NaCl-Supplemented Alfalfa-Based TMR Improves Meat Quality by Enhancing Essential Amino Acids and Optimizing Fatty...

Saline-alkaline soils are increasingly reducing global forage productivity and may indirectly compromise the nutritional quality of animal-derived foods for human consumption. Alfalfa, grown under saline-alkaline conditions, often accumulates sodium, thereby altering its nutritional composition and digestibility. NaCl was added to an alfalfa-based total mixed ration (TMR) to model saline-alkaline alfalfa with high salt content. This method is a simplified modeling approach wherein sodium chloride is used to simulate saline stress. We have studied, using this model, changes in growth performance, nutrient digestibility, amino acid composition, and meat quality of AOHU (Hu × Australian White) lambs. The levels of dietary NaCl were set at 0.43% (to reflect the baseline NaCl content of standard alfalfa-based TMR and 1.71% (to reflect a level of high-salt alfalfa produced under saline-alkaline growing conditions). Compared to the control group, supplementation with NaCl enhanced the average daily gain, feed conversion efficiency, relative growth rate, and dry matter intake (p < 0.05). Apparent digestibility of dry matter, organic matter, crude protein, ether extract, fiber fractions (NDF and ADF), and gross energy was also improved (p < 0.001), reflecting enhanced nutrient utilization. Total saturated fatty acids had decreased, while meat redness increased, and the PUFA/SFA ratio increased, reflecting a leaner and healthier lipid profile. Moreover, essential amino acids-threonine, valine, methionine, isoleucine, leucine, and lysine-were significantly higher (p < 0.05), revealing a better meat nutritional quality. In summary, dietary NaCl supplementation in an alfalfa-based TMR effectively simulates saline-alkaline conditions that improve growth performance, nutrient digestibility, and meat nutritional composition. Results from this study show how NaCl supplementation in alfalfa-based rations-used here to mimic the elevated salt levels found in alfalfa grown on saline-alkaline soils-affects growth performance, nutrient digestibility, and meat quality in lambs, providing insight for feeding strategies in salt-affected production systems.