The Direct Sire Comparison Method for Ranking of Sires for Milk Production in the Swedish Dairy Cattle Population
- 1 January 1982
- journal article
- research article
- Published by Taylor & Francis in Acta Agriculturae Scandinavica
- Vol. 32 (1) , 47-64
- https://doi.org/10.1080/00015128209435732
Abstract
The direct sire comparison method was applied on 1st-lactation records of 478, 789 (SRB) Swedish Red breed and 181,274 Sweedish Friesian cows, calving between Jan. 1966 and Feb. 1978. There were 2329 SRB and 693 SLB sires represented with daughters in the data. Predicted differences (PD) were obtained for all sires, using a mixed model which included the effects of herd-year-season, sire group and sire within group. The additive relationship between sires was considered. Percentages of records lost due to lack of contemporaries in the same herd-year-season decreased over the period studied and were, for the last year, 11 and 18%, respectively for SRB and SLB. These losses can be neglected in sire evaluation for milk yield. Breeding values (M-value) estimated in the ordinary progeny testing of sires by means of the herdmate method were used in a comparison between PD and M-value of the same sire. Product-moment correlations between PD and M-value in groups of unselected sires ranged from 0.85-0.93. The indices also were compared by selecting on each of them and using the average PD of selected sires to evaluate the differences in efficiency. Ranking on PD gave on average 13% higher genetic merit of selected sires when selection was within years and studs. The difference increased to 16% for selection across studs among all SRB sires in 1 generation. When selection was among several sire generations, the differences were 16% in SLB and 23% in SRB. The mentioned differences represent the maximum increase in efficiency obtainable when using the theoretically better of the 2 methods, which the direct sire comparison method must be considered. The efficiency of selection over several generations of sires and over all studs, as in bull-sire and bull-dam selection, is greatly improved if the direct sire comparison method for evaluation of sires is used. Regressions of son''s index (PD and M-value) on sire''s index were higher than expected for PD in both breeds and for M-value in SLB. The regression was much lower than expected in SRB. The estimates varied between +0.11 and -0.10, indicating that the variance due to bias accounted for a large part of the variation among the SRB bull-sires. Average PD based on the 2nd batch of daughters for selected sires was 27 kg lower for 49 SRB sires and 9 kg higher for 25 SLB sires. The difference in PD did not indicate that selective matings of proven sires is a serious problem in sire evaluation. Genetic progress in the sire and cow populations was calculated by using the sires'' PD''s. The genetic trend was estimated to about 50 kg FCM/year in both breeds. The average genetic merit of different sire generations increased with time but showed wide fluctuations from 1 yr to another, especially in SLB.This publication has 18 references indexed in Scilit:
- Repeatability As An Indicator of Stability in Contemporary Comparison Sire EvaluationsJournal of Dairy Science, 1979
- Untersuchungen über Effizienz und Korrekturfaktoren bei der Zuchtwertschätzung von BullenZeitschrift für Tierzüchtung und Züchtungsbiologie, 1979
- Estimation of Genetic Trends from Cow and Sire EvaluationsJournal of Dairy Science, 1978
- AI bull evaluation standards for dairy and dual purpose breedsLivestock Production Science, 1977
- COMPARISON OF SIRE EVALUATION METHODS FOR FAT TESTCanadian Journal of Animal Science, 1977
- Estimation of sire's breeding valueZeitschrift für Tierzüchtung und Züchtungsbiologie, 1976
- Inverse of a Matrix of Relationships Due to Sires and Maternal GrandsiresJournal of Dairy Science, 1975
- Comparison of Alternative Sire Evaluation MethodsJournal of Animal Science, 1975
- An Extension Approach to New Sire SummariesJournal of Dairy Science, 1974
- General Flexibility of Linear Model Techniques for Sire EvaluationJournal of Dairy Science, 1974