J. Anim Sci. 2007. 85:373-379. doi:10.2527/jas.2005-755
© 2007 American Society of Animal Science
Evaluation of reciprocal differences in Bos indicus x Bos taurus backcross calves produced through embryo transfer: II. Postweaning, carcass, and meat traits1
T. S. Amen,
A. D. Herring,
J. O. Sanders and
C. A. Gill2
Department of Animal Science, Texas A&M University, College Station 77843
 |
Abstract
|
|---|
Angus (A) x Bos indicus (B; Brahman or Nellore) reciprocal backcross, embryo transfer calves belonging to 28 full-sib families were evaluated for differences in feedyard initial BW, feedyard final BW, carcass weight, LM area, adjusted fat thickness, intramuscular fat, and Warner-Bratzler shear force. Two methods of analysis were investigated; method I made no distinction between how the F1 parents were produced, whereas method II distinguished the 2 types of F1 parents (AB vs. BA, corresponding to A x B vs. B x A, respectively). No significant reciprocal differences for these weight and carcass traits were detected under method I analyses, although the same trend existed for subsequent BW rankings as for birth weight and weaning weight. For each weight phase, the cross that involved a larger proportion of B in the sire in relation to the amount in the dam (F1 x A and B x F1) ranked heavier than the respective reciprocal cross (A x F1 and F1 x B). As a whole, A backcross calves had larger (P < 0.001) LM area, more (P < 0.001) marbling, and lower (P < 0.001) Warner-Bratzler shear force than B back-cross calves, but no consistent trends were detected between reciprocal crosses for any of these traits, in contrast with the trends observed for the weight traits. Furthermore, males were heavier than females entering (P < 0.001) and leaving (P < 0.001) the feedyard, produced a heavier carcass (P < 0.001), and had larger LM area (P < 0.05) with less adjusted fat (P < 0.001). No difference existed between the sexes for Warner-Bratzler shear force or marbling. No interactions involving sex, sire type, and dam type were observed for any of these traits. The results were similar under methods I and II analyses, with the exception that a significant sire type x dam type interaction was observed for initial feedyard BW. Results from this study suggest that for weight-related traits, both the breed constitution of the embryo transfer calf and the cross that produces the calf play an important role in its ultimate performance for B crossbred calves. For body composition and meat-related traits, it appears that the breed makeup of the embryo transfer calf itself is more important to animal performance than the specific cross used to produce the calf.
Key Words: beef cattle • carcass • embryo transfer • feedyard • meat • reciprocal cross
|
INTRODUCTION
|
|---|
Crossbreeding between Bos indicus (B) and Bos taurus breeds has been studied at length, and the benefits of parasite and heat resistance, heterosis, and female longevity are well documented in crossbreds (Cartwright, 1980
; Franke, 1980; Turner, 1980). Because of these advantages, the inclusion of B breeds in areas of the southern United States and other subtropical and tropical areas is appropriate for effective and integrated beef production systems.
Performance differences between B x Bos taurus reciprocal crosses have been reported (Roberson et al., 1986; Baker et al., 1989; Thallman et al., 1993). However, research in this area has focused primarily on preweaning traits, likely because reciprocal cross, performance differences in nonembryo transfer calves were assumed to be caused by maternal uterine and rearing effects. Consequently, little evaluation has been carried out on postweaning growth, or reproductive and carcass traits of these reciprocal crosses. Thallman et al. (1993) showed a yearling BW difference in Brahman x Simmental reciprocal cross, embryo transfer calves. Brahman-sired calves were significantly heavier than Simmental-sired calves; and the difference in reciprocal cross bulls was twice the difference in reciprocal cross females.
Using data collected from the Texas A&M University Angleton project, the aim of this study was to evaluate differences in reciprocal cross performance for postweaning and carcass traits of Angus (A) and B backcross cattle produced through embryo transfer.
|
MATERIALS AND METHODS
|
|---|
All procedures involving animals were approved by the Texas A&M University Institutional Animal Care and Use Committee.
Data from embryo transfer calves belonging to 28 full-sib families that were raised and slaughtered between 1990 and 1996 were evaluated for differences in BW entering the feedyard (INWT, n = 495), BW leaving the feedyard (OUTWT, n = 492), carcass weight (HCW, n = 493), LM area (REA, n = 492), adjusted 12th-rib fat thickness (ADJFAT, n = 489), marbling score (MARB, n = 483), and Warner-Bratzler shear force (WBSF, n = 459).
