254 



MANAGEMENT AND BREEDING OF HORSES 



note the conditions that produce it, particularly since' by 

 modifying these conditions, we can aid in producing 

 variation in a desired direction. Thus, if we wish to 

 increase the size of the horse, the conditions that cause 

 the animal to vary in that direction are of interest and 

 should be well understood. In horse breeding the prin- 

 cipal causes of variation are the environment, crossing 

 find use. 



Environment. — By this term is meant the surroundings 



of the animal. The 

 chief factors of en- 

 vironment, through 

 which we seek to 

 improve our horses, 

 are those of climate, 

 food and care. 



The climate is of 

 interest largely as it 

 controls the food 

 supply, although it 

 does affect the ex- 

 ternal coat to some 

 extent. When the 

 horse is exposed to 

 cold, damp weather, 

 the hair becomes longer and thicker than if protected. 

 The natural effect of the climate is modified by housing, 

 and we can move the horse from one climate to another 

 without serious results. 



No single factor influences development to a greater 

 extent than the food supply. Full feeding increases the 

 size and the constitutional vigor, while withholding the 

 food not only arrests growth, but weakens the capacity 

 for future development as well. In order to secure in- 

 creased development of all the organs, the animals must 

 be supplied with more food than is required for the per- 

 formance of the normal function. 



Fig. 12S. — Percheron Stallion "Galba" 



