Sixteen growing Angora male kids weighed average 14.5 kg live body weight and aged about seven months were divided into four similar groups (4 kids each) to carry out of feeding trial. The kids were assigned randomly to fed one of the following four experimental rations:
Group 1 : Concentrate feed mixture (CFM) + rice straw (control ration, G1).
Group 2 : G1 + 1.3% urea of the CFM (without bentonite, G2).
Group 3 : G2 + 2.5% bentonite of the CFM (G3).
Group 4 : G3 + 5% bentonite of the CFM (G4).
Four digestibility trials were carried out by using three animals from each group at the end of the feeding trial to evaluate the experimental rations.
Results indicated that digestibility of the dry matter (DM), crude protein (CP), crude fiber (CF), ether extract (EE) and nitrogen free extract (NFE) and nutritive values as total digestible nutrients (TDN) and digestible crude protein (DCP) improved by adding bentonite clay to the concentrate mixtures. Values of pH were unaffected, while ruminal ammonia nitrogen (NH3-N) concentration increased significantly (P<0.05) in all groups that fed diets containing urea comparing with the control group, but the groups fed the diets containing bentonite (G3 and G4) had a lower (P<005) NH3-N concentration comparing with those fed ration containing urea without bentonite (G2). However, total ruminal volatile fatty acids (VFA's) concentrations indicated a contrarily trend with that of NH3-N for G3 and G4 compared to G2.
Blood urea and globulin concentrations decreased (P<0.05) by addition of bentonite, while most of blood constituents slightly fluctuated by adding bentonite to concentrate ration.
Average daily gain, dry matter intake and nitrogen retention, were improved by adding bentonite compared to the ration containing urea-only.
Feed conversion efficiency (kg DM/kg gain) increased by 15.96 and 23.48%, also economical efficiency increased by 18.62 and 33.51%, however, feed cost decreased by 15.76 and 25.14% for groups 3 and 4 (fed rations containing bentonite), respectively compared to group 2 (fed ration containing urea without bentonite).