The data collected were from A x B (Brahman or Nellore) reciprocal backcross, embryo transfer calves born in spring and fall seasons at the Texas Agricultural Experiment Station at Angleton. All of the progeny were 
A 
B or B A, with 8 family types being created through the use of purebred and F1 sires and dams, to produce a total of 32 families. To obtain each family type, 4 breeding schemes were used: F1 bulls from A sires and B dams (AB) or from B sires and A dams (BA) were mated to purebred (A or B) cows; or, conversely, purebred (A or B) bulls were mated to F1 (AB or BA) females (Table 1). All calves were born to recipient dams that were approximately 
Brahman and British and were 3 to 17 yr old.
Preweaning management was described by Amen et al. (2007). All calves were weaned at approximately 7 mo of age and backgrounded on pasture at Angleton, TX, for an average of 215 d. Calves were then shipped to the Texas A&M University Research Center at McGregor, where they were finished on a series of corn-based diets (Int-1, Int-2, Int-3, Int-4, Int-5, CMF-1, CMF-2, and CMF-3; Table 2) for an average of 150 d. Calves were slaughtered at the Rosenthal Meat Science and Technology Center on the Texas A&M University campus in College Station. Carcass quality and yield grade data were collected 48 h postmortem by Texas A&M University meat science personnel. Warner-Bratzler shear force was taken after 14 d of aging, with 6 cores per steak, and an average of the 6 cores was used for analysis.
All traits were analyzed through analysis of covariance using the MIXED procedure (SAS Inst. Inc., Cary, NC). Independent variables common to all traits analyzed were sex, breed type, sire-type x dam-type interaction within breed type [ST x DT (BT)], and the 3-way interaction of sex x ST x DT within breed type [S x ST x DT (BT)]. Analysis for each trait also included regression on age; for INWT, this was the age of the calf upon entering the feedyard, whereas for the remainder of the traits age at slaughter was used (SLAGE). For all traits, sire, dam, and birth season nested within year were included as random effects. When an F-test showed a significant difference for an effect (P < 0.05), least squares means were separated by 2-tailed t-tests.
Each trait was analyzed by 2 methods. Although the independent variables were the same for each method, ST and DT were slightly different. Method I pooled AB and BA parents into a single F1 category, whereas method II separated F1 parents into AB or BA categories (first letter denotes sire type, second letter denotes dam type).
|
RESULTS AND DISCUSSION
|
|---|
Feedyard Initial BW
Results from the statistical analysis are presented in Tables 3 (method 1) and 4 (method 2). Variables responsible for variation in calf BW upon entering the feed yard included, sex, BT, and age of the calf upon entering the feedyard. Among A backcrosses calves for method I, those with F1 sires weighed 344.3 ± 14.8 kg, and A-sired calves weighed 331.9 ± 14.1 kg (P = 0.255), whereas B backcrosses with F1 sires weighed 317.4 ± 14.6 kg, and B-sired calves weighed 328.4 ± 14.0 kg (P = 0.294). For A and B backcrosses, calves ranked heavier when the sire possessed more B influence than the dam as was the case with birth weight (Amen et al., 2006), though these differences were not statistically significant (Figure 1).
View larger version (24K):
[in this window]
[in a new window]
|
Figure 1. Least squares means (kg) and SE for feedyard initial BW for method I, where A = Angus and B = Bos indicus.
|
|
For method II, reciprocal differences were observed only when the F1 parental type was AB. The A x AB calves averaged 26.0 kg lighter than AB x A (P = 0.02) and B x AB calves averaged 15.2 kg heavier than AB x B (P = 0.160). Again, there was a trend for cattle with more B influence in the sire than in the dam to be heavier than their reciprocals (Figure 2). Furthermore, in crosses that had a higher proportion of B in the sire than in the dam, AB F1 parents produced calves that ranked heavier than BA F1 parents. It is important to note that the BA F1 parents (all 3 sires and 2 out of 5 dams) had more Nellore influence than AB parents (4 sires and 4 dams) that had only Brahman influence; possibly more importantly, the A cows that were used to produce the Nellore-sired BA parents were smaller at maturity than the A that were used to produce the other crosses.
