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Copyright © 1999, Mousekateers Cattery, All Rights Reserved.
Unauthorized Duplication Prohibited
 
 
 
 
Breeding Methods

In order to discuss breeding methods, its useful to review basic genetic principles and terminology.  I find the use of charts very helpful as a way to organize and review data, so I've made several of them just for that purpose.  After reviewing the chart data, I will go on to discuss cattery breeding methods. 
  
          
        Normal and Major Mutant Gene Inheritance in the Cat     
        (Principles of Mendelian Inheritance)
        Normal:     

        Except for the XY, there is a pair of genes for each function located at the same loci on sister chromosomes.  One pair of normal genes is represented as dots on a homologous pair of chromosomes.     
         

        Dominant:     

        A single mutant (changed) gene is dominant if it causes an evident abnormality.   The chance of inheritance of the mutant gene (left)  is the same as the chance of inheriting a particular chromosome of the pair:  50%.

          Heterozygous recessive:     

        A single mutant gene is recessive (left) if it causes no evident abnormality, the function being well covered by the normal partner gene (its allele).  Such a cat may be referred to as a heterozygous carrier.

        Homozygous recessive:     

        When both genes are a recessive mutant, the abnormal effect is expressed.  The parents are generally carriers, and their risk of having another affected offspring is the chance of receiving the mutant from one parent (50%) times the chance from the other parent (50%), or 25 % for each offspring.

             
         X   Y
        X-linked recessive:     

        An X-linked recessive will be expressed in the male because he has no normal partner gene.  His daughters, receiving the X, will all be born carriers, and his sons, receiving the Y, will all be normal.

             
         X  X
        X-linked recessive:     

        An X-linked recessive will not show overt expression in the female because at least part of her "active" X's will contain the normal gene.  The risk for affected sons and carrier daughters will each be 50%.

         

 
Comparison of Dominant and Recessive Genes in Feline Genetics 
Dominant Gene
Recessive Genes
Possible Genotypes
Typical Phenotypes
    
(agouti)      
Tabby coat     
pattern
    
(non-agouti)      
Black coat masks    
tabby pattern
AA     
Aa     
aa
(Homozygous agouti)     
(Heterozygous agouti)     
(Homozygous non-agouti)
Visible tabby pattern      
Visible tabby pattern      
Solid coat color,     
tabby pattern is masked
    
(black)
    
(chocolate)    
    
bl     
(cinnamon)
BB     
Bb     

Bbl     
     
bb     
bbl     

blbl

(Homozygous black)     
(Heterozygous black,     
  chocolate carrier)     
(Heterozygous black,     
  cinnamon carrier)     
(Homozygous chocolate)     
(Heterozygous chocolate,     
  cinnamon carrier)     
(Homozygous cinnamon)
Black     
Black     

Black     

Chocolate     
Chocolate     

Cinnamon

    
(full color)
ca    
(albino,    
 blue-eyed)     

c       
(albino,    
 pink-eyed)    
    
cb     
(Burmese)    
    
cs     
(Siamese)     
     
 

CC     
Cca     
Ccb     
Cc     
Ccs     
caca     
cac     
cbca     
cbcb     
cbc     
cc     
csca     
cscb     
cscs
(Homozygous full )     
(Heterozygous full, albino carrier)     
(Heterozygous full, Burmese carrier)     
(Heterozygous full, albino carrier)   
(Heterozygous full, Siamese carrier)   
(Homozygous albino)   
(Heterozygous albino)   
(Heterozygous Burmese)   
(Homozygous Burmese)   
(Heterozygous Burmese)   
(Homozygous albino)   
(Heterozygous Siamese)   
(Heterozygous siamese)   
(Homozygous siamese)
Full coat color    
Full coat color    
Full coat color    
Full coat color    
Full coat color    
Albino    
Albino    
Burmese    
Burmese    
Burmese    
Pink-eyed albino    
Tonkinese    
Siamese    
Siamese
Cu     
(curled ears)
cu     
(straight ears)
CuCu    
Cucu    
cucu
(Homozygous curled ears)    
(Heterozygous curled ears)    
(Homozygous straight ears)
American Curl    
American Curl   
Straight ears
    
(non-diluted)
    
(diluted coat)
DD    

Dd    

dd

(Homozygous non-diluted coat)    

(Heterozygous non-diluted coat)    

(Homozygous diluted coat)

