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Relationships Between Charolais Sire Expected Progeny Differences and Progeny Performance in Commercial Beef Herds1
The Professional Animal Scientist 20 (2004):503–505
Relationships Between Charolais Sire Expected Progeny Differences and Progeny Performance in 1 Commercial Beef Herds S. C. CLARK, D. W. MOSER2, and R. E. WILLIAMS3 Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-0201
Abstract Data on Charolais-sired calves in 31 commercial herds were analyzed to evaluate progeny performance relative to sire expected progeny differences (EPD). The traits analyzed were BW at birth (BBW; n = 3554) and at weaning (WBW; n = 3604) of crossbred progeny from nationally evaluated sires. Sire BBW EPD and WBW EPD were evaluated as predictors of performance in these commercial herds. Published sire BBW EPD and WBW EPD were averaged and weighted on the numeric accuracy published for each EPD. The average weighted sire BBW EPD was 0.4 kg, and the WBW EPD was 7.0 kg with an average accuracy of 0.79 and 0.75, respectively. Random regression coefficients were estimated for progeny BBW on sire EPD of 1.03 ± 0.09 kg/kg of BBW EPD, and for progeny WBW, 0.66 ± 0.11 kg/kg of WBW EPD. Correlations for sire effect solutions in commercial herds with published sire BBW and WBW EPD were 0.59 and 0.39, respectively. Sire BBW
1
Contribution no. 04-407-J from the Kansas Agricultural Experiment Station. 2 To whom correspondence should be addressed: [email protected] 3 American-International Charolais Association, Kansas City, MO.
EPD and WBW EPD were favorably related to actual progeny performance. Therefore, selection based on sire EPD should result in change of crossbred progeny performance. This further validates use of EPD as a selection tool for BBW and WBW in commercial herds. However, WBW response was less than expected, possibly a result of management practices in commercial herds compared with seedstock herds. (Key Words: Beef Cattle, Birth Weight, Expected Progeny Difference, Progeny Performance, Weaning Weight.)
Introduction Commercial beef cattle producers rely on expected progeny differences (EPD) for sire selection. These values enhance the accuracy of selection decisions by establishing the relative genetic value of a sire within a breed (Long and Marshall, 1994). Today, EPD are widely used and successively implemented into commercial beef cattle enterprises. Sire evaluations currently published by beef breed associations are based on progeny performance data collected in seedstock herds. However, the nutritional and health management of seedstock herds may be more favorable than
that of commercial herds. Therefore, it is worthwhile to evaluate sire EPD in a commercial setting, to determine whether response to selection in commercial herds is similar to expected values based on seedstock data. In previous studies, positive relationships between sire EPD and crossbred progeny performance in experimental and field trials have been reported (Nunez-Dominguez et al., 1993; Basarab et al., 1994; Long and Marshall, 1994; Kemp and Sullivan, 1995). However, large amounts of data under true commercial production conditions in the U.S. have not been examined. The purpose of this study was to evaluate progeny performance relative to sire EPD in a large data set of commercial crossbred calves in many herds across the U.S.
Materials and Methods The structured sire evaluation database of the American-International Charolais Association (AICA, Kansas City, MO) was obtained for analysis to provide information on progeny sires, herds, birth BW (BBW), and weaning BW (WBW) records that were collected from 1988 to 2001. The sires used in the study were randomly mated to crossbred commercial cows in 31 cooperator herds.