View larger version (29K):
[in this window]
[in a new window]
|
Figure 2. Least squares means (kg) and SE for feedyard initial BW for method II. For F1 sires and dams (AB and BA), sire type is listed first, followed by dam type. A = Angus; B = Bos indicus.
|
|
Feedyard Final BW
Sex, BT, and SLAGE (P < 0.05) were responsible for variation in the BW of calves leaving the feedyard. The A x F1 calves (524.4 ± 15.1 kg) were 17.2 kg lighter (P = 0.40) than F1 x A calves (541.6 ± 16.7 kg; Figure 3). The difference among B backcrosses was 25.2 kg (P = 0.207), with B-sired calves being heavier than F1-sired calves (508.2 ± 14.9 and 483.0 ± 16.8 kg, respectively). No significant reciprocal cross differences were observed for method II (Figure 4). Though, as with INWT, there was a tendency for larger reciprocal differences to exist when the F1 parents were AB as opposed to BA. When AB was the F1 parental type, the reciprocal difference was 31.1 and 31.8 kg for A and B backcrosses, respectively (P > 0.10). Reciprocal differences for BA F1 parents were 6.8 and 13.0 kg for A and B backcrosses (P > 0.25).
View larger version (24K):
[in this window]
[in a new window]
|
Figure 3. Least squares means (kg) and SE for feedyard final BW for method I, where A = Angus and B = Bos indicus.
|
|
View larger version (31K):
[in this window]
[in a new window]
|
Figure 4. Least squares means (kg) and SE for feedyard final BW for method II. For F1 sires and dams (AB and BA), sire type is listed first, followed by dam type. A = Angus; B = Bos indicus.
|
|
For both analysis methods the trend still existed for calves with a larger proportion of B in the sire than the dam to weigh more when leaving the feed yard. These differences were not statistically important for either method, likely because they were overshadowed by the large differences (P < 0.01) that existed between breed types (A backcrosses vs. B backcrosses). The breed type difference was 37.4 and 39.1 kg for method I and method II, respectively (for each method, A back-cross calves outweighed B backcrosses).
Chase et al. (1998) showed reciprocal differences occurred in postweaning traits when crossing Hereford and Senepol. Hereford-sired F1 calves were heavier than Senepol-sired F1 calves entering and leaving the feedlot, and produced heavier carcasses with a larger REA and more ADJFAT. Johnston et al. (1992) reported a 13.6 kg difference (nonsignificant) in slaughter weight for reciprocal F1 Devon-Hereford steers that was a carryover effect from weaning weight, and these authors found no significant reciprocal differences for any carcass trait in these Bos taurus crosses.
Carcass Weight (HCW)
Sex, BT, and SLAGE were responsible for significant variation in HCW for method I and method II. The difference among A reciprocal backcrosses was 7.5 kg, on average, with F1-sired cattle (328.3 ± 10.4 kg) producing a heavier (P = 0.541) carcass than A-sired cattle (320.8 ± 9.8 kg). Carcasses from B x F1 calves averaged 18.0 kg heavier (P = 0.133) than carcasses from F1 x B cattle (311.5 ± 9.6 and 293.4 ± 10.5 kg, respectively; Figure 5).
View larger version (24K):
[in this window]
[in a new window]
|
Figure 5. Least squares means (kg) and SE for carcass weight for method I, where A = Angus and B = Bos indicus.
|
|
For method II, as with INWT and OUTWT, reciprocal cross differences for calves with AB F1 parents ranked greater than when BA was the F1 parental type. For both comparisons, the cross with more B-influence in the sire compared with the dam produced calves with heavier carcasses (Figure 6).
View larger version (31K):
[in this window]
[in a new window]
|
Figure 6. Least squares means (kg) and SE for carcass weight for method II. For F1 sires and dams (AB and BA), sire type is listed first, followed by dam type. A = Angus; B = Bos indicus.
|
|
Though no significant differences existed between AB vs. BA parents for HCW, trends seem to exist. In crosses where there is more B in the dam in relation to the amount in the sire (A x AB, A x BA, AB x B, and BA x B), the BA F1 parents produced calves with heavier carcasses, on average, than the AB F1 parent. In crosses where the sire possessed more B influence than the dam (AB x A, BA x A, B x AB, and B x BA), the AB F1 parent produced calves with heavier carcasses than the BA F1 parent. This same trend was seen for birth weight and weaning weight in these calves.
For both models, calves from the A backcrosses had heavier carcass weights than B backcrosses (324.5 vs. 302.4 kg for method I and 324.7 vs. 301.7 kg for method II; Figures 5
and 6). Wheeler et al. (2001) reported A-sired steers to have heavier carcass weights than Brahman-sired steers when bred to A, Hereford, and MARC III cows. Contrary to these findings, results from Paschal et al. (1995) found that in calves born (in the fall) and raised in Texas, those with Brahman sires had heavier carcasses than A-sired calves when both were bred to Hereford cows. This difference is possibly attributable to a genotype x environment interaction as has been studied by Brown et al. (1993), or differences in genetic values for size in the samples of A and Brahman cattle used in the different studies, or both.
