A randomised controlled trial to evaluate the impact of indoor living space on dairy cow production, reproduction and behaviour
As a global society, we have a duty to provide suitable care and conditions for farmed livestock to protect animal welfare and ensure the sustainability of our food supply. The suitability and biological impacts of housing conditions for intensively farmed animals is a complex and emotive subject, yet poorly researched, meaning quantitative evidence to inform policy and legislation is lacking. Most dairy cows globally are housed for some duration during the year, largely when climatic conditions are unfavourable. However, the impact on biology, productivity and welfare of even the most basic housing requirement, the quantity of living space, remains unknown. We conducted a long-term (1-year), randomised controlled trial (CONSORT 10 guidelines) to investigate the impact of increased living space (6.5m2 vs 3m2 per animal) on critical aspects of cow biology, behaviour and productivity. Adult Holstein dairy cows (n = 150) were continuously and randomly allocated to a high or control living space group with all other aspects of housing remaining identical between groups. Compared to cows in the control living space group, cows with increased space produced more milk per 305d lactation (primiparous: 12,235L vs 11,592L, P < 0.01; multiparous: 14,746L vs 14,644L, P < 0.01) but took longer to become pregnant after calving (primiparous: 155d vs 83d, P = 0.025; multiparous: 133d vs 109d). In terms of behaviour, cows with more living space spent significantly more time in lying areas (65min/d difference; high space group: 12.43h/day, 95% CI = 11.70-13.29; control space group: 11.42h/day, 95% CI = 10.73-12.12) and significantly less time in passageways (64min/d), suggesting enhanced welfare when more space was provided. A key physiological difference between groups was that cows with more space spent longer ruminating each day. This is the first long term study in dairy cows to demonstrate that increased living space results in meaningful benefits in terms of productivity and behaviour and suggests that the interplay ...