504
Dams were of all ages, but age of dam was not recorded in the data. Generally, breed combination of dam was relatively consistent within contemporary group, but breed composition of dams was not recorded. Male calves were castrated either at birth, at time of initial vaccination (1 to 3 mo of age), or at weaning. Although age at castration varied in the study, it was uniform within contemporary group. Carcass data from these calves were used to calculate Charolais carcass EPD, but the BBW and WBW data used in this analysis were independent of those used in the AICA national cattle evaluation. The final data set consisted of BBW records on 3554 animals and WBW on 3604 animals, which were progeny of 224 sires. A contemporary group for the progeny measurements was defined as animals born and raised in the same herd and management group in the same year. Age at weaning was between 140 and 270 d, consistent with AICA performance programs for seedstock herds. There were 56 contemporary groups in the data set. The commercial database was merged to the sire EPD database to provide sire BBW EPD and WBW EPD records that were collected on Charolais sires enrolled in the AICA national cattle evaluation program by AICA members (AICA, 2002). The sires used in the commercial data set had an average sire BBW EPD of 0.4 kg and WBW EPD of 7.0 kg with an average accuracy of 0.79 and 0.75, respectively, weighted by the number of progeny in the commercial data set. Accuracy values were calculated in accordance with Beef Improvement Federation Guidelines (BIF, 1996). Initially, the progeny BBW and WBW were analyzed using the MIXED procedure in SAS威 (SAS Institute, Cary, NC). The statistical linear model used for BBW included a categorical fixed effect of contemporary group and a continuous random effect of sire BBW EPD. The same model was used for WBW, substituting WBW EPD for BBW EPD. This
Clark et al.
model calculated a random regression coefficient for BBW and WBW on sire EPD. In both models, sire EPD was considered a random effect because inferences were to be made about EPD of all Charolais sires, not just the sires in this study and because sires transmit a randomly determined onehalf of their chromosomes to each progeny (Searle, 1971). A second analysis was performed to estimate individual sire effects in the commercial data, similar to an EPD. The statistical model used for BBW and WBW included a fixed effect of contemporary group and a random sire effect. This model did not account for any genetic relationships among project sires, and few dams contributed more than one offspring and had unknown pedigree, so dam effects were not included in the model. Correlations were obtained between sire effects in commercial herds and published sire EPD for both BBW and WBW. Because sire effects should be more strongly correlated with EPD as more progeny of each sire are measured, the model weighted sire effects on number of progeny and weighted EPD on accuracy.
Results and Discussion The means and standard deviations of the progeny performance and sire EPD are summarized in Table 1. BBW. The random regression coefficient for progeny BBW on sire EPD was 1.03 ± 0.09 kg/kg of BBW EPD, very similar to its expected value of 1.0 kg/kg. This expectation is the
same whether sire EPD is modeled as a random effect, as in this study, or as a fixed effect, as in previous studies. These results are similar to the pooled values reported by Long and Marshall (1994), who estimated regression coefficient of 1.17 ± 0.31 kg/kg for BBW. Nunez-Dominguez et al. (1993) estimated pooled regression coefficients for BBW of 1.04 ± 0.10 kg/ kg of EPD. Notter and Cundiff (1991) also gave similar pooled results of 1.09 ± 0.12 kg/kg of BBW EPD. Basarab et al. (1994) reported a regression coefficient for BBW of 1.06 ± 0.14. The results suggest that the random regression coefficient of BBW based on published Charolais sire EPD agrees closely with the expected value of 1.0 kg/kg of EPD. Thus, the impact of environmental and managerial differences is minimal during this point between seedstock and commercial herds. Therefore, selection based on BBW EPD should be effective and consistent with theoretical expectation. Commercial producers should expect, on average, the same response in BBW suggested by sire EPD. WBW. The regression of progeny WBW on sire EPD was 0.66 ± 0.11 kg/kg of WBW EPD. This value is considerably different from the theoretical expected value of 1.0 kg/kg. These results are similar to the pooled values reported by Long and Marshall (1994), who estimated a regression coefficient of 0.75 ± 0.28 kg/kg for WBW. Nunez-Dominguez et al. (1993) obtained a pooled regression coefficient for WBW of 0.88 ± 0.11 kg/kg of EPD. Notter and Cundiff (1991) also gave similar pooled results
