Dependence on corn may increase feed costs and supply vulnerability in tropical livestock systems. This study evaluated replacing corn with whole-fruit jackfruit (Artocarpus heterophyllus Lam.) silage in feedlot lamb diets. Sixteen castrated male Santa Inês crossbred lambs (26.2 ± 3.6 kg) received diets in which jackfruit silage replaced 0, 333, 666, or 1000 g/kg of corn dry matter in the concentrate. Jackfruit silage had lower non-fibrous carbohydrate gas volume (132.9 vs. 182.9 mL), degradation rate (0.081 vs. 0.096 h⁻¹), and total carbohydrate gas volume (238.5 vs. 298.2 mL) than corn (p < 0.05). Dry matter intake increased linearly, whereas organic matter digestibility, final body weight, and total weight gain decreased linearly as replacement increased (p ≤ 0.011). Feed conversion ratio increased from 6.6 to 12.3 kg dry matter intake/kg gain. Nevertheless, 333 g/kg replacement maintained 98.5% of final body weight and 96.0% of total weight gain. Carcass yields and Longissimus muscle area were unaffected. One-third replacement reduced corn use by 26.2% per kilogram of gain while maintaining productive viability. Jackfruit silage is therefore a strategic partial, rather than complete, substitute for corn in tropical sheep diets.

This study aimed to investigate the interactive effects of dietary starch concentration (220 or 420 g/kg DM) and supplementation with calcium salts of palm fatty acids (CSPFAs; 0 or 30 g/kg DM) on carcass characteristics and meat quality in lambs. Thirty-two castrated Dorper × Santa Inês male lambs (initial body weight 25.0 ± 2.85 kg) were randomly assigned to four experimental diets in a 2 × 2 factorial arrangement for 44 days. Although carcass yield remained unaffected (average 49.4%; p > 0.05), CSPFA supplementation significantly increased fat deposition, including perirenal fat mass (590 vs. 400 g; p = 0.005), renal fat score (2.90 vs. 2.66; p = 0.035), and subcutaneous fat thickness (3.8 vs. 1.9 mm; p = 0.017). A starch × CSPFA interaction (p = 0.014) was observed for carcass cooling, where high-starch diets reduced the 24 h temperature only in lambs not receiving CSPFA (7.45 vs. 8.48 °C; p = 0.028). CSPFA also altered the muscle fatty acid profile by increasing C16:0 and total saturated fatty acids (SFA) while reducing polyunsaturated fatty acids (PUFA). In conclusion, palm-oil–derived CSPFA enhances carcass fatness but compromises the nutritional value of lamb meat by promoting an unfavorable fatty acid profile.