No abstract

Changes in chemical composition and digestibility of peanut hulls after a variety of thermochemical treatments were monitored. Mineral acids and base under elevated temperature (121°C) were generally ineffective for decreasing the fibrous, lignocellulosic component of the hulls. Only nitric acid-treatment effectively decreased the relative lignin content of the hulls. The 1ignin:nitrogen ratio and carbohydrate content of treated hulls were both highly correlated with in-vitro digestibility. Overall, thermochemical treatments did not increase the digestibility of peanut hulls.

Changes in the chemical composition of peanut hulls inoculated with the white-rot fungus, Coriolus versicolor, the brown-rot fungus, Poria placenta, the imperfect mould, Trichoderma reesei, the bacterium Arthrobacter sp. KB-1, a mixture of the four organisms, and the natural microflora associated with freshly shelled hulls were monitored over a 90 day period. At the conclusion of the incubation period, the in-vitro digestibility of the hulls was determined. Although there was a substantial increase in protein content of all samples, there was drastic reduction in the in-vitro digestibility. Of the four components monitored, lignin content was found to be significantly negatively correlated with digestibility. These results suggest that pretreatment of peanut hulls with microorganisms alone will not increase the ruminant digestibility of the hulls.

Two bermudagrass (Cynodon dactylon L. Pers.) hybrids, ‘Tifton 78’ (Tilt‐78) and ‘Coastal’ (CBG), differ in dry matter digestibility. The objective of this study was to distinguish factors at the ultra‐structural level which may contribute to the differences in digestibility. Percent tissue types and histological reactions for lignin were similar for both cultivars. Scanning electron microscopy (SEM) leaf blades incubated in rumen fluid or cellulase revealed that non‐lignified tissues were digested to a greater extent in Tift‐78 than in CBG. Pretreatment with 0.1 M HCI or acid‐pepsin augmented cellulase digestion of the more slowly.degraded tissues. Transmission electron microscopy showed that Tift‐78 had a higher number of attached bacteria during incubation with rumen fluid. The ratio of attached Bacteroides to Ruminococcus morphotypes also varied between cultivars. After 24 h, Tift‐78 supported a population of predominantly Bacteroides (74%), whereas CBG had only Bacteroides. By 72 h, the attached population of Ruminococcus and Bacteroides had shifted to 59% and 17%, respectively, for Tift‐78 and 60% and 0%, respectively, for CBG. A SEM‐energy dispersive X‐ray spectroscopic analysis of the elemental composition of parenchymal bundle sheath and epidermal cell walls revealed that CI was significantly higher in untreated tissues of CBG than Tift‐78 but higher in Tift‐78 after cellulase incubation. The higher concentration of CI in CBG may prevent initial colonization of cell walls by specific bacterial morphotypes and reduce the number of attaching bacteria, thus reducing digestibility. Silicon, which has been described as an antiquality factor, did not differ between cultivars. Responses to enzymes indicated that structural carbohydrates in specific cell walls varied in digestibility between bermudagrass cultivars, and differences in cell walls further influenced the adherence of fiber‐digesting bacteria.

Nocardia polychromogenes is an aerobic, gram (+), non-motile, partially acid-fast actinomycete with primary mycelia that fragment into bacillary and coccoid elements.For scanning electron microscopy, N. polychromogenes culture strain Waksman 3409-A was grown on Potato Dextrose Agar at 25 C for 12-72 h. Five mm2 sections of the colonies, including portions of the interior and perimeter were fixed by exposure to osmium fumes for 16-24 h and air dried for 2 h. Specimens, mounted on stubs and sputter coated with gold, were viewed in a Cambridge Stereoscan Mark II scanning electron microscope. For transmission electron microscopy, the organism was grown on Potato Dextrose Agar at 25 C for 12-32 h. Whole colonies, 1-2 mm in diameter, were fixed by exposure to osmium fumes for 24 h. After suspension in noble agar, cells taken from the periphery of the fixed colonies were stained with 0. 5% uranyl acetate made in acetate-veranol buffer.