Dietary yeast culture supplementation improves meat quality and fat metabolism-related gene expression in lambs

<br />This study evaluated the effects ofdietary yeast culture (YC) supplementation onlamb growth performance and meat quality. After 14days ofacclimation, 20three-month-old lambs (30.46± 1.77kg) were randomly assigned tothe control (CON, basal diet) orYC-supplemented group (0.625g/kgDM) for 50days. While YC induced nosignificant improvements ingrowth parameters (average daily gain, average daily feed intake, and feed togain ratio; <i>P</i>>0.05), itenhanced the <i>longissimus thoracis</i> (LT) meat quality byelevating the <i>L</i>* (lightness) and <i>a</i>* (redness) values (<i>P</i><0.05), reducing shear force (<i>P</i><i><</i>0.05), increasing intramuscular fat (EE, <i>P</i><0.05), and decreasing crude protein (<i>P</i><0.05). YC modified fatty acid profiles byreducing atherogenic saturated fatty acids (<i>P</i><0.05) and elevating C16:1 (<i>P</i><0.05). Transcriptional analysis revealed the depot-specific regulation: YC suppressed subcutaneous adipogenesis via downregulation of<i>PPARγ</i>/<i>SREBP-1</i>/<i>HSL</i> and upregulation of<i>LPL</i> and promoted intramuscular fat deposition inLTthrough the coordinated activation of<i>PPARγ</i>/<i>SREBP-1</i>/<i>FAS</i>/<i>ACC</i> and inhibition of<i>LPL</i> (<i>P</i><0.05). These findings demonstrate the capacity of YC to optimise meat sensory attributes and lipid healthfulness through tissue-specific metabolic modulation, supporting its application as a functional feed additive in precision lamb production.