Rumen degradability of dehydrated beet pulp and dehydrated citrus pulp

Abstract

The rumen degradation of dry matter (DM) and crude protein (CP) of 10 samples of dehydrated beet pulp (DBP) and 2 samples of dehydrated citrus pulp (DCP) were studied in three rumen cannulated wethers using nylon bag and rumen outflow rate techniques. The animals were fed with a mixed diet of prairie hay and concentrate (2:1 on DM) at an intake level of 40 g DM·kg BW -0.75. The effective degradability (ED) values of all feeds of each group were estimated from the rumen outflow rate determined on a sample of each kind of pulp; no significant differences (P > 0.05) were observed between these values (4.66 and 3.52%·h-1, for DBP and DCP, respectively). The samples of DBP showed a great variability for the chemical composition as well as for both DM and CP degradation. Thus, the ED values of DM ranged from 41.0 to 70.8% and those of CP from 34.3 to 73.1%. Both values were correlated (r = 0.874; P < 0.001). A good prediction of the ED of DM (R 2 = 0.933) was obtained from the contents of neutral detergent fibre and acid detergent fibre as the first and second predictive variables. In the same manner, the best prediction (R2 = 0.954) of the ED of CP was derived from the concentrations of CP and neutral detergent fibre. For DCP samples, mean values of ED of DM and CP were 81.0 and 74.2%, respectively. The equation obtained from DBP to predict the ED of DM also allowed a close prediction in these last samples, which seems to indicate that DM degradation is conditioned by the same factors in both kinds of pulps. On the contrary, this fact was not observed for CP degradation.