Thursday, February 16, 2012

Split Eyelids

Well, we got our first three lambs but apparently their Mamas were early birds.

There are more ewes that are almost there and they are definitely looking ready to drop.  We're learning to be able to tell which ewes are going to drop lambs next but it's certainly not an exact science.  Not only do their udders start to "bag up," they start to slow down and look like they are tired of lugging around that huge thing so many call "cute", just like humans do.

If you've ever been pregnant or the partner to someone pregnant, I'm sure you remember the feeling and the look.

The third cutie born was a little ewe lamb.  Her only issue is that she has a split eyelid.
It is a bit difficult to discern from this photo but if you look carefully, at the uppermost point of her eyelid, you'll notice a small triangular jog where it should be a smooth curve.  This particular example is a moderate split.  Sometimes all you'll be able to see is an unusual tuft of fur in that same location.

The gene for this deformation is connected to the polycerate gene a.k.a. the multiple horn gene.  Essentially when the hornbuds split in utero, the split extends through the eyelid and is not totally knit together.  The reason for this gene being bad is that the split can lead to less than ideal protection of the eye itself which in turn could result in partial or total blindness in the affected eye.  This defect is also highly heritable.

On the good side highly heritable genes are relatively easy to find.  I can discern pretty quickly which individual has the gene and thus which animal must be designated as a "terminal" sire or dam.  That means that all the offspring from that animal will be meat animals and not considered when determining which lambs to keep for the breeding flock.  While each individual case may or may not be a big deal to the individual animal, having the gene in one's flock knowingly poses, I feel, an animal welfare issue.  In keeping an animal with the split eye gene or with a split eyelid, you are knowingly exposing that animal's offspring to the risk of bodily harm and pain.  If possible, the good shepherd will work to eliminate this gene from their flock for the good of the flock.

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