Breeding age of sows:  It is very important to breed sows at the proper age of 8-11 months old and when they are well developed. They should also be a good weight and size.  This is especially true for the skinny pigs as they are not the same as you would breed regular guinea pigs and are generally smaller in size.  We have been breeding them for many years and have never had issues with them getting a fused pelvis known as dystocia and it is likely a myth. The pelvis does not fuse in older sows, it stiffens making first delivery at over one year of age more difficult.  It is more common in over weight cavies.  If you breed them at a younger age you will have complications of having weaker babies and your sow may die or have complications. 

Breeding age of boars:  Boars can be bred at 7 months or older.  This is important so that you don’t have weak litters.

To view an article written by Cathy Tharp on genetic info and recommendations for out crossing of Skinnies check out:

http://forum1.aimoo.com/RVBG/Genetic-Pedigree-Questions/Skinny-genetics-1-1117825.html

Skinny Pig X Skinny Pig
When you breed two Skinny Pigs together, 100% of their babies will all be
Skinny Pigs and hairless.

Skinny Pig X Skinny Pig Gene Carrier
There is a 50-75% or about half chance that the babies bred by a Skinny
Pig and a haired Skinny pig gene carrier, will have hairless Skinny pig
babies.  The rest of the babies will just be skinny pig gene carriers.

Skinny Pig Gene Carrier  X Skinny Pig Gene Carrier
There is only a 25% chance that 1 or so hairless skinny babies will be born
in these litters.

Skinny Pig X Regular haired breed guinea pig(not a gene carrier of
skinny)
None of them will be a hairless skinny pig.  There is a chance that most of
the babies will be haired Skinny Pig gene carriers which can then be bred
back to the Skinny Pig.  

Skinny Pig Gene Carrier X Regular haired breed guinea pig(not a
gene carrier of skinny)
There is no chance a Skinny Pig pup will be born from a Skinny Pig gene
Carrier bred to a regular haired guinea pig(not a gene carrier).

Skinny Pig X Baldwin(breeding not recommend)
None of the babies will be hairless like the Skinny Pigs and or Baldwins.
They will all have hair and look like a regular haired guinea pig, but 50% of
the babies will carry either the gene for Skinny Pigs or Baldwins and you
won't know which ones they are.  

Hairlessness varies with the Skinny Pigs depending on their parent's lines
and genetics. You won't know which babies are the true Skinny Pig gene
carriers until you breed them.  It takes several generations to have very
hairless skinny pigs in your lines.  When you first breed them from the
carriers/regular haired pigs most of the babies will be hairy hairless skinny
pigs with fuzz. It is best to work with the best strong very hairless lines out
there so that you can produce very hairless hardy Skinnies.  

Baldwins are completely bald with absolutely no hair at all or
very minimal on their feet, but they do not come out like that when
they are born like the skinny pigs do. They are born completely
haired like a regular haired guinea pig. After just a few days of
their birth from 2-5 days old their hair falls out from the head to
their bottoms until they are completely bald at around 2 months of
age or so.  

Skinny pigs and Baldwin guinea pigs seem to be the consequence
of different separate recessive mutations in one gene each so the
conditions only occurs in the homozygous state. The skinny and
  Baldwin genes do not appear to be related to each other at all
and they do not go together. When you breed a skinny pig to a
  Baldwin you will only produce haired babies in the first generation,
so they are defiantly genetically different from one another.

Baldwins are said to lack a thymus gland, and are thought to have
anatomical abnormality difficulties, and reproductive problems
specifically with the males(there are only a few with these
problems but it is very rare).  There is some thought though that if
Baldwin's seem to be hardier, sufficient to develop, and
successfully breed, than their immune systems seems to perhaps
be made more capable with each generation.

We have now been producing very hardy Baldwins in our caviary
that thrive and are just as healthy as our skinny pigs.  Carol Miller
the originator of Baldwins also does not believe this to be true as
the Baldwins have come a long way and are producing very hardy
lines.

The Baldwins have a rubbery texture to their skin when you touch
them.