Feeding motivation in pregnant sows: effects of fibrous diets in an operant conditioning procedure

The effect of fibrous diets fed to pregnant sows on their feeding motivation was studied by an operant conditioning procedure. Fifteen multiparous pregnant sows were assigned to three dietary treatments, which differed in the nature of the fibrous components, according to a 3=3 Latin square design. Each sow received consecutively during three 3-week periods a concentrate low Ž . fibre diet, enriched in starch S diet: 2.44 kgrday , and two high-fibre diets, each based on one of Ž . Ž these major fibre sources: sugar beet-pulp BP diet: 2.74 kgrday and wheat bran WB diet: 2.90 . kgrday . All diets provided the same daily metabolisable energy supply of 33.4 MJ. Two 45-min operant conditioning sessions were performed 4.5 and 23 h after the meal on d16 of each 3-week period. Whatever the diet, no differences in the number of rewards received by sows were Ž . recorded 4.5 and 23 h after the single meal P)0.05 . In addition, there was no effect of time elapsed since food delivery on the feeding motivation of sows. In conclusion, there is no evidence that high-fibre diets reduce feeding motivation as measured by an operant conditioning technique over a medium and a long-term period after a meal. The use of operant tests to measure motivation is considered in the discussion. q 2000 Elsevier Science B.V. All rights reserved.