Physical form of maize grain in finishing rations of ram lambs

English: The effect of whole (WMG), ground (GMG) and fine (FMG) maize grain in finishing rations for lambs containing 20 and 40% lucerne hay respectively was investigated. Thirty 3-month-old SA Mutton Merino lambs were randomly allocated to 6 treatments of 5 animals each. A digestibility and production study was carried out (60 lambs in total). All lambs were kept in individual pens for the duration of the various studies. The dry matter intake (DMI) of the lambs in the digestibility study consuming the ration with WMG was significantly (P=0.0052) lower than those fed FMG. Processing of maize grain resulted a significant (P<0.05) reduction in the apparent digestibility of dry matter, crude protein, acid detergent fibre and gross energy as well as digestible crude protein and metabolisable energy (ME). In contrast with DMI (P>0.05) the apparent digestibility of dry matter, crude protein and gross energy were significantly (P<0.05) decreased with an increase in roughage level to 40%. Acid detergent fibre digestibility showed no statistical significant (P>0.05) differences between dietary roughage levels. Lucerne hay level did not influence (P>0.05) the ME-content of the finishing rations within a specific physical form. Physical form of maize grain in finishing rations for lambs did not significantly (P>0.05) influence DMI, feed conversion and carcass characteristics. The inclusion of FMG in a finishing ration with 40% lucerne hay resulted in a significant (P=0.0013) lower MEintake. A significantly (P<0.05) poorer weight gain and energy efficiency were observed for lambs fed WMG in the ration. The inclusion of 20 and 40% lucerne hay in finishing rations of lambs did not significantly (P>0.05) influence DMI, ME-intake and weight gain as well as feed and energy efficiency. A higher (P<0.05) carcass weight and dressing percentage occurred when 20% compared to 40% lucerne hay was included in the lamb-finishing ration. It was concluded that the physical form of maize grain in finishing rations has no influence on the performance of lambs. Accordingly no physical form x roughage level (20 to 40% lucerne hay) interaction exists in finishing rations for lambs.