Performance of lambs fed either hay or silage supplemented with canola or fish meals

Forty-eight lambs (29.0 +/- 4.7 kg BW) were used to study the effects of protein supplementation of forages on performance and diet digestibility. Lambs were fed grass hay or silage ad libitum plus a daily supplement of either: C, a control supplement supplying 1.2 g kg(-1) BW of dry molasses and 0.6 g kg(-1) BW of minerals, vitamins and lasalocid; CM, control supplement + 5.48 g kg(-1) BW of canola meal; or FM, control supplement + 3 g kg(-1) BW of fish meal. Apparent digestibility of all dietary components was higher in lambs fed silage than in those fed hay (P < 0.04). Addition of CM or FM improved apparent digestibility of energy and crude protein (CP) of lambs fed hay (P < 0.02) and CP digestibility of lambs fed silage (P < 0.01). Apparent digestibility of CP was higher in lambs fed FM than in those fed CM with either hay or silage (P < 0.03). Addition of CM or FM tended to decrease ADF digestibility of silage-based diets (P < 0.06). Apparent ADF digestibility of hay-based diets was lower in lambs fed CM than in those fed FM (P < 0.02). Forage DM intake was similar for all treatments. Addition of CM or FM to the diets improved average daily gains by 24% (P < 0.03), an effect that was higher with hay (35.1%, P < 0.02). Feed efficiency was 23.6% better in lambs fed protein-supplemented hay than in those receiving C (P < 0.04). Neither dressing percentage nor carcass lean yield was affected by protein supplementation. Digestible DM and TDN intakes were higher in lambs fed silage (P < 0.03) as a result of higher apparent digestibility for silage than hay. Furthermore, CM increased TDN intake by 7.6 and 8.2% in lambs fed hay and silage, respectively, compared with lambs fed FM. Addition of canola and fish meals improved forage nutritive value for lambs.