Evaluation of alternative feeding methods in restricted-fed gilts using operant conditioning and heart rate

摘要

Since the early 1970's, scientists have used preference tests to answer questions about animal welfare, with the assumption that animals make choices in function of their needs. In addition to establishing the animals' preferences, it is relevant toget some indication of their motivation to obtain the rewarding choice, and of their physiological responses. One example of an instrumental procedure developed to measure the animals' motivation is the operant conditioning procedure, where the animal works to gain access to a reward. This methodology was used in conjunction with heart rate recordings to compare the efficiency of a high-fibre diet fed to pregnant gilts in 1 or 2 meals (vs a concentrate diet, also in 1 or 2 meals) to reduce feeding motivation and consequently improve welfare. During the operant conditioning tests, gilts fed fibrous diets worked less and received fewer food rewards than gilts fed concentrate diets, whatever the number of meals per day. The increase in heart rate beforefeed distribution was 40 percent higher in concentrate fed than in high-fibre fed gilts. These results illustrate how technologies can complement the analysis of the welfare status of animals.