Determining the nutritive value of some commercial pulse screenings using in sacco and in vitro methods

Abstract

The present study aimed at determining in sacco and in vitro the nutritive value of lentil screenings (LS), common vetch screenings (CVS) and bitter vetch screenings (BVS). For this purpose, three experiments (Exp.) were conducted. Ruminal degradation characteristics of the screenings were determined in Exp. 1 by the nylon bag technique using three ruminally fistulated rams. Gas production kinetics, and ruminal degradability and fermentation indices of the screenings were determined using 144 and 24-h incubations, respectively in Exp. 2. In Exp. 3, a basal growing ration for lambs (control) was supplemented by 175 or 350 g/kg of either LS, CVS or BVS (LS175, LS350, CVS175, CVS350, BVS175 and BVS350 respectively), and ruminal degradability and fermentation of the rations were evaluated in vitro. Soluble and potentially degradable fractions of protein were 0.321 and 0.719, 0.362 and 0.688, and 0.333 and 0.707, for LS, BVS and CVS respectively. Metabolisable energy was 11.1, 11.6 and 12.1 MJ/kg DM for LS, BVS and CVS respectively. The screenings had comparable gas production profiles, ruminal digestibility and total volatile fatty acid concentration. However, CVS and BVS had a higher propionate and a lower acetate:propionate ratio than LS (P < 0.05). Including BVS and LS in the mixed ration increased total volatile fatty acid at both inclusion levels, but only BVS enhanced propionate proportion and lowered the acetate:propionate ratio (P < 0.05). These results revealed that these screenings have a good nutritional value and can be used in ruminant diets without adversely affecting the rumen fermentation.