Effect of pasture vs. concentrate feeding with or without antioxidants on carcass characteristics, fatty acid composition, and quality of Uruguayan beef

Fat-borne volatiles and sheepmeat odour.

Limousin-cross steers (n=135; 258+/-26 kg) were used to compare forage vs grain feeding on carcass composition and palatability attributes of beef when time on feed was controlled. Diets included a 95% alfalfa silage ration (AS) or a 68% high-moisture corn, 25% alfalfa silage ration (HMC). These were incorporated into six treatments to allow comparisons of end points based on similar days on feed or backfat finish. Dietary treatments included 1) HMC (4 mm), or cattle allowed ad libitum intake of HMC until slaughter at 4 mm ultrasound backfat; 2) AS (HMC-4), or cattle allowed ad libitum intake of AS until slaughter, regardless of finish, when HMC (4 mm) cattle were slaughtered; 3) AS (4 mm), or cattle allowed ad libitum intake of AS until slaughter at 4 mm backfat; 4) HMC (AS-4), or cattle allowed ad libitum intake of HMC until slaughter, regardless of finish, when AS (4 mm) cattle achieved 4 mm backfat; 5) HMC (RES), or cattle fed HMC at restricted intakes until slaughter at 4 mm backfat with feed offered at 75% of intake achieved by HMC (4 mm) and HMC (AS-4) cattle; and 6) AS (8 mm) or cattle allowed ad libitum intake of AS ration until slaughter at 8 mm backfat. Grain feeding generally increased (P .10) by diet with the exception of slightly less beef flavor and more off-flavor in forage-fed vs grain-fed beef. Higher (P < .01) concentrations of linolenic acid and lower (P < .10) concentrations of oleic acid in forage-fed beef may be partially responsible for diet differences in flavor.

Effects of forage vs grain feeding on carcass characteristics, fatty acid composition, and beef quality in Limousin-cross steers when time on feed is controlled.

Influence of feeding intensity, grazing and finishing feeding on meat and eating quality of young bulls and the relationship between muscle fibre characteristics, fibre fragmentation and meat tenderness

Angus-cross steers (n = 128; initial BW = 270 ± 3.8 kg) were used in a 3-yr study to assess effects of forage species grazed before slaughter versus concentrate fi nishing on carcass and meat quality. At the completion of the stockering phase, steers were randomly allotted to mixed pasture (MP; n = 36/yr) or corn-silage concentrate (CON; n = 12/yr) fi nishing treatments. At 40 d before harvest, MP steers were randomly divided into 3 forage species treatments: alfalfa (AL), pearl millet (PM), or mixed pasture (MP). Average daily BW gain was great- er (P = 0.001) for CON than for forage-fi nished (FOR) steers during the early and overall fi nishing phase. During the late fi nishing phase when FOR steers were grazing difference forage species, ADG was greater (P = 0.03) for PM than MP or AL. Harvest weight and HCW were greater (P 0.78) between CON and FOR and were not altered (P > 0.40) by forage species. Trained sensory panel juici- ness, initial tenderness, and overall tenderness scores did not differ (P > 0.17) by fitreatment or forage species. Beef fl avor intensity was greater (P 0.05) total lipid content of the LM. Oleic acid concentration and total MUFA of the LM were 21% and 22% less (P = 0.001) for FOR than CON. Concentrations of all individual (lino- lenic acid, eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosadexaenoic (DHA) acids) and total n-3 fatty acids were greater (P < 0.001) for FOR than CON. Finishing on AL increased (P = 0.017) the concentration of linolenic acid compared with MP or PM. The ratio of n-6 to n-3 fatty acids was greater (P = 0.001) for CON than FOR and did not differ (P = 0.88) by forage species. Concentrate fi nishing increases carcass weight with same time endpoints and accelerates deposition of MUFA in comparison with FOR, which reduces carcass weight and fat deposition but maintains high concentrations of n-3 and CLA fatty acids. Finishing system or forage species grazed 40 d before slaughter did not alter beef tenderness but FOR had greater off-fl avors according to both trained and descriptive sensory panelists.

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C. W. Cook

Papers

Palatability, Shelflife and Chemical Differences between Forage- and Grain-Finished Beef