A farmer was left stunned when her flock of 37 white sheep gave birth to 60 lambs - that are all black. Sally Du Toit, 39, and husband Jacob, 29, helped deliver the first black lamb on April 2 this year at their smallholding near Royston, Herts. Since then their flock of 37 white ewes has given birth to a total of 60 black lambs, all sired by a one-year-old ram called Rowley. Incredibly, the South African Dorper ram also has a white fleece, leaving mother-of-one Mrs Du Toit baffled by the freak births.
In sheep, a white fleece is the result of a dominant gene that actively switches colour production off - that is why most sheep are white. This means a black fleece in most sheep is recessive, so if a white ram and a white ewe are each heterozygous (have the black and white forms of the gene for fleece colour), in about 25 per cent of cases they will produce a black lamb.
Photo from SWNS.
This is quite a rare occurrence though, and in most white sheep breeds only a few white sheep are heterozygous for black, so black lambs are usually much rarer than this. That is why this case is so special. Mrs Du Toit said: 'We have had 60 lambs this month and every single one of them is black but all of their parents are white.
'Usually you see just one black sheep in an entire flock and that's where you get the saying from, but all of ours have this jet black coat. It is amazing. We don't know why it has happened. When the first few were born we thought it was great but now lamb after lamb has come out black. We feel blessed. I love the colour. People are stopping on the cycle path and in their cars to look at the lambs and ask us if they are a special kind of breed.'
1 comment:
Even if the ram had chimerism so its testicles were actually obtained in the womb from a sibling black ram and with all the sheep being heterozygous, that would still increase the odds to only 50%.
Ww x ww => Ww, Ww, ww, ww with (ww being recessive (black) sheep and Ww being heterozygous (white) sheep).
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