Ge 30:25 And it came to pass, when Rachel had borne Joseph, that Jacob said to Laban, "Send me away, that I may go to my own place and to my country.

26 "Give me my wives and my children for whom I have served you, and let me go; for you know my service which I have done for you."

27 And Laban said to him, "Please stay, if I have found favor in your eyes, for I have learned by experience that the LORD has blessed me for your sake."

28 Then he said, "Name me your wages, and I will give it."

29 So Jacob said to him, "You know how I have served you and how your livestock has been with me.

30 "For what you had before I came was little, and it has increased to a great amount; the LORD has blessed you since my coming. And now, when shall I also provide for my own house?"

31 So he said, "What shall I give you?" And Jacob said, "You shall not give me anything. If you will do this thing for me, I will again feed and keep your flocks:

32 "Let me pass through all your flock today, removing from there all the speckled and spotted sheep, and all the brown ones among the lambs, and the spotted and speckled among the goats; and these shall be my wages.

The speckled and spotted sheep, the brown lambs and the spotted and speckled goats were rare animals. In this arrangement, Jacob would have less while the remaining greater part would be Laban's.

33 "So my righteousness will answer for me in time to come, when the subject of my wages comes before you: every one that is not speckled and spotted among the goats, and brown among the lambs, will be considered stolen, if it is with me."34 And Laban said, "Oh, that it were according to your word!"

Laban was quick to agree seeing that the arrangement was favorable to him.

35 So he removed that day the male goats that were speckled and spotted, all the female goats that were speckled and spotted, every one that had some white in it, and all the brown ones among the lambs, and gave them into the hand of his sons.Ge 30:36 Then he put three days' journey between himself and Jacob, and Jacob fed the rest of Laban's flocks.

Laban was very crafty against Jacob. The considerable distance would ensure that the marked animals of Jacob would not breed with Laban's flock. This would also mean that Jacob would have a lesser flock to tend and obtain his own wages from.

37 Now Jacob took for himself rods of green poplar and of the almond and chestnut trees, peeled white strips in them, and exposed the white which was in the rods.

38 And the rods which he had peeled, he set before the flocks in the gutters, in the watering troughs where the flocks came to drink, so that they should conceive when they came to drink.

39 So the flocks conceived before the rods, and the flocks brought forth streaked, speckled, and spotted.

40 Then Jacob separated the lambs, and made the flocks face toward the streaked and all the brown in the flock of Laban; but he put his own flocks by themselves and did not put them with Laban's flock.

41 And it came to pass, whenever the stronger livestock conceived, that Jacob placed the rods before the eyes of the livestock in the gutters, that they might conceive among the rods.

Whether this has scientific basis or not I could not be sure. It could have been a superstitious belief on the part of Jacob. In Bisaya, we call it "Lihi." Personally, I believe that it was the result of God's blessing. It was a miracle. God blessed Jacob despite his superstitious belief.

42 But when the flocks were feeble, he did not put them in; so the feebler were Laban's and the stronger Jacob's.

43 Thus the man became exceedingly prosperous, and had large flocks, female and male servants, and camels and donkeys.

Moses seeks to show his original Israelite readers here that God was with Jacob. Even Laban recognized this. Despite all the scheming against Jacob by Laban, God still blessed and prospered Jacob exceedingly. God was faithful to His promise to Jacob.

Israel should learn that God will also be with them to bless them and fulfill His word. The scheming of their enemies against them cannot prevent God from blessing them. As He blessed Jacob despite  Laban's schemes so He can bless them despite their enemies' plots against them.