This study aimed to estimate the correlations between each lactation days based on number of records and analysed the effects on the genetic evaluation of sires using Random Regression test-day model (RRTDM). Estimation of genetic parameter and breeding value for sire's used REMLF90 and BLUPF90 program. The genetic correlations with each of the test-day were generally revealed to be low in case of low numbers of the records at the end of the milking period. Sire's rank of breeding value varied widely depending on the records on the number of lactation from start to the late generation. Study showed that change in breeding value ranked if daughter's test recode more so it should have at least 5 test-day records. The use of RRTDM in dairy cattle genetic evaluation would be desirable if complete lactation records for late generation daughters of young bulls when selection for proven bulls. Random Regression test-day model require at least 5 complete lactation recode.

K. H Cho, S. H Na, K. S Seo, B. H Park, J. G Choi, S. Kim, Y. C Lee, T. J Choi, A. Salces

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume , , 01.51, 2006
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