Roundworms in Hogs

We also found a simple, inexpensive, and practical method of ridding Pigs of large intestinal roundworms or ascarids, the most widespread and most injurious parasites affecting swine. Nearly all swine producers are familiar with the worms, and parasitologists have studied them for decades without finding a really good treatment. American wormseed oil—Oil of chenopodium—was about 70 percent effective, but it is rather toxic and involves the usual difficulties of treating swine individually. Early enthusiasm for phenothiazine as a substitute for oil of chenopodium-especially because phenothiazine could be administered with the feed—unfortunately was not sustained. Later investigations disclosed that phenothiazine was about as toxic to swine as oil of chenopodium, it sometimes produced rather alarming symptoms, and was less effective.

In 1944 and 1945 we tested a number of fluorine compounds. Sodium fluoride, a cheap and readily available chemical used to eliminate cockroaches and remove lice from livestock and poultry, pretty well filled the rigid requirements of the ideal remedy for large roundworms. When mixed with the feed in the proportion of 1 part by weight of the chemical to 99 parts of the feed, sodium fluoride was generally eaten by swine. One day's normal feeding with this medicated feed ration was enough, in most cases, to remove nearly all the ascarids.

In practice, a successful method of treating pigs with sodium fluoride is: On the day before the medicated feed is given, the pigs are slightly underfed; on the day of treatment, the medicated feed is given in the morning in amounts the animals normally consume in 1 day; the next morning, regular feed is mixed with any left-over medicated feed and the usual feeding continued thereafter.

Whether fed to suckling pigs, to pigs shortly after weaning, or to pigs ready for market, the medicated feed caused expulsion of from 90 to 100 percent of all the roundworms. The treatment was effective whether given to pigs individually or to groups up to 30, and was nontoxic, except to pigs suffering from intestinal inflammation or other serious disorders.

Skim Milk and Whey for Internal Parasites

When fed liberally, skim milk and whey were found to be effective in protecting swine from internal parasites. Either was fed to pigs for 3 days in succession at intervals of 2 weeks, in place of all other feed, or was fed once daily instead of the regular afternoon feeding of grain. Otherwise, the pigs got a balanced ration of grain, tankage, and minerals. Although the treated pigs were kept under conditions that favored the acquisition of heavy loads of internal parasites, they escaped, for the most part, from acquiring any large number of stomach worms, ascarids, nodular worms, and whipworms, - parasites that localize in the alimentary canal.

This special feeding did not keep them from getting lungworms and other parasites that live outside the alimentary canal. Comparable pigs, fed only the balanced ration, became rather heavily parasitized with stomach and intestinal worms. Although our evidence is that pigs fed whey or skim milk acquired ascarids, which migrated in the usual way to the liver and lungs, the worms that reached the alimentary canal following the early migrations were evidently swept out by the purgative action of the whey and skim milk.

It is known, however, that cathartics of various kinds do not exert any significant anthelmintic action, and it cannot be concluded that only the purgative action of the dairy products used was largely responsible for the removal of the parasites from the alimentary canal. Whatever the nature of the vermifuge action of skim milk and whey, the fact is that, when used as indicated, these dairy products prevented the accumulation in the stomach and intestines of pigs of the various species of the nematode parasites. Pigs thus kept free of worms grew better than their litter mates that were not fed skim milk or whey. The difference in gains is evidence of how parasites cut pork production.

We do not recommend the indiscriminate feeding of dairy products to pigs as a substitute for sound management to control parasites, but this method should be useful where skim milk or whey is available and where other practices designed to control parasites are not instituted, or for special reasons cannot be.