Estimation of genetic parameters for mature weight in Angus cattle1

Abstract

The aim of this study was to estimate genetic parameters for BW of Angus cattle up to 5 yr of age and to discuss options for including mature weight (MW) in their genetic evaluation. Data were obtained from the American Angus Association. Only records from herds with at least 500 animals and with >10% of animals with BW at ≥ 2 yr of age were considered. Traits were weaning weight (WW, n = 81,525), yearling weight (YW, n = 62,721), and BW measured from 2 to 5 yr of age (MW2, n = 15,927; MW3, n = 12,404; MW4, n = 9,805; MW5, n = 7,546). Genetic parameters were estimated using an AIREML algorithm with a multiple-trait animal model. Fixed effects were contemporary group and departure of the actual age from standard age (205, 365, 730, 1,095, 1,460, and 1,825 d of age for WW, YW, MW2, MW3, MW4, and MW5, respectively). Random effects were animal direct additive genetic, maternal additive genetic, maternal permanent environment, and residual. Estimates of direct genetic variances (kg(2)) were 298 ± 71.8, 563 ± 15.1, 925 ± 52.1, 1,221 ± 65.8, 1,406 ± 80.4, and 1,402 ± 66.9; maternal genetic variances were 167 ± 4.8, 153 ± 6.1, 123 ± 9.1, 136 ± 12.25, 167 ± 18.0, and 110 ± 14.0; maternal permanent environment variances were 124 ± 2.9, 120 ± 4.3, 61 ± 7.5, 69 ± 11.9, 103 ± 15.9, and 134 ± 35.2; and residual variances were 258 ± 3.8, 608 ± 8.6, 829 ± 34.2, 1,016 ± 38.8, 1,017 ± 52.1, and 1,202 ± 63.22 for WW, YW, MW2, MW3, MW4, and MW5, respectively. The direct genetic correlation between WW and YW was 0.84 ± 0.14 and between WW and MW ranged from 0.66 ± 0.06 (WW and MW4) to 0.72 ± 0.11 (WW and MW2). Direct genetic correlations ranged from 0.77 ± 0.08 (YW and MW5) to 0.85 ± 0.07 (YW and MW2) between YW and MW, and they were ≥ 0.95 among MW2, MW3, MW4, and MW5. Maternal genetic correlations between WW and YW and MW ranged from 0.52 ± 0.05 (WW and MW4) to 0.95 ± 0.07 (WW and YW), and among MW they ranged from 0.54 ± 0.14 (MW4 and MW5) to 0.94 ± 0.07 (MW2 and MW3). Genetic correlations suggest that a genetic evaluation for MW may be MW2-based and that including BW from older ages could be accomplished by adjusting records to the scale of MW2.

Estimation of genetic parameters for growth traits in Tabapuã cattle using a multi-trait model

“…In the animal breeding context, this means that selection on any of the evaluated traits will significantly impact the others and reinforces how important it is to apply a multivariate approach when working with growth traits. These results agree with those reported by Boligon (2008), Baldi Rey (2008) and Costa et al (2011). Additionally, these authors reported significantly higher direct additive genetic correlations between weaning weight and/or yearling weight and mature weights, implying that selection for weight at younger ages will lead to an increase in mature weight (Baldi Rey, 2008).…”

“…Direct heritability estimates (h 2 ) were higher than those reported by Ferraz Filho et al (2002) and lower than those reported by Campêlo et al (2004) (Table 3). Boligon (2008), Baldi Rey (2008) and Costa et al (2011), who worked, respectively, with Nellore, Canchim and Angus breeds, reported, using a multi-trait model, higher h 2 than this study (>0.25) for weaning and yearling weights. Moderate and similar responses to selection are expected when selecting for weights at the four evaluated ages, since h 2 were similar and of average magnitude.…”

“…Baldi Rey (2008) reported lower h 2 m than those found in this study, 0.03 and 0.02 for weaning and yearling weights, respectively. Yet Costa et al (2011) reported h 2 m close to 0.25 and 0.13 for weaning and yearling weight, respectively. A decrease in h 2 m for weights at advanced ages was found, agreeing with Ferraz Filho et al (2002), Campêlo et al (2004), Baldi Rey (2008) and Costa et al (2011).…”

“…Yet Costa et al (2011) reported h 2 m close to 0.25 and 0.13 for weaning and yearling weight, respectively. A decrease in h 2 m for weights at advanced ages was found, agreeing with Ferraz Filho et al (2002), Campêlo et al (2004), Baldi Rey (2008) and Costa et al (2011). Although of low magnitude, greater selection response for maternal ability in Tabapuã herds can be achieved by selecting on weights near the weaning period (240 days).…”

“…Among the models that can be used for the estimation of (co)variance components and genetic parameters for growth traits, the multi-trait model is an interesting alternative that has been applied in beef cattle studies, e.g., Boligon (2008), Baldi Rey (2008) and Costa et al (2011). The choice of multi-trait models aims at achieving greater selection response by more efficiently using the available information, considering the existence of missing values caused by sequential selection and exploiting the correlations between the traits (Marques et al, 2001).…”