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The importance and welfare implications of pasture access for lactating dairy cattle
Secondary Supervisor(s): Dr Emma Bleach
University of Registration: Harper Adams University
BBSRC Research Themes: Sustainable Agriculture and Food (Animal Health and Welfare)
Project Outline
Discussions around mega dairies and zero-grazed dairy cattle are topical and highly debated. In the UK, the majority of dairy cattle are housed indoors for at least part of the year, with many farmers moving to year-round housing [1]. Indoor housing protects cattle from environmental extremities and allows for greater feed control, allowing cows to meet their nutritional demands. However, indoor housing increases the incidence of diseases such as lameness and mastitis and restricts natural behaviour. Pasture is a natural environment for dairy cattle, allowing them to express natural behaviours such as grazing and to lie in stretched positions [2]. The incidence of lameness is reduced when cows are on pasture, it is the housing system preferred by citizens and milk quality improves. However, pasture alone does not always allow the cows to meet their nutritional demand, so they may become hungry, which is a welfare problem [2]. In addition, they are exposed to climatic conditions, heat stress and may damage the pasture. Research from Harper Adams University (HAU) was some of the first, internationally to investigate the preference of dairy cows for indoor cubicle housing or pasture [3,4]. The results of these highly cited studies show that dairy cows prefer to spend their time outside during the night, however, overall preference of dairy cattle for pasture is complex and there is little research on which aspects of pasture are most valued by dairy cattle, and how much time dairy cattle require at pasture, to meet their needs and improve their health and welfare, compared o zero grazed systems, without compromising production. Such research could enhance our comprehension of the importance of pasture access. Moreover, it could help us to further understand the needs of dairy cattle and inform future dairy cow housing.
Aims
The aims of the study are to understand the importance of pasture access for lactating dairy cows and to develop practical strategies to allow dairy cows access to pasture in conditions which improve their welfare compared to zero grazed cattle, whilst also maintaining milk production.
Objectives
1. To establish whether dairy cattle prefer an indoor open lying area or pasture
2. To investigate whether dairy cows are motivated to access pasture when they have access to an open indoor lying area, through varying walking distance between indoor housing and pasture.
3. To explore a range of grazing strategies which are practical for farmers and improve welfare, compared to zero grazed cows, whilst maintaining production.
Methods
A preference test will be conducted, allowing lactating dairy cows to choose between an indoor open lying space, such as a straw yard and pasture. Using sensors, time budgets will be monitored, welfare will be assessed, and health and milk production recorded. A further study will be conducted to establish the strength of the preference, using either a weighted gate or walking distance to assess motivation to access the preferred location. Time budgets, milk production and climatic conditions will be recorded and welfare assessed. A range of grazing strategies will be evaluated to develop practical approaches to grazing lactating dairy cattle. Part time pasture access, such as daytime and night time pasture access will be compared to full time pasture access and zero grazed cattle, during suitable grazing seasons. Data will be collected using individual and herd level technologies and sensors.
References
[1] March et al. http://dx.doi.org/ 10.3168/jds.2014-8265.
[2] Charlton and Rutter https://doi.org/10.1016/j.applanim.2017.05.015.
[3] Charlton et al., https://doi.org/10.1016/j.applanim.2010.11.018.
[4] Charlton et al. https://doi.org/10.3168/jds.2011-4172.