BUREAU OF ANIMAL INDUSTRY. 149 



stomach- worm infection in the pastures (forage fields) by monthly 

 treatments with copper-sulphate solution during the summer season. 

 The question of the ultimate effects of these treatments upon the 

 health of the sheep is still under investigation. 



In connection with the experiments on roundworms, investigations 

 have been carried on concerning the question of preventing tapeworm 

 infestation. These investigations are still incomplete, iSut results 

 thus far obtained indicate that eradication of tapeworms from small 

 flocks of sheep can be accomplished without a great deal of trouble 

 or expense. 



ROUNDWORMS OF HOGS. 



Field work on the problem of preventing losses from roundworms 

 {Ascaris) among young pigs has been carried on in McLean County, 

 111., where about 3,500 pigs on 20 farms are under observation. 

 The following method of management has been emplo3'^ed: Before 

 farrowing time all loose litter is removed from the farrowing pens 

 and the pens are thoroughly scrubbed with boiling water and lye. 

 About a week or 10 days before the sows are expected to farrow, 

 their udders are thoroughly cleaned to remove any adherent dirt and 

 the sows then placed in the clean pens. As soon as practicable after 

 farrowing, the sows and pigs are removed to clean pasture. Small 

 sheds or houses, which are moved occasionally to new locations in the 

 pasture, are provided as shelters. 



This method is designed to minimize the chances of roundworm 

 infection during the first few months of life, during which time it 

 has been found by investigations recorded in previous reports that 

 pigs are most susceptible to and most likely to suffer seriously from 

 infection. By observing special precautions during this time, as 

 indicated above, the pigs can be tided safely over a critical period in 

 their life, so far as concerns parasitic infection, and reared to an age 

 when they are less likely to be injuriously affected by roundworms. 

 The results have been very satisfactory in those cases in which the 

 method was carefully followed, and on farms where in former years 

 considerable loss was experienced among young pigs by death and 

 stunted growth there has been practically no loss the present year. 

 The field investigations will be continued in order, if possible, to 

 establish a simple, practicable procedure in the management of hogs, 

 that can be depended upon to give uniform results in preventing 

 losses from roundworms. 



In connection witli the question of destroying eggs of Ascaris some 

 observations have been made as to their thermal death point. It 

 has been found that eggs in early stages of segmentation when placed 

 in liot water maj' survive two minutes' exposure to a temperature of 

 G0° C, but that under the same conditions eggs that liave reached the 

 infective stage die after one and a half minutes' ex])osure. 



Further experimental work has been done with reference to Ascaris 

 infection in sheep. A lamb fed with the eggs of Ascans suum when 

 a few days old was killed 111 days after feeding, and was found to 

 harbor 6 ascarids 7 to 10 centimeters long. Another lamb that was 

 similarly fed at the age of 4 weeks and killed 82 days after feeding 

 was found free from ascarids. Three other lambs, about G months 

 old, have been fed with eggs of Ascaris suurn^ all of them showing 

 symptoms of pneumonia a few days later. Ascaris larva? were 



