Economic and environmental impacts of sub-optimal mobility in Irish grassbased dairy farming

Dairy farming in Ireland is primarily based on low-cost grass-based milk production, with an average farm size of 52.8 hectares (Hanrahan et al., 2017). Cattle are housed only during part of the winter and are grazed for the rest of the year (Somers and O’Grady, 2015a). Following the dismantling of the EU milk quota regime and the subsequent dairy industry expansion, the average Irish dairy farm has increased from just over 44.4 cows pre-quota abolition 2010, (Hanrahan et al., 2017) to close to 80 dairy cows per farm in 2017. It is vital that future expansion is monitored and planned to ensure a sustainable intensification of the Irish dairy industry. This sustainable intensification refers not only to the environmental sustainability, but also to both the economic and social pillars of sustainability.
An important influencer of sustainable milk production is dairy cow health. Lameness or sub-optimal mobility is a multifactorial health issue and can be caused by various contributing factors including environment, behaviour, management, nutrition, infection, and conformation or genetics or through a combination of all of those issues together (Vermunt and Parkinson, 2002). There is an overestimated perception that lameness in a grass-based system is less of a problem compared with zero-grazing or confinement systems of production; the incidence rate of lameness in both systems, however, is quite similar (Olmos et al., 2009). Compared to cows in confinement systems, cows in pasture-based systems are exposed to different types of mobility issues. While cows in confinement systems are at risk to infectious hoof disorders such as mortellaro, sole ulcers and foot rot, cows in pasture-based systems are vulnerable to physical injuries, such as overgrown claws, sole bruising and white line disease (Barker et al., 2009). Sub-optimal mobility results in reduced (re)production and can eventually lead to culling. It is also shown in an Irish study on ten dairy farms that Irish dairy cows are exposed to significant risk factors associated with housing and indeed grazing (Doherty et al., 2014). Economically, diseases and sub-optimal animal health cause productive losses in dairy cows (Hortet and Seegers, 1998, Warnick et al., 2001, Hagnestam-Nielsen et al., 2009). Socially, there is increasing pressures with a more nuanced consumer that is demanding ever higher standards. Consumers are increasingly aware and concerned of how ethically and animal-friendly their food is produced. Moreover, social sustainability is an area of interest for the dairy industry, as it is acknowledged that, for example, lameness is associated with pain and discomfort. Environmentally, the Irish agricultural sector accounts for about 32% of total Irish greenhouse gas (GHG) emissions
(Department-of-Agriculure, 2015). Although the Irish GHG emission per unit of output is quite low, net emissions is an area of increasing interest and sometimes concern for the sector. The aim of this research is to quantify the production losses of a sub-optimally mobile cow, and then to convert these production losses into economic euro values and to quantify environmental impacts associated with sub-optimal mobility, specifically in terms of GHG emissions, nitrogen and phosphorus
efficiency, eutrophication, and acidification (Olmos et al., 2009). This research fills the gap in knowledge surrounding the economic and environmental impacts of lameness in grass-based systems.
The objectives of this project are to
1) To establish cow characteristics (e.g. body condition score, foot lesions, season, the effect of trimming and mobility scores) associated with lameness/sub-optimal mobility in dairy cows in a grass-based system.
2) To quantify the production, reproductive and culling effects associated with lameness/suboptimal mobility in grass-based dairy systems and then to convert these (re)productive effects into economic values
3) Quantify the environmental impacts (GHG emissions, acidification and eutrophication potentials) associated with lameness in a grass-based dairy system.
4) To predict the likelihood of lameness outbreaks on a grass-based dairy farm and to explore economic benefits of various strategies to mitigate lameness in Irish dairy herds.