Dr. Sewall Wright discusses the coefficients of inbreeding and relationship in the breeding of domestic animals. He notes that while consanguineous matings are common, line breeding is often preferred to concentrate the blood of a notable individual. Pearl introduced a coefficient to measure inbreeding by comparing the number of ancestors in each generation to the maximum possible. However, this coefficient has limitations, as it may not reflect the actual effects of inbreeding. To address this, Pearl developed a partial inbreeding index that accounts for the relationship between the sire and dam. Inbreeding has two main effects: a decline in vigor and an increase in uniformity and prepotency. The decrease in vigor is attributed to the accumulation of recessive unfavorable genes. The percentage of homozygosis is directly related to the inbreeding coefficient. Wright suggests a formula, 2h - 1, where h is the proportion of complete homozygosis, to calculate the inbreeding coefficient. This formula is also related to the correlation between gametes. The coefficient of relationship, r_bc, is used to measure the genetic relationship between individuals. It is calculated by summing the coefficients for all connecting paths. The formula for the correlation between gametes, which is also the inbreeding coefficient, is derived from the relationship between the sire and dam. Wright illustrates the application of these coefficients using the pedigrees of Roan Gauntlet and Charles Collings' bull, Comet. The inbreeding coefficient for Roan Gauntlet is 14.1%, while for Comet, it is 47.1%, reflecting the degree of inbreeding in their respective pedigrees. These examples show how inbreeding coefficients can be used to compare different breeding systems.Dr. Sewall Wright discusses the coefficients of inbreeding and relationship in the breeding of domestic animals. He notes that while consanguineous matings are common, line breeding is often preferred to concentrate the blood of a notable individual. Pearl introduced a coefficient to measure inbreeding by comparing the number of ancestors in each generation to the maximum possible. However, this coefficient has limitations, as it may not reflect the actual effects of inbreeding. To address this, Pearl developed a partial inbreeding index that accounts for the relationship between the sire and dam. Inbreeding has two main effects: a decline in vigor and an increase in uniformity and prepotency. The decrease in vigor is attributed to the accumulation of recessive unfavorable genes. The percentage of homozygosis is directly related to the inbreeding coefficient. Wright suggests a formula, 2h - 1, where h is the proportion of complete homozygosis, to calculate the inbreeding coefficient. This formula is also related to the correlation between gametes. The coefficient of relationship, r_bc, is used to measure the genetic relationship between individuals. It is calculated by summing the coefficients for all connecting paths. The formula for the correlation between gametes, which is also the inbreeding coefficient, is derived from the relationship between the sire and dam. Wright illustrates the application of these coefficients using the pedigrees of Roan Gauntlet and Charles Collings' bull, Comet. The inbreeding coefficient for Roan Gauntlet is 14.1%, while for Comet, it is 47.1%, reflecting the degree of inbreeding in their respective pedigrees. These examples show how inbreeding coefficients can be used to compare different breeding systems.