TABLE 1. Descriptive statistics of sires and progeny. Item Progeny Birth BW, kg Weaning BW, kg Sire Birth BW EPD, kg Weaning WW EPD, kg
Number
Mean
SD
3554 3604
40.0 226.6
5.7 49.9
224 224
0.4 7.0
1.1 5.6
Response to Expected Progeny Differences Selection in Commercial Beef Herds
of 0.79 ± 0.14 kg/kg for WBW EPD. Basarab et al. (1994) reported an even lesser regression coefficient for WBW of 0.45 ± 0.001 kg/kg. In this study, sire EPD differences for WBW were not completely expressed in commercial conditions. This may be a result of environmental differences, such as nutritional and health management among commercial and seedstock herds. Thus, commercial producers may not observe as dramatic a response as expected when selecting for increased growth using WBW EPD. Notter and Cundiff (1991) suggested that WBW EPD differences among sires might not be fully expressed unless the nutritional environment approaches that of the seedstock herds in which sire EPD were derived. Kemp and Sullivan (1995) also reported a WBW regression less than expected and attributed the difference to the various types of environments in which the crossbred progeny are raised, and the seedstock herds in which progeny contributing data to a sire’s EPD are raised. Therefore, the genetic potential might not have been fully expressed in the crossbred progeny because of differences in nutrition and management when compared with seedstock herd environments. Castration of male calves prior to weaning in some herds might have also limited response to selection on WBW EPD. Correlations Between Sire Effects and EPD. Positive correlations were obtained for sire effect in commercial
herds with published sire BBW and WBW EPD. Weighted correlations for sire effect solution with sire BBW and WBW EPD were 0.59 and 0.39, respectfully. Sire effect is favorably correlated with BBW EPD and WBW EPD; thus, EPD calculated from seedstock data do a reasonable job of describing genetic effects in commercial herds. Although sires were mated randomly within the commercial herds, the moderate correlations could be a result of ignoring both direct genetic and maternal dam effects. Dams might have contributed different genetics to their progeny, and their ability to produce milk could have varied. This could cause a difference among progeny performance and decrease the relationship of sire effect in commercial herds with sire BBW EPD or WBW EPD.
Implications Sire EPD for BBW and WBW were positively related to actual progeny performance, although response to selection was less than expected for WBW. The use of BBW EPD as a selection tool in commercial herds should be effective and response should be consistent with expectations. The less-than-expected response to selection on WBW EPD was likely a result of management practices in commercial herds compared with seedstock herds. Thus, commercial producers should expect slightly less response than suggested by sire WBW EPD, especially when nutrition and health
505
management are less than optimum. Calculation of selection indices for profitability may need to account for this reduced response.
Literature Cited AICA. 2002. Fall 2002 Sire Summary. American-International Charolais Association, Kansas City, MO. Basarab, J. A., D. Milligan, and J. Stitt. 1994. Relationship between expected progeny differences of Canadian Hereford sires and performance of their progeny in commercial herds. Can. J. Anim. Sci. 74:555. BIF. 1996. Guidelines for Uniform Beef Improvement Programs. (7th Ed.). Beef Improvement Federation, Kansas State Univ., Colby. Kemp, R. A., and P. G. Sullivan. 1995. The relationship between progeny performance and sire expected progeny differences for central test postweaning gain. Can. J. Anim. Sci. 75:169. Long, M. B., and D. M. Marshall. 1994. Relationship of beef sire birth weight and expected progeny differences to actual performance of crossbred offspring. South Dakota Beef Report. p 31. South Dakota State University, Brookings. Notter, D. R., and L. V. Cundiff. 1991. Acrossbreed expected progeny differences: Use of within-in breed expected progeny differences to adjust breed evaluations for sire sampling and genetic trend. J. Anim. Sci. 69:4763. Nunez-Dominguez, R., L. D. Van Vleck, and L. V. Cundiff. 1993. Breed comparisons for growth traits adjusted for within-breed genetic trend using expected progeny differences. J. Anim. Sci. 71:1419. Searle, S. R. 1971. Linear Models. John Wiley and Sons, New York, NY.
