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Schätzung von Heterosiswirkungen in Merkmalen der Laktation und Fruchtbarkeit in 3 Kreuzungsversuchen zwischen Holstein Friesian und Dt. Schwarzbunten unter heiβen klimatischen Bedingungen
Author(s) -
Khalil M. H.,
Afifi E. A.,
Salem M. A.,
Zahed S. M.
Publication year - 2000
Publication title -
journal of animal breeding and genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.689
H-Index - 51
eISSN - 1439-0388
pISSN - 0931-2668
DOI - 10.1046/j.1439-0388.2000.00230.x
Subject(s) - crossbreed , ice calving , lactation , heterosis , zoology , biology , dairy cattle , holstein cattle , agronomy , pregnancy , genetics , hybrid
Summary Lactation traits and reproductive performance of three trials of crossing Holstein cattle (H) and German Friesians (F) raised in a hot climatic were evaluated. The first 90‐day (M90), 305‐day (M305) and total milk yield (TMY), 305‐day milk yield per day of calving interval (MCI1), total milk yield per day of calving interval (MCI2) along with length of lactation period (LP), age at first calving (AC1) and calving interval (CI) were used. For these traits, a genetic model was applied for each trial separately to obtain estimates of individual (G I ) and maternal (G M ) additive effects, individual (H I ) and maternal (H M ) heterosis and individual recombination effect (R I ). Data of 8045 normal lactations from the three trials were analysed. Among the crossbreds obtained in the three trials, cows of 3/4H 1/4F) ranked first in their lactational performance. Estimates of G I and G M were generally large and in favour of H cows (daughters) and dams for most milk‐yield traits, CI and AC1 in the three trials. Estimates of H I in crossbred cows for milk traits, CI and AC1 were mostly negative and reveal that crossing F with H was associated with a reduction in milk‐yield traits, shorter CI and earlier AC1 along with longer LP in the three trials. Estimates of H M for milk yields, LP, AC1 and CI in daughters of crossbred dams were mostly negative. Recombination losses in crossbred cows were negative for milk‐yield traits, AC1 and CI in most cases.