High-Fibre feeding in gestation - The Gestating and Lactating Sow - page 88

5.4 Impact of dietary fibres on behavioural activity

Investigations of the effects of dietary fibre on the behavioural activity of pigs have focused
on feeding patterns and feeding motivation as signals of the satiation-satiety state. Other
activities associated with eating behaviour, such as non-feeding oral activities, are also
considered to signal frustration due to food restriction, and aggressive behaviour may
reflect food competition in group-housed sows. Yet, apart from reflecting changes in time
spent on feeding behaviour, fibres (e.g. resistant starch, RS) may also reduce activity per
se (De Leeuw et al., 2008), and foraging and exploratory behaviours if sows are kept in
enriched housing where substrates provided on the floor may serve as nutritional sources
of dietary fibre (D'Eath et al. , 2009; De Leeuw et al. , 2008; Meunier-Salaün et al. , 2001;
Le Gall et al. , 2009; Philippe et al. , 2008). Although these studies used different breeds,
housing conditions, dietary fibres and recording periods (pre, or postprandial, or the
whole day), general conclusions can be drawn regarding the effects of fibrous diets on
the behaviour of sows. The major effects are an increase in the consummatory phase
of the feeding pattern, a reduced occurrence of non-feeding oral activities, including
stereotypies, a decreased aggression in group-housed sows, and a decline in general
activity. Nevertheless, the intensity of responses depends on factors related to the animals,
feeding conditions and characteristics of the diet supplied, as described below.

5.4.1 Feeding patterns and feeding motivation

Pregnant sows fed a fibrous diet generally spend more time to consume the increased
quantity supplied to provide the same amount of energy compared with a conventional,
more energy-dense diet. They can spend up to 5 times more time to eat, depending on
the fibre type supplied (Brouns et al. , 1994, 1997), both in individually-housed sows
and in group-fed sows housed outdoor (Brouns et al. , 1995; Martin and Edwards, 1994;
Ramonet et al. , 1999; Table 5.2). This can be explained by changes in the feeding pattern,
with sows spending more time to chew fibrous diets. Guillemet et al. (2006) showed a
break within the meal when sows were fed a 31% NDF diet compared with very scarce
breaks for a 17% NDF diet. These changes in feeding pattern are also associated with a
lower feeding rate (Brouns et al. , 1997; Guillemet et al. , 2006; Mroz et al. , 1986; Philippe
et al. , 2008; Ramonet et al. , 2000a; Rijnen et al. , 2003). However, the effects of fibrous diets
on feeding rate may depend on housing conditions. For instance, stronger effects were
reported in individually-housed sows compared with sows housed in groups of six which
were fed simultaneously using six troughs. This was likely related to the competitive
situation in the latter case which generates a high number of displacements at the troughs
(Courboulay et al. , 2001).

Changes in feeding pattern may also be related to the palatability of the fibre source.
Studies have shown, for instance, a lower preference of feeds incorporating sugar beet
pulp or dehydrated alfalfa compared with wheat bran (Brouns et al. , 1995; Guillemet et
al. , 2007a; Sola-Oriol et al. , 2011). The fibre source and its inclusion rate, and freshness
of the feed can affect palatability, and thus may have an impact on short term intake by
inducing feelings of fullness and meal termination where oral sensory stimulation would
play an important role. Metabolic effects linked to stomach distension, delayed gastric