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 motivatio n was studied by an operant conditioning procedure. Fifteen multiparous pre gnant sows were assigned to three dietary treatments, which differed in the nature of the fibrous components, according to a 3 x 3 Latin square design . Each sow received consecutively during three 3-week periods a concentrate low fibre diet, enriched in starch (S diet: 2.44 kg/day), and two high-fib re diets, each based on one of these major fibre sources: sugar beet-pulp ( BP diet: 2.74 kg/day) and wheat bran (WB diet: 2.90 kg/day). All diets prov ided the same daily metabolisable energy supply of 33.4 MJ. Two 45-min oper ant 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 recorded 4.5 and 23 h after the single meal ( P > 0.05). In addition, there was no effect of time elapsed since food deli very 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. T he use of operant tests to measure motivation is considered in the discussi on. (C) 2000 Elsevier Science B.V. All rights reserved.