(in weak solution") 



(in very weak solution) 



(in weak solution) 



Jine and pyridine, on the other hand, are both vor3- lethal to 

 the free-living stages of sclerostomea. 



The cost of treating faeces can also be reduced if a lethal 

 by-product is available or if a chemical is being bought in 

 bulk for other purposes. In these eases the possibility of the 

 presence of impurities must be considered, as they may alter 

 the lethal value of the chemical or they may make it unsuit- 

 able by containing a plant poison. 



A large number of chemicals has been tested at the Insti- 

 tute of Parasitology for their effect, under controlled labo- 

 ratory conditions, on the pre-infective stages of horse sclero- 

 stomes. The more ' ' practical ' ' of these are given in the fol- 

 lowing table, with the percentage required to completely steril- 

 ize small quantities of horse manure: 



Percentage Chemical Brmarls 



0.04.'5 Chloropicrin 



0.19 Calcium cyanide 



0.2.T Paradiihlorbenzene 



0.33 Formalin 



Sodium fluoride 

 0.37 Phenol 



Naphthalene 



0.62 Cresol (in weak solution) 



0.75 Urea (in strong solution) 



1.0 Sodium borate (in weak solution') 

 Zinc chloride (in weak solution) 

 Ammonium thiocyanate (in medium solution) 



1.25 Calurea 



1.5 Potassium cyanate 



1.9 ' ' Powdered' ' Cyanamide 



2.5 "Granular" Cyanamide 



Sodium chloride (in medium solution) 



Sodium hydroxide 



3.1 Carbon disulphide 



Calnitro (in medium solution") 



Ammonium nitrate (in medium solution) 



Kaiuit (in medium solution) 



3.75 Sodium nitrate (in medium solution) 



4.4 Potassium nitrate (in strong solution) 



4.5 Nitro chalk (in medium solution) 

 5.75 Calcium hypochlorite (in strong solution) 

 6.0 Ammonimum sulphate (in medium solution) 

 6.25 Carbonate of potash (in medium solution) 

 8.0 Carbon tetrachloride 



14.0 Sulphate of potash (in strong solution) 



20.0 2i)'/c Superphosphate 



Phenothiazine 

 23.0 Dog urine 



Horse urine 

 37.0 Cow urine 



40.0 16% Superphosphate (in strong solution) 



50.0 Quicklime 



65.0 Hydrated lime 



Of Xo Value 



Flowers of sulphur 



Ground limestone 



Raw rock phosphate 



Basic slag 



Pyrethrum powder 



Derris powder 



White hellebore powder 

 Among the numerous other chemicals tested, in attempts to 

 find reasons for the lethal factors, compounds of iodine were 

 found to be of a very high efficiency indeed ; thus for example, 

 0.01% of methyl iodide (in a dilution of over 1:200) was com- 

 pletely etfeetive. Iodine salts, however, are expensive. 



On farms the most easily obtained (in efficiently drained 

 stables) is urine; in addition there are many artificial fertiliz- 

 ers with lethal properties, part or all of the cost of which may 

 be recovered in added manurial value. 



The chemical and lethal composition of urine varies consid- 

 erably, not only according to the species, but also according 

 to the food and health of the animal from which it is taken. 

 In a few cases its lethal value may be almost nil, but generally 

 speaking, about 30 to 40 percent of the weight of urine to 

 fresh faeces kills the free-living stages of selerostomes. Of the 

 artificial fertilizers, urea is the most potent, requiring about 

 three-quarters of 1 percent by weight of the fresh faeces to 

 sterilize them against selerostomes. Calurea should be used at 

 the rate of 1% percent, while about 2 percent of powdered 

 cyanamid is needed and another half of 1 percent if used in the 

 granular form. A high grade kaiuit is one of the next most 

 lethal fertilizers and it should be used at the rate of 5 lbs. to 

 100 lbs. of manure. Closely following in potency are many 

 other artificial fertilizers which should be iised at the rate of 

 about 6 percent or slightly over, compared with the weight of 

 fresh faeces. 



It must be remembered that the addition of some alkali fer- 

 tilizers to faeces will cause the loss of ammonia. With urea 

 and calurea, much ammonia escapes as gas. 



