The following review questions are intended to point out
 out and help you understand some of the major points in
 the recommended reading material in Scientific Farm Animal
 Production (8th Ed.) by R. E. Taylor and T. G. Field.
   
  CHAPTER 13:  Genetic Change Through Selection
  CHAPTER 14:  Mating Systems
  
  13-1.   Most of the economically important traits are affected
          by how many pairs of genes?
  
  13-2.   Most economically important traits in farm animals
          show "continuous variation."  What does this mean?
  
  13-3.   The phenotypic selection of a trait is influenced by
          what two factors?
  
  13-4.   Define selection.
  
  13-5.   What is selection differential (S.D.)?  If selected
          replacement heifers average 40 lb. heavier than the
          herd they came from, does this mean that offspring
          born to these heifers will average 40 lb. heavier than
          the herd?  Why?
  
  13-6.   What is heritability?  How does heritability relate to
          S.D. in terms of predicting genetic progress as the
          result of phenotypic selection?  Work through the
          sample problem in the section on "Predicting Genetic 
          Change."  You may see a problem like this again!
  
  13-7.   Define generation interval.  How does the G.I. affect
          the rate of genetic change in a herd or flock?
  
  13-8.   If selection is practiced on more than one trait at a
          time, what effect does the number of traits selected
          for have on the genetic progress for any one trait?
  
  13-9.   Some traits are genetically correlated.  What does
          this mean?  Why does it occur?
  
  13-10.  Can use of artificial insemination increase the rate
          of genetic improvement?  How?
  
          ** We will not discuss "Selection Methods." **
  
  
  CHAPTER 14:  MATING SYSTEMS
  
  14-1.   Why is a knowledge of breeding (or mating) systems
          important?
  
  14-2.   What are the two major systems of mating?  Define
          each.  Understand the relationship between these two
          major systems.  (Study Fig. 14.2)
  
  14-3.   What are the two forms of inbreeding?  (The word
          "intensive" was left off by your instructor when he
          discussed the effects of inbreeding in class.)
  
  14-4.   What are the genetic effects of using inbreeding?
  
  14-5.   Why would a producer want to linebreed?
  
  14-6.   What are the four types of outbreeding?  Define each.
  
  14-7.   Why can we achieve a species cross but not a genus
          cross?
  
  14-8.   What are the two primary reasons for crossbreeding?
  
  14-9.   Define heterosis.  It is not unusual for the
          performance of the crossbred to be less than one of
          the parents.  How do we justify crossbreeding in this
          situation?
  
  14-10.  How is heterosis related to the heritability of the
          trait being considered?
  
  14-11.  What is the difference between a rotational
          crossbreeding system and a terminal crossbreeding
          system?
  
  14-12.  What is grading up?  How does this breeding system
          allow a commercial producer to keep his herd
          productivity at a level similar to a purebred herd?
  
  14-13.  How has the process of grading up helped us introduce
          new breeds into the United States and Canada?