Genesis 30:37-43 Jacob's Breeding Scheme

Laban apparently does not realize who he is dealing with when he attempts to thwart the increase of Jacob's flocks.  Jacob, it seems, has a plan of his own.  Whether this scheme developed in response to Laban's not-so-benevolent move of relocating Jacob's flock three days away (so that there was less of a chance of those speckled and striped ones mating with his own flocks) or not is unclear.

"Jacob, however, took fresh-cut branches from poplar, almond and plane trees and made white stripes on them by peeling the bark and exposing the white inner wood of the branches.  Then he placed the peeled branches in all the watering troughs, so that they would be directly in front of the flocks when they came to drink.  When the flocks were in heat and came to drink, they mated in front of the branches.  And they bore young that were streaked or speckled or spotted."  (Genesis 30:37-39 NIV)

Whether this method actually had any effect upon the production of animals which were striped or speckled or streaked is unknown.  Striped, speckled and streaked animals were born, but this could be merely because God was blessing Jacob as He had promised.  Hopefully Jacob was using his branches in a scientific and not a magical way.  I think he was actually thinking that this method had some merit, for he goes through an awful lot of manipulating of branches and animals otherwise.

Not only did Jacob employ his 'branches' method of breeding, but he also separated his flocks from Laban's and used the stronger animals to breed with his own flocks.  Eventually, the stronger animals were regularly going to Jacob's flocks and the weaker animals were left for breeding with Laban's flocks.  (v.40-42)

"In this way the man grew exceedingly prosperous and came to own large flocks, and maidservants and menservants, and camels and donkeys." (Genesis 30:43 NIV)
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Note:  Jacob himself admits that it is God who has increased his flocks. (Genesis 31:9)
Also, the process of Jacob becoming wealthy took six years of hard work. (Genesis 31:41)  From that verse we also see that Laban was actively trying to thwart this increase.  Laban was no match, however, for the plans of God.