וַיֶּחֱמ֥וּ הַצֹּ֖אן אֶל־הַמַּקְל֑וֹת וַתֵּלַ֣דְןָ הַצֹּ֔אן עֲקֻדִּ֥ים נְקֻדִּ֖ים וּטְלֻאִֽים׃
And the flocks conceived at the sight of the rods, and the flocks brought forth streaked, speckled, and spotted.
Radak on Genesis
ויחמו, a reference to the males. However, as we learned earlier, the females would be in heat simultaneously.