248 ANNUAL, REPORTS OF DEPARTMENT OF AGRICULTURE. 



ROUNDWORMS AND OTHER INTERNAL PARASITES OF SHEEP. 



Further experiments at the Government sheep farm at Vienna, 

 Va., confirm previous experience as to the efficacy, against stomach 

 worms, of the 1 per cent copper sulphate sohition administered in 

 single or repeated doses. The results indicate that the eradication of 

 stomach worms from sheep and pastures by this method is possible, 

 though it may be difficult as a practical matter owing to traffic in 

 sheep under actual farming conditions. Without attaining complete 

 eradication, however, the treatment may be used to reduce the num- 

 ber of worms to a point where the growth of the sheep and the yield 

 of wool will not be interefered with and losses will be avoided. The 

 treatment with copper sulphate is described in Farmers' Bulletin 

 1330, Parasites and Parasitic Diseases of Sheep. Infestation with 

 stomach worms has been purposely maintained on the Government 

 farm so that experiments may be continued. 



The thread-necked roundworms, species of Nematodirus, appear 

 to be distinctly injurious parasites, although not so important as the 

 stomach worm. Hookworms, formerly present on the experiment 

 farm, were not found during the year; apparently they are more 

 readily controlled by the measures used than are stomach worms. 

 Nodular worms are also less abundant than formerly and likewise 

 appear susceptible to some degree of control by the measures used. 

 The small intestinal trichostrongyles are still present. 



Observations at slaughterhouses indicate that when tapew^orms are 

 present in a flock of sheep there is commonly a 100 per cent infesta- 

 tion. In the experiment flocks treated with copper sulphate the 

 number of animals infested with tapeworms continually diminishes. 

 In two flocks of the same age and breeding, one treated and one not 

 treated, tapeworms were more prevalent in the untreated animals. 

 The injury to sheep from tapeworms appears to be slight compared 

 wnth that due to roundworms. 



Many farmers prefer lambing in April, but there is general com- 

 plaint that these late lambs do not do so well as earlier ones. For 

 various reasons, such as market conditions, avoidance of parasites, 

 etc., there are advantages in lambing in January and Februar3^ 

 These early lambs may be marketed before treatment for parasites 

 is necessary. The ewe lambs to be kept, however, must be treated, 

 but with their rapid early growth subsequent treatment is easy. As 

 a part of a test to determine the most favorable lambing season in 

 relation to parasitism, the 1923 lamb crop at the Vienna farm was 

 dropped in March for the most part. These lambs did well and most 

 of them were in marketable condition in August. 



As an extension of the work at the Vienna farm, some field experi- 

 ments on the control of stomach worms were begun in Schuyler 

 County, Mo., in October, 1922. Ten farms were selected, the owners 

 agreeing to the plans and offering their full cooperation in carrying 

 out dosing of their flocks once a month with a 1 per cent solution of 

 copper sulphate for the purpose of studying the effects of this treat- 

 ment on stomach worms under practical farm conditions. The work 

 was begun with 1,200 sheep, which received monthly treatment 

 throughout the autumn, winter, and spring. Including the 1923 

 Iamb crop and one more farm flock which was added in June, 1923, 

 more than 2,000 sheep were under supervision in the experimental 