Relationships Between Charolais Sire Expected Progeny Differences and Progeny Performance in 1 Commercial Beef Herds S. C. CLARK, D. W. MOSER2, and R. E. WILLIAMS3 Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-0201
Abstract Data on Charolais-sired calves in 31 commercial herds were analyzed to evaluate progeny performance relative to sire expected progeny differences (EPD). The traits analyzed were BW at birth (BBW; n = 3554) and at weaning (WBW; n = 3604) of crossbred progeny from nationally evaluated sires. Sire BBW EPD and WBW EPD were evaluated as predictors of performance in these commercial herds. Published sire BBW EPD and WBW EPD were averaged and weighted on the numeric accuracy published for each EPD. The average weighted sire BBW EPD was 0.4 kg, and the WBW EPD was 7.0 kg with an average accuracy of 0.79 and 0.75, respectively. Random regression coefficients were estimated for progeny BBW on sire EPD of 1.03 ± 0.09 kg/kg of BBW EPD, and for progeny WBW, 0.66 ± 0.11 kg/kg of WBW EPD. Correlations for sire effect solutions in commercial herds with published sire BBW and WBW EPD were 0.59 and 0.39, respectively. Sire BBW
1
Contribution no. 04-407-J from the Kansas Agricultural Experiment Station. 2 To whom correspondence should be addressed: [email protected] 3 American-International Charolais Association, Kansas City, MO.
EPD and WBW EPD were favorably related to actual progeny performance. Therefore, selection based on sire EPD should result in change of crossbred progeny performance. This further validates use of EPD as a selection tool for BBW and WBW in commercial herds. However, WBW response was less than expected, possibly a result of management practices in commercial herds compared with seedstock herds. (Key Words: Beef Cattle, Birth Weight, Expected Progeny Difference, Progeny Performance, Weaning Weight.)
Introduction Commercial beef cattle producers rely on expected progeny differences (EPD) for sire selection. These values enhance the accuracy of selection decisions by establishing the relative genetic value of a sire within a breed (Long and Marshall, 1994). Today, EPD are widely used and successively implemented into commercial beef cattle enterprises. Sire evaluations currently published by beef breed associations are based on progeny performance data collected in seedstock herds. However, the nutritional and health management of seedstock herds may be more favorable than
that of commercial herds. Therefore, it is worthwhile to evaluate sire EPD in a commercial setting, to determine whether response to selection in commercial herds is similar to expected values based on seedstock data. In previous studies, positive relationships between sire EPD and crossbred progeny performance in experimental and field trials have been reported (Nunez-Dominguez et al., 1993; Basarab et al., 1994; Long and Marshall, 1994; Kemp and Sullivan, 1995). However, large amounts of data under true commercial production conditions in the U.S. have not been examined. The purpose of this study was to evaluate progeny performance relative to sire EPD in a large data set of commercial crossbred calves in many herds across the U.S.
Materials and Methods The structured sire evaluation database of the American-International Charolais Association (AICA, Kansas City, MO) was obtained for analysis to provide information on progeny sires, herds, birth BW (BBW), and weaning BW (WBW) records that were collected from 1988 to 2001. The sires used in the study were randomly mated to crossbred commercial cows in 31 cooperator herds.
