Effects of a digestive modifier, browse plus on ruminal and intestinal breakdown of forages containing high tannin levels
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The potential for enhancement of forage utilization of two high tannin containing tropical browse trees and three legumes through the use of a digestive modifier called Browse Plus was investigated in this study. The study was carried out in 1995. The main objective of the study was to evaluate the potential for improving digestibilities of dry matter (DM) and crude protein (CP) of two browse tree species, namely; Acacia albida and Colophospermum mopane and three herbaceous legumes, namely; Chamaecrista rotundifolia, Stylosanthes scabra, and Stylosanthes guif/iensis by use of Browse Plus. The legumes were sampled at three’phases of growth in 1994, making a total of nine samples. Forages were obtained from Sanyati, a semi-arid area of Zimbabwe. Total tannin levels in the forage samples were determined using the radial diffusion technique and in WvoDM and CP digestibilities were determined using the mobile nylon bag technique following infusion of 0-3 g of Browse Plus Into rumens of each of the three cannulated Holstein steers that were used. Ruminal infusion of Browse Plus enhanced (P<0.05) DM and CP digestibilities of 9 and 10 of the 11 forages tested, respectively. Improvement in DM and CP digestibilities tended to be higher between Browse Plus inclusion levels 0-2 g, thereafter, improvement was minimal. These were, however, not significant. There was no relationship (P>0.05) between total tannin level, DM and/or CP digestibilities. The results from this study indicated that Browse Plus can improve DM and CP digestibilities of forages containing high tannin levels. This is likely to increase nutrient availability at the level of the small intestines, thereby enhancing utilization of such forages by ruminants. From the results, we recommend that Browse Plus be utilized at an inclusion rate of 2 g per animal per day in order to realize benefits from improved utilization of forages high in tannins.