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

Abstract

Validation of economic indexes under a controlled experimental environment, can aid in their acceptance and use as breeding tools to increase herd profitability. The objective of this study was to compare intake, growth and carcass traits in bull and steer progeny of high and low ranking sires, for genetic merit in an economic index. The Beef Carcass Index (BCI; expressed in euro (h) and based on weaning weight, feed intake, carcass weight, carcass conformation and fat scores) was generated by the Irish Cattle Breeding Federation as a tool to compare animals on genetic merit for the expected profitability of their progeny at slaughter. A total of 107 male suckler herd progeny, from 22 late-maturing 'continental' beef sires of high (n 5 11) or low (n 5 11) BCI were compared under either a bull or steer production system, and slaughtered at approximately 16 and 24 months of age, respectively. All progeny were purchased after weaning at approximately 6 to 8 months of age. Dry matter (DM) intake and live-weight gain in steer progeny offered grazed grass or grass silage alone, did not differ between the two genetic groups. Similarly, DM intake and feed efficiency did not differ between genetic groups during an ad libitum concentrate-finishing period on either production system. Carcasses of progeny of high BCI sires were 14 kg heavier ( P , 0.05) than those of low BCI sires. In a series of regression analyses, increasing sire BCI resulted in increases in carcass weight ( P , 0.01) and carcass conformation ( P 5 0.051) scores, and decreases in carcass fat ( P , 0.001) scores, but had no effect on weaning weight or DM intake of the progeny. Each unit increase in sire expected progeny difference led to an increase in progeny weaning weight, DM intake, carcass weight, carcass conformation score and carcass fat score of 1.0 (s.e. 5 0.53) kg, 1.1 (s.e. 5 0.32) kg, 1.3 (s.e. 5 0.31) kg, 0.9 (s.e. 5 0.32; scale 1 to 15) and 1.0 (s.e. 5 0.25; scale 1 to 15), respectively, none of which differed from the theoretical expectation of unity. The expected difference in profitability at slaughter between progeny of the high and low BCI sires was h42, whereas the observed phenotypic profit differential of the progeny was h53 in favour of the high BCI sires. Results from this study indicate that the BCI is a useful tool in the selection of genetically superior sires, and that actual progeny performance under the conditions of this study is within expectations for both bull and steer beef production systems.

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

“…There was no further divergence during the second winter. This pattern of LW change over time is almost identical to that observed by Campion et al (2009a) and similar to that reported by Clarke et al (2009), who studied progeny from Irish beef cows. Unlike previously (Campion et al, 2009a), where breed type by genetic merit interactions for live weights were detected no such interactions were detected in this study, indicating that EPD CWT effects were consistent across the two breed types.…”

“…However, slaughter weight per day of age was significantly greater for H. Campion et al (2009a) also found that slaughter weight per day of age was greater for high EPD CWT animals even though the only significant difference in LW gain was during the first grazing season. Thus, the results of all three studies (Clarke et al, 2009;Campion et al, 2009a and this study) that have evaluated the Irish beef genetic evaluation system agree that genetic merit for growth, as measured by EPD CWT, is more strongly expressed early in life than during finishing.…”

“…To date, the ICBF beef genetic index and its components have not been widely evaluated. Clarke et al (2009) compared progeny from beef cows of high and low Beef Carcass Index (BCI). This is an aggregate index comprising weaning weight, feed intake, carcass weight, carcass conformation class and carcass fat class.…”

Live animal measurements, carcass composition and plasma hormone and metabolite concentrations in male progeny of sires differing in genetic merit for beef production

“…The efficacy of this economic index was first examined under a controlled environment in contrasting production systems, and results showed that the observed differences in profitability of progeny of sires differing in BCI were in good agreement with the expected values (Clarke et al, 2009). Furthermore, for each unit increase in sire EPD for weaning weight, DM intake, carcass weight, carcass conformation score and carcass fat score, progeny performance increased for each of the respective traits by 1.0, 1.1, 1.3 kg, 0.9 (scale 1 to 15) and 1.0 (scale 1 to 15); none of which differed from the theoretical expectation of unity.…”

“…Bulls were individually offered a barley-based concentrate diet ad libitum using Calan-Broadbent gates (American Calan, Northwood, New Hampshire, USA) until slaughter on 26 June 2006 as described by Clarke et al (2009). Steers were offered grass silage ad libitum and a concentrate supplement for most of the winter, and were turned out to pasture on 18 April.…”