Scutellaria baicalensis straw improves nutritional and flavor quality of mutton via regulating the expression of IMP-related genes.

Scutellaria baicalensis straw (SBS) is a potential feed ingredient, but its optimal inclusion level for improving mutton quality remains unclear. This study examined the influence of dietary SBS supplementation on meat quality, fatty acid profile, amino acid composition, inosine monophosphate (IMP) content, and the expression of IMP-related genes in the longissimus muscle of rams. Sixty Bainuburke lambs (4-5 months old, initial body weight 27.08 ± 3.12 kg) were randomly allocated to six groups (n = 10 per group) and fed isonitrogenous and isoenergetic pelleted diets supplemented with 0, 6, 12, 18, 24%, or 30% SBS on a dry matter basis. The feeding trial lasted 80 days, including a 10-day adaptation period followed by a 70-day experimental period. The 24% SBS group (SBS24) showed significantly higher muscle pH and redness (a* value), and lower cooking loss compared to the control (CON, 0% SBS; P < 0.05). SBS24 also increased crude protein content, total essential and non-essential amino acids, and IMP content (P < 0.05). For intramuscular fatty acid composition, the SBS24 group achieved remarkable reductions in saturated fatty acids (SFA), primarily palmitic acid (C16:0) and stearic acid (C18:0), while dramatically raising the concentrations of health-beneficial unsaturated fatty acids including oleic acid (C18:1n9c), linoleic acid (C18:2n6c) and α-linolenic acid (C18:3n3) (P < 0.01). Furthermore, SBS24 up-regulated PRPS1, ADSL, ATIC, and AMPD1 (IMP-related genes) while down-regulating ADSSL1 and IMPDH1 (P < 0.05). Dietary inclusion of 24% SBS improves mutton nutritional quality by enhancing protein deposition, beneficial fatty acids, flavor-related amino acids, and IMP metabolism. Therefore, 24% SBS is recommended for Bainuburke rams production.