398 DISEASES OF CATTLE, SHEEP, GOATS, ETC. 



Lactation. The influence of lactation in preventing the toxic 

 action of cotton seed, illustrated by the relative immunity of milch 

 cows as compared with growing and fattening cattle, may be attrib- 

 uted to the constant elimination in the milk of some toxic principle 

 derived from the cotton seed directly or formed in the system from 

 substances contained in cotton seed. (The assumption being that 

 in dry animals this accumulates in the system). That such an im- 

 munity exists is shown by the frequency of cotton seed poisoning in 

 beef cattle fatted at the oil mills in the south, as compared with the 

 apparent exemption from this trouble in dairy farms where cotton 

 seed meal is quite generally fed in all sections of the country.* 



Other Poisonous Plants. Other poisonous plants are the box, 

 water hemlock, equisetum, lupine (under special conditions), to- 

 bacco, green acorns (when eaten in excessive quantities by horses or 

 cattle), green sorghum and Kafir corn forage (when stunted or 

 frosted), lily of the valley, aconite oleander, jimson weed, green po- 

 tatoes and potato sprouts, and poison rye grass (Lolium temulentum.) 



Ergotism. The poisonous effects of ergot appear chiefly in the 

 winter and spring of the year and among cattle. It is developed 

 among grasses grown on rich soil in hot, damp seasons. Rye seems 

 more liable to ergot than any of our other crops. Of the grasses 

 which enter into the composition of hay, bluegrass is the most likely 

 to become affected. Ergot may also affect redtop, oats, grasses, and 

 grains. On the plant the fungus manifests itself on the seeds, where 

 it is easily recognized when the hay is examined in the mow. The 

 ergotized seeds are several times larger than the natural seeds hard, 

 black, and generally curved in shape. 



The effect of the protracted use of ergot in the food is pretty 

 well understood to be that of producing a degeneration and obstruc- 

 tion of the smaller arterial branches. The result is to shut off the 

 blood supply to the distal parts of the body, where the circulation is 

 weakest, and thus to produce a mummification or dry gangrene of the 

 extremities, as the ears, tail, feet, etc. Cattle seem to be more sus- 

 ceptible than other animals to the influence of ergot, possibly on ac- 

 count of the slowness of the heart's action. When the effect of the 

 poison has become sufficient to entirely arrest the circulation in any 

 part, the structures soon die. The disorder manifests itself as lame- 

 ness in one or more limbs ; swelling about the ankle which may result 

 in only a small slough or the loss of a toe, but it may circumscribe 

 the limb at any point below the knee or hock by an indented ring, 

 below which the tissues become dead. The indentation soon changes to 

 a crack, which, like it, extends completely round the limb, forming 

 the line of separation between the dead and living structures. The 

 crack deepens till the parts below drop off without loss of blood, and 

 frequently with very little pus. Ergot may cause serious irritation 

 of the digestive tract, or by acting upon the nervous system it may 



*It is assumed that milking cows do not suffer from cotton seed poisoning 

 because instances of such poisoning have not been recorded, but it is quite probable 

 that such cases do occur, their true nature not being recognized. It seems improb- 

 able that a complete immunity can exist. 



