, the impact of these feed supplements on AMR burden and spread of is largely unknown. This emphasises the importance of fundamental research into how feed supplementation contributes to not only animal health and immunity but to AMR burden and transmission, specifically in the dairy industry, currently worth £4.4bn in market prices.

Therefore, in this study, we will investigate potential of using milk permeate as a feed supplement in transition dairy cows to improve animal health while assessing the effect this will have on the AMR burden of dairy.

Milk permeate, is a major by-product of milk processing for cheese and yogurt production Its dried is sometimes used to replace starches in dairy cow diets. However, the use of this product has been limited due to the cost associated with drying and transport and as such, there is always an oversupply of milk permeate. For example, >1M and 30M litres of milk was dumped in the UK and Canada respectively in 2020.

We aim to assess the potential of using surplus milk permeate (in its liquid form), which would otherwise be dumped, as feed supplements to improve immunity and health for transition dairy cow. This allows us address of creating a circular economy.

We will also address the gaps in knowledge regarding dietary change and feeding management using milk permeate and the corresponding effect on the presence and transmission of ARGs during the transition period of dairy cows.

Dietary changes often with feed supplementation is commonly employed in livestock production especially during stressful production periods, such as the transition period in dairy cows. This period is characterised by drastic metabolic, immune and endocrine changes, rendering cows extremely susceptible to diseases.

This incidence of disease often leads to increase use of antibiotics and consequent increase in antimicrobial resistance genes (ARGs) due to selection pressure. Therefore, feeding management and dietary change are especially crucial for metabolic adaptation of the transition dairy cows.

Moreover, livestock have also been shown to excrete ARGs from their gut bacteria, attributable to stress response mechanism of gastrointestinal microbiota in relation to diet, and infection by opportunistic and pathogen bacteria. Diet has also been shown to have important effects on the complement of ARGs in the rumen microbial community and playing a critical role in the gastrointestinal microbiology and dissemination of ARGs from the dairy cow.

Due to the problem of antimicrobial resistance (AMR), and the emergence of livestock as a reservoir for AMR, there has been a shift to non-antibiotic feed supplementation in production. And while numerous alternative feedstuffs and feed additives including liquid supplementation have been used in an attempt to reduce dysbiosis, promote energy intake, and reduce the incidence of illness, their impact on ARG burden and dissemination and implications for One Health remains largely unknown.

Therefore, in this project, we aim to investigate the impact of liquid supplementation using milk permeate, a by-product of milk processing, on the burden and transmission of ARGs in transition dairy cows, whilst assessing its influence on cow, metabolism via microbiome changes, and immunity.

This will no doubt address the knowledge gaps in feeding management influences on AMR, while potentially creating a circular economy.