Kittens as they are growing usually heal pretty well.
You can clean the cuts with betdine iodine solution or 3% hydrogen peroxide and then put Neosporin or Triple antibiotic ointment on the sores. Mom may lick the ointment off but it should not hurt her. I'd keep an eye on the sore areas and you can put a small amount of ointment on them a couple times a day until they heal.
If they appear to not be healing over the next day or so then you would want to see your vet for more care.
Hope this helps you!
I'd leave it open as covering it can allow anaerobic bacteria to cause infection.
You can watch for signs of pus, infection, him not being willing to eat, lots of crying, the kitten feeling flaccid instead of full and firmly packed when you pick him up or his mother pushing him away and refusing to nurse him with him feeling chilled.
You should see some scabbing and healing of the edges towards each other. You can put ointment on the scab too as it will penetrate.
Cat and kitten skin is really thin and tears easily so I believe you about it looking quite ugly!
Cat Health, Behavior, Care Expert
30+ years cat owner, rescue, breeding, study of behavior & health care