154 Sheep-Farming 



Some of the best American fine-wool flocks are line- 

 bred. In other cases in which the rams have been 

 selected from within the flock for a number of gener- 

 ations, there has been a most serious decrease in 

 size and robustness, the latter sometimes especially 

 noticeable in young lambs. 



Before attempting to explain the varied results 

 from close matings, the two terms in common use, 

 in-breeding and line-breeding, may be considered. 

 In-breeding and line-breeding are essentially the 

 same. The distinction between them is not one of 

 principle, but of degree. There is no agreed line of 

 demarcation between them, and what some persons 

 call in-breeding may be referred to by others as 

 line-breeding. Animals that are in-bred have 

 parents that are related much more closely than are 

 the parents of line-bred animals. The mating of 

 sons and daughters of the same ram or of the same 

 ewe is in-breeding. A close mating such as that of 

 sire to daughter or son to dam would be a close form 

 of in-breeding. Any mating less close than that of 

 being half brother and sister would be more prop- 

 erly spoken of as line-breeding. Line-breeding, or 

 breeding in line, implies a succession of sires that 

 trace their descent to a common animal not too far 

 removed. 



The explanation of line-breeding is not to be 

 found in the fact of the relationship of the parents. 

 Because such parents have a common near-by ances- 



