וַיַּצֵּ֗ג אֶת־הַמַּקְלוֹת֙ אֲשֶׁ֣ר פִּצֵּ֔ל בָּרֳהָטִ֖ים בְּשִֽׁקֲת֣וֹת הַמָּ֑יִם אֲשֶׁר֩ תָּבֹ֨אןָ הַצֹּ֤אן לִשְׁתּוֹת֙ לְנֹ֣כַח הַצֹּ֔אן וַיֵּחַ֖מְנָה בְּבֹאָ֥ן לִשְׁתּֽוֹת׃
他把那些剝出條紋的枝子插在水溝裡，就是羊群來喝水的飲水槽中，正對著羊群；羊群來喝水的時候，就發情受孕。
Shenei Luchot HaBerit
We are now able to understand an allusion to the future contained in 30,39 in which a procedure used by Jacob to encourage the sheep to give birth to certain skin patterns is described. Rabbi Oshiyah says in Bereshit Rabbah 73,10 that the water the sheep drank was turned into sperm inside of them. How can we understand the remarks of Rabbi Oshiyah which suggest that G–d created a new instrument of impregnating animals, something that had not been created during the six days of creation!? Did not Solomon in Kohelet 1,9 say that there is nothing new added on this planet?