Daniel M. Schaefer

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Population development of key groups of bacteria involved in municipal refuse conversion to methane was measured from the time of initial incubation through the onset of methane production. Hemicellulolytic bacteria, cellulolytic bacteria, hydrogen-producing acetogens, and acetate- and H(2)-plus-CO(2)-utilizing methanogens were enumerated by the(More)
Ammonia saturation constants were determined for representative pure cultures of predominant, anaerobic, fermentative rumen bacteria. Based on growth experiments with ammonia limited continuous cultures, average estimates for ammonia saturation constants of Bacteroides amylophillus and Bacteroides ruminicola were 10.5 and 23.5 microM ammonia-nitrogen,(More)
Supplementary alpha-tocopheryl acetate (vitamin E) was fed to provide none (E0), 2,000 IU/d (E2000), 5.8 IU/kg live weight (E5.8), or 8.6 IU/kg live weight (E8.6) to steers that were individually fed mainly a corn diet. Three steers were placed on each of 10 treatments: E0, E2000, E5.8, E5.8 to d 126 then E0 to d 266, E0 to d 126 then E5.8 to d 266, E8.6,(More)
Color is a primary factor used by consumers to judge beef quality, especially freshness. Recent studies indicate that dietary supplementation of vitamin E to beef cattle increases the alpha-tocopherol concentration in muscle and its membranous subcellular fractions. The increased tissue alpha-tocopherol concentration protects not only membranal lipids but(More)
Effects of dietary supplementation and postmortem addition of vitamin E on pigment and lipid stability in raw ground beef were examined in this study. Six Holstein steers were fed a control diet for 232 or 252 d and six Holstein steers were supplemented with 1,500 IU of vitamin E per animal daily for 232 or 252 d. Three aliquots of ground beef from each(More)
The effects of modified atmosphere (80% O(2): 20% CO(2)) and illumination on the discoloration rate of pork bone (lumbar vertebrae) and muscle (longissimus lumborum), and on muscle lipid stability were studied in vitamin E-supplemented and unsupplemented pigs. Bone-in pork chops were placed in 80% O(2): 20% CO(2) at 0 °C and stored for 5 days in the dark.(More)
Three experiments were conducted to examine the effects of vitamin E supplementation on feedlot cattle. Vitamin E supplementation did not affect feedlot performance or carcass characteristics of cattle fed a high-concentrate diet (P greater than .1). The major finding was the effectiveness of vitamin E in extending the color stability of displayed beef (P(More)
Saponins isolated from alfalfa by ethanol extraction and acid hydrolysis were incorporated into protein-free purified diets at 0, .5, 1, 2, and 4% of dietary dry matter to investigate the effect of saponins on fermentation by mixed rumen bacteria maintained in continuous culture. Inoculum was obtained from a lactating dairy cow fed alfalfa hay and a 13%(More)
A study of Escherichia coli O157:H7 transmission and shedding was conducted with bull calves housed in individual pens within a confined environment. For comparative purposes, the numbers and duration of E. coli O157:H7 shedding in naturally infected calves were monitored after a single purchased calf (calf 156) tested positive prior to inoculation. During(More)
Color stability was investigated in longissimus lumborum (LL), semimembranosus (SM), and gluteus medius (GM) muscles from Holstein steers fed diets including doses of alpha-tocopheryl acetate that were 0 (EO), 250 (E250), 500 (E500), and 2,000 (E2000) mg.steer-1.d-1 for 42 or 126 d. Longissimus lumborum was aged for 14, 28, and 56 d and GM and SM were aged(More)