PRELIMINARY OBSERVATIONS ON THE PRE-WEANING BEHAVIOUR OF CROSS-FOSTERED
PIGLETS.
S. Robert1, G.P. Martineau2 1 Agriculture et agro-alimentaire Canada, Lennoxville,
2Faculte de medecine veterinaire, Universite de Montreal. Quebec, Canada.
Cross-fostering is widely use in segregated early weaning units in order
to maximize and uniformize body weights. However, cross-fostering does
not only have positive effects on the piglets. Extensive cross-fostering
of piglets maintains a continuous cycle of PRRS transmission, thereby increasing
preweaning mortality and postweaning uncontrolled PRRS infections. Moreover,
repeated changes from one litter to another could have detrimental effects
on the behavior of sows and piglets. Indeed, suckling piglets develop teat
fidelity within the first days after birth and suckle almost always at
the same teat or pair of teats until weaning. Teat fidelity is an advantage
to suckling young because it reduces competition and fighting at the udder.
Piglets that do not develop teat fidelity fight a lot throughout lactation
and have a lower weight gain. Previous studies reported that only 25 to
50 % of piglets fostered after two days of age had suckled six hours after
adoption. Moreover, piglets fostered at seven days of age had a reduced
weight gain.These observations suggest that cross-fostering disrupts the
teat order and induces fightings between resident and fostered piglets.
This hypothesis was tested in the following experiment. Twenty-four multiparous
sows were distributed between control and treated groups. All the litters
were uniformized at 10q1 piglets the day after birth. Once every three
days, all piglets were weighed and cross-fosterings were done between two
treated litters. The three heavier piglets of one litter were exchanged
with the three lighest piglets of the other litter. In this way, a piglet
could be fostered one to six times, the last fostering being done at 16
days of lactation. The behavior of sows and piglets was noted during the
first two hours following cross-fostering for the treated litters or weighing
for the control litters. The number of fights was much higher in treated
litters than in control litters and 80 % of these fights involved a resident
and a fostered piglet. Most of these were teat disputes where piglets fought
to gain access to a specific teat. Non-productive milk let-downs were more
frequent in treated than in control litters during the two hours of observation,
whereas sows from treated litters had less successfull milkings Sows have
more milkings after fostering but that many of these milkings are non-productive.
Typically, piglets started to fight and vocalize at the udder as soon as
the sow took the milking position and began to grunt. The sow showed frequent
signs of nervousness while lying down and suddenly stood up or sat down
after a few minutes. Data on lying behavior reflect this pattern of behavior.
Indeed, the percentage of time spent lying on the side was 17 to 32 % lower
in treated sows than in control sows from days 4 to 16 of lactation. Also,
treated sows snapped at their piglets more often than control sows and
this aggressive behavior was almost always directed towards a fostered
piglet. These data confirm the importance of teat stability in suckling
piglets and question the validity of cross-fostering from the welfare point
of view. Indeed, our data show that cross-fostering is stressfull for piglets
and sows in the short-term. Additional research will have to be done in
order to determine the impact of this management practice on aggressive
behavior of piglets and on later maternal and reproductive performance
of sows. Moreover, the high frequency of face lacerations noted in fostered
piglets suggests that cross-fostering may be one of the factors involved
in the development of exsudative epidermatitis. These results show that
in order to progress towards a more balanced form of intensive production
and improve husbandry conditions, we will have to take welfare into consideration
when making technical decisions .
Attached to this abstract are two short video clips showing the behaviour
of crossfostered piglets within the first 24 hrs of being placed onto a
surrogate sow.
Click to load the video of a cross-fostered
piglet fighting a resident piglet for the same teat during a nursing
bout.
Click to load the video of a cross-fostered
piglet searching for a teat. Watch piglet #14 eventually give up trying
to locate a teat. He leaves the udder, walks around the sow towards the
water fountain and subsequently misses the entire nursing bout.