Impacts of toxic plants on the welfare of grazing livestock

Authors: Pfister, James; Green, Benedict - Ben; Welch, Kevin; PROVENZA, FREDERICK - Utah State University; Cook, Daniel

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/4/2016
Publication Date: 8/30/2016
Citation: Pfister, J.A., Green, B.T., Welch, K.D., Provenza, F.D., Cook, D. 2016. Impacts of toxic plants on the welfare of grazing livestock. In:Villalba, J.J., editor. Animal Welfare in Extensive Production Systems. Sheffield, U.K.:5m Publishing. p. 78-102.

Interpretive Summary: Interest in farm animal welfare has been increasing for several decades. Animal health is an integral part of animal welfare, but the concept of animal welfare has evolved from an emphasis on physical health, and coping ability to a greater sensitivity to and recognition of animals’ experiences of positive and negative feelings and emotions. The “Five Freedoms” provide an important framework for assessing animal welfare in livestock, including: 1) freedom from thirst, hunger, and malnutrition; 2) freedom from discomfort; 3) freedom from pain, injury and disease; 4) freedom to express normal behavior; and 5) freedom from fear and distress. One could argue that over-ingestion of plant toxins may negatively affect all of these freedoms. The public perception is that the welfare of extensively grazed livestock is greatly enhanced because of their ability to express natural behaviors compared to more intensively managed animals. However, relatively little work has been done to evaluate animal welfare within extensive systems. Further, livestock grazing on rangelands may encounter conditions very different from either their early background or environment under which their species evolved, including encounters with plant secondary metabolites (PSMs) that occur in virtually all plants. The ingestion of toxic plants by livestock grazing in extensive environments has the potential to adversely impact animal health through increased stress and suffering, as well as the potential to benefit animal welfare at low doses of PSMs. Animals that can cope and adapt to encounters with toxic plants may not experience more than a temporary reduction in welfare and may benefit from mild stress imposed by secondary compounds. However, animals are likely to experience short-term or long-term suffering if they are unable to cope with the challenges from encounters with toxic plants. In this chapter we review grazing animal welfare in relation to selected toxic plants, highlight areas where improvements in welfare can be made, and identify potential research needs.

Technical Abstract: Interest in farm animal welfare has been increasing for several decades. Animal health is an integral part of animal welfare, but the concept of animal welfare has evolved from an emphasis on physical health, and coping ability to a greater sensitivity to and recognition of animals’ experiences of positive and negative feelings and emotions. The “Five Freedoms” provide an important framework for assessing animal welfare in livestock, including: 1) freedom from thirst, hunger, and malnutrition; 2) freedom from discomfort; 3) freedom from pain, injury and disease; 4) freedom to express normal behavior; and 5) freedom from fear and distress. One could argue that over-ingestion of plant toxins may negatively affect all of these freedoms. The public perception is that the welfare of extensively grazed livestock is greatly enhanced because of their ability to express natural behaviors compared to more intensively managed animals. However, relatively little work has been done to evaluate animal welfare within extensive systems. Further, livestock grazing on rangelands may encounter conditions very different from either their early background or environment under which their species evolved, including encounters with plant secondary metabolites (PSMs) that occur in virtually all plants. The ingestion of toxic plants by livestock grazing in extensive environments has the potential to adversely impact animal health through increased stress and suffering, as well as the potential to benefit animal welfare at low doses of PSMs. Animals that can cope and adapt to encounters with toxic plants may not experience more than a temporary reduction in welfare and may benefit from mild stress imposed by secondary compounds. However, animals are likely to experience short-term or long-term suffering if they are unable to cope with the challenges from encounters with toxic plants. In this chapter we review grazing animal welfare in relation to selected toxic plants, highlight areas where improvements in welfare can be made, and identify potential research needs.