There are several possible reasons as to why a female cat bites a kitten's throat. Here are a few possible explanations:
1.The mother cat is teaching the kittens: The mother cat will often teach, correct and train the kittens by biting the neck. This is a common behavior in cat populations, where female cats will give a small bite to the kitten as a warning or corrective behavior. This behavior is usually temporary, and will decrease or stop as the kittens grow up and learn to adapt to the rules of the pack.
2.Female cats taking care of their kittens: Female cats often use licking motions to help clean the kittens and stimulate their bowel movements and urination. Sometimes female cats may be tempted to bite the kitten's neck to help scrub or irritate.
3.Female cats protecting kittens: Female cats may feel threatened by their kittens and will bite their kittens' throats to protect them. This can happen when an alien person or animal enters their habitat.
4.Aggressive behavior in female cats: Sometimes, female cats may exhibit aggressive behavior, which may be due to excessive stress or anxiety, or to the adverse effects of early socialization. In this case, the female cat may express her displeasure or hostility by biting the kitten's throat.
If the female cat continues to bite the kitten's throat and it is accompanied by other aggressive behaviors, then you need to consult with a veterinarian as soon as possible to determine if there are any underlying health or behavioural issues.