Effect of increasing energy intake and foraging behavior on the development
of stereotypies in pregnant sows.
R. Bergeron and H.W. Gonyou, Prairie Swine Centre Inc. Saskatoon, Canada
The persistence of a high feeding motivation after the meal in food restricted
pregnant sows appears to be a major factor involved in the development
of stereotypies. This study was designed to better understand the relative
role of two consequences of food restriction (lack of energy and lack of
foraging substrate) in the post-feeding persistence of feeding motivation
expressed in stereotypies. Twenty-four second parity sows in their 8th
week of gestation were classified in four groups according to their activity
level (group 1: more active to group 4: least active). Then, sows within
each group were randomly assigned to either a "high-energy" (HE- 1.7 times
more energy than control diet), a "high-foraging" (HF- device placed inside
the feeder for one hour at meal time to increase feeding time), or a control
treatment (C), each one providing a similar volume of food. The animals
were observed once a week by scan sampling, for 9 consecutive weeks. Observations
made in the 90-min post-feeding period (starting one hour after food delivery)
revealed that HE and HF sows spent more time inactive than C sows, with
HE sows being the least active (P<0.01). C and HF sows tended to perform
almost twice as much chain manipulation as HE sows (P<0.10), and sham
chewing tended to be higher for C sows (P<0.10). In the following 5-hour
period, chain manipulation tended to be higher for HF sows (P<0.10),
but sham chewing was not affected by treatments. For both observation periods,
sows that had been initially classified as most active were also the most
active (P<0.01), spending more than twice as much time manipulating
the chain (P<0.05). These results suggest that the long-term satiety
induced by an increased energy level can potentially reduce repetitive
oral behaviors such as chain manipulation and sham chewing. However, providing
more opportunity to forage at meal time without increasing meal size or
energy level appears to reduce the activity level, without consistently
affecting repetitive oral behaviors.
Keywords: sows, stereotypies, energy intake, foraging behavior.