First of all, let me say that even the word fiber has no single
interpretation among nutritionists. Is it crude fiber, dietary fiber, or
something in between these two extremes?
For all practical reasons, we will remain with the
most commonly used term, crude fiber, which although it does not include all
such compounds that could potentially impart a 'fiber' effect, it nevertheless
is a widely available figure in most nutrition books and it is well understood
by nutritionists and producers alike.
Adult breeding sows
Right! So, how much fiber sows need? Adult breeding
sows have the digestive capacity to ingest and digest quite large amounts of
fiber, but for practical reasons, we certainly want to limit this.
So, starting from lactating sows, from which we
anticipate maximal feed intake, crude fiber concentration should be limited to
around 3-4%. This, of course, may cause digestive upsets, namely constipation,
but it is here where the use of chemical and/or natural laxatives should be used
to maximum benefit.
It is quite the opposite in gestating sows. Here, we want
to limit feed intake to prevent fatness and as such gestating sows are usually
offered a quantity of feed that barely covers their hunger, in other words
satiety is not achieved.
Thus, it is quite beneficial to offer high-crude fiber diets to gestating
sows. In limited-fed animals, crude fiber should be around 6-8%, but in ad
libitum fed animals, crude fiber concentration can be as high as 12-15%.
And, of course, in this case, laxatives are not
needed, which might be an obvious conclusion, but I have seen a fair number of
gestating diets with high fiber and a strong laxative!
Young developing gilts
Finally, we should evaluate the 'needs' for crude
fiber for young developing gilts. Again, we should split them into limit-fed
versus ad libitum-fed animals. In the first case, diets should contain around
3-5% fiber, whereas in the second case crude fiber can be as high as 12-15%.
A word of caution is needed here. As genetic maturity is quite variable
among commercial breeds and growth/development targets are different from farm
to farm, gilt diets should be always custom-made to match required growth and
thus, crude fiber concentration should also be adjusted accordingly. So, a
single size does not fit all, at least for gilts!
In the next installment of this topic, we shall examine sources of fiber
suitable for sow dietsâ€¦