Complex sentence: Homozygous mutant males displayed increased aggression towards their pups and therefore had reduced fecundity, mutants of both sex had increased susceptibility to infection with both "Citrobacter" and "Salmonella".
Split into simpler sentences: Homozygous mutant males displayed increased aggression towards their pups and therefore had reduced fecundity. Mutants of both sex had increased susceptibility to infection with both "Citrobacter" and "Salmonella".