Book M. IMPROVING THE BREED OF ANIMALS. 999 



Chap. VIII. 



Principles of improving the Domestic Animals used in Agriculture. 



1993. The animals in use in British agriculture are few, and chiefly the horse, ox, 

 sheep, swine, and domestic fowls. The first is used solely as a laboring animal, and the 

 rest chiefly as furnishing food. In applying the general principles of physiology to these 

 animals with a view to their improvement for the use of man, we shall consider in suc- 

 cession the principles of breeding, rearing, and feeding. 



Sect. I. Of improving the Breed of Animals. 



1994. By improvement of a breed is to be understood the producing such an alteration 

 in shape or description, as shall render the animal better fitted for the labors he has to per- 

 form ; better fitted for becoming fat ; or for producing milk, wool, eggs, feathers, or 

 particular qualities of these. The fundamental principle of this amelioration is the pro- 

 per selection of parents. Two theories have obtained notice on this subject, the one in 

 favor of breeding from individuals of the same parentage, called the in-and-in system, 

 and the other in favor of breeding from individuals of two different offsprings, called the 

 system of cross breeding. As is usual in such cases, neither theory is exclusively correct, 

 at least as far as respects agricultural improvement ; for, as will afterwards appear, the 

 principles on which a selection for breeding so as to improve the carcase of the animal 

 depends, will lead occasionally to either mode. 



1995. That the breed of animals is improved by the largest males, is a very general 

 opinion ; but this opinion is the reverse of the truth, and has done considerable mischief. 

 The great object of breeding, by whatever mode, is the improvement of form, and expe- 

 rience has proved that crossing has only succeeded in an eminent degree, in those in- 

 stances in which the females were larger than in the usual proportion of females to males ; 

 and that it has generally failed where the males were disproportionally large. {Culleys 

 Introduction, &c.) The following epitome of the science of breeding, is by the 

 late eminent surgeon, Henry Cline, who practised it extensively on his own farm at 

 Southgate. 



1996. The external form of domestic animals has been much studied, and the propor- 

 tions are well ascertained. But the external form is an indication only of internal 

 structure. The principles of improving it must, therefore, be founded on a knowledge 

 of the structure and use of internal parts. 



1997. The lungs are of the first importance. It is on their size and soundness that the strength and 

 health of animals principally depends. The power of converting food into nourishment, is in proportion to 

 their size. An animal with large lungs is capable of converting a given quantity of food into more 

 nourishment than one with smaller lungs ; and therefore has a greater aptitude to fatten. 



1998. The chest, according to its external form and size, indicates the size of the lungs. The form of 

 the chest should approacli to the figure of a cone, having its apex situated between the shoulders, and its 

 base towards the loins. Its capacity depends on its form more than on the extent of its circumference ; 

 for where the girth is equal in two animals, one may have much larger lungs than the other. A circle 

 contains more than an ellipsis of equal circumference; and in proportion as the ellipsis deviates from the 

 circle it contains less. A deep chest, therefore, is not capacious ; unless it is proportionably broad. 



1999. The pelvis is the cavity formed by the junction of the haunch bones with the bone of the rump. 

 It is essential that this cavity should be large in the female, that she may be enabled to bring forth 

 her young with less difficulty. When this cavity is small, the life of the mother and her offspring is en- 

 dangered. The size of the pelvis is chiefly indicated by the width of the hips, and the breadth of the 

 waist, which is the space between the thighs. The breadth of the loins is always in proportion to that of 

 the chest and pelvis. 



2000. The head should be small, by which the birth is facilitated. Its smallness affords other advantages, 

 and generally indicates that the animal is of a good breed. Horns are useless to domestic animals, and 

 they are often a cause of accidents. It is not difficult to breed animals without them. The breeders of 

 horned cattle and horned shei'p, sustain a loss more extensive than they may conceive ; for it is not the 

 horns alone, but also much bone in the skulls of such animals to support their horns, for which the butcher 

 pays nothing ; and besides this there is an additional quantity of ligament and muscle in the neck, which 

 is of small value. The skull of a ram with its horns, weighed five times more than a skull which was 

 hornless. Both these skulls were taken from sheep of the same age, each being four years old. The great 

 difference in weight depended chiefly on the horns, for the lower jaws were nearly equal ; one weighing 

 seven ounces, and the other six ounces and three quarters, which proves that the natural size of the head 

 was the same in both, independent of the horns and the thickness of bone which supports them. In 

 horneil animals the skull is extremely thick. In a hornless animal it is much thinner, especially in that 

 part where the horns usually grow. To those who have reflected on the subject, it may appear of httle 

 consequence whether sheep and cattle have horns ; but on a moderate calculation it will be found, that 

 the loss in farming stock, and also in the diminution of animal food, is very considerable, from the pro- 

 ductions of horns and their appendages. A mode of breeding which would prevent the production of 

 these, would afford a considerable profit in an increase of meat, wool, and other valuable parts. 



2001. The length of the neck should be proportioned to the height of the animal, that it may collect its 

 food with ease. 



2002. The muscles, and the tendons which are their appendages, should be large; by which an animal 

 is enabled to travel with greater facility. 



2003. The bones, when large, are commonly considered an indication of strength ; but strength does not 

 depend on the size of the bones, but on that of the muscles. Many animals with large bones are weak, 

 their muscles being small. Animals that have been imperfectly nourished during growth, have their bones 

 disproportionately large. If such deficiency of nourishment originated from a constitutional defect, which- 



