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ARS Home » Pacific West Area » Dubois, Idaho » Range Sheep Production Efficiency Research » Research » Publications at this Location » Publication #112079
Title: EFFECT OF THE CALLIPYGE GENE ON MUSCLE GROWTH, CALPASTIN ACTIVITY, AND TENDERNESS OF THREE MUSCLE ACROSS THE GROWTH CURVE

Author
item DUCKETT, SUSAN - UNIVERSITY OF IDAHO
item Snowder, Gary
item COCKETT, NOELLE - UTAH STATE UNIVERSITY

Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/7/2000
Publication Date: 12/12/2000
Citation: Duckett, S.K., Snowder, G.D., Cockett, N.E. 2000. Effect of the callipyge gene on muscle growth, calpastin activity, and tenderness of three muscle across the growth curve [abstract]. Journal of Animal Science 78:2836-2841.

Interpretive Summary: Characterization of the muscle growth patterns of callipyge may help us understand how the significant increase in muscle size occurs and when certain muscles become less tender. This study investigates these issues. It was found that at 20 kg of live weight most muscles from callipyge lambs are heavier than the same muscles in normal lambs. Muscles in the shoulder did not differ between callipyge and normal lambs until the lambs reached 69 kg of live weight. Enzyme activity (calpastatin) related to muscle tenderness decreased in callipyge lambs as the lambs got heavier but remained high in normal lambs. Therefore, measures of tenderness decreased in callipyge lambs as they became heavier. This information contributes to our scientific understanding of the relationship between muscle hypertrophy and tenderness of a muscle.

Technical Abstract: Forty (20 = CLPG; 20 = N) lambs were slaughtered at live weights (LW) of 7, 20, 36, 52, and 69 kg to assess changes in muscle growth, calpastatin activity, and tenderness of three muscles from callipyge (CLPG) and normal (N) lambs. At 24 h postmortem, the longissimus (LM), semimembranosus (SM), and supraspinatus (SS) muscles were removed, weighed and samples obtained for calpastatin activity (CA; 24 h) and Warner-Bratzler shear force (WBS; aged 6 d). For muscle weights and calpastatin activity, the weight group by muscle by phenotype interaction was significant (P < .05). Muscle weights were similar (P > .05) between phenotypes for all three muscles at 7 kg LW. At 20 kg LW, the LM and SM muscles from the CLPG lambs were heavier (P < .05) than those from N; however, the SS did not differ (P > .05) between phenotypes at 7, 20 and 52 kg. From 20 to 69 kg LW, the SM and LM weights were 33 to 69% heavier (P < .05) in CLPG than N. Calpastatin activity of the CLPG LM was higher (P < .05) than N LM at 36, 52 and 69 kg. In the CLPG LM, CA was similar (P > .05) at 20, 36, and 52 kg LW and did not differ (P > .05) from 7 kg or 69 kg values. Calpastatin activity declined (P < .05) across the growth curve for the SM and SS but values were higher (P < .05) in the SM for CLPG than N. Shear force values of the LM were lower (P < .05) for N at 36, 52 and 69 kg LW than CLPG. In the SM and SS, WBS values decreased (P < .05) across the growth curve but values were higher (P < .05) for CLPG in the SM only. The CLPG phenotype established increased muscle mass in the loin and leg from 20 to 69 kg. However, the higher levels of calpastatin and Warner-Bratzler shear force indicate reductions in palatability of the hypertrophied muscles.