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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Varying Degrees of Muscularity and Muscular Hypertrophy in Hereford, Limousin, and Piedmontese F2 Crossbred Calves on Traits Measured at Slaughter

Authors
item Short, Robert
item Grosz, Michael
item Macneil, Michael
item Grings, Elaine

Submitted to: Western Section of Animal Science Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 1, 1999
Publication Date: June 1, 1999
Citation: SHORT, R., GROSZ, M.D., MACNEIL, M.D., GRINGS, E.E. EFFECTS OF VARYING DEGREES OF MUSCULARITY AND MUSCULAR HYPERTROPHY IN HEREFORD, LIMOUSIN, AND PIEDMONTESE F2 CROSSBRED CALVES ON TRAITS MEASURED AT SLAUGHTER. WESTERN SECTION OF ANIMAL SCIENCE PROCEEDINGS. 1999. v. 77(Suppl. 1). p. 158.

Interpretive Summary: Breeds that are similar in mature weight but differ in muscularity, especially with breeds that express muscular hypertrophy (double muscling), may differ in quantity, quality, and efficiency of beef production. Hereford (normal muscling, H), Limousin (moderate muscling, L), and Piedmontese (muscular hypertrophy, P) sires (20 to 25 per breed) were bred to crossbred cows at random to produce F1 calves. F1 progeny were inter se mated within sire breed to produce F2 calves that were weaned at 6 mo of age and placed on a growing diet until females reached 341 kg and males reached 386 kg. Calves were fed a finishing diet for either 90 or 132 d and then slaughtered. P cross calves were genotyped for the G-A transition mutation at the myostatin locus characteristic of P, and their genotypes were classified on the basis of having 0 (P0), 1 (P1), or 2 (P2) copies of the mutant allele (mhP). Tenderness of a rib steak was evaluated using the Warner-Bratzler shear test. Muscle score was estimated visually using a score of 1 (low) to 9 (high). Included in the ANOV model were breed, sex, time-on-feed, year, and selected 2-way interactions for live wt, kg (WT +/- 21); carcass wt, kg (CAR +/- 12); dressing % (DRE +/- 2.0); rib eye area, cm**2 (REA +/- 8.4); marbling score (MAR +/- .94); % of the carcass in the 5 primal cuts (PRI +/- 1.9); muscle score (MUS +/- .64); and W-B shear test, kg (SHR +/- .91). We conclude differences in muscularity affect most traits and when differences in muscularity include the mhP allele, there is an incremental, but not equal, change in all traits except WT and SHR with the addition of each copy of the mhP allele indicating that a portion of the genetic control is additive.

Technical Abstract: Breeds that are similar in mature weight but differ in muscularity, especially with breeds that express muscular hypertrophy (double muscling), may differ in quantity, quality, and efficiency of beef production. Hereford (normal muscling, H), Limousin (moderate muscling, L), and Piedmontese (muscular hypertrophy, P) sires (20 to 25 per breed) were bred to crossbred cows at random to produce F1 calves. F1 progeny were inter se mated within sire breed to produce F2 calves that were weaned at 6 mo of age and placed on a growing diet until females reached 341 kg and males reached 386 kg. Calves were fed a finishing diet for either 90 or 132 d and then slaughtered. P cross calves were genotyped for the G-A transition mutation at the myostatin locus characteristic of P, and their genotypes were classified on the basis of having 0 (P0), 1 (P1), or 2 (P2) copies of the mutant allele (mhP). Tenderness of a rib steak was evaluated using the Warner-Bratzler shear test. Muscle score was estimated visually using a score of 1 (low) to 9 (high). Included in the ANOV model were breed, sex, time-on-feed, year, and selected 2-way interactions for live wt, kg (WT +/- 21); carcass wt, kg (CAR +/- 12); dressing % (DRE +/- 2.0); rib eye area, cm**2 (REA +/- 8.4); marbling score (MAR +/- .94); % of the carcass in the 5 primal cuts (PRI +/- 1.9); muscle score (MUS +/- .64); and W-B shear test, kg (SHR +/- .91). We conclude differences in muscularity affect most traits and when differences in muscularity include the mhP allele, there is an incremental, but not equal, change in all traits except WT and SHR with the addition of each copy of the mhP allele indicating that a portion of the genetic control is additive.

Last Modified: 9/29/2014
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