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fectants have a markedly unpleasant odor, and for commercial advantages 

 much credit has been given the one that gives the most offensive odor. The 

 odor does not destroy the disease germs. Again, disinfectants are not ail 

 equally applicable to the destruction of all disease producing germs; there- 

 fore, disinfectants of known quality should be used for particular needs. No 

 single disinfectant is appropriate in all cases. Select the proper substance, 

 apply it liberally, allow ample time for the disinfectant to do its work, for 

 success depends in a large part upon the care and exactness of the person 

 who prepares and applies the disinfectant. 



I thank you. 



PRESIDENT MANN: Now if there is any question that any of you 

 would like to ask this is the time to ask it. 



Q. I would like to ask what kind of a floor would you recommend for 

 a hog pen? 



Dr. McDONALD : That depends on the man that has the hog house. 

 Some of them prefer dirt floors, others cement, and others wooden floors. 

 Many of them prefer the cement floors with the wooden floor on top of it. 

 a floor that can be taken off of the cement and cleaned out. Really, I would 

 not know which to recommend. It is a matter of opinion. 



Mr. HAYNES: Will the suckling pigs carry that immunity through 

 life? 



Dr. McDONALD: That is a question that is very much in discussion. 

 I don't believe they will. The chances are that if you take pigs from sows 

 that have never been vaccinated and give them the treatment early, up to 

 four or five weeks of age, they may retain that permanent immunity, but 

 I have never advised anyone that had to vaccinate his pigs that early to 

 get the idea that he might have immune hogs. I always advise that they 

 revaccinate them after they get older. If you expect to keep them for 

 breeding purposes I would advise that they be revaccinated after they get 

 older. 



Mr. TULLOCK: What age do you advise is about the best age for 

 vaccination? 



Dr. McDONALD: The best age for all purposes is a week before 

 weaning or a week after weaning. I don't like to vaccinate pigs at the time 

 you take them off the nurse. The change of food sometimes makes a big 

 difference. 



Mr. HAYNES: If the mother has not been vaccinated you would have 

 to vaccinate the mother too, would you not, at that time? 



Dr. McDONALD: I certainly would. I would not want to use any 

 virus around any hogs that had not been vaccinated. I would not let any 

 unvaccinated hogs come in contact with hogs that had been recently vac- 

 cinated. Dr. Conway has proven on numerous occasions that hogs carried 

 the virus in their blood virulent enough to produce disease in nearly all 

 hogs up to six days after viccination, and he has produced the disease with 

 blood drawn twenty-one days after vaccination from a vaccinated hog. So 

 virus is one of the most dangerous propositions we have to deal with in the 

 hog raising business. 



Mr. TULLOCK: In the case of hog cholera, after inoculation, under 

 ordinary conditions how much time would have to elapse before it would 

 be safe to restock? 



Dr. McDONALD: It would never be safe to restock on a lot that was 

 badly infected unless it was thoroughly disinfected. You take a lot where 

 they were feeding cattle, where the hogs have burrowed deep in the ground 

 for feed, infection will stay there almost indefinitely. If the lot can be 

 plowed up it would help a whole lot. The sunlight will destroy the germ 

 there in a very short time, but in a damp, cold place where the germs can 

 thrive it will stay almost indefinitely. 



Q. In the case of forage poison what are the symptoms? 



Dr. McDONALD: They vary. Sometimes you don't find any symptoms. 

 Sometimes they die so quick you don't see them. Sometimes they lie with- 

 out any temperature and apparently in a comatose condition, the tempera- 

 ture may be subnormal, and lie that way for maybe twenty-four hours 



