Graduate Student Literature Review: Integrating concepts of animal welfare and health-related quality of life for preweaning dairy calves.

Dairy calf welfare assessment tools focusing on the preweaning period have been proposed in recent research. Despite the existence of these tools, assessing the welfare and health-related quality of life (HRQoL) of dairy calves remains challenging. These difficulties may stem from the complexity of assessing all dimensions of calf welfare and the validity, reliability, and feasibility of the indicators used in assessment tools. This review aims to discuss welfare and HRQoL concepts and integrate them into a framework to facilitate the understanding of dairy calf welfare and HRQoL. The review also identifies on-farm dairy calf welfare indicators and explores how their validity, reliability, and feasibility have been evaluated. Health-related quality of life, as a component of the quality of life concept, is used to determine how an animal feels during illness using behavioral expressions of affective states. In this review, we adapted a human HRQoL framework for dairy calves, illustrating the interconnection of 3 domains of animal welfare (behavior, mental state, and health) in assessing calves' HRQoL. It is worth noting that a limited number of HRQoL assessment tools have been developed for dairy calves, and there is no standard way to assess the welfare of preweaning dairy calves. Some studies focus on specific aspects of animal welfare, whereas others address this concept more broadly. Although behavioral indicators have been explored in dairy science, they often remain disconnected from the concept of HRQoL. After reviewing various welfare assessment tools focusing on preweaning dairy calves, 44 welfare indicators were selected. Considering the selected welfare indicators, we observed that their validity, reliability, and feasibility have not been extensively explored. This review contributes to understanding welfare and HRQoL concepts for preweaning dairy calves and highlights opportunities to enhance the assessment of welfare and HRQoL for these animals.