Cat Genetics 4.1: Inbreeding Calculator, Detailed Instructions and Interpretation
The Inbreeding Calculator by Labgenvet is provided to breeders as a simple and rapid tool for calculating the inbreeding coefficient of an animal based on its pedigree. It is designed to be helpful in performing virtual breeding trials as an aid in making management decisions. The calculator is based on four generations of ancestors (parents, grandparents, great-grand parents and great-great-grandparents), including 30 ancestors in total, using a simplified version of the formula proposed by Sewell Wright for calculating inbreeding coefficients:
In order to further simplify the process, a number is used to designate a specific animal within the pedigree, rather than the complete name of the animal which can be cumbersome. For the first parental pedigree (Pedigree A with ancestors numbered 1 to 15), the numbers are fixed and the parent (animal #1) can be the father or the mother of the offspring in question. For the second parental pedigree (Pedigree B, with ancestors numbered 16 to 30), the numbers can be changed to match common ancestors found in the first parental pedigree. The relative position of common ancestors between the two parental pedigrees is important for the function of the calculator. It is important to note that ancestors in common within a parental pedigree are not utilized in the calculation, only ancestors in common between the parental pedigrees. This further simplification may result in an underestimation of the absolute value of the inbreeding coefficient calculated for a given animal, however this should not interfere with conclusions made when comparing pedigrees and potential mating partners when performing virtual crosses.
The Inbreeding Calculator is provided as a tool for breeders and is the result of the vision and implementation of Benoit Bouchard, MsEng, a long-time breeder of Pug dogs, in collaboration with Labgenvet and with the help and consultation of Dr. Guy Labbé, DVM. It must be stated that an inbreeding coefficient is just one tool amongst many others available to breeders to help them in making breeding decisions. Breeders are responsible for having an adequate understanding of inbreeding coefficients and for a judicious use of the calculator.
Calculate the inbreeding coefficient for a given animal
To calculate the inbreeding coefficient for a given animal, the paternal pedigree (Pedigree A, representing ancestors 1 to 15) is compared to the maternal pedigree (Pedigree B, representing ancestors 16 to 30). The relative position of an ancestor in common between the paternal and maternal pedigrees is important for the proper functioning of the calculator. Note that in Pedigree A, positions 2, 4, 6, 8, 10, 12 and 14 are marked by blue rectangles and represent male animals while positions 3, 5, 7, 9, 11, 13 and 15 are marked by pink rectangles and represent female animals. In a similar fashion, in Pedigree B, positions 17, 19, 21, 23, 25, 27 and 29 represent male animals while positions 18, 20, 22, 24, 26, 28 and 30 represent female animals.
Evidently, for ancestors in common between the two pedigrees, male animal numbers from Pedigree A (2, 4, 6, 8, 10, 12 and 14) should only replace male positions in Pedigree B (17, 19, 21, 23, 25, 27 and 29). In a similar fashion, female animal numbers from Pedigree A (3, 5, 7, 9, 11, 13 and 15) should only replace female positions in Pedigree B (18, 20, 22, 24, 26, 28 and 30). The positions of the parents are marked by yellow rectangles. If the father is represented by position 1 in Pedigree A then the mother will be represented by position 16 in Pedigree B. Alternatively, if the mother is represented by position 1 in Pedigree A then the father will be represented by position 16 in Pedigree B.
In this version of the calculator, the inbreeding coefficient is calculated based on common ancestors found between the two parental pedigrees but does not consider common ancestors within parental pedigrees. Remember to reinitialize the calculator between calculations by pressing the Reset button.