Omasal flow of soluble proteins, peptides, and free amino acids in dairy cows fed diets supplemented with proteins of varying ruminal degradabilities.

Three ruminally and duodenally cannulated cows were assigned to an incomplete 4 x 4 Latin square with four 14-d periods and were fed diets supplemented with urea, solvent soybean meal, xylose-treated soybean meal (XSBM), or corn gluten meal to study the effects of crude protein source on omasal canal flows of soluble AA. Soluble AA in omasal digesta were fractionated by ultrafiltration into soluble proteins greater than 10 kDa (10K), oligopeptides between 3 and 10 kDa (3-10K), peptides smaller than 3 kDa (small peptides), and free AA (FAA). Omasal flow of total soluble AA ranged from 254 to 377 g/d and accounted for 9.2 to 15.9% of total AA flow. Averaged across diets, flows of AA in 10K, 3-10K, small peptides, and FAA were 29, 217, 50, and 5 g/d, respectively, and accounted for 10.3, 71.0, 17.5, and 1.6% of the total soluble AA flow. Cows with diets supplemented with solvent soybean meal had higher flows of Met, Val, and total AA associated with small peptides than those whose diets were supplemented with XSBM, whereas supplementation with corn gluten meal resulted in higher total small peptide-AA flows than did XSBM. Averaged across diets, 27, 75, and 93% of soluble AA in 10K, 3-10K, and peptides plus FAA flowing out of the rumen were of dietary origin. On average, 10% of the total AA flow from the rumen was soluble AA from dietary origin, indicating a substantial escape of dietary soluble N from ruminal degradation. Omasal concentrations and flows of soluble small peptides isolated by ultrafiltration were substantially smaller than most published ruminal small peptide concentrations and outflows measured in acid-deproteinized supernatants of digesta.

The occurrence of fungi in bovine tissues in relation to portals of entry and environmental factors.

The occurrence of fungi in tissue specimens from 72 cattle was examined by culture, histopathology and indirect immunofluorescence staining (IIF). Groups of 12 animals each had been fed either concentrate or roughage and had been housed either in tie stalls, on slatted floors or on deep bedding. Specimens were obtained from the lung, omasum and Peyer's patches of the ileum and corresponding lymph nodes. Both hyphae and spores were made visible by IIF and by combination of IIF, morphology and conventional staining it was possible to differentiate between aspergilli and zygomycetes. In the lungs, aspergilli were detected at the same rate by morphology and IIF, whereas zygomycetes were found nearly twice as often by IIF than by culture. Fungi in pulmonary tissue were most frequent in cattle tied or kept on deep bedding (P < 0.01) as assessed by IIF. Within lymph nodes only spores were found, and Aspergillus fumigatus was the predominant species. Lesions devoid of fungi, especially ulcerations, were observed on the edges of the largest omasal laminae with a notable preference for the aboral third. The localization and histopathology suggested a reflux of acid abomasal contents to be the pathogenic principle. Granulomas with centrally located plant material were found more frequently in cattle fed roughage than in cattle fed concentrate (P = 0.01) and were differentiated from mycotic granulomas.

Ruminant forestomach and abomasal mucormycosis under rumen acidosis.

Spores of Absidia corymbifera were inoculated orally into sheep with ruminal acidosis produced by feeding barley. Lesions, which developed in forestomachs of all four inoculated cases, included desquamation of superficial layers of the mucosae and focal necrosis from lamina propria to muscular layers. Granulomatous lesions were in the submucosa of three sheep. Lesions in the abomasum (two sheep) included focal necrosis, diffuse hemorrhages, and infiltration of neutrophils. All lesions were accompanied by mycotic proliferation. These results show that A. corymbifera can invade forestomach mucosae through degenerate epithelium resulting from ruminal acidosis.