Food Preference and Demand in a Ramp Task in Guinea Pigs (Cavia porcellus)

Guinea pigs (Cavia porcellus) are popular pets and used as laboratory animals, however, their dietary preferences are under-studied. It is important for guinea pig owners and carers to increase the opportunity for good animal welfare by providing personalized and enriching dietary options. Thus, this study aimed to assess the use of paired-stimulus and multiple-stimulus-without-replacement preference assessments to determine the food preferences of seven male guinea pigs and test the validity of the methods by testing the demand for the most- and least preferred foods as reinforcers for climbing an elevated ramp. Generally, the preference assessments identified the same foods as the most preferred for each guinea pig, but not the least preferred foods. Guinea pigs climbed up to the steepest angle for both most and least preferred foods, but a non-linear least squares regression and demand analysis indicated faster climbing and inelastic demand for most preferred foods compared to slower climbing and elastic demand for least preferred foods. Both preference assessment methods were valid in identifying a preferred food, however, the multiple-stimulus-without-replacement assessment was more efficient to conduct. High-preference foods such as parsley and dandelion are recommended as future training reinforcers for guinea pigs and as foods to consider using as enrichment in captive guinea pig systems to encourage good welfare.