K. Larry Smith

Enteric viral infections of calves and passive immunity.

Abstract At least eight viruses have been identified, four within the last 5 yr, that produce diarrhea and pathological intestinal lesions in experimentally inoculated calves. Coronavirus and rotavirus frequently are associated with the neonatal calf diarrhea syndrome, but the etiologic role of the newly identified viruses is undefined. All diarrheal viruses replicate within small intestinal epithelial cells, resulting in variable degrees of villous atrophy. Immunity against these viral infections, therefore, must be directed toward protection of the susceptible intestinal epithelial cells. Because most of these viral infections occur in calves<3 wk of age, passive lactogenic immunity within the gut lumen plays an important role in protection. This report reviews methods of boosting rotavirus antibody responses in bovine mammary secretions and analyses of passive and active immunity in calves supplemented with colostrum and challenged by rotavirus. Results indicate rotavirus immunoglobulin G1 antibodies in colostrum and milk were elevated after intramuscular and intramammary vaccination of pregnant cows with an Ohio Agricultural Research and Development Center rotavirus vaccine but not after intramuscular immunization with a commercial rota-coronavirus vaccine. Feeding colostrum from intramuscular plus intramammary immunized cows to newborn calves challenged by rotavirus prevented diarrhea and shedding of rotavirus.

Managing environmental mastitis.

Many of the practices and principals of management for reducing the exposure of dairy cows to environmental mastitis pathogens were introduced a quarter of a century ago22–25 and have been the subject of numerous reviews.1,3,21 The common theme for reducing mastitis pathogens in the cows’ environment is reducing moisture and organic contamination.1 Frequent manure removal, avoiding overstocking of cows, taking precautions to eliminate stagnant water around cows, and providing clean, dry inorganic bedding for cows to lay on are important management considerations. These factors of environmental hygiene transcend stall barns, manure pack barns, open corrals, and pasture systems. The emphasis of control should center on protecting periparturient animals during wet, hot periods of the year when mastitis pathogen growth in the environment is greatest. As the dairy industry in North America changes and progresses to adapt to economic, social, and environmental demands, the old adage of keeping cows cool, dry, and comfortable remains paramount in managing environmental mastitis.

Electroimmunodiffusion on cellulose acetate: A rapid method for analysis of bovine lactoferrin in chromatography effluents☆

Abstract The cellulose acetate EID method is described in terms of the dynamic behavior of the system relative to electrophoresis time, antiserum concentration, and antigen concentration. As expected, the behavior of the system is virtually identical to the agarose EID system described by Laurell (4). The method has been applied to the direct quantitation of the milk iron-binding protein lactoferrin and its use in determining the elution profile of this nonenzymatic protein from chromatography effluents has been demonstrated. Guidelines are given for the development of the assay toward other proteins.