Document Type

Thesis - University Access Only

Award Date

2005

Degree Name

Master of Science (MS)

Department / School

Animal Science

Abstract

Calpain and calpastatin activity are thought to be the determining factors for meat tenderness, and calcium (Ca) plays a role in calpain activity. The present theory is to manipulate beef cattle diets to change muscle Ca levels and consequently calpain activity and shear force. To test whether dietary Ca manipulations affect tenderness, Angus-based steers (n=20), from a single source, were assigned to pairs based on an allotment weight. One steer from each pair was assigned to the control treatment (CO) and the other to the dietary Ca depletion/repletion treatment (DR). All cattle were fed a typically high grain finishing (0.50% Ca) diet starting at 343 kg body weight (BW); dietary Ca depletions began 113 d later at 561 kg BW. The DR received a 0.28% Ca diet for 14, 21, or 28 d prior to harvest and was returned to the CO diet for one feeding 16 h prior to slaughter. Individual performance and carcass data were collected. Post mortem muscle temperature and pH were determined for the Longissimus dorsi, Triceps brachii, and Semimembranosus muscles from each carcass at 1, 3, 6, 24 and 48 h post mortem. Warner-Bratzler shear force was determined on three steaks from each muscle from each carcass, on d 5, 10 and 15 post mortem. SDSPAGE and Western Blot were used to determine the degradation of desmin in samples from the SM on d 5 and 15 post mortem. There appeared to be no adverse affect on DMI or ADG when fed on a depletion/repletion program. Serum Ca levels at exsanguination were higher (P<0.0 1) for DR cattle the CO ( 11.9 v. 9.3 mg/dL). Muscle pH was higher (P<0.05) for DR at 1 h (6.47 v. 6.25), 3 h (6.16 v. 5.97), and 48 h (5.61 v. 5.57) post mortem. Wamer-Bratzler shear force values did not differ (P>0.2) between treatments on d 5, 10 and 15 for the LO (3.0 kg± 0.18) and TB (3.1 kg± 0.15). Shear force was lower (P<0.05) for DR on d 5 post mortem (3.6 v. 4.2 kg). The overall frequency of tough cores from Warner-Bratzler shear force was lower (P<0.05) for DR than CO (3.33% v. 6.94%). Analysis of SDSPAGE concluded that there was no differences in fragmentation of protein of the 55,000 to 29,000 Dalton range between DR and CO samples on d 5. The depletion of Ca from finishing diets did not appear to have adverse affects on performance, but did increase serum Ca levels, altered pH and shear force values of the Semimembranosus.

(Key Words: Beef, Muscle, Calcium, Tenderness)

Library of Congress Subject Headings

Beef -- Quality

Beef cattle -- Feeding and feeds

Calcium -- Metabolism

Format

application/pdf

Number of Pages

49

Publisher

South Dakota State University

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