504
Dams were of all ages, but age of dam was not recorded in the data. Generally, breed combination of dam was relatively consistent within contemporary group, but breed composition of dams was not recorded. Male calves were castrated either at birth, at time of initial vaccination (1 to 3 mo of age), or at weaning. Although age at castration varied in the study, it was uniform within contemporary group. Carcass data from these calves were used to calculate Charolais carcass EPD, but the BBW and WBW data used in this analysis were independent of those used in the AICA national cattle evaluation. The final data set consisted of BBW records on 3554 animals and WBW on 3604 animals, which were progeny of 224 sires. A contemporary group for the progeny measurements was defined as animals born and raised in the same herd and management group in the same year. Age at weaning was between 140 and 270 d, consistent with AICA performance programs for seedstock herds. There were 56 contemporary groups in the data set. The commercial database was merged to the sire EPD database to provide sire BBW EPD and WBW EPD records that were collected on Charolais sires enrolled in the AICA national cattle evaluation program by AICA members (AICA, 2002). The sires used in the commercial data set had an average sire BBW EPD of 0.4 kg and WBW EPD of 7.0 kg with an average accuracy of 0.79 and 0.75, respectively, weighted by the number of progeny in the commercial data set. Accuracy values were calculated in accordance with Beef Improvement Federation Guidelines (BIF, 1996). Initially, the progeny BBW and WBW were analyzed using the MIXED procedure in SAS威 (SAS Institute, Cary, NC). The statistical linear model used for BBW included a categorical fixed effect of contemporary group and a continuous random effect of sire BBW EPD. The same model was used for WBW, substituting WBW EPD for BBW EPD. This
Clark et al.
model calculated a random regression coefficient for BBW and WBW on sire EPD. In both models, sire EPD was considered a random effect because inferences were to be made about EPD of all Charolais sires, not just the sires in this study and because sires transmit a randomly determined onehalf of their chromosomes to each progeny (Searle, 1971). A second analysis was performed to estimate individual sire effects in the commercial data, similar to an EPD. The statistical model used for BBW and WBW included a fixed effect of contemporary group and a random sire effect. This model did not account for any genetic relationships among project sires, and few dams contributed more than one offspring and had unknown pedigree, so dam effects were not included in the model. Correlations were obtained between sire effects in commercial herds and published sire EPD for both BBW and WBW. Because sire effects should be more strongly correlated with EPD as more progeny of each sire are measured, the model weighted sire effects on number of progeny and weighted EPD on accuracy.
Results and Discussion The means and standard deviations of the progeny performance and sire EPD are summarized in Table 1. BBW. The random regression coefficient for progeny BBW on sire EPD was 1.03 ± 0.09 kg/kg of BBW EPD, very similar to its expected value of 1.0 kg/kg. This expectation is the
same whether sire EPD is modeled as a random effect, as in this study, or as a fixed effect, as in previous studies. These results are similar to the pooled values reported by Long and Marshall (1994), who estimated regression coefficient of 1.17 ± 0.31 kg/kg for BBW. Nunez-Dominguez et al. (1993) estimated pooled regression coefficients for BBW of 1.04 ± 0.10 kg/ kg of EPD. Notter and Cundiff (1991) also gave similar pooled results of 1.09 ± 0.12 kg/kg of BBW EPD. Basarab et al. (1994) reported a regression coefficient for BBW of 1.06 ± 0.14. The results suggest that the random regression coefficient of BBW based on published Charolais sire EPD agrees closely with the expected value of 1.0 kg/kg of EPD. Thus, the impact of environmental and managerial differences is minimal during this point between seedstock and commercial herds. Therefore, selection based on BBW EPD should be effective and consistent with theoretical expectation. Commercial producers should expect, on average, the same response in BBW suggested by sire EPD. WBW. The regression of progeny WBW on sire EPD was 0.66 ± 0.11 kg/kg of WBW EPD. This value is considerably different from the theoretical expected value of 1.0 kg/kg. These results are similar to the pooled values reported by Long and Marshall (1994), who estimated a regression coefficient of 0.75 ± 0.28 kg/kg for WBW. Nunez-Dominguez et al. (1993) obtained a pooled regression coefficient for WBW of 0.88 ± 0.11 kg/kg of EPD. Notter and Cundiff (1991) also gave similar pooled results
