Комментарий к Берешит 30:39

אל המקלות means at the sight of the rods.

ויחמו הצאן, this is a masculine construction.

ויחמו, a reference to the males. However, as we learned earlier, the females would be in heat simultaneously.

To the appearance of the sticks. [Rashi explains this] because the sticks did not make the animals have ringed, speckled and spotted offspring. It was the sticks’ appearance that did this, i.e., the uncovered white. You might ask: How could Yaakov commit this trickery? There are many explanations, but it seems to me that Yaakov did it with his own flock, [not with Lavan’s.] The offspring of Yaakov’s flock rightfully belonged to Yaakov even without these signs, but Lavan wanted to take even those offspring from him. Yaakov thought: I will make sticks so that the offspring of my flock will all be speckled and spotted, to gain what is rightfully mine. (Maharshal)

ויחמו הצאן, “the flocks grew heated;” the Torah did not mind in this case to use the singular mode when speaking of numerous animals; we know of other examples of a similar construction such as Judges 21,21: אם יצאו בנות שילה, “as soon as the daughters of Shiloh will come forth,” where the masculine mode is applied to the girls of Shiloh.

עקודים RING-STRAKED — the word is connected with the root עקד “to bind” — differently coloured at that place where they are bound, viz., the ankles of the forelegs and hindlegs.

אל המקלות, toward the sticks.

אל המקלות, “in response to the sticks;” the word אל does not mean to approach physically;” similar to Genesis 41,57: לשבור אל יוסף, “to buy grain from Joseph,” where it also has not been used in a physical sense. Another interpretation: “on account of the sticks.” This would be similar to Yaakov saying in Genesis 37,35: כי ארד אל בני שאולה, “for I will join my son on the way down to hades” (a grave in the nether regions of the earth).

ותלדן הצאן, the sheep would give birth to young with the skin patterns Yaakov desired, as their imagination had been fired at a time when they were more than usually impressionable.

ותלדנה הצאן עקודים, “the flocks gave birth to young with striped birth patterns on the skins of their feet.” From then on Yaakov did not again bother to erect the sticks near the troughs, but he simply separated the animals that had displayed the skin patterns in accordance with his agreement Lavan from the brownskinned ones that were Lavan’s.