Longevity data from 48933 Spanish Holstein-Friesian cows were used to compare the analysis on the overall functional longevity (FL) vs. the analysis of longevity on a lactation basis using a common baseline for all lactations (FLB) or stratified baselines within lactation class (FLBS). The Kaplan Meier estimate of the survivor functions showed small differences among baseline functions Three alternative definitions of the stage of lactation effect (SL) were used in the FL and FLB analyses. Several goodness of fit criteria were used to compare alternative models. A sirematernal grandsire model was fitted for the best definition of SL. The model including a larger number of points to define the SL effect resulted in the best goodness of fit for all criteria. FLB was the best approach. FLBS would not be required in this population. Log scale and effective heritability estimates were around 3 and 6%, observing nearly no influence of the type of analysis.

Z. Chirinos, D. Hernandez, C. Diaz, M. J Carabano

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume , , 01.50, 2006
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