Effects of supplemental fat on growth performance and quality of beef from steers fed corn finishing diets

To measure the effects of dietary fat on feedlot performance and carcass characteristics, and on beef appearance, moisture binding, shelf life, palatability, and fatty acid content, 126 crossbred beef steers (321.1 +/- 0.57 kg of BW) were allotted to a randomized complete block (3) design with a 3 x 2 + 1 factorial arrangement of dietary treatments. The main effects were level of yellow grease (0, 3, or 6%) and alfalfa hay (3.5 or 7%) in corn-based diets containing 15% potato by-product (PB). The added treatment was 6% tallow and 7% alfalfa in a barley-based diet containing 15% PB. Dry matter intake and ADG were not affected by diet; however, G:F and diet NE content increased linearly (P < 0.10) with yellow grease. Kidney, pelvic, and heart fat (2.0 to 2.3 +/- 0.07) and yield grade (2.8 to 3.1 +/- 0.09) increased linearly (P < or = 0.05) with yellow grease. Steers fed corn plus 6% yellow grease had lower (P < 0.05) beef firmness and beef texture scores but greater (P < 0.01) fat color score than those fed barley plus 6% tallow. Moisture retention of beef was not affected by dietary treatment, except purge score during retail storage, which was decreased linearly (P < 0.01) from 2.1 to 1.6 +/- 0.06 by level of yellow grease. Steaks from steers fed barley plus 6% tallow had greater (P < 0.05) shear force than those from steers fed corn plus 6% yellow grease, and beef flavor increased linearly (P < 0.05) from 6.2 to 6.7 +/- 0.11 as the level of yellow grease increased. Level of yellow grease linearly increased (P < 0.01) transvaccenic acid (TVA) by 61% and CLA content of beef by 48%. Beef from steers fed corn plus yellow grease had lower (P < 0.05) palmitoleic and oleic acids and greater (P < 0.05) linoleic, TVA, and CLA than beef from steers fed the barley-tallow diet. Feeding yellow grease increased diet energy content, which increased carcass fatness, and altered beef fatty acid content, which increased beef flavor without affecting moisture retention, shelf life, or cooking properties of the beef. Additionally, beef from steers fed corn plus 6% yellow grease was more tender and had more polyunsaturated fatty acid content and CLA than beef from steers fed barley plus 6% tallow.     

Comparison of a commercial enzyme-linked immunosorbent assay with electron microscopy, fluorescent antibody, and virus isolation for the detection of bovine and porcine rotavirus

The purpose in this study was to compare the sensitivity of a commercial enzyme-linked immunosorbent assay (ELISA) with electron microscopy (EM), fluorescent antibody (FA), and virus isolation (VI) for the detection of bovine and porcine rotavirus (RV). Seventy-three bovine and 116 porcine accessions were evaluated by 1 or all 4 diagnostic tests, where suitable specimens were available. For the bovine samples, agreement was 33% between FA and EM, 33% between FA and ELISA, and 92% between EM and ELISA. For the porcine samples, agreement was 79% between EM and FA, 72% between EM and ELISA, and 82% between ELISA and FA. Virus was isolated from 68% and 41% of the bovine and porcine fecal samples, respectively. Commercial ELISA was as sensitive as EM, but was more sensitive than FA or VI for the detection of RV in bovine feces. Electron microscopy was more sensitive than FA, ELISA, or VI for detection of RV in porcine feces. The ELISA was an advantageous alternative to the conventional methods of EM, FA, and VI for the diagnosis of RV in calf feces, but not for porcine feces.