TABLE 1. Descriptive statistics of sires and progeny. Item Progeny Birth BW, kg Weaning BW, kg Sire Birth BW EPD, kg Weaning WW EPD, kg
Number
Mean
SD
3554 3604
40.0 226.6
5.7 49.9
224 224
0.4 7.0
1.1 5.6
Response to Expected Progeny Differences Selection in Commercial Beef Herds
of 0.79 ± 0.14 kg/kg for WBW EPD. Basarab et al. (1994) reported an even lesser regression coefficient for WBW of 0.45 ± 0.001 kg/kg. In this study, sire EPD differences for WBW were not completely expressed in commercial conditions. This may be a result of environmental differences, such as nutritional and health management among commercial and seedstock herds. Thus, commercial producers may not observe as dramatic a response as expected when selecting for increased growth using WBW EPD. Notter and Cundiff (1991) suggested that WBW EPD differences among sires might not be fully expressed unless the nutritional environment approaches that of the seedstock herds in which sire EPD were derived. Kemp and Sullivan (1995) also reported a WBW regression less than expected and attributed the difference to the various types of environments in which the crossbred progeny are raised, and the seedstock herds in which progeny contributing data to a sire’s EPD are raised. Therefore, the genetic potential might not have been fully expressed in the crossbred progeny because of differences in nutrition and management when compared with seedstock herd environments. Castration of male calves prior to weaning in some herds might have also limited response to selection on WBW EPD. Correlations Between Sire Effects and EPD. Positive correlations were obtained for sire effect in commercial
herds with published sire BBW and WBW EPD. Weighted correlations for sire effect solution with sire BBW and WBW EPD were 0.59 and 0.39, respectfully. Sire effect is favorably correlated with BBW EPD and WBW EPD; thus, EPD calculated from seedstock data do a reasonable job of describing genetic effects in commercial herds. Although sires were mated randomly within the commercial herds, the moderate correlations could be a result of ignoring both direct genetic and maternal dam effects. Dams might have contributed different genetics to their progeny, and their ability to produce milk could have varied. This could cause a difference among progeny performance and decrease the relationship of sire effect in commercial herds with sire BBW EPD or WBW EPD.
Implications Sire EPD for BBW and WBW were positively related to actual progeny performance, although response to selection was less than expected for WBW. The use of BBW EPD as a selection tool in commercial herds should be effective and response should be consistent with expectations. The less-than-expected response to selection on WBW EPD was likely a result of management practices in commercial herds compared with seedstock herds. Thus, commercial producers should expect slightly less response than suggested by sire WBW EPD, especially when nutrition and health
505
management are less than optimum. Calculation of selection indices for profitability may need to account for this reduced response.
Literature Cited AICA. 2002. Fall 2002 Sire Summary. American-International Charolais Association, Kansas City, MO. Basarab, J. A., D. Milligan, and J. Stitt. 1994. Relationship between expected progeny differences of Canadian Hereford sires and performance of their progeny in commercial herds. Can. J. Anim. Sci. 74:555. BIF. 1996. Guidelines for Uniform Beef Improvement Programs. (7th Ed.). Beef Improvement Federation, Kansas State Univ., Colby. Kemp, R. A., and P. G. Sullivan. 1995. The relationship between progeny performance and sire expected progeny differences for central test postweaning gain. Can. J. Anim. Sci. 75:169. Long, M. B., and D. M. Marshall. 1994. Relationship of beef sire birth weight and expected progeny differences to actual performance of crossbred offspring. South Dakota Beef Report. p 31. South Dakota State University, Brookings. Notter, D. R., and L. V. Cundiff. 1991. Acrossbreed expected progeny differences: Use of within-in breed expected progeny differences to adjust breed evaluations for sire sampling and genetic trend. J. Anim. Sci. 69:4763. Nunez-Dominguez, R., L. D. Van Vleck, and L. V. Cundiff. 1993. Breed comparisons for growth traits adjusted for within-breed genetic trend using expected progeny differences. J. Anim. Sci. 71:1419. Searle, S. R. 1971. Linear Models. John Wiley and Sons, New York, NY.