Breed comparisons for growth traits adjusted for within-breed genetic trend using expected progeny differences

Abstract

Records (2,910) of birth (BWT), weaning (WW), and yearling weight (YW) of F1 calves produced in a top-cross experiment involving Angus, Hereford, Pooled Hereford, Charolais, Limousin, Simmental, Gelbvieh, Maine-Anjou, Chianina, Tarentaise, Shorthorn, and Salers bulls mated to Hereford and Angus cows and records (4,592) of WW on three-breed-cross calves out of 986 F1 females of the same breed crosses were used in this study. The purposes were to estimate how much of the EPD of the sires was realized in crossbred calves and to estimate sire breed effects for the traits adjusted for genetic trend and sire sampling. Published EPD for BWT, WW, YW, net maternal ability (MLK), and maternal WW (MAT) were used. Average regressions (kilograms/kilogram +/- SE) of BWT, WW, and YW of F1 calves on EPD of the sire were 1.04 +/- .10, .88 +/- .11, and 1.40 +/- .11, respectively. The regressions (b, kilograms/kilogram) were similar to the expected values of 1.0 except for YW. For WW of three-way-cross calves on MLK EPD of the maternal grandsire, b was 1.02 +/- .11, which was not different from the expected value of 1.0. Estimated sire-breed means were adjusted to a 1982 genetic base by adding b times the difference of the 1982-breed-mean EPD and mean EPD of sires used in the study. Three different adjustments were compared using the b pooled across breeds, a separate b for each breed, and the expected b of 1.0. In general, the adjustments tended to regress breed of sire means toward the average of all breeds, particularly for BWT and WW of F1 calves, and for WW of three-breed crosses. The effect of type of adjustment varied among breeds, but in most cases small differences resulted from using average or expected b. For WW, the range for net maternal effects among breeds was larger than that for direct breed effects.

Intake, growth and carcass traits in male progeny of sires differing in genetic merit for beef production

“…However, the regression coefficients of weaning weight on sire EPD for weaning weight were significantly lower (0.66) than expected, which those authors suggested may have been due to a genotype by environment interaction between seedstock and commercial herds (Williams et al, 2004). A similar observation was recorded by Nú ñ ez- Dominguez et al (1993) with lower than expected responses to sire genetic merit for weaning weight in F 1 crossbred progeny. However, there is a deficit of information published pertaining to economically weighted genetic selection indices, particularly on an across-breed basis.…”

“…5 0.53) per kg increase in sire EPD WWT . Similarly, Barkhouse et al (1998) and Nú ñ ez- Dominguez et al (1993) observed an increase in weaning weight of 0.98 kg and 0.88 kg, respectively, per kg increase in sire EPD WWT . Williams et al (2004) reported an observed weaning weight of 0.66 (s.e.…”

“…Although the animals used in this study were included as progeny in the genetic evaluation of the sires for weaning weight and carcass traits, since it was not possible to request a separate genetic evaluation, the effect on the results is expected to be minimal because all sires were of high reliability. Although earlier studies have investigated the association between sire EPD and subsequent progeny performance (Nú ñ ez- Dominguez et al, 1993;Crews, 2002;Williams et al, 2004), the authors are unaware of any other study that has evaluated the effect of the economic index of a sire on the performance of his progeny. The performance of the animals in the present study was similar to the findings of Drennan et al (1994) and Drennan et al (2005a) for similar bull and steer production systems, respectively, using the suckled progeny of beef cows.…”

“…Another reason for the differences between studies may be due to the statistical model used for the regression analysis. For example, Williams et al (2004) undertook the regression analysis using a mixed model with sire EPD treated as a random effect, whereas both Barkhouse et al (1998) and Nú ñ ez- Dominguez et al (1993) treated sire EPD as a fixed effect, although the latter study used a mixed model with year of birth as a random effect. Numerous studies have shown that the main determinant of pre-weaning live-weight gain and consequently weaning weight in suckled calves is milk yield of the dam (Drennan and Bath, 1976;Gregory et al, 1992;McGee et al, 2005a).…”

Effects of genetic merit for carcass weight, breed type and slaughter weight on performance and carcass traits of beef × dairy steers

“…Basarab et al (1994) found that in straight-bred Herefords a 1 kg change in birth weight EPD corresponded to a 1.06 kg change in actual birth weight, while a 1 kg change in weaning or yearling weight EPD corresponded to 0.45 and 0.78 kg changes in 200-day and 365-day live weights, respectively. Similarly, Nunez-Dominguez et al (1993) reported EPD regressions (kg/kg) on birth, weaning and yearling weights of 1.04, 0.88 and 1.40, respectively. In Ireland, Keane and Diskin (2007), using an earlier within-breed genetic evaluation system, found that a change in EPD for carcass weight matched the observed change in carcass weight.…”