Effects of Trypanosoma congolense and nutritional supplements on establishment and outcome of pregnancy in trypanotolerant Djallonke ewes

Interactions between Trypanosoma congolense and nutritional status were studied in 42 ewes, bred at the peak of parasitaemia after synchronisation of oestrus. As experimental design a randomised block design was used with four treatment combinations (2 x 2 factors), of which two were on a restricted diet (L), the remainder on an unrestricted diet (H) and half of each nutritional group infected with T. congolense (LI, HI), the remainder serving as controls (LC, HC). Severity of parasitaemia was not influenced by supplementation and mortality rates were higher in the HI and LC groups, but these differences were found not significant. Progesterone levels during the synchronised cycle were significantly lower in the infected groups. Levels of pregnant specific protein B (PSPB) in pregnant sheep at days 21 and 26 were not significantly affected by nutrition or infection, despite the tendency of a decrease in infected groups. T. congolense clearly affected establishment of pregnancy, as shown by lower rates of pregnancy and extended intervals between breeding and confirmation of pregnancy, nor was there any benefit of nutritional supplementation. Mean progesterone concentration during pregnancy, in those ewes which lambed, was not different between groups. The effect of the T. congolense infection on the outcome of pregnancy was not clear with the LI and HC performing well and poor pregnancy outcomes in groups HI and LC, although differences in litter size might explain these anomalies. It is concluded that the most pronounced effect of T. congolense was a negative influence on establishment of pregnancy, with nutritional supplementation unable to overcome this effect but having a beneficial influence on maintenance and successful outcome of pregnancy. However, individual exceptions indicate that same ewes cope better with thr negative effects of infection and poor nutrition. (C) 1998 Elsevier Science B.V.