The 5th plague on the Egyptians was upon their livestock:-
Exo 9:1-3 NET The Fifth Blow: Disease
Then the LORD said to Moses, "Go to Pharaoh and tell him, 'Thus says the LORD, the God of the Hebrews, "Release my people that they may serve me! [v. 2] For if you refuse to release them and continue holding them, [v. 3] then the hand of the LORD will surely bring a very terrible plague on your livestock in the field, on the horses, the donkeys, the camels, the herds, and the flocks.
However, this did not kill
all livestock. In the Notes on Exodus 9:3 in "The MacArthur Study Bible" Dr John MacArthur says :-
in the field: Apparently stabled animals did not succumb to the pestilence. Although incredibly severe, some animals were still alive afterwards for Egypt to continue without total loss to an economy which depended upon domesticated animals. A few months later, when the 7th plague struck, there were still some cattle which, if left in the field, would have died.
The 7th plague only killed the cattle of the Egyptians
left in the open, not those which had been put under cover by the Egyptians in fear of the plague to come:-
Exo 9:18-21 NET I am going to cause very severe hail to rain down about this time tomorrow, such hail as has never occurred in Egypt from the day it was founded until now. [v. 19] So now, send instructions to gather your livestock and all your possessions in the fields to a safe place. Every person or animal caught in the field and not brought into the house - the hail will come down on them, and they will die!" ' " [v. 20] Those of Pharaoh's servants who feared the word of the LORD hurried to bring their servants and livestock into the houses, [v. 21] but those who did not take the word of the LORD seriously left their servants and their cattle in the field.
(By this time, the Egyptians would have been saying that Moses had a pretty good strike rate so far and they had better do as he said or else.)
In the 10th plague, not all the cattle died: just the first-born cattle:-
Exo 11:4-5 NET Moses said, "Thus says the LORD: 'About midnight I will go throughout Egypt, [v. 5] and all the firstborn in the land of Egypt will die, from the firstborn son of Pharaoh who sits on his throne, to the firstborn son of the slave girl who is at her hand mill, and all the firstborn of the cattle.
Exo 12:29 NET The Deliverance from Egypt
It happened at midnight - the LORD attacked all the firstborn in the land of Egypt, from the firstborn of Pharaoh who sat on his throne to the firstborn of the captive who was in the prison, and all the firstborn of the cattle.
The cattle that died were all those that were not put under cover for protection, and the first-born cattle of the survivors. Not all the cattle would have been wiped out: there still would have been some left.
All the cattle that died belonged to the Egyptians, not the Israelites.