Adjusted Fat Thickness
Sex and SLAGE were sources of variation for AD-JFAT for method I and method II. Female calves produced carcasses with 0.4 cm more fat than male calves for method I and method II. Further, there was an obvious tendency for A calves to produce a carcass with more fat (P > 0.25) than B calves (1.28 vs. 1.15 cm for method I and 1.27 vs. 1.14 cm for method II, respectively). The results for BT for both methods are consistent with the findings of Wheeler et al. (2001), where Brahman-sired calves possessed 0.24 cm less fat than A-sired calves. Crouse et al. (1989) also reported A-sired calves to have more 12th-rib fat than Brahman-sired calves. However, Crouse et al. (1989) reported that percent B had no consistent effect on ADJFAT. Paschal et al. (1995), on the other hand, found no difference in ADJFAT between A- and B-sired F1 calves.
LM Area
Sex, BT, and SLAGE were significant sources of variation in REA for method I and method II. Male calves averaged 1.5 cm2 larger REA than females for method I and method II. The A backcross calves had larger REA than B backcrosses for both methods (79.4 ± 1.66 cm2 vs. 71.7 ± 1.66 cm2, respectively, for method I, and 79.4 ± 1.73 cm2 vs. 71.7 ± 1.73 cm2, respectively, for method II). No differences were detected between reciprocal crosses (all P > 0.25), and no difference existed between AB vs. BA F1 parental types (all P > 0.25).
Paschal et al. (1995) and Wheeler et al. (2001) reported larger REA when adjusted for carcass weight for A-sired calves compared with Brahman-sired calves. Crouse et al. (1989) found level of B influence to have no consistent effect on REA.
Intramuscular Fat
Breed type and SLAGE accounted for variation in MARB for method I and method II. Both methods showed a greater amount of marbling for A calves in relation to B (451.4 ± 15.1 vs. 356.1 ± 14.6, respectively, for method I and 451.5 ± 15.5 vs. 354.5 ± 15.0, respectively, for method II), though no significant reciprocal cross differences were found for either method. These breed type results are not unexpected, as it has been shown repeatedly that A cattle marble well, whereas Brahman cattle are often scored lower for marbling (Crouse et al., 1989; Paschal et al., 1995; Wheeler et al., 2001).
Warner-Bratzler Shear Force
Breed type and SLAGE were significant sources of variation for method I and method II. Both methods agree that on average, A calves produce carcasses with lower shear force values than B calves (3.25 ± 0.19 kg vs. 3.83 ± 0.19 kg, respectively, for method I and 3.25 ± 0.19 kg vs. 3.84 ± 0.20 kg, respectively, for method II). No reciprocal differences were detected for either method.
Wheeler et al. (2001) reported WBSF values for Brahman-sired calves of 7.3 and 6.0 kg when aged 7 and 14 d, respectively, whereas values for A-sired calves aged 7 and 14 d were 5.1 and 4.0 kg, respectively. Crouse et al. (1989) showed that an increase in WBSF and more variability in tenderness were associated with an increase in B influence.
Evaluation of calf weight at various stages of life revealed a consistent trend for method I (Table 5). As discussed previously (Amen et al., 2007), F1 x A calves were heavier at birth and weaning than A x F1 calves, and B x F1 calves were heavier at these same weights than F1 x B calves. This difference continued as the calves were weighed upon entering and leaving the feedlot. There is a trend for calves with a greater proportion of B in the sire in relation to the amount in the dam to be heavier through at least 20 mo of age.
No consistent performance differences dependent upon AB vs. BA F1 parental type were detected for method II for postweaning traits. At birth, calves with AB F1 parents were heavier for all family types, with the exception of B backcross calves with F1 sires; here, BA-sired calves were heavier at birth than AB-sired calves. Weights taken at weaning and upon leaving the feedyard showed that the advantage of AB vs. BA F1 parental types depended on the proportion of B in the sire when compared with the dam. Entering the feedlot, calves with AB F1 parents were heavier than calves with BA F1 parents for all family types. These differences appear to be significant at least through 18 mo of age and are consistent with other studies involving B and Bos taurus crosses (Thallman et al., 1993). These results suggest that for weight-related traits, both the breed composition of the calf and the cross that produces the calf play an important role in its ultimate performance even for embryo transfer calves. For carcass-related traits, it appears that the breed makeup of the calf itself is more significant in influencing performance than the cross used to produce the calf. Throughout this study, for weight traits from birth to slaughter, weights tended to be heavier for those embryo transfer animals that had more B in the sire relative to the amount of B in the dam.
