RESUMEN
Data on porcine and bovine bone marrow composition indicate high calcium content, which may be erroneously elevated owing to the marrow recovery process. A method of bone marrow recovery was developed that involved passing marrow extracted from bone through a filter-press mechanism to remove very fine bone particles and dust, allowing a more accurate analysis of marrow. Calcium values were reduced approximately 90% and ash values reduced more than 50% compared to other reported data. The new recovery method did not require sawing away the hard bone and it removed particulate that may have interfered with analyses. Bone marrow was characterized by bone type. Rib bone marrow had higher protein, iron, non-heme iron and total pigment than scapula, aitch/hip bone or vertebrae marrow. Fat ranged from 17·81 to 26·76% and calcium ranged from 27·25 to 44·33mg 100g(-1) among bone types. The pH of bone marrow ranged from 7·14 to 7·53. Bone marrow appears to contribute to some of the properties of meat obtained from advanced meat recovery systems.
RESUMEN
Cull cows, thin to moderate in initial condition scores, were randomly assigned within breed to slaughter groups and fed a high-concentrate diet for 0, 14, 28, 42 or 56 d (n = 40). Carcass data were collected, and one side of each carcass was fabricated into boneless subprimals, lean trimmings, fat, and bone. Live and carcass weights, ADG, and dressing percentage increased through 28 d of feeding (P < .05), and lean firmness increased (P < .05) through 42 d of feeding. Adjusted preliminary yield grades and final yield grades increased (P < .05) with feeding, but not to levels requiring knife trimming of fat. Fat color became whiter (P < .05) but marbling was not affected (P > .05) by feeding. Weights of fat-free lean, fat, and bone and percentages of fat in soft tissues of cow carcasses increased (P < .05) by 28 d on feed. Overall steak tenderness was higher (P < .05) for cows fed 56 d than for cows fed 0 or 14 d. Warner-Bratzler shear force was not affected by feeding. Amounts of soluble collagen increased (P < .05) in the longissimus muscle between 0 and 28 d on feed, and total collagen decreased (P < .05) in the biceps femoris muscle between 0 and 42 d on feed. Continental European cow carcasses yielded more fat-free lean and less fat (P < .05) and dairy cows generally provided the most tender product across all slaughter periods. In general, sensory tenderness and yields of cow carcass components increased without requiring excessive trimming of fat by feeding cull beef and dairy cows for periods up to 56 d.