Heritabilities and phenotypic and genetic correlations for bovine postrigor calpastatin activity, intramuscular fat content, Warner-Bratzler shear force, retail product yield, and growth rate1

Abstract

To estimate the heritability (h2) of postrigor calpastatin activity (CA), 555 steers were reared and processed conventionally. Breed-types included purebreds (Angus [A], Braunvieh [B], Charolais [C], Gelbvieh [G], Hereford [H], Limousin [L], Pinzgauer [P], Red Poll [RP], and Simmental [S]), composite populations (MARC I [1/4 C, 1/4 B, 1/4 L, 1/8 H, 1/8 A], MARC II [1/4 S, 1/4 G, 1/4 H, 1/4 A], and MARC III [1/4 RP, 1/4 H, 1/4 P, 1/4 A]), and F1 crosses (H, A, C, G, P, Shorthorn, Galloway, Longhorn, Nellore, Piedmontese, or Salers x H or A). Steers were serially slaughtered on an age-constant (across breed groups) basis. Heritability estimates for CA, i.m. fat content (IMF), Warner-Bratzler shear (WBS) force, retail product yield (RPY), and ADG were .65 +/- .19, .93 +/- .02, .53 +/- .15, .45 +/- .18, and .32 +/- .26, respectively. The genetic correlations (rg) of CA with WBS, RPY, and ADG were .50 +/- .22, .44 +/- .25, and -.52 +/- .37, respectively. The rg of IMF with WBS, RPY, and ADG were -.57 +/- .16, -.63 +/- .15, and -.04 +/- .11, respectively. These h2 and rg estimates indicate that it should be possible to select for improvements in CA, IMF, and WBS. However, selection against CA may be a more suitable approach for improving meat tenderness than selection for increased IMF because the level of genetic antagonism between CA and RPY was not as great as that between IMF and RPY.

Breed variation and genetic parameters for growth and body development in diverse beef cattle genotypes

“…The heritability estimates of muscularity measures herein were comparable to average values of 40 -47% for rib eye area (Koots et al, 1994a) and of 42 to 47% for retail product yield (Shackelford et al, 1994;Gregory et al, 1995). Similar estimates have been reported also in Australian pure (53%) and crossbred (44%) cattle (Newman et al, 2002) for actual retail beef yield.…”

Brahman and Brahman crossbred cattle grown on pasture and in feedlots in subtropical and temperate Australia. 2. Meat quality and palatability

“…However, we found no sire breed differences for ultimate pH in the LT or ST, which is consistent with other studies (Wythes et al 1989;Whipple et al 1990). As B. indicus content increases, an increase in calpastatin activity, and in some cases a decrease in calpain activity, leads to reduced myofibrillar degradation (Wheeler et al 1990;Whipple et al 1990;Shackelford et al 1991Shackelford et al , 1994Pringle et al 1997;Ferguson et al 2000). This would support our finding that straightbred Brahmans had tougher SFLT and lower sensory palatability than crossbreds, but it does not explain our SFST results.…”

Quantitative and molecular genetic influences on properties of beef: a review

“…Wulf et al (1996) reported that 24-h calpastatin activity was genetically highly correlated (r g >1.00 for shear force measures between 1 and 35 days post mortem), but phenotypically, only moderately correlated with Warner Bratzler shear force values (r p ≤0.31). Shackelford et al (1994a) reported lower genetic correlations (r g = 0.50 ± 0.22) and similar phenotypic correlations (r p = 0.27 ± 0.04) between 24-h calpastatin activity and Warner Bratzler shear force values. Both studies were based on relatively small numbers of animals (392 and 555 respectively) and the average number of progeny per sire in the Shackelford et al (1994a) study was <2.4, meaning that results from both studies should be regarded as preliminary.…”

“…Initial yield (kg), an index of the myofibrillar contribution to meat toughness Warner Bratzler peak force Peak force, also known as shear force (kg), which represents the total meat toughness Peak force -initial yield Difference between peak force and initial yield (kg), which is an index of the contribution of connective tissue to meat toughness Compression Compression (kg) , measured to determine differences in connective tissue content between muscles (Harris and Shorthose 1988) Cooking loss Cooking loss (%), determined from weights taken before and after cooking at 80°C for 1 h in a thermostatically controlled waterbath Tenderness index Index of meat tenderness that relates to consumer scoring of meat tenderness on a scale of 0 = extremely tender to 15 = extremely tough using the equation: Index = (1.4 × compression) + (0.6 × peak force) + (0.12 × cooking loss) -2.6 (Harris and Shorthose 1988) Myofibrillar fragmentation index A biochemical measure of beef tenderness predicted by absorbance (Barkhouse et al 1996), with low values indicating tough meat and high values indicating tender meat Calpastatin activity Amount of calpastatin activity measured in M. longissimus dorsi at 24 h post-slaughter, according to the method of Shackelford et al (1994a) Subjective sensory panel tests Tenderness/juiciness/flavour/overall acceptability Sensory taste panel tests use subjective scores of individual components of beef eating quality (tenderness, juiciness and flavour) and also an overall eating quality score, combining tenderness, juiciness and flavour. Panellists may be either trained or untrained, and the scoring scale varies considerably across experiments…”

“…Application of processing techniques such as electrical stimulation, tenderstretching and correct aging of meat can be used to overcome the effects of cold shortening (Harris and Shorthose 1988). It is therefore possible that beef tenderness measured either with or without correct application of processing techniques to overcome cold Barkhouse et al (1996); Crews and Franke (1998); Gregory et al (1994b); Gregory et al (1995); Hirooka et al (1996); Johnston et al (1992a); O'Connor et al (1997); Shackelford et al(1994a); Splan et al (1998);Van Vleck et al (1992); Wheeler et al (1996); Wulf et al (1996). B Individual estimates of heritability were weighted by the relative amount of information (inverse of their estimated sampling variance).…”