Effects of exogenous fibrolytic enzymes on ruminal fermentation and digestion of Guinea grass hay

The objective was to determine the effects of an exogenous fibrolytic enzyme mixture (enzyme) on intake, digestion and ruminal fermentation of Guinea grass (Panicum maximum var. Mombasa) hay cut at 35 and 90 d of growth using four Suffolk lambs (74.0 ± 2.01 kg body weight) fitted with ruminal and duodenal cannulae. The experimental design was a repeated Latin Square within a 2×2 factorial arrangement (i.e., enzyme, 0 and 3 g/d/lamb; Guinea grass, 35 and 90 d). Crude protein (CP) intake was higher, but acid detergent fibre (ADF) intake was lower, with Guinea grass 35 d versus 90 d. Except for CP, daily duodenal and fecal flow of dry matter (DM), CP, neutral detergent fibre (NDF) and ADF were higher with Guinea grass 90 d versus 35 d. Ruminal, duodenal and total tract digestion, and ruminal ammonia and acetate were higher, but ruminal pH, propionate and butyrate were lower, with Guinea grass 35 d versus 90 d. Fibrolytic enzymes reduced duodenal ADF flow and forestomach digestion. There were no enzyme effects on DM intake, N balance, ruminal degradation, total tract digestion, ruminal fermentation, as well as ruminal protozoal counts. These exogenous fibrolytic enzymatic did not increase ruminal digestion of Guinea grass.