DIGESTIBILITY AND NITROGEN-BALANCE IN LAMBS FED GRAIN-SORGHUM SILAGE, SWEET SORGHUM SILAGE OR FESCUE HAY

Twelve Suffolk wether lambs, averaging 47.3 kg BW, were fed in a four-treatment digestion trial: 1. Fescue hay (FH); 2. Grain sorghum silage (GSS); 3. Brandes sweet sorghum silage (BS); and 4. Theis sweet sorghum silage (TS). Grain and sweet sorghums were harvested at the late dough stage. Lambs had ad libitum access to their respective feeds. In addition, they received 454 g concentrate daily, Digestibility of DM, OM, CP, ash, GE, and NDF was comparable (P > 0.05) among treatment groups. Lambs fed GSS had lower (P < 0.05) digestibility of ether extract (EE) than those fed BS, TS, or FH. Higher (P < 0.05) digestibility of ADF occurred in lambs fed BS compared to those fed GSS or TS. Both sweet sorghum silages had higher (P < 0.05) cellulose digestibility than GSS. Percent absorbed N retained was comparable among treatment groups. Plasma urea N was higher (P < 0.05) in lambs fed BS than in those fed TS. Higher (P < 0.05) rumen ammonia N was found in lambs fed FH and BS than in those fed GSS or TS. Ruminal VFA was comparable among treatment groups. Results of this study suggest that nutrients in the diets were utilized similarly.