Although freedom from hunger is a key pillar of animal welfare, feed restrictions are common on most farms. For instance, on dairy farms, pre-weaned calves are typically fed less than 50% of ad libitum consumption (4-6L of milk when they would drink up to 16L[1]). Calves also experience hunger when forced to transition from milk to solid feed much earlier and faster than would occur naturally[2]. Growing heifers and dry cows (animals in late gestation) are often kept on restrictive diets too[3]. Dairy cows thus typically experience various levels of hunger at many points in their life. Although we have a relatively good understanding of the impacts on development (e.g. restrictive diets slow growth and increase signs of hunger in calves[4]) and ability to express important natural behaviours such as play[5], little is known about other effects of these experiences on affective states, cognitive abilities, and resilience to stressors. Whilst the feeling of hunger remains largely unexplored in non-human animals[6], feed restrictions are expected to be associated with intense negative affective states[7]. Early experience of chronic hunger is also predicted to have both immediate and long-term effects on cognitive abilities[8], feeding[9] and social behaviours[10], as well as reducing overall productivity.
Aims and objectives
1) Assess short-term effects of feed restriction on dairy calves.
H1: Feed restrictions lead to negative affective states and impaired cognition (e.g. memory deficits; impulsivity).
2) Explore long-term and cumulative effects of feed restriction on feeding and social behaviour
H1: Feed restrictions result in enhanced competition for feed access, increased aggressiveness, and decreased willingness to share resources.
3) Explore the implications in terms of animal welfare, production, and sustainability goals
H1: Feed restrictions generate lower resilience to stressors and higher vulnerability to disease, hence negatively affecting dairy farm sustainability.
Methodology
Standard feeding will be compared to ad-libitum feeding during pre-weaning and post-weaning phases of calf development at UoB’s John Oldacre Centre Wyndhurst Farm (Langford). Effects of feed restriction on calf affective states and learning ability will be investigated using established tests [11,12] coupled with new biomarkers of cumulative stress and aging [13]. Resilience will be explored by measuring how animals respond to routine stressors (e.g. hoof trimming; increased competition for food access). The project will also provide longitudinal data describing effects of feeding level on health, disease vulnerability and measures of productivity. This will allow lifecycle analysis to be performed hence providing key missing information to fully assess effects of feed restriction on dairy cattle welfare, health and sustainability.
The student will acquire skills in experimental design, develop and conduct state-of-the-art behavioural tests in large animals, collect, analyse and interpret physiological data, and carry out statistical analysis. They will also have the opportunity to learn techniques in life-cycle analyses that are commonly used in sustainability research, in collaboration with experts at BVS. These skills will be transferrable to other species and research questions in the wider fields of animal science and sustainable agriculture.
How to apply for this project
This project will be based in Bristol Veterinary School in the Faculty of Health Sciences at the University of Bristol.
Please visit the Faculty of Health Sciences website for details of how to apply
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