Inoculation of 40-day-old piglets with 10cc of hog cholera crystal violet inactivated vaccine (CVV) gave rise to a mild, transitional postvaccinal reaction in them, but that with 10cc of hog cholera tissue culture vaccine (TCV) hardly caused such reaction. A dose of 10cc was more than three times the conventional dose for a young pig weighing less than 20kg. Piglets inoculated with 10cc of CVV or TCV at the age of 30 days, or 10 days before weaning, acquired immunity a little stronger than those injected with 3 or 6cc at the same period, but a little weaker than those vaccinated with 10cc at the age of 40 days, or 2 days after weaning. They withstood challenge inoculation with hog cholera virus made 3 months after vaccination, exhibiting mostly mild or severe reaction.
Some piglets received a total amount of 9cc of CVV divided into 3 doses of 3cc each at 5 days' intervals beginning with 30 days after birth. Others were inoculated with 2 doses of 4.5 cc each of CVV at 30 and 40 days of age. All of them were weaned 40 days after birth. As a result, they withstood challenge inoculation made 3 months after vaccination, as well as piglets injeted with a single dose of 9cc of CVV 40 days after birth, showing mild or no reaction.
Taking the results of two previous experiments of theirs into consideration, the authors concluded that even piglets and young pigs would be expected to acquire such immunity as equal or close to that of adolescent or adult pigs, if an adequate dose of vaccine was inoculated at an appropriate time (age and before or after weaning) or at suitable intervals of time.
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