Pig trypanosomiasis: effects of infection on feed intake, liveweight gain and carcass traits.

Forty growing pigs were used in an experiment to determine the probable cause of retarded growth or weight loss in animals suffering from trypanosomiasis caused by Trypanosoma brucei, T. congolense or T. simiae. Animals infected with T. brucei or T. congolense had mild or symptomless infections with no significant effect on packed cell volume (PCV), voluntary feed intake, mean liveweight gain, feed conversion efficiency, carcass traits or feed cost per unit of weight gain. Uninfected pigs gained slightly more and required slightly less feed per unit of weight gain than pigs infected with T. brucei or T. congolense but the differences were non-significant. Pigs infected with T. simiae showed a marked drop in PCV and a significantly poor performance which was reflected in curtailment of feed intake, impaired feed conversion efficiency, growth failure, poor carcass traits and extremely high and uneconomical feed cost per unit of weight gain. Growth failure or weight loss in trypanosomiasis would appear to be due largely to the combined effect of reduced feed intake and impaired efficiency of feed conversion.