Changes in small intestinal morphology and flora associated with decreased energy digestibility in calves with naturally occurring diarrhea
Youanes, Y.D.; Herdt, T.H.
American Journal of Veterinary Research 48(4): 719-725
1987
ISSN/ISBN: 0002-9645 PMID: 3592372 Document Number: 291662
Fecal composition was studied in 5 healthy Holstein calves and in 10 with naturally occurring diarrhea. The calves were between 5 and 21 days of age. The mean fecal contents of fat, lactate, and acetate were higher in the calves with diarrhea than in the healthy calves (P < 0.01). On the basis of calculated values, the mean caloric uptake from milk was decreased by 31% in diarrheal calves, compared with that in controls. At least half of the diarrheal calves were calculated to be in negative energy balance during the fecal collection period. This occurred in spite of consumption of a diet sufficient to provide more than enough energy for maintenance in healthy calves. The mean values for villous lengths were decreased at all portions of the small intestine in the calves with diarrhea, compared with those values in healthy calves. Similarly, the mean intestinal epithelial lactase activities were decreased in the calves with diarrhea, compared with those activities in healthy calves. Villous length was negatively correlated with fecal lactate content (r = -0.88 in the duodenum, r = -0.66 in the jejunum, and r = -0.80 in the ileum), but not with fecal fat content. Intestinal lactase activity in the cranial portion of the intestine tended to be negatively correlated with fecal lactate content. The mean concentration of total viable bacteria in the ileum was 1,000-fold higher in the diarrheal calves than in the healthy calves (109 vs 106/5-cm intestinal segment; P < 0.001), whereas the mean concentrations of total viable bacteria in the duodenum and jejunum of healthy and diarrheal calves were approximately the same. The concentration of coliform organisms was higher in the principal calves than that in the healthy calves in all 3 small intestinal sections (P < 0.05). The concentrations of coliform organisms in the duodenum was positively correlated with fecal lactate content (r = 0.77, P < 0.05). It was concluded that fat and carbohydrate malabsorption occurs frequently in calves > 5 days of age that have diarrhea. The accompanying decrease in dietary energy digestibility was substantial and may contribute to the death of these calves, particularly in cold weather. Small intestinal epithelial damage seemed to cause carbohydrate malabsorption, but the mechanism responsible for fat malabsorption was not apparent. Small intestinal bacterial overgrowth with a predominance of coliform organisms is common in calves with diarrhea and malabsorption and its occurrence is probably independent of the inciting cause.