|
IMPLICATIONS
|
|---|
There appears to be a biological phenomenon in B x Bos taurus crosses, even among animals produced by embryo transfer, where there is increased BW through 18 mo of age, when the mating that produced the animals has more B influence in the sire relative to the amount in the dam, and these differences should be considered in breeding programs. For body composition and meat quality traits in B x Bos taurus crossbreds, the specific cross that produces the calf does not seem to explain performance differences, as it does for weight traits.
|
Footnotes
|
|---|
1 Financial support for the resource population and phenotypic data collection was provided in part by the Texas Agricultural Experiment Station. Postslaughter data collection was funded in part by beef and veal producers and importers through their one-dollar per head checkoff. 
2 Corresponding author: clare-gill{at}tamu.edu
Received for publication December 22, 2005.
Accepted for publication September 8, 2006.
|
LITERATURE CITED
|
|---|
Amen, T. S., A. D. Herring, C. A. Gill, and J. O. Sanders. 2007. Birth and weaning traits in Bos indicus – Bos taurus reciprocal backcross calves produced through embryo transfer. I. Birth and weaning traits. J. Anim. Sci. 85:365–372.[Abstract/Free Full Text]
Baker, J. F., C. E. Dorn, and G. A. Rohrer. 1989. Evaluation of direct genetic and maternal effects on birth weight and gestation length. McGregor Field Day Report. Texas A&M University.
Brown, M. A., A. H. Brown Jr., W. G. Jackson, and J. R. Miesner. 1993. Genotype x environment interactions in postweaning performance to yearling in Angus, Brahman, and reciprocal-cross calves. J. Anim. Sci. 71:3273–3279.[Abstract]
Cartwright, T. C. 1980. Prognosis of Zebu cattle: Research and application. J. Anim. Sci. 50:1221–1226.[Abstract/Free Full Text]
Chase, C. C., T. A. Olson, A. C. Hammond, M. A. Menchaca, R. L. West, D. D. Johnson, and W. T. Butts Jr. 1998. Preweaning growth traits for Senepol, Hereford, and reciprocal crossbred calves and feedlot performance and carcass characteristics of steers. J. Anim. Sci. 76:2967–2975.[Abstract/Free Full Text]
Crouse, J. D., L. V. Cundiff, R. M. Koch, M. Koohmaraie, and S. C. Seideman. 1989. Comparisons of Bos indicus and Bos taurus inheritance for carcass beef characteristics and meat palatability. J. Anim. Sci. 67:2661–2667.[Abstract/Free Full Text]
Franke, D. E. 1980. Breed and heterosis effects of American Zebu cattle. J. Anim. Sci. 50:1206–1214.[Abstract/Free Full Text]
Johnston, D. J., J. M. Thompson, and K. Hammond. 1992. Additive and nonadditive differences in postweaning growth and carcass characteristics of Devon, Hereford, and reciprocal-cross steers. J. Anim. Sci. 70:2688–2694.[Abstract]
Paschal, J. C., J. O. Sanders, J. L. Kerr, D. K. Lunt, and A. D. Herring. 1995. Postweaning and feedlot growth and carcass characteristics of Angus-, Gray Brahman-, Gir-, Indu-Brazil-, Nellore-, and Red Brahman-sired F1 calves. J. Anim. Sci. 73:373–380.[Abstract]
Roberson, R. L., J. O. Sanders, and T. C. Cartwright. 1986. Direct and maternal genetic effects on preweaning characteristics of Brahman, Hereford and Brahman-Hereford crossbred cattle. J. Anim. Sci. 63:438.[Abstract/Free Full Text]
Thallman, R. M., J. O. Sanders, and J. F. Taylor. 1993. Non-Mendelian genetic effects in reciprocal cross Brahman x Simmental F1 calves produced by embryo transfer. Pages 8–14 in Progress Report No. 5053, Beef Cattle Research in Texas, 1993. Texas A&M University.
Turner, J. W. 1980. Genetic and biological aspects of Zebu adaptability. J. Anim. Sci. 50:1201–1205.[Abstract/Free Full Text]
Wheeler, T. L., L. V. Cundiff, S. D. Shackelford, and M. Koohmaraie. 2001. Characterization of biological types of cattle (Cycle V): Carcass traits and Longissimus palatability. J. Anim. Sci. 79:1209–1222.[Abstract/Free Full Text]
Top
Abstract
INTRODUCTION
