To assess how daytime versus nighttime feeding schedules affect nutrient digestion, blood biochemistry, gastrointestinal microbiota, and metabolic profiles in sheep.
Twelve 7-month-old Dorper × Hu crossbred rams (initial body weight 47 ± 2.42 kg) housed in metabolism crates were randomly allocated to daytime feeding (08:00–20:00, n = 6) or nighttime feeding (20:00–08:00, n = 6) on an identical diet.
Following a 7-day adaptation period, feces and urine were collected for 7 days, blood was sampled across 4 consecutive days, and ruminal, cecal, and longissimus dorsi samples were harvested post-slaughter for multi-omics analysis.
Daytime feeding resulted in significantly higher ether extract digestibility (P = 0.012), nitrogen digestibility (P = 0.041), and plasma urea concentrations (P = 0.011) compared to nighttime feeding.
Nighttime feeding significantly elevated circulating levels of malondialdehyde, total antioxidant capacity, interferon-γ, interleukin-10, tumor necrosis factor-α, glucagon-like peptide-1, serotonin, and melatonin (all P ≤ 0.017).
Feeding schedules shifted ruminal and cecal microbial composition and metabolite profiles, whereas carcass traits and physical meat quality did not differ between groups.