Masters Theses

Date of Award

5-1990

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science and Technology

Major Professor

M. James Riemann

Committee Members

H. Dwight Loveday, William R. Backus

Abstract

Angus, Hereford, Angus X Hereford and crossbred steers were used to determine the effect of grain feeding time (DOF) and pasture type on carcass traits and sensory, chemical and physical characteristics of the longissimus muscle. The steers were backgrounded for 8 mo. on either ryegrass (n=18), orchardgrass (n=18), Kentucky 31 Fescue (n=18) or fescue-clover mixed (n=32) pasture. They were placed in a drylot in July and August, fed whole shelled corn, and serially slaughtered. Steers from the ryegrass, orchardgrass, Kentucky 31 Fescue and fescue-clover mixed pasture all had grain feeding periods of 0, 56, and 112 DOF. The steers from the fescue-clover mixed pasture had additional DOF increments of 28, 84 and 140.

Carcass weights increased linearly from 191.7 kg (0 DOF) to 300.6 kg (112 DOF). Adjusted fat thickness also increased (P<.05) linearly from 4.3 mm (0 DOF) to 11.4 mm (112 DOF). The least square mean quality grade and yield grade for the 0, 56 and 1 12 DOF steers were high Standard, 1.8; average Select, 2.1; and low Choice 2.8, respectively. The least square mean quality and yield grade for the steers from the ryegrass, Kentucky 31 Fescue, orchardgrass, and fescue-clover mixed pastures were low Select, 2.25; low Select, 2.21, average Select, 2.61; and low Select, 1.96, respectively.

The 0 DOF steers had less (P<.05) lipid (2.57%) and more (P<.05) moisture (75.42%) in the uncooked longissimus muscle than the 56 or 112 DOF groups. The 0 DOF cattle had more (P<.05) soluble collagen (2.93 mg/g) than the 56 DOF (2.64 mg/g) or the 112 DOF (1.86 mg/g) steers. There was no difference (P>.05) In total collagen for any of the DOF groups. Pasture type had no effect (P7gt;.05) on soluble collagen or total collagen.

Flavor of the loin steaks changed (P<.05) from 0 DOF (slight milky-oily) to 56 DOF (slight beef fat flavor), but did not change (P>.05) from 56 to 112 DOF. Steaks became juicier, more tender, and higher in acceptability (P<.05) as DOF increased from 0 to 112 DOF. Pasture type had no affect (P>.05) on any of the sensory parameters of flavor, juiciness, tenderness or overall acceptability.

The fescue-clover backgrounded steers were fed in drylot for up to 140 DOF. Quality grade improved (P<.05) from 0 DOF (low standard) up to 140 DOF (high good). Numerical yield grade increased (P<.05) from 0 DOF (1.4) up to 140 DOF (2.6). Wholesale cut weights also increased with increasing DOF. There was no difference (P>.05) in total collagen content across DOF. Sensory panel evaluated tenderness, juiciness and overall acceptability scores tended to improve up to 140 DOF.

Warner-Bratzler shear force values were obtained for medial, center and lateral sections of the loin steaks. Warner-Bratzler shear force data from the 0, 56 and 112 DOF cattle were pooled. Shear force values for the cores taken from the center of the steaks were lower (P<.05) than shear force values for cores taken from the medial and lateral sections.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS