Table 2.
The effects of genotype of the cast_736 SNP on the tenderness phenotypes, Warner–Bratzler shear force (WBSF) and myofibril fragment length (MFL) of representative purebred South African beef bulls during three to 20 days of ageing and on the muscle protease enzyme system during the first 20 h post-mortem.
| cast_736 | *GG (n = 19) | GT (n = 54) | TT (n = 93) |
p-Value (Simplified) |
Genotype Effect |
|---|---|---|---|---|---|
| WBSF (d 3) | 5.90 ± 0.38 b | 6.05 ± 0.17 ab | 6.22 ± 0.12 a | 0.0130 $ | −5.1% |
| WBSF (d 9) | 4.70 ± 0.33 b | 4.77 ± 0.14 ab | 4.92 ± 0.11 a | 0.0111 $ | −4.6% |
| WBSF (d 14) | 3.78 ± 0.28 y | 4.17 ± 0.12 z | 4.21 ± 0.09 z | 0.0950 ! | −10.3% |
| WBSF (d 20) | 3.63 ± 0.27 | 3.89 ± 0.12 | 3.90 ± 0.09 | 0.1343 | − |
| MFL (d 3) | 39.29 ± 1.89 | 34.51 ± 0.81 | 35.64 ± 0.61 | 0.4293 | − |
| MFL (d 9) | 28.20 ± 1.23 z | 25.36 ± 0.53 y | 26.50 ± 0.40 y | 0.0895 | +6.4% |
| MFL (d 14) | 24.42 ± 1.16 a | 23.17 ± 0.50 b | 24.20 ± 0.38 ab | 0.0074 | # −4.2% |
| MFL (d 20) | 20.96 ± 0.94 b | 21.26 ± 0.41 b | 21.97 ± 0.31 a | 0.0448 | −4.6% |
| calpastatin (1 h) | 2.15 ± 0.10 z | 2.03 ± 0.04 y | 2.02 ± 0.03 y | 0.0811 ! | +6.4% |
| calpastatin (20 h) | 1.87 ± 0.12 | 1.66 ± 0.05 | 1.72 ± 0.04 | 0.1819 | − |
| calpain-1 (1 h) | 1.53 ± 0.08 | 1.46 ± 0.04 | 1.40 ± 0.03 | 0.8459 | − |
| calpain-1 (20 h) | 1.17 ± 0.09 | 1.06 ± 0.04 | 1.10 ± 0.03 | 0.3287 | − |
| calpain-2 (1 h) | 1.02 ± 0.04 | 1.00 ± 0.02 | 0.98 ± 0.01 | 0.3944 | − |
| calpain-2 (20 h) | 1.03 ± 0.04 | 1.02 ± 0.02 | 1.01 ± 0.01 | 0.4279 | − |
| calpastatin/calpain-1 (1 h) | 1.40 ± 0.07 b | 1.44 ± 0.03 ab | 1.49 ± 0.02 a | 0.0398 | −5.9% |
| calpastatin/calpain-1 (20 h) | 1.66 ± 0.13 | 1.80 ± 0.06 | 1.68 ± 0.04 | 0.9142 | − |
| calpastatin/calpains(1 h) | 0.84 ± 0.03 a | 0.84 ± 0.01 a | 0.86 ± 0.01 a | 0.0105 | n/a |
| calpastatin/calpains (20 h) | 0.83 ± 0.04 | 0.82 ± 0.02 | 0.81 ± 0.01 | 0.1441 | − |
*GG—the genotype that favored tenderness; least squares means (LSM) ± standard errors (SE) that were significantly different within rows or ageing periods (p ≤ 0.05) were indicated with different ascending letter superscripts (a, b), and those that tended to be significantly different (p ≤ 0.10) with different descending letter superscripts (z, y). n/a—LSM differences were biologically negligible. # means difference of *GG compared to GT; $ adjusted p-values only tended to be significant, ! false positive association; MFL—myofibril fragment length; WBSF—Warner–Bratzler shear force.