Chemical composition of four parasitic plants harvested over a period of 6 months from two sites in Botswana

Abstract

Samples of four parasitic plants, Tapinanthus lugardii, Erianthenum ngamicum, Viscum rotundifolium, and V. verrucosum were obtained from Sebele Research Station and Sunnyside Ranch. Sampling took place in the 6 months (June–November) of 1998. The first 15–20 cm of the shoots (i.e. stem and leaves) were harvested and used to analyse for crude protein (CP), acid detergent fibre (ADF), condensed tannins and minerals. There was a significant species (P<0.001) and site (P<0.05) effect on CP, but no (P>0.05) month effect was observed. V. rotundifolium had the highest levels of CP, 128 compare to 119, 113 and 79 g/kg for T. lugardii, E. ngamicum and V. verrucosum, respectively. Samples from Sebele were higher in CP (118 versus 101 g/kg) than those from Sunnyside. Interaction between species and site was observed (P<0.05) for CP. However no interaction was observed for ADF even though both species and site effects were highly significant (P<0.001). Plants from Sebele had lower levels of ADF. ADF increased (P<0.01) from June to November as the plants matured. There was no difference (P>0.05) in calcium (Ca), phosphorous (P) and copper (Cu) between species. Month only had an effect (P<0.05) on P and Cu. Site effects were observed for Ca (P<0.001) and P (P<0.05) but not (P>0.05) for Cu. It is speculated that difference in soil type was responsible for difference in the level of Ca and P at the two sites. Interaction was observed for Ca (P<0.05) but not (P>0.05), for P and Cu. Though Ca was statistically the same throughout the sampling period it tended to increase with time. Condensed tannins were found to be significantly (P<0.001) affected by species and site, but not (P>0.05) by month. V. rotundifolium was found to have the lowest levels of condensed tannins (31 g/kg) than T. lugardii, E. ngamicum, and V. verrucosum (56, 67 and 75 g/kg, respectively). Samples from Sebele had the lower values for condensed tannins (37 versus 77 g/kg for Sebele and Sunnyside, respectively). Difference in chemical composition due to site may need to be considered when using these plants as feed for livestock.