Vol. XIII No. 306. 



THE AGEICULTURAL NKWS. 



2.3 



LIVE STOCK NOTES. 



THE CONTROL OF CARRIERS OF 

 DISEASE. 



In the eradication of disease, particularly trypanosome 

 diseases, it is imperative to locate the guilty insect carrier 

 Viefore preventive measures can be satisfactorily undertaken. 

 In the case of a disease like surrah, recent work in the 

 Philippines has brought out several interesting features. It 

 was the first thought that blood-sucking insects like 

 Stoiuo.'ijs ralcitrans might be the agent of transmission, but 

 results showed that this fly must be regarded as practically 

 a negative factor. Experiments with TuUimts stimtus, 

 however, have yielded positive results, and it is now known 

 that this common horse fly of the Philippines is a carrier of 

 surrah. In regard to the two insects just mentioned, it may 

 be pointed out that Stomoxi/s calrilran$ occurs in the West 

 Indian islands, but ToUinus striding does not; there is 

 one species of Tobanus recorded in these islands, however. 



It may be of interest to note parenthetically for 

 those who are not acquainted with these insects, that 

 ^toiiio.i-i/s ralcitrans is a small fly not unlike the common 

 house fly, whereas the Tobanidae are generally larger, and 

 have a remarkably wide head as a characteristic morphologi- 

 cal feature. 



Work in other countries besides the Philippines has given 

 rise to evidence which incriminates the lini,-e fly as a very 

 general carrier of surrah. It has been ascertained that a 

 species of the Tobanidae in northern Africa is a carrier of 

 Trypanomiasis whilst Tobanus has also been proved experi- 

 mentally to beone of the carriers of surrah in India and 

 in the Federated Malay States. 



C>f extreme importance in connexion with the spread of 

 surrah is the predilection of blood-sucking flies for particular 

 hosts. It has been established that if .suspected flies are not 

 attracted by the infected hosts disease does not result. The 

 attraction, for instance, may take the form of colour, odour, 

 and degree of temperature. In the matter of colour, certain 

 flies are attracted towards white, but most species are 

 attracted by dark animals. The relation of temperature 

 to parasitism is believed to be of some economic impor- 

 tance, although thus far the matter is rather in the theoreti- 

 cal stage. It has been experimentally demonstrated by 

 Howlett in India that mosquitoes are positively attracted by 

 a temperature higher than the normal. This theory may be 

 extended to the bloodsucking flies generally. Other things 

 being equal, the parasites are attracted towards an animal of 

 high temperature. It has even been asserted in all serious- 

 ness by ( irassi, the Italian expert on mosquitoes, that these 

 insects are attracted to persons who talk a great deal. 



In the matter of the destruction of horse flies, insecti- 

 cides have been used but these have not proved as satisfac- 

 tory as the measures which have been exerted in relation to 

 the aquatic habits of Tobanus. Petroleum has been 

 employed for spraying on the surface cf stagnant water over 

 which Tobanus eggs are layed so that the larvae when they 

 hatch must pass through the film of oil. In the Philippines 

 blood-sucking flies are generally trapped and collected. 



Animals at work or at pasture inaj' be protected from 

 bloodsucking flies by a protective wash. Sores and skin 

 abrasions of all sorts should be kept covered with tar or 

 some other antiseptic greasy substance, disagreeable to flies 

 both of the blood-sucking and biting species. 



The last point of interest to which attention will be 

 called is the influence of light intensity upon the presence of 

 these flies. The influence of a dark stable is quite marked in 



reducing the number of species of flies which obtain access to- 

 draft animals. It is recommended that the animals' sheds be 

 constructed with the roof as low as the height of the animals 

 will permit. This can be done without interfering with the 

 supply of fresh air. 



Further information in connexion with the matters- 

 dealt with above may be obtained by referring to the- 

 Philippine A;/ricultura/ Rerieiv (Vol. VI, No. S) from which 

 most of the foregoing facts have been extracted. 



COTTONSEED MEAL POISONING: 



IRON AS AN ANTIDOTE. 



The followinpr note is taken from the Experiment 

 Station Record, Vol. XXIX, No. .5: — 



In the course of experiments continuing work previously- 

 noted (E.S.H. 29, p. 70), the authors were led to the 

 hypothesis that the toxic principle of cotton-seed meal was^ 

 a constituent group of the protein molecule containing loosely 

 bound sulphur which exerted its toxic effect upon the iron of 

 the blood. Experiments already performed as bearing on 

 this hypothesis will be published in a later paper, and the 

 present paper deals principally with the efficiency of iron as. 

 an antidote for cotton-seed meal poisoning. The iron was- 

 fed in the form of citrate of iron and ammonia. 



Comparing the results obtained with the feed, it was 

 found that the iron fed rabbits consumed nearly .5 times the 

 amount of meal which proved fatal to the average rabbit 

 without iron, and more than twice as much as the greatest 

 amount of meal necessary to kill the rabbit which ate the 

 most meal; that the iron fed rabbits have survived more than 

 3 times as long as the average rabbit without iron, and nearly 

 twice as long as the hardiest rabbit: that every rabbit fed 

 with iron and meal gained in weight and each rabbit fed 

 with meal without iron lost in weight. 



Each of the 22 rabbits receiving cotton-seed meal without 

 iron died (average, 13 days), while each of the II rabbits- 

 taking iron with cotton-seed meal survived. 



PREVENTION OF CONTAGIOUS 

 ABORTION. 



Practically the only method of coping with this serious- 

 disease is through prevention. No medicinal treatment has 

 thus far been discovered for the cure of the disease, and the 

 best methods of disinfection known to science are required to- 

 eradicate it from a herd. According to Circular No. 216, 

 Bureau of Animal Industry, United States Department of 

 Agriculture, as soon as an an animal has aborted, the fetus 

 and membranes should be immediately carried away and 

 destroyed by either burning or by deep burial after covering 

 with lime, as the abortion bacilli are extremely numerous in 

 these tissues. The after-birth, which is retained in most 

 abortions occurring during the later months of pregnancy, 

 should be removed within a few days. If it does not come- 

 away readily, it should not be forcibly removed, but the 

 uterus should be irrigated with a gallon or two of a warm 

 disinfectant solution twice daily. 



It is not advisable to breed a cow for at least two- 

 months after she has aborted, and not even then if the , 

 discharge has not ceased. Every care should be taken ta, 

 prevent the hull from carrying the infection from a diseased 

 to a healthy cow by the systematic api'lication of disinfect- 

 ants. Care must also be taken to disinfect thoroughly, 

 cattle sheds and yards, together with all implements used in 

 connexion with milking. 