Black, chocolate,    
 cinnamon, red    
Black, chocolate,    
 cinnamon, red    
Blue, liliac, fawn, cream
Fd     
(folded ears)
fd     
(straight ears)
FdFd    
Fdfd    
fdfd
(Homozygous folded ears)    
(Heterozygous folded ears)    
(Homozygous straight ears)
Scottish Fold   
Scottish Fold   
Straight ears
Hr     
(normal coat)
hr     
(hairless coat)
HrHr    
Hrhr    
hrhr
(Homozygous normal coat)    
(Heterozygous normal coat)    
(Homozygous hairless coat)
Normal coat    
Normal coat    
Sphynx
I    
(inhibitor coat   
pigment -    
affects the   
undercoat)
i   
(coat pigment   
non-inhibited)
II   

Ii   

ii

(Homozygous inhibited)   

(Heterozygous inhibited, carriers   
 non-inhibited)   
(Homozygous non-inhibited)

Silver (Chinchilla, Shell,    
            Shaded, Smoke)   
Silver (Chinchilla, Shell,    
           Shaded, Smoke)   
Solid coat 
L   
(short hair)
l   
(long hair)
LL   
Ll   

ll

(Homozygous short hair)   
Heterozygous short hair, long hair   
 carrier)   
(Homozygous long hair)
Short hair   
Short hair   

Long hair

M   
(Manx tail)
m   
(normal tail)
MM   
Mm   

mm

(Homozygous manx tail)   
(Heterozygous normal tail, carrier of   
 manx tail gene)   
(Homozygous normal tail)
Manx   
Manx   

Normal tail

O (X))   
(orange gene,   
linked with the   
female X    
chromosome)    
"Phaeno-"   
melanin
o (X or Y)   
(non-orange)   
   
   

"Eu-"   
melanin

OO (XX)   
Oo (XX)   

O- (XY)   

oo (XX)   
o-  (XY)

(Homozygous orange)   
(Heterozygous orange, carrier of    
 non-orange)   
(Heterozygous orange, carrier of   
 non-orange)   
(Homozygous non-orange)   
(Homozygous non-orange)
Red female   
Tortoiseshell female   

Red male   

Black female   
Black male

R   
(straight hairs;   
guard, awn, and   
down)
r   
(curly hairs and   
lack of guard   
hairs)
RR   
Rr   

rr

(Homozygous straight hairs)   
(Heterozygous straight hairs,  carrier   
 of curly hairs)   
(Homozygous curly hairs)
Straight hairs   
Straight hairs   

Cornish Rex

Re   
(straight hairs of   
all 3 types)
re   
(curly hairs of   
all 3 types)
ReRe   
Rere   

rere

(Homozygous straight hairs)   
(Heterozygous straight hairs,  carrier   
 of curly hairs)   
(Homozygous curly hairs)
Straight hairs   
Straight hairs   

Devon Rex

Ro   
(straight hairs of   
all 3 types)   
 
ro   
(curly hairs of   
all 3 types)
RoRo   
Roro   

roro

(Homozygous straight hairs)   
(Heterozygous straight hairs, carrier   
 of curly hairs)   
(Homozoygous curly hairs)
Straight hairs   
Straight hairs   

Oregon Rex

S   
(white   
piebald   
spotting)
s   
(no white   
spotting)
SS   
Ss   

ss

(Homozygous piebald spotting)   
(Heterozygous piebald spotting,   
 carrier of no-white spotting)   
(Homozygous no white spotting)
Bicolor   
Bicolor   

Solid

Se   
(curly hairs of   
all 3 types)
se   
(straight hairs of   
all 3 types)
SeSe   
Sese   

sese

(Homozygous curly hairs)   
(Heterozygous curly hairs, carrier of    
 straight hairs)   
(Homozygous straight hairs)
Selkirk Rex   
Selkirk Rex   

Straight hairs

Ta   
(ticked tabby)   
(incomplete   
dominance)
T   
(mackerel tabby)   
tb   
(blotched tabby)   

Note:  Mackerel   
tabby is    
dominant over   
blotched tabby.

TaTa   
TaT   

Tatb   

Ttb   

TT   
tbtb

(Homozygous ticked tabby)   
(Heterozygous ticked tabby, carrier   
 of mackeral tabby)   
(Heterozygous ticked tabby, carrier   
 of blotched tabby)   
(Heterozygous mackerel tabby,   
 carrier of blotched tabby)   
(Homozygous mackerel tabby)   
(Homozygous blotched tabby)
Ticked tabby   
Ticked tabby   

Ticked tabby   

Mackerel tabby   

Mackerel tabby   
Blotched tabby

W   
(white - color   
masking gene)
w   
(non-white, true   
color is not   
masked)
WW   
Ww   

ww

(Homozygous white)   
(Heterozygous white, carrier   
 of non-white color )   
(Homozygous non-white)
White   
White   

Color other than white

Wh   
(wire hair)   
 
wh   
(straight hair)   
 
WhWh   
Whwh   

whwh

(Homozygous wire hair)   
(Heterozygous wire hair, carrier of   
 straight hair)   
(Homozygous straight hair)
American Wirehair   
American Wirehair   

