MEAT COMPOSITION AND PALATABILITY OF HOLSTEIN AND BEEF STEERS AS INFLUENCED BY FORAGE TYPE AND PROTEIN-SOURCE

This experiment determined meat composition and palatability changes resulting from feeding Holstein (HOL) and crossbred beef (XB) steers diets containing corn silage (CS) or alfalfa haylage (AH) (forage type) and soybean meal (SM) or fish meal (FM) (protein source). Fifty-nine steers (30 HOL and 29 XB) were randomly assigned to diet combinations for a 2 x 2 x 2 (breed x forage x protein) factorial arrangement. Steers were fed to a fat-constant end point (fat depth over the longissimus muscle measured by ultrasound: 1.0 cm XB, .6 cm HOL). Proximate and fatty acid analysis and sensory evaluation were conducted on a rib eye roast and steaks, respectively, removed from the left side of each carcass at ribs 9 to 12. Proximate analysis of the longissimus muscle showed no significant difference (P > .05) in moisture, protein, or fat content due to breed, forage, or protein treatment. Forage type had no significant effect (P > .05) on amount of individual fatty acids found in longissimus muscle. However, total polyunsaturated fatty acids were higher (P > .05) for AH than for CS-fed animals. Longissimus muscle from steers fed FM had higher palmitoleic and lower stearic acid contents (both P < .05) than longissimus muscle from animals fed SM. Muscle from HOL had higher palmitoleic and lower stearic acid contents than that from XB steers (both P < .05). There was no significant interaction (P > .05) of breed with either diet treatment for individual fatty acid contents. Trained sensory panelists found no differences (P > .05) in hardness, juiciness, number of chews, residual juiciness, or residual hardness due to breed, forage, or protein type. In the current study, HOL and XB steers fed to .6 cm and 1.0 cm of backfat depth, respectively, were similar in longissimus muscle composition and palatability.