The Rural Voice, 1983-06, Page 51those over 2 lbs. at birth survive.
Obviously, to get to a 10% mortality rate
we have to pay attention to the needs of
those low birthweight pigs.
Why do low birthweight pigs die and
do they always die? The answer to the
second question is no. The answer to the
first is not known for sure.
If we knew why they die we could do
something about it; adapt our behavior to
the needs of the pig, not the other way
around. We do know that almost 70% of
pigs die from a combination of crushing
and what is euphemistically known as
"low viability." Scours are the major
cause of the remaining deaths. A
significant number of the "low viability"
pigs are crushed or starved due to their
slow reaction to the grunting of the sow
to tell them to get out of the way or come
and suckle. To get to our target of 10%
pre -weaning mortality, we must deal with
those low viability pigs.
Most of these are also small at birth.
Low birthweight means that the piglet
has a larger surface area per unit of
weight than a normal pig. A larger
surface area means a greater loss of
energy and a greater use of glycogen to
keep warm. As the glycogen reserves run
out, slower reaction, sluggishness, a
lack of aggression and a loss of will to
survive combine to lead to crushing,
starvation and death. Keep environmen-
tal temperatures up.
We know that if we even up piglet
weights in litters, through cross -foster-
ing, many of the low viables will survive.
My theory is that a major factor in piglet
survival is the ability to fight. As in most
fights, a good big one will always beat a
good little one. Pigs fight each other
almost as soon as they are born, an
average of 41.6 fights in the first 8 hours
of life.
Piglets fight exactly the same way as
adult hogs, by leaning, pushing and
snapping. Weight is the deciding factor.
The winner gets the best milk source.
The loser gets more fights, possible
starvation, exhaustion, hypolgycemia
and death.
If a little pig is continually being
beaten for the best teats, he spends a lot
of energy fighting and doesn't get much
milk or colostrum to replenish his supply
of glycogen which is used up providing
energy for fighting and keeping warm.
Those little pigs are just mismatched.
That's why, I believe, 80% of those
little pigs will survive if they are put in a
litter with other small pigs. They are
more evenly matched, aren't continually
losing fights and being pushed off the
teat, and they don't use up so much of
their precious glycogen.
So if you cross -foster, even up fighting
weights, not litter numbers. Just think
what happens when you cross -foster. If
you move the smallest pig to another
litter when he is already a few hours old,
he is going to have a whole new series of
fights to establish himself, leading to
exhaustion and reduced viability. If you
transfer the largest pig, he is going to
have another series of fights to establish
himself and this is going to go all the way
down the line, so our mismatched little
pig is going to have more fights and get
pushed to a worse milk supply, leading
to exhaustion and reduced viability.
Enough of "low viability," what about
scours?
The keys to the minimization of
mortality from scours are heat, hygiene
and immunity. I want to re-emphasize the
significance and vital importance of heat.
I have noted. how crucial it is to the
survival of the "low viables." It is equally
crucial as a component of scour control.
A colleague recently completed an
experiment in which he kept, from birth,
half the pigs from several litters at 35°C
(95°F) and the other half at 25°C (77°F).
Once an hour the piglets were put back
on the sow to suckle. At 18 hours they
were all challenged with a pathogenic. E.
coli. Those kept at 35°C had no
ill-effects, while those at the lower
temperature had severe scours and
dehydration. In a survey on temperature
of the environment at piglet level, we
found ranges from 22° to 32°C, with an
average of 25.6°C. about the same as the
lowest level in the study. Li
/tt
NAR
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PG. 50 THE RURAL VOICE, JUNE 1983