DETERMINATION OF LACTOSE AND XYLOSE MALABSORPTION IN PRERUMINANT DIARRHEIC CALVES

In preliminary studies feeding the poorly absorbed carbohydrate sorbit ol at 2.3 g/kg body weight as an indication of maximal fermentative ca pacity failed to produce the expected large increase in breath hydroge n excretion but did produce a transient diarrhea in five out of six co ntrol calves. Twelve healthy control and eighteen diarrheic calves wer e fed lactose or D-xylose on consecutive days at 1.15 g/kg body weight and a concentration of 46 g/L. Breath and blood samples were collecte d at 1 h intervals from 0 to 7 h. After administration of lactose, the re was a significant increase in breath hydrogen excretion in diarrhei c versus control calves. The increase in plasma glucose concentrations was delayed in diarrheic calves but the area under the absorption cur ve was similar in control and diarrheic calves. After administration o f D-xylose, breath hydrogen excretion did not increase significantly b ut plasma D-xylose concentrations were significantly reduced in diarrh eic calves. The pathogens commonly isolated from the feces were Crypto sporidium species, rotavirus and coronavirus. The number of pathogens and the severity of the calves' acid-base deficit were not related to the severity of carbohydrate malabsorption. Decreased absorption of la ctose and D-xylose may be the result of intestinal villous atrophy cau sed by viral or parasite infection. It was concluded that carbohydrate malabsorption rather than a specific lactose maldigestion is a signif icant problem in diarrheic calves. Diarrheic calves appear to digest a nd absorb lactose when fed in small amounts.