APPARENT DIGESTIBILITY OF NUTRIENTS AND NITROGEN-BALANCE DURING EXPERIMENTAL-INFECTION OF CALVES WITH EIMERIA-BOVIS

The apparent digestibilities (AD) of dry matter (DM), organic matter ( OM), crude ash (CA), crude fiber (CFi), crude fat (CFa) crude protein (CP) and nitrogen-free extracts (NFE) and the nitrogen balance were in vestigated during experimental Eimeria bovis coccidiosis in calves. no ninfected pair-fed controls and controls fed on a normal plan of nutri tion were included in the study to allow differentiation between the e ffects of infection and of changes in feed intake. Primary infection w ith 5 X 10(4) oocysts (n = 4, group A) caused mild diarrhea and calves infected primarily with 1 X 10(5) oocysts (n = 5, group B) suffered f rom mild (three calves) to severe hemorrhagic (two calves) diarrhea. N o clinical disease was seen after reinfection of the group A calves wi th 1 X 10(5) oocysts. The primary infection with 5 X 10(4) oocysts or reinfection with twice the primary inoculum did not affect AD of nutri ents or the overall nitrogen balance (RT). AD of DM, NFE or OM were hi gher in group B during patency and in the pair-fed group C calves (n = 5) than in the reinfected but healthy group A calves. AD of CFi of th e group B calves even exceeded the values of the pair-fed controls. Th e two calves of group B that suffered from hemorrhagic diarrhea and an orexia had low values of AD of CP during the acute phase of the diseas e and the plasma nitrogen levels were reduced in this group. Severe cl inical coccidiosis transiently reduced the nitrogen balance. It is con cluded that the transient increase of AD of nutrients, especially of C Fi, during clinical coccidiosis reflect hypomotility and that anorexia and intestinal leakage impair the nitrogen balance and cause weight d epression. (C) 1998 Elsevier Science B.V. All rights reserved.