Cultures of lactobacilli identified as Lactobacillus acidophilus from the intestinal contents of young calves varied in their ability to grow in broth containing .3% oxgall compared with control broth. Frozen concentrated cultures were prepared from a strain exhibiting low tolerance to bile and from a strain exhibiting high tolerance to bile. Plate counts were comparable from the concentrated cultures before and after frozen storage on lactobacilli MRS agar with and without .15% oxgall. In a feeding trial involving newborn dairy calves supplementation of the diet with the more bile resistant strain of Lactobacillus acidophilus caused greater increases of numbers of facultative lactobabilli in the upper small intestines than did the strain exhibiting lower resistance to bile. It was not possible to determine whether the lactobacilli would prevent intestinal infections in the calves challenged with enteropathogenic Escherichia coli. This portion of the study failed as the challenge with Escherichia coli did not cause infections even in control animals.
Supplementation of dairy rations with steroidal sapogenins was evaluated in an in vitro, an in situ, and a production trial. Sixteen in vitro semicontinuous rumen cultures were supplied a 55:45 concentrate to roughage substrate with Sarsaponin concentrations of 0, 33, 55, and 77 ppm of air-dry feed for 22 d. Supplementation decreased protozoa numbers and increased bacterial numbers and acid detergent fiber digestion. Digestion of feed nitrogen tended to be lowest at the highest concentration of Sarsaponin, whereas microbial nitrogen output was similar for all concentrations. In rumen-cannulated animals fed a typical dairy ration, in situ rate of disappearance of organic matter, acid detergent fiber, and nitrogen of a complete ration substrate tended to be lower with 77 ppm added Sarsaponin. In a production trial, 16 primiparous dairy cows 6 to 10 wk postpartum were fed rations containing either 0 or 77 ppm Sarsaponin. Sarsaponin did not alter dry matter intake, digestibility, body weight change, or milk production and composition. Supplementation had no significant effect on ruminal fermentation in vivo as reflected by concentrations of ruminal ammonia nitrogen, blood urea, or molar ratios and concentrations of ruminal volatile fatty acids.
Immunoglobulin absorption by the calf has been the subject of considerable research. Despite these efforts little is known about the cytological events that occur at the level of the intestinal epithelial cell. These events have been studied extensively and characterized in the laboratory rodent; however, there have been few attempts to make corollaries between the two species. All neonatal animals display certain similarities in their intestinal morphology that may be correlated, with immunoglobulin absorption. Selectivity in absorption appears to be variable among neonatal animal species; however, all demonstrate some selectivity. Selectivity in absorption implies that receptors are a necessary component in the transport of immunoglobulins. Selectivity further requires binding of immunoglobulins to an endocytic vesicle membrane to ensure transport through the cell, circumvention of intracellular digestion, and release at the basolateral cell membrane. A decrease of immunoglobulin absorption may be accomplished in a variety of ways such as competition between intestinal microbes and immunoglobulins for a common receptor on the intestinal epithelial cell. An additional consideration is aberrant synthesis or recycling of the cell membrane receptor, as induced by metabolic decelerators such as cortisol. Failure to recycle immunoglobulin receptors also would decrease efficiency of absorption.
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