The Effect of Concentrate- and Silage-Based Finishing Diets on the Growth Performance and Carcass Characteristics of Suffolk Cross and Scottish Blackface Lambs

Abstract

In the present study 48 Suffolk x Mule (S x M) and 48 Scottish Blackface (SBF) wether lambs were used in a 2 breeds x 2 diets x 4 replications factorial experiment with 6 lambs per pen. Lambs were offered either a concentrate (CONC) finishing diet (DM: 876 g kg-1, estimated ME: 10.9 MJ kg-1 of DM, estimated DUP: 32.4 g kg{-1} of DM) ad libitum, together with 100 g hay head-1 day-1, or silage (SIL) offered ad libitum (D value: 67.2), together with up to 450 g head-1day-1of a concentrate supplement (DM: 888 g kg-1, estimated ME: 10.9 MJ kg-1 of DM, estimated DUP: 63.9 g kg-1 of DM). Lambs were slaughtered at estimated MLC fat class 2 to 3L. Both breed and diet had a significant effect on daily live weight gain (DLWG) (S x M: 282 vs. SBF: 210 g; CONC: 383 vs. SIL: 109 g) and the food conversion ratio (FCR) was significantly affected by diet (CONC: 5.3 vs. SIL: 7.7). Breed x diet interactions were significant for both DLWG and FCR. Conformation score was better in the S x M lambs than in the SBF lambs (3.2 vs. 2.6; scale E = 5, P = 1), whereas diet influenced the estimated subcutaneous fat proportion (CONC: 121.5 g kg-1vs. SIL: 113.2 g kg-1).