Does the number of daily meals affect feeding motivation and behaviour of gilts fed high-fibre diets?

Abstract

We compared feeding motivation and feeding-related stereotypies of pregnant gilts fed high-fibre (HF) or concentrate (C) diets in one or two daily meals. Twenty-four gilts were fed either a concentrate diet or high-fibre diet with the same daily intake of energy and major nutrients. The effect of the number of daily meals (one versus two) was tested with a switch-back design, each feeding period lasting 1 month. Duration of eating was increased by HF diet ( P<0.001) but was not affected by feeding frequency. Before meals, stereotypies and vocalizations were less frequent for gilts fed the HF diet compared to the C diet, and for gilts fed once a day compared to twice ( P<0.05). Before the morning meal, HF gilts were less active when fed twice a day than once, but frequencies were similar in C gilts, regardless of the number of meals ( P<0.05). During the observation period preceding the afternoon mealtime (or comparable non-meal period for gilts fed one meal), C gilts lay down less often when fed in two meals compared to one meal ( P<0.01), while there was no difference for gilts fed HF. After meals (or comparable non-meal period for afternoon observation of gilts fed once), the frequency of drinking, licking the empty feeder and performing stereotypies was lower ( P<0.05) and the frequency of lying was higher ( P<0.01) for gilts fed the HF diet compared to the C diet, and when gilts were fed one compared to two meals. Object biting was the most frequently observed stereotypy before the morning meal. During the morning post-feeding and both afternoon observation periods, the most frequent stereotypy was vacuum chewing, except in C gilts fed two meals where vacuum chewing and chain manipulation occurred at similar frequencies. During operant conditioning tests measuring the motivation to work for food rewards by pushing repeatedly a button with the snout, HF gilts obtained less rewards than C gilts, before and after feeding ( P<0.01). The number of meals did not affect the operant performance, except that gilts tended to work for a shorter time during the afternoon test when they had been fed two meals before the test (in the morning and the afternoon) rather than only one in the morning ( P<0.1). The heart rate values were higher in the C than in the HF gilts at the arrival of food ( P<0.01) and during feeding ( P<0.05). In conclusion, a high-fibre diet is more effective in reducing feeding motivation when fed in one large daily meal rather than in two smaller ones.