Estimates of crossbreeding parameters in a multibreed beef cattle crossbreeding project

Abstract

Data from purebred and crossbred cattle, consisting of the Afrikaner (A), Simmentaler (S) and Hereford (H) breeds managed in a relatively intensive but high stocking rate environment, were analysed to estimate breed direct effects, individual heterotic effects, breed maternal and maternal heterotic effects for birth weight (BW) and weaning weight (WW). Simmentaler breed direct effects, expressed as deviation from the general mean, were positive (P ≤ 0.01) for both traits. Hereford and Afrikaner breed direct effects were negative (P ≤ 0.01) for both traits while the Afrikaner breed direct effects exceeded those of the Hereford. Afrikaner direct maternal effects were positive (P ≤ 0.01) for both traits. The Hereford direct maternal effect was negative (P ≤ 0.05) (-2.9%) for WW. Simmentaler maternal effect was negative (P ≤ 0.01 ) for BW but non-significant (P ≥ 0.05) for WW. Individual heterotic effects for BW were significant (P ≤ 0.01) in H x S (3.5%) and S x A (11.0%) only. Individual heterotic effects were positive (P ≤ 0.01) for WW, with that of the H x A (9.8%) and S x A (6.7%) crosses exceeding the S x H (3.1%) cross. Maternal heterotic effects were non-significant (P ≥ 0.05) for both BW and WW .

The effect of Charolais and Hereford sires and straightbred and crossbred dams on pre-weaning growth of calves

“…Large positive direct effects compared to small positive or even negative maternal effects which were also reported elsewhere, supported this view (Newman et al, 1993;Franke et al, 2001). For Hereford, the direct additive effect for BW was positive in some reports (Gregory et al, 1978;Schoeman et al, 1993), but negative in other crossbreeding studies (Alenda et al, 1980;Skrypzeck et al, 2000a). Skrypzeck et al (2000b) assessed the contribution of the Hereford breed in the same multibreed beef cattle herd and suggested higher levels of Hereford contributions in crossbreeding for the prevention of dystocia.…”

“…The cattle were located at the two farms of the Johannesburg Metropolitan Council. Breeding systems, herd management, recording and selection procedures were described by Paterson et al (1980), Schoeman & Jordaan (1999) and Skrypzeck et al (2000a;b).…”

The influence of outliers on a model for the estimation of crossbreeding parameters for weaning weight in a beef cattle herd

“…In these studies, as well as others (Dillard et al, 1980;Alenda & Martin, 1981;Schoeman et al, 1993;Skrypzeck, et al, 2000) appreciably lower standard errors for these estimates were obtained. This together with the change in the b i estimates, could be caused by extreme multi-collinearity amongst the independent (assumed) variables.…”

“…More details regarding feeding and management regimes and replacement and selection procedures are found in Paterson (1978;1981), Paterson et al (1980), MacGregor (1997 and Skrypzeck et al (2000).…”

“…These techniques were based mainly on linear functions of the various cross means or multiple regression procedures (Alenda et al, 1980;Dillard et al, 1980;Robison et al, 1981;Cunningham & Magee, 1988;Schoeman et al, 1993;Skrypzeck et al, 2000). Generally, the importance of additive, maternal and non-additive genetic effects was determined and used for prediction of the performance of crosses that have not actually been tested.…”