A note on the properties of the cumulative difference method for sire evaluation

SUMMARYSeveral of the various dairy sire evaluation methods now in use account for the genetic level of contemporary herdmates. In the cumulative difference method of Bar-Anan and Sacks the contemporary comparison estimate is first calculated and then adjusted by taking into account the genetic level of the contemporaries. These estimates depend on the genetic level of the herdmates. A modification of the procedure in which account is taken of the herdmates' genotype before regressing for small numbers would remedy this deficiency without increasing computing costs.

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Relationship between the cumulative difference and best linear unbiased predictor methods of evaluating bulls

Animal Science ◽

10.1017/s0003356100031032 ◽

1976 ◽

Vol 23 (1) ◽

pp. 15-24 ◽

Cited By ~ 6

Author(s):

R. Thompson

Keyword(s):

Difference Method ◽

Best Linear Unbiased Predictor ◽

Theoretical Justification ◽

Sire Evaluation ◽

Cumulative Difference ◽

Best Linear Unbiased ◽

The Relationship

SUMMARYThe relationship between two methods of sire evaluation (Bar-Anan and Sacks's cumulative difference method (CD) and Henderson's best linear unbiased predictor method (BLUP)) is shown. This relationship suggests a modification, with more theoretical justification, to the CD method.

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Sire evaluation and estimation of genetic gain in Israeli dairy herds

Animal Science ◽

10.1017/s0003356100017256 ◽

1974 ◽

Vol 18 (1) ◽

pp. 59-66 ◽

Cited By ~ 6

Author(s):

R. Bar-Anan ◽

J. M. Sacks

Keyword(s):

Breeding Value ◽

Dairy Herds ◽

Time Interval ◽

Base Population ◽

Genetic Progress ◽

Sire Evaluation ◽

Genetic Level ◽

Cumulative Difference ◽

Two Measures ◽

Residual Variances

SUMMARYThe Israeli procedure for measuring sire breeding values and genetic progress due to selection is described. The estimate of sire breeding value has two components, the current contemporary comparison (CC) and an adjustment for the average genetic deviation of the contemporaries from the original base population. The combined value is called the cumulative difference (CD). For practical purposes the CD was found to be free of the time trends observed for CC, and the residual variances of the two measures were approximately equal. The relative genetic level in any given time interval was measured by the average CD of all sires used during the period October 1964 o t January 1971 in Israel. The analysis indicates that essentially all of the progress in 122-day FCM yields was due to sire selection, whereas 60% of the progress in 305-day FCM yields was due to selection and 40% to improved management.

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