Title: Genetic correlation between persistency and calving interval of Holsteins in Japan
Abstract: Examined in this study were the effects of calving intervals (CI) on lactation curves. Genetic correlations among lactation yields, lactation persistency, increase in milk yield at an earlier stage of lactation and CI were estimated. Data included 31,227 cows with 293,982 test-day records obtained from the DHI program between 1997 and 2001. Persistency and increase in milk yield at an earlier stage of lactation were calculated for each cow defined as the difference between test day milk yields at 60 days in milk (DIM) and 150 DIM (calculated as milk yield at 150 DIM minus milk yield at 60 DIM). Increase in milk yields at an earlier stage of lactation (IEL) was defined as the difference between test day milk yields at 5 DIM and 35 DIM (calculated as milk yield at 35 DIM minus milk yield at 5 DIM). A random regression model (RRM) was applied to this analysis, and the GIBBS3F90 program was used to estimate the effects of CI classes on lactation curves. The RRM included the fixed effects of herd-test-day, age, calving season, and CI classes as well as random effects of animal, permanent environment and heterogeneous residuals with 10 intervals by DIM. The genetic correlations were estimated using the AIREMLF90 program with a model including fixed effects of herd, age, and calving season as well as random effects of animal and residual. Results indicated that lactation curves were affected by the length of CI when the DIM was longer than 150. A slightly positive genetic correlation was estimated between persistency and CI (0.20), but a slightly negative correlation was estimated between persistency and IEL (-0.19).
Publication Year: 2009
Publication Date: 2009-11-28
Language: en
Type: book-chapter
Indexed In: ['crossref']
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Cited By Count: 3
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