noun
bedding straw; litter
Straw used as bedding for livestock or pets; often found in stables or cages.
馬小屋に新しい寝藁を敷いた。
I spread fresh bedding straw in the stable.
敷き藁 refers more broadly to straw spread on the ground, not necessarily for sleeping; 寝藁 specifically means straw used as bedding.
Compound of 寝 (ne, 'sleep') and 藁 (wara, 'straw').