Estimation of individual cross‐breeding effects on milk‐production traits of the German Black Pied dairy cattle using different genetic models*

Abstract

Milk performance data of cross-breds in the synthetic breed German Black Pied Dairy Cattle (SMR), that had calved for the first time between 1970 and 1984, were used to estimate individual cross-breeding effects on milk production traits. Three million pure-bred and cross-bred cows that were in their first lactation and had originated from conventional housing systems were involved. For 1111331 cows genetic groups according to their respective ancestry could be formed. The additive breed differences and heterosis effects estimated by the Dickerson model correspond to those effects determined by the majority of other authors. For milk yield, highly significant negative effects were obtained for the Holstein-Friesian × Black Pied Cattle and Jersey, respectively. The estimates ranged between 4.8 % and 5.0 % of the mean of all cross-breeding groups. In cross-breds with Jersey the recombination loss for fat percentage was between 5.3 % and 6.0 %. These results support the theory that recombination loss occurs predominantly when breeds, which have been selected for a long period for certain traits, are crossed. The recombination loss for fat yield attains values between 1.9 % and 6.8 %. Different genetic models for the estimation of cross-breeding effects were compared. In contrast to the Dickerson model, the modified genetic models of Jakubec et al. (1991) and Mather and Jinks (1971) (models A, B, C and D) and those of Kinghorn (1980, 1982, 1987) enabled estimation of the genetic components underlying heterosis. Model A accounts for additive, dominant and additive × additive effects and this model can be transformed by linear functions into the Dickerson model. As model A shows an exact separation of the heterosis and epistatic effects, this model is preferred to that of Dickerson (1969, 1973). The estimated additive × dominance effects, obtained using model B, are significant and half as large as the additive × additive effects. The extent of dominance × dominance effects (models C and D) could not be determined with the restrictions used. If these epistatic interactions are taken into consideration, the standard errors of the estimates increase and the accuracy of the estimates decreases. ZUSAMMENFASSUNG: Schätzung individueller Kreuzungseffekte für Milchleistungsmerkmale beim Schwarzbunten Milchrind unter Verwendung verschiedener genetischer Modelle Die Untersuchung individueller Kreuzungseffekte für Milchleistungsmerkmale basiert auf den Milch-leistungsdaten von Rein- und Kreuzungszuchttieren der synthetischen Rasse Schwarzbuntes Milchrind (SMR), die zwischen den Jahren 1970 und 1984 zum ersten Mal abgekalbt haben. Insgesamt standen 3 Millionen Erstlaktierende aus herkömmlichen Haltungssystemen zur Verfügung. 1 111 311 Kühe konnten entsprechend ihrer Abstammung eindeutig definierten Kreuzungsgruppen zugeordnet werden. Die Schätzwerte für die additiven Rassenunterschiede und Heterosis im Dickerson-Modell (1969) korrespondieren weitgehend mit den von anderen Autoren publizierten Ergebnissen. Hoch signifikante, negat...

Fit of Wood's function to daily milk records and estimation of environmental and additive and non-additive genetic effects on lactation curve and lactation parameters of crossbred dual purpose cattle

“…The estimate of recombination effects for TM for the H × BS cross was positive. This is consistent with several studies in the temperate (Grosshans et al, 1994;Wolf et al, 1995) and tropical regions (Khalil et al, 2000;Demeke et al, 2003) for B. taurus ×B. taurus crosses.…”

“…In both models, the H contributed more to TM than the BS (433.76 ± 185.9 vs. 376.30 ± 234.6 and 450.25 ± 188.7 vs. 188.15 ± 227.4 for Dickerson and Kinghorn models,respectively). This was expected because of the biological and production differences between the H and BS which has been confirmed in several crossbreeding experiments and populations (Thorpe et al, 1993;Grosshans et al, 1994;Wolf et al, 2005).…”

“…However, with this model it is impossible to distinguish between different breed combinations when three and more breeds are considered. This is because the epistatic effects are described by only one parameter (e x ) (Grosshans et al, 1994). The epistasis effects were significant for b and c and the absolute value of e x was larger than the value estimated for dominance effects between different crosses with respect to dominance effect were noted.…”

“…This hypothesis is generally adopted to estimate crossbreeding parameters (Koch et al, 1985;Hirooka et al, 1998;Kahi et al, 2000a). The difference of coefficients between the Dickerson and Kinghorn models was given by Koch et al (1985) and Grosshans et al (1994). In both models, PROC GLM of SAS (1999) was used for analysis of environment and genetic effects on milk yield parameters.…”

“…Of the epistasis effects, the additive × additive interactions are the most important. Therefore, the most important effects would be captured by a model with additive population differences together with heterosis effects caused by dominance gene effects and additive × additive interactions (Grosshans et al, 1994).…”