i] Introduction 3 



especially true of sheep. We have often observed sheep eating greedily 

 on one day plants which they could scarcely be persuaded to eat on the 

 following day on the same range." In the case of one flock of sheep on a 

 foothill range at an altitude of 4,600 ft. " a few of the sheep were observed 

 eating large quantities of wild sunflower {BalsamorJiiza sagittata), a few 

 ate freely of false lupine (Thermopsis rhombifoUa), some confined their 

 attention largely to the wild geranium, while others ate false esparcet 

 {Astragalus bisuhatus) almost exclusively. Two sheep were seen eating 

 the leaves of lupine, and about fifty ate a greater or less quantity of 

 Zygadenus venenosus, while the majority of sheep in the band fed 

 exclusively upon the native grasses on the range." 



Horses also have been known to acquire in America a depraved 

 appetite for horsetail and loco-weed. 



The different species of five stock are often quite differently affected 

 by poisonous plants, some being very susceptible to a given plant while 

 others may be little or not at all susceptible. One species (e.g. the pig) 

 may readily vomit the poison of a plant which is emetic, while another 

 {e.g. the horse) may be unable to do so and hence be the more seriously 

 injured. The variabihty of the different classes of live stock in this 

 respect is frequently brought out in Chapters n to vi. Poisonous 

 effects may also vary with the individuality and age of animals of the 

 same species. 



At certain periods of the year — e.g. in early spring, and during dry 

 summers, — ^there may be a scarcity of green herbage, and this may 

 induce animals to eat any green plants which are especially early, 

 including poisonous ones, which they would otherwise refuse. 



In some cases poisonous plants which do not lose their toxic pro- 

 perties on drying {e.g. meadow saffron) may be included in hay, and 

 hence find their way to stock in such a form that they may not be dis- 

 tinguished. It has been found, however, that some poisonous plants 

 or parts of them are refused by stock when mixed with good herbage 

 in hay. Care should be exercised that poisonous plants are not included 

 with hay or green fodder, and in cases of poisoning aU forage should be 

 examined. 



Animals may also be poisoned by certain toxic seeds {e.g. com 

 cockle) fed to them with cereal grains, in feediag stuffs generally, or in 

 the refuse seeds from the sources mentioned. Here again judgment 

 is necessary, and it is probably advisable on all counts to bum the 

 weed seeds and similar refuse from the sources mentioned. Poisonous 

 seeds inay occur in low quahty feeding stuffs, and poisonous seeds of 



1—2 



