Based on your requirements, developing a scale for good practices in livestock feeding and feed safety entails a customized approach based on the specific environment or region. It would involve a review of previous studies as well as interviewing animal science and animal nutrition experts, along with professionals experienced in working on farms. This multifaceted approach will help in devising a comprehensive and tailored scale that encompasses the nuances of specific environments and practices.
For literature review, you can use these keywords such as "animal nutrition," "livestock feeding practices," "feed safety," and "good practices in animal feeding" to refine your search.