From world data it seems that too many sows are not
making it to a fourth parity. Leg problems are the secondmost reason for a
premature culling of sows, after reproductive problems. There are definitely
ways to deal with it.
Legs - a recurring problem
Leg problems is still the secondmost
reason for premature culling of sows, after reproductive
problems.
After several recent trips to hot humid countries, legs was
a common theme for discussion over the railings. On return I had to prepare some
figures for a paper I'm giving on Sow Longevity for an American
conference.
From world data it seems that too many sows are not
making it to a fourth parity. I calculate that on the economics of most pig
industries worldwide this reduces the potential lifetime income of a sow between
a third to a half - which is a considerable waste of investment and
skill.
Robust legs
So are the seedstock houses tending to
breed gilts with insufficiently robust legs?
Generally not, although
at the back of my mind I'm a little cautious about those very fine-boned legs
which they prefer as it goes well with good feed conversion in the
progeny.
When working with Britain's largest breeding farm of the
time I had to select many thousands of gilts - and got quite good at it to judge
by the requests from local farmers to do the job for them too; the spare-time
cash came in useful as well!
Oval
I tended to go for a
slightly more oval cross-section to the leg bones than the streamlined shape we
all favour today, as we seemed to get less leg problems - and especially joint
problems - in our somewhat heavy and milky matrons.
I certainly
avoided poorly-sprung pasterns and a tendency to stand 'tippitoes' - a feature
of some meaty North American breeds and which I still see in hot countries and
parts of North America.
No, don't blame the breeding companies, as
floor maintenance, infection and possibly nutrition of the gilt in particular
must be important contributory factors on the farms I visit where the subject of
legs is in the frame.
Gilt-rearing diet
I have long been in
favour of a special gilt-rearing diet. The first two above are self-evident/
remedying and I've always supported a special rather more expensive gilt-rearing
diet angled nutritionally towards what the scientists know about legformation,
which is probably not enough?
And in slowing the gilt down to grow
steadily towards first service so that her pins are mature and robust enough to
withstand the heavy demands on her physiology which her first few litters will
demand.
'Gilt Selection Route-Map'
Incidentally, my five
years experience of selecting gilts commercially encouraged me to publish a
'Gilt Selection Route-Map' round the gilt's body which any scrutineer can use in
any language.
Look for it in an article on 'Legs' in this journal
shortly, as it attempts to turn a rather subjective approach into a more
disciplined one, culminating in a target score below which the gilt doesn't
pass.
In my early days I found I was missing some things which the
boss picked up when the gilts arrived home.
'Needs must when the
Devil drives', as the old saying goes. And he was a bit of a
devil!