THE EFFECT OF THE QUALITY OF ROUGHAGE ON THE COURSE OF TRYPANOSOMA-VIVAX INFECTION IN WEST-AFRICAN DWARF GOATS - I - ORGANIC-MATTER INTAKE,BODY-WEIGHT CHANGE AND EFFICIENCY OF NITROGEN-METABOLISM

Twenty nine West African Dwarf goats were randomly allotted to either a diet of pelleted lucerne with a high N content (Crude protein level = 172 g/kg DM; n = 14) or chopped grass straw with a low N content (Cr ude protein level = 68 g/kg DM; n = 15). Nine animals fed lucerne and 10 animals fed grass straw were infected with Trypanosoma vivax to stu dy its effects on feed intake and efficiency of N utilization during t he first 6 weeks of infection, Infection reduced organic matter intake (OMI) from 55 (s.e. 2) to 38 (s.e. 2) g kg(-0.75) d(-1) (P < 0.001). OMI was not affected by feed type (P > 0.10). The relative decrease of digestible organic matter intake (DOMI) due to infection was the same in animals fed lucerne or grass straw (36 and 35%). Retention of N wa s lower in infected animals and in animals fed grass straw. By relatin g N retention to DOMI the efficiency of N utilization, corrected for f eed intake level, was estimated. No effect of infection or feed type o n the efficiency of N utilization was detected. One overall regression equation was estimated: N Retention = -0.45 (s.e. 0.04) + 0.017 (s.e. 0.002) X DOMI (n = 29; r(2) = 0.86). Serum urea concentration was hig her in the goats fed lucerne than in the goats fed grass straw; only i n the lucerne group, infected animals showed a lower serum urea concen tration post infectio (p.i.) than control animals. Serum creatinine co ncentration was higher in grass straw-fed animals than in lucerne-fed animals. From the former group, infected animals had a lower creatinin e concentration p.i. than controls. It is concluded that infection aff ected feed intake, but not the efficiency of N utilization. (C) 1998 E lsevier Science B.V.