Impact of nano-selenium supplementation on in vitro gas production, methane mitigation, and in vivo performance of Ossimi Egyptian Sheep.

This study evaluated the impact of nano-sized selenium (nano-Se) supplementation in sheep diets through in vitro and in vivo experiments. The in vitro trial examined 13 levels of nano-Se (0–1000% of NRC [2001] requirements) in a diet comprising 60% concentrate and 40% roughage, incubated for 24 h. Results demonstrated that rations with 25%, 50%, and 75% nano-Se inclusion improved dry matter digestibility (DMD), and neutral detergent fiber digestibility (NDFD) compared to the control. Nano-Se supplementation reduced protozoa and methanogenic bacteria, leading to lower methane (CH4) production, suggesting its potential as a sustainable dietary additive for ruminants. The in vivo trial involved 16 male Ossimi lambs (6 months old, 20.1 ± 1.1 kg LBW), divided into four groups: a control group fed a basal diet without nano-Se and three experimental groups with 25%, 50%, and 75% nano-Se supplementation. Over 140 days, lambs receiving 50% nano-Se requirements showed the most significant improvements in digestibility (DM, OM, CP, NDF, and ADF), total volatile fatty acids (TVFAs), and bacterial counts while reducing protozoa and methanogenic bacteria. Also, growth performance was enhanced, with higher total gain (32.5 kg) and average daily gain (235 g/day) compared to the control (24.5 kg and 175 g/day). Nano-Se also improved blood serum protein and globulin levels without affecting liver or kidney function, indicating no adverse health effects. In conclusion, nano-Se supplementation in sheep ration enhances nutrient digestibility, rumen microbial activity, and growth performance while reducing methane emissions, with 50% inclusion showing optimal results.