Agriculture Reference
In-Depth Information
when they compared 5 groups of 15 sows with either physical, fence line or no contact
with boars. In their study, physical presence of a boar somewhat reduced aggression levels
between sows, but at the same time appeared to increase the levels of salivary cortisol,
compared with the absence of boars. Overall, boar presence seems to have a beneficial
effect on aggression, albeit that the effect can be small.
Learning social skills
Aggressiveness on introduction of gilts to a sow group can be reduced by familiarising
gilts with elder sows first. Backus
et al.
(1997) investigated an elaborative way to test this
hypothesis. They exposed breeding gilts at 3 weekly intervals to sows in a large outdoor
run. Following this treatment, the cyclic pattern of gilts was more predictable, and the
gilts were involved in less aggressive interactions on introduction to the main group of
sows. Van Putten and Buré (1997) suggested that the latter may have been due to the
fact that the gilts had acquired more social skills, in particular how to show submissive
behaviour when engaging with older, more dominant sows.
Kennedy and Broom (1994) used a more practical approach by allowing gilts a degree
of contact for 5 d prior to introduction with the group of sows they were going to be
housed with. The gilts were housed in a pen adjacent to the sow group and were able to
see, smell, hear and occasionally touch the resident group through the bars of their pen.
In comparison with gilts which were not allowed this pre-exposure, the exposed gilts
received less aggression following the first weeks after introduction to the main group. It
appears that the animals established a dominance relationship, despite the fact that they
could not actually engage in fighting to confirm it.
3.2.3
The feeding system
Sequential and consecutive feeding systems
The design of the feeding system affects the level of aggression related to competition for
food. Basically, two types of feeding systems can be considered in this context: simultaneous
and sequential feeding systems. Simultaneous feeding systems are characterized by once
or twice daily bursts of activity during which the animals want to get access to the feed
and eat. Common simultaneous systems are trough feeding in conjunction with free
access stalls, floor feeding and long trough (wet) feeding systems. Sequential feeding
systems are those where animals feed one after the other. Electronic sow feeding (ESF)
systems are used most in this category, but the so called Fitmix system has also received
attention recently (Chapinal
et al.
, 2008; Van der Mheen
et al.
, 2003). However, being
protected by fences during restricted feeding, such as with ESF, is preferred. The ESF
systems can provide an adequate level of welfare and performance, as long as they are
well designed and managed.
For simultaneous feeding systems, the level of protection given to individual animals
during feeding is crucial in particular when solid food is provided. Fast-eating sows will
thus be less quickly rewarded if they try to scare off smaller and slower sows. Individual
