Chocolate to yellow is not something anyone would specifically do for no 'good' reason... but if the dog required for your bitch was a y/b and the bitch was a c/b then the litter would be all black... If the dog and bitch complimented each other in every way and more, then there is no reason why you could not do this mating... There are 3 colours in Labradors.. but 81 genetic possibilites for coat colour .. a good breeder knows her dogs, what dogs she wants to use and why... and will know exactly what colours any of those 81 connotations will produce in their litter..
BB = black Lab, no chocolate gene
Bb = black Lab, carries chocolate gene
bb = chocolate Lab, no black gene
Yellow is produced by the presence of a recessive epistatic gene which has the effect of masking the the black or chocolate genes.
EE = no yellow gene
Ee = yellow carrier but apears either black or chocolate
ee = yellow Lab
So....
EEBB =Basic Black (BB)
EEBb =Black that carries Choc. (Bc)
EeBB =Black that carries Yellow(By)
EeBb =Black that carries Yellow and chocolate (Byc)
eeBB =Yellow (Yy) [does not carry chocolate]
eeBb =Yellow that carries Chocolate (Yc)
eebb =chocolate pigmented yellow ~ No Black Pigment (NBP)
EEbb =Chocolate (CC) [does not carry yellow]
Eebb =Chocolate that carries yellow (Cy)
http://www.blueknightlabs.com/color/coatcolor.htmlThis is a super page for helping understand the outcome of each colour 'pairing
scroll down the lefthand side and click over the coloured 'matings' and it will show you in the box on the right, what the litter colour will be..
The only thing we cannot plan is the % of litter colour... a litter of10 pups may have 9 black, 1 yellow.. or 5 black 5 yellow from a yb to yy mating.
A good breeder will know exactly what they are doing/planning and why ;)