Background and Aim: Grass is often scarce for ruminants during the dry season in Indonesia; thus agricultural by-products are widely used as a substitute for grass. This study aimed to determine the effect of replacing Napier grass (NG) with agricultural by-products on the productivity and carcass characteristics of lambs.

Materials and Methods: Twenty-four 3-month-old male lambs with initial body weights of 13.26±1.29 kg (coefficient of variation=9.73%) were allocated into a completely randomized design with four treatments and six replications. The treatments included: NG=100% NG; corn cobs (CCs)=50% NG and 50% CCs; bagasse (BG)=50% NG and 50% BG; and peanut shells (PSs)=50% NG and 50% PSs. All treatment diets were pelleted and consisted of 40% fibrous feed and 60% concentrate feed, and contained 10.36-11.65% crude protein and 55.47-57.31% total digestible nutrients. Parameters observed included dry matter intake (DMI), dry matter digestibility, body weight gain (BWG), feed conversion ratio (FCR), feed cost per gain (FC/G), and carcass characteristics.

Results: Lambs fed the PSs diet had the highest (p<0.05) DMI (781 g/d), digestibility, and body weight gain (92.5 g/d; p<0.05). The FCR of the PSs diet (9.13) was similar to NG. The FC/G of the PSs diet (IDR 23,541/kg) was the lowest of all diets. The BG diet had the lowest (p<0.05) digestibility, body weight gain (54.4 g/d), and the highest (13.53) FCR. No significant differences (p>0.05) were found in the carcass or meat characteristics of any diets. The averages of slaughter weight, carcass weight, and carcass percentage were 20.03 kg, 8.02 kg, and 40.0%, respectively. The average meat bone ratio was 3.67.

Conclusion: It was concluded that agricultural wastes could be used as an alternative to NG at the level of 50% in the diet of lambs without a negative effect on production performance and carcass traits.

Keywords: bagasse, corn cobs, digestibility, feed efficiency, meat-bone ratio, peanut shells.