Masters Theses

Date of Award

3-1977

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science and Technology

Major Professor

M.J. Riemann

Committee Members

S.K. Winfree, W.R. Backus

Abstract

Thirty-nine steers were allotted in three feeding treatments (pasture, limit-grain-fed and grain fed Ad libitum) so the effect of feed source (pasture versus limit-fed) and level of energy intake (pasture and limit-fed versus fed Ad libitum) on certain carcass, cooked meat and histological characteristics could be evaluated.

The pasture steers had higher percentages, on a live weight basis of edible offal (P < .01) and inedible offal (P < .0001) than the limit-fed steers. Pasture steers had lighter slaughter weights (P < .01), lighter chilled carcass weights (P < .0001), less fat over the 12th rib (P < .0001), smaller loin eyes (P < .05) and produced less total pounds (P < .0001) of retail meat than the limit fed steers. As expected, the pasture steers had lower estimated percent fat (P < .05) expressed as a percent of the dressed carcass. There was no difference in percent lean between pasture and limit-fed steers. Carcasses from the pasture steers had less finish over the first sacral vertebra (P < .05) and chilled at a significantly faster rate but there was no statistical difference in post-mortem muscle pH. Taste panelists rated steaks from the pasture steers lower for tenderness (P < .0001), flavor (P < .01) and overall acceptability (P < .001). Warner-Bratzler Shear values were higher (P < .0001) for the pasture steers.

The limit-fed steers had higher marbling scores (P < .001) and thus higher quality grades (P < .0001) than the pasture steers.

Steers on the high energy diet were heavier at slaughter (P < .0001), had heavier hot carcass (P < .0001) and chilled carcass weights (P < .0001) and yielded more pounds of retail meat (P < .0001) than either the pasture or limit-fed groups. The Ad libitum fed steers had larger (P < .01) loin eyes, more fat over the 12th rib (P < .0001) and higher yield grades (P < .0001), Steers on the high energy diet were more highly marbled (P < .0001) and had higher quality grades (P < .0001), Estimations of carcass composition, based on the 9-10-11 rib separation, showed a higher percentage of fat (P < .0001) and bone (P < .01) in the Ad libitum fed steers as compared to the low energy fed steers. Ad libitum fed steers had lower percentages of inedible offal (P < .0001), head (P < .001) and shank (P < .0001) on a live weight basis. Due to greater fat thickness (P < .01) (measured at the first sacral vertebra) carcasses of the Ad libitum fed steers chilled at a significantly slower rate. The pH was lower at six hours (P < .0001) and 12 hours (P < .05) post-mortem in the high energy fed steers but at 24 hours was the same as the low energy fed steers. An inverse relationship was found between temperature and pH, Carcasses with lower muscle temperatures had higher pH values, indicating the lower temperature inhibited enzymatic activity and glycogen breakdown. Taste panelists rated steaks from the Ad libitum fed steers higher on tenderness (P < .01), juiciness (P < .05) and overall acceptability (P < .001). Warner-Bratzler Shear values were lower (P < .01) for steaks from the high energy fed steers.

There were no statistical differences found in sarcomere lengths but there was a trend that agreed with both taste panel tenderness and Warner-Bratzler Shear scores. The pasture cattle had the shortest sarcomeres (X = 2.33μ) while there was no difference between the limit fed and Ad libitum fed steers (X = 2.42μ, X = 2.41μ, respectively).

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