Multiple trait selection for maternal productivity in beef cattle

Abstract

Summary The aim of this study was to develop a multiple trait genetic evaluation and selection tool for maternal productivity in beef cattle, particularly in the Hereford breed. Component traits of the maternal productivity index (MPI) were chosen on the basis of their potential to contribute to consistently weaning heavy calves over a sustained herd life, while controlling cow maintenance costs. (Co)variance components were estimated with a multiple trait model including direct and maternal birth weight, direct and maternal weaning weight, weight of the cow at the time her calf is weaned and survival, defined as the ability of a female to produce at least three calves given she became a dam. Although direct and maternal birth weight were included in the (co)variance parameters model, these traits were not included in the index. Estimates of heritability were 0.19, 0.18, 0.50 and 0.07 for direct and maternal weaning weight, cow weight, and survival, respectively. The correlation between direct and maternal components of weaning weight was −0.42. The genetic correlation estimated between direct weaning weight and cow weight was 0.85, while a low genetic correlation of −0.17 was estimated between maternal weaning weight and cow weight. Survival had a near zero (−0.01) genetic correlation with maternal weaning weight, but negative genetic correlations with direct weaning weight (−0.52) and cow weight (−0.48). The MPI was constructed as a linear function of derived economic weights multiplied by estimated breeding values for the four component traits from the model. Estimated economic values were $3.00, $2.70, $−0.49 and $2.39 for direct and maternal weaning weight, cow weight, and survival (expressed as a percentage), respectively. Relative economic weights were 0.30, 0.26, 0.17 and 0.27 for direct and maternal weaning weight, cow weight, and survival, respectively. A simulation study indicated that positive genetic trend would be expected in all component traits although increases in cow weight would be moderate.

Der Einfluss des Kuhgewichts auf die Betriebsrentabilität und auf die ökonomischen Gewichte der Fleischrindmerkmale

“…Tabelle 2 Untersuchte Merkmale und ihre genetische Standardabweichungen (nach BÖBNER 1994, MIESENBERGER 1997, PŘIBYL et al 2003 Investigated genetic characteristics and their standard deviations (after BÖBNER 1994, MIESENBERGER 1997, PŘIBYL et al 2003 (MWANSA et al 2002, FERNÁNDEZ-PEREA und JIMÉNEZ 2004.…”

Characterization of the variable cow's age at last calving as a measurement of longevity by using the Kaplan–Meier estimator and the Cox model

“…For beef cattle enterprises to be profitable, cows need to remain in production until their rearing and maintenance costs have been paid (Formigoni et al, 2002;Mwansa et al, 2002). Cows' longevity, expressed as their continuing presence in the herd, is an economically important trait that is directly related to the yield of the meat production system through its relationship with production efficiency (Van Melis et al, 2007).…”

Genetic parameters for cow weight at calving and at calf weaning in South African Simmental cattle (Short communication)

“…It is also similar to the results obtained by Urioste et al (1998) in pasture-fed Uruguayan beef cattle as well as those of Nephawe (2004) in Bonsmara cattle using random regression models. The estimates are, however, lower than those Mwansa et al (2002) in Hereford cows and Nephawe et al (2004) in Hereford Angus cows. It is also lower than the average of the estimates listed by Koots et al (1994) in a review article.…”