ציטירנדיקער פּירוש אויף בראשית 46:34

We need to provide an additional explanation, as to why He began all the commandments with the sanctification of the new moon, and why this commandment was placed adjacent to the commandment of the Passover sacrifice. The explanation for this is that the Egyptians believed that the zodiac sign of Aries [the ram] shepherded all of existence, for a zodiac sign [can] make one wise, a zodiac sign [can] make one wealthy (Shabbat 156a). Therefore, all shepherds are an abomination to Egypt because it is inappropriate to say that the leader [the ram] should be led by others, for it is the shepherd. For this reason, God commanded to slaughter the Passover sacrifice, because the zodiac sign of Aries is the first and firstborn of all the zodiac signs, and through the slaughter of the ram, God will punish the host of heaven on high and afterward it will descend upon the earth upon all the firstborn of Egypt.
Now, the month of Nisan is the time when the sun enters the zodiac sign of Aries, and this month was made the head of the months of the year so that the remembrance of the Exodus from Egypt would always be before our eyes. There is a concern that perhaps through this commandment, it might give an opportunity to those who err to dispute and say that because of the importance of the zodiac sign of Aries, which serves in this month, this month was made the head of the months of the year. Therefore, the living God immediately commanded to slaughter the ram in sight of all observers, and to take it on the 10th of the month, in the first third of the month, for it is then that the zodiac sign is at its strongest, yet it is powerless to save the sheep under its dominion. Through this, they would recognize and know that there is a God high above all that is high.
Therefore, He placed the commandment of sanctifying the month before [the commandment of the Passover sacrifice] because He commanded to take the lamb on the 10th of the month, so He needed to inform him from which day to begin counting these 10 days. And He said to him, See like this and sanctify, and from that day onward he should count these 10 days to make known the weakness of the firstborn of the zodiac signs, and with its punishment, all the firstborn of Egypt who placed their confidence in the firstborn of the zodiac signs would be punished. This is the reason why He gave them commandments to engage with the blood of the Passover sacrifice and the blood of circumcision, for the blood of the Passover sacrifice was to nullify the belief of those who believed in the zodiac sign of Aries, and the blood of circumcision because it says regarding Passover, No uncircumcised person shall eat of it.

BEHOLD, THE HAND OF THE ETERNAL IS UPON THY CATTLE WHICH ARE IN THE FIELD. Scripture speaks of the ordinary custom that most cattle are in the field, but the plague was also upon the cattle in the houses, just as it is said, And all the cattle of Egypt died.²⁰⁰Verse 6. It is possible that because every shepherd is an abomination unto the Egyptians,²⁰¹Genesis 46:34. the Egyptians removed the cattle from the cities except for the use of horses for riding and asses for loading. Thus the cattle were located far from Egypt, grazing in the fields bordering upon Goshen, and in those pastures the cattle of the Egyptians and of the Israelites would intermingle. Therefore it was necessary that it be said, And the Eternal shall make a division between the cattle of Israel and the cattle of Egypt.²⁰²Verse 4. It may be that the division was necessary because since the pestilence was caused by the change of air, it should naturally spread over the whole district, [affecting the cattle of the Israelites as well], but G-d dealt wondrously with them.²⁰³See Joel 2:26.

Nachmanides writes that the reason the Torah mentions the word בשדה in connection with the cattle is that the Egyptians kept their cattle outdoors on a permanent basis. The reason was that shepherds of cattle were considered an abomination in Egypt (compare Genesis 46,34). These cattle were grazing far from Egypt proper, on the border of the province of Goshen, so that the cattle of the Israelites and that of the Egyptians intermingled. The fact that none of the Israelites’ cattle were affected by the plague was therefore all the more remarkable. Another reason why this was remarkable could have been that the bacteria causing the plague came from the same airspace so that it could have been expected to affect all the animals in equal measure