Summary
Analyses were conducted to estimate the influence of environmental effects, the genetic determination of retained placenta and its genetic and phenotypic relationships to some production and reproduction traits. Data were recorded in an experimental Simmental herd in Lower Austria. After applying restrictions, 2895 records of first and 2082 of second calving remained. For estimation of variance–covariance components a REML procedure based on an animal model was used. All estimates for heritabilities and phenotypic correlations of threshold traits were transformed to a hypothetical underlying normal distribution.
The estimated heritabilities of retained placenta at first and second calving were 0.14 and 0.07 with a genetic correlation of 0.79. For twinning rate the corresponding figures were 0.19, 0.02 and 1.00, respectively. High genetic correlations were estimated for retained placenta and birth weight of calf at first parity (0.49) as well as between retained placenta and twinning rate at second calving (0.99). The estimated genetic correlations between retained placenta at first and second calving and first lactation milk yield were 0.14 and 0.56 and between retained placenta at first calving and subsequent days open 0.54. Phenotypic correlations were mostly equal in sign but substantially smaller than the corresponding genetic correlations. No significant genetic cytoplasmic effects could be found for retained placenta.
There was strong evidence (p < 0.001) that twin‐births, calving difficulties (dystocia) and relatively short and long gestation periods substantially affected the incidence of retained placenta. Partial and complete retention of the placenta at first calving led to an increase of 34 and 4 days open (p < 0.001), respectively. The estimated decrease of first lactation milk yield (250 days) was 67 and 128 kg due to partial and complete retention of the placenta (p = 0.154).
The results obtained suggest that the genetic determination of placental retention is strong enough to be considered in breeding strategies even if its heritability should be somewhat lower under field conditions than in the analysed experimental herd.
Zusammenfassung
Nachgeburtsverhaltung: Nicht‐genetische Effekte, genetische Determinierung und Korrelationen zu relevanten Leistungsmerkmalen beim Rind
Ziel der vorliegenden Untersuchung war die Schätzung der genetischen Determinierung und des Einflusses nicht‐genetischer Effekte auf zeitliche Unterschiede im Abgang der Nachgeburt beim Rind, sowie deren genetische und phänotypische Korrelation zu relevanten Milchleistungs‐ und Reproduktionsmerkmalen. Für die Untersuchung standen die Milchleistungsprüfergebnisse der Jahre 1972 bis 1995 von Tieren der Fleckvieh‐Versuchsherde der niederösterreichischen Bundesversuchswirtschaft Wieselburg zur Verfügung, bei denen das Merkmal ‘Nachgeburtsverhaltung’ erhoben worden war (2895 bzw. 2082 Erhebungen für 1. bzw. 2. Abkalbung).
Die geschätzte Heritabilität für das Merkmal Nachgeburtsverhaltung betrug für die 1. und 2. Abkalbung 0.14...