The quantities mentioned above would be too great in many 

 cases for common manurial practice if the whole manure heap 

 had to be treated, but since the heat of fermentation, lack of 

 oxygen and other factors, prevent the development of larvae 

 in the centre of a well-built heap, is should only be necessary 

 to treat the top and sides, provided that the faeces are put 

 there as soon as they are passed, that the fertilizer is immedi- 

 ately well mixed in, and that the pile is sufficiently well- 

 packed and protected to keep the fertilizer in contact for 

 some time. 



The use of a well constructed manure pit is highl3' desirable 

 and ideally should be divided into two portions — one to con- 

 tain manure under treatment while the other is being filled; 

 the first portion is then emptied and the procedure reversed. 

 The size and design will depend on local circumstances. Ma- 

 nure stored in yards, no matter how stored, should be inaccessi- 

 ble to stock. 



Selective Dispos.\l. As there is normally a marked speci- 

 ficity shown by the parasites of various species of animals, the 

 manure, especially if untreated, should be used on ground 

 which is inaccessible to the species of animal from which it 

 came. Thus, horse manure should not be used for top-dressing 

 liastures to be used by horses, but it is safe — or reasonably so 

 — to use it for pastures used by cattle and sheep. It may also 

 be used for growing crops — except hay crops which will subse- 

 quently be fed to horses. 



Plowing Under. Wherever possible, manure should be 

 plowed under. However, this procedure cannot be guaranteed 

 to keep eggs and larvae below ground. Earthworms bring some 

 to the surface and strongyle larvae are capable of a certain 

 degree of upward migration. The horse selerostomes have 

 practically no migrating ability in clay soil (provided that 

 there are no cracks in the soil), but in sandy clay they can 

 migrate 4 inches and in sandy loam '< inches upwards; more- 

 over, they can live for over 4 years under these circumstances.. 

 The sheep nematodes Osterlagia and Xematodirus can regain 

 the surface after being plowed under and survive for S to 10 

 months; Hacmonchus survives less well. Plowingin may 

 actuallj' assist development by breaking up the soil and faeces. 



Fly Destructiox. Flies are important in connection with 

 manure as mechanical carriers of worm eggs (e.g. Ascari.s) and 

 as actual essential intermediate hosts of worms (e.g. Habro- 

 iiciiia) ; the part they play as mechanical carriers is probably 

 of secondary importance. 



From the second point of view, flies must be prevented from 

 feeding on horse manure; this, if perfect, would completely 

 eradicate Eabrotieina from horses. Cleanliness in stables is 

 essential, even small quantities of manure being removed daily. 

 Spraying manure with hellebore (V-i lb. dissolved for 24 hours 

 in 10 gallons of water, will treat 10 cubic feet) or powdered 

 borax (at the rate of 1 lb. to 16 cubic feet) are recommended 

 by the United States Department of Agriculture for the pre- 

 vention of fly breeding. The hellebore has no injurious effect ; 

 the borax also is not injurious if the manure is not used in 

 excess of l."i short tons to the acre. Creosote oil also has been 

 recommended as a deterrant ; it is mainly useful under war 

 conditions and for dead horses. 



The heat generated in the centre of a well-constructed ma- 

 nure pile or throughout the manure in a box will destroy many 

 maggots. The outer layers of the pile, however, will not be- 

 come sufficiently hot and will require treatment. 



Comparatively few eggs or larvae leave the host other than 

 in the faeces. Those that do include the pinworms, trichina 

 worms, kidney worms and microfilaria. 



Pinworms. The female O.ryuris equi, the only known pin- 

 worm of importance in domestic mammals, leaves the host to 

 deposit her eggs on the perianal skin or stable furnishings; 

 sometimes she is evacuated in the faeces or, dying in the rec- 

 tum, her eggs are so passed, but this is exceptional and the 

 few cases in which it occurs are provided for by the usual 

 procedures. Most eggs are actually laid on the skin and al- 

 though very little is yet known of their bionomics, it would 

 seem that excess of water is quickly fatal to them. Accord- 

 ingly, washing of stable, stable furniture, grooming kit and 

 perianal skin, would reduce the possibilitj' of reinfection. The 

 removal of eggs from the skin by washing will also reduce the 

 local irritation and render reinfection less i)robable, while in 

 heavy infections, warm water enemata will remove gravid fe- 

 males mechanically and so reduce the egg output. Infection is 

 by swallowing the embryonated eggs either directly from the 

 skin (where the irritation causes the horse to bite) or as a 

 contamination in food. General cleanliness and the use of hot 

 water (as for Ascarids) will undoubtedly reduce infections. 



Trichina. While a few larvae pass in the faeces of car- 



304 