Straight hair

 

 
Comparison of Four Major Breeding Methods
Close Inbreeding
Linebreeding
(Moderate inbreeding)
Linecrossing
(Outcrossing within a breed)
Crossbreeding
(Outcrossing with another breed.)
Examples:    
Mother to son   
Father to daughter   
Brother to sister   
Grandchildren to grandparents
Examples:   
The mating of more distant    
relatives within the same   
bloodline. If much homozygosity is already established in the bloodline,   
it is still considered close   
inbreeding.  Common ancestors of the parents must be found only in the very beginning of the breed's formation for it to be considered true line breeding.
Examples:   
The mating of good breed examples from one bloodline to good breed examples from another bloodline.  The cats from one bloodline should compliment the cats from the other bloodline.  If a cat from bloodline A has great boning but a poor ear set, it should be mated with a cat from bloodline B that has a great ear set, but average boning.
Examples:   
The mating of good breed examples from one breed to good breed examples of another breed.   
 
Uses:   
Fixes desired traits   
Increases homozygosity
Uses:   
Fixes desired traits   
Increases homozygosity   
Allows for some phenotypic and genotypic differences between individuals.  This allows for greater subsequent genetic manipulations than inbreeding.
Uses:   
Produces exceptional show quality cats while maintaining vigor. 
Uses:   
Produces new breeds such as the Ocicat (Abyssinian breed with Siamese).  Also introduces new genes into a breed which was the base of the color point (Himalayan) Persian.  Definitely increases hybrid vigor.  (The offspring are genetically and physically healthier than their parents.)
Problems:   
Brings out deleterious genes   
Loss of vigor   
Immunodeficiency becomes   
fixed
Problems:   
Brings out deleterious genes   
Loss of vigor   
Immunodeficiency becomes fixed
Problems:   
Requires thought and planning.  Breeder must be patient because results are not seen as quickly as with inbreeding, or line breeding.
Problems:   
New breed committees must present a very unique cat that is consistent over many breedings. 
 
   
 
How do I know if my cats are too inbred?
Signs of loss of vigor in your breeding program   
  • Smaller litter sizes
  • Larger numbers of kittens succumb to infectious diseases
  • Immune deficiencies as evidenced by  fifty percent of a litter dies of a single infection
  • Increased failure-to-thrive cases (if not blood type mismatch)
  • Increased incidences of congenital abnormalities
  • Smaller cats, even at adulthood
  • Low fertility in males or females
  • Increased spontaneous abortions
 

References: 
Bodmer, W.F., Cavalli-Sforza, L. Genetics and the Evolution of Man, San Francisco: W.H. Freeman; 1976 
Brown T. Genetics.  A Molecular Approach, 2nd ed. London:  Chapman & Hall: 1992 
Dorland's Illustrated Medical Dictionary. 28th Ed. Philadelphia: WB Saunders; 1994. 
Emery AFH.  Elements of Medical Genetics. 6th ed. Edinburgh:  Churchill Livingstone; 1983 
Lewin B. Genes V. Oxford:  Oxford University Press; 1994 
Rieger R., Michaelis A. Green MM. Glossary of Genetics and Cytogentics. 5th ed. Berlin: Springer Verlag; 1979 
Robinson, R; Genetics for Cat Breeders, 3rd Ed., Pergamon Press, London, 1991 
Smith, DW, Jones, K L; Recognizable Patterns of Human Malformation, 3d Ed., WB Saunders; 1982 
Suzuki DT, Griffiths AGF, Miller JH, Lewontin RC. An Introduction to Genetic Analysis, New York: WH Freeman; 1986. 
Watson JD. Molecular Biology of the Gene. 3rd ed. Menlo Park, California: W.A. Benjamin; 1976 
Whitehouse HLK. Towards an Understanding of the Mechanisms of Heredity. 3rd ed. London:  Edward Arnold; 1973. 
 

 
 The Cats 

 
Angela Bassett 
 
Benny 
 
Billi 
 
Cameron Diaz 
 
Chipmunk 
 
Christina Ricci 
 
Halle Berry 
 
Honey 
 
Jennifer Lopez 
 
Lassie Cheyenne 
 
Laurel 
 
Lindsay Lohen 
 
Peggy Sue 
 
Reba McIntire 
 
Tyra Banks 
 
Vanessa Williams 
 
Wooly Bully

  
 
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Music 
Theme from Pink Panther 

Pachebel 

Georgia on my Mind 

Ray Blues 

Tears in Heaven 

Dreams 

Theme from the X Files 

Over Drive 

House Rocker 

Travels 

Theme from Mickey Mouse Show 

BoogieWoogie 

Al Jarreau 

Mrs. Robinson