Pelleted high-concentrate diets containing different fiber sources for finisher lambs of distinct genotypes

This study assessed the effects of pelleted high-concentrate dietary strategies formulated with different fiber sources on intake, nutrient digestibility, growth performance, and carcass traits of finisher lambs from four genotypes. Eighty male lambs were used in a 4 × 4 factorial arrangement with four genotypes [Santa Inês (SI), ½ Dorper × ½ Santa Inês (DS), ½ Texel × ½ Santa Inês (TS), and ½ Somalis × ½ Santa Inês (SS)] and four dietary fiber sources [sugarcane bagasse (SCB), alfalfa hay (ALH), citrus pulp (CPP), and soybean hulls (SBH)]. Genotype influenced dry matter intake (DMI), with TS lambs exhibiting lower intake than the other groups, although DMI as %BW did not differ. Fiber source significantly affected nutrient utilization; lambs fed SCB and ALH diets had higher crude protein intake and digestibility than those fed CPP and SBH. Average daily gain (ADG) was highest in lambs fed the SCB diet, particularly when compared to those fed SBH. Genotype was the primary driver of performance, with TS lambs showing the best feed-to-gain ratio (3.20 kg:kg) and DS lambs requiring fewer days to reach slaughter weight. Significant genotype × fiber source interactions were observed for carcass yields, viscera, offal, internal fat, neck, and rib yields. ALH+SS and ALH+TS combinations produced the lowest carcass yields (~44.9% hot; ~43.4% cold), while SCB+SS exhibited the highest offal yield (18.8% hot; 19.3% cold). Furthermore, internal fat peaked in SS lambs fed ALH and SBH (~15.9%), whereas neck (5.2–10.5%), rib (5.5–7.0%), and viscera yields varied moderately across specific treatment combinations. Genotype also affected commercial cuts, with TS lambs presenting superior shoulder and leg yields. In conclusion, pelleting ensured uniform intake across fiber sources, but sugarcane bagasse promoted slightly better growth performance. While dietary responses can vary by genotype, especially carcass yield, the fiber source (sugarcane bagasse, citrus pulp, and soybean hulls) can effectively replace conventional forages like alfalfa in pelleted diets for finisher lambs without compromising productive efficiency.