Effects of Replacing Corn Stover Silage with Sweet Sorghum Silage on Dry Matter Intake, Fibre Digestibility, and Milk Composition in Thai Holstein Crossbred Dairy Cows

Milk production in tropical smallholder systems is constrained by limited high-quality roughage during the hot–dry season. Sweet sorghum silage is drought-tolerant and may replace corn stover silage. Twelve Holstein–Friesian crossbred cows were assigned to the same commercial concentrate plus either corn stover silage or sweet sorghum silage as the primary roughage source (n = 6 per diet). Intake, apparent digestibility, milk yield and composition, and feed-use efficiency were evaluated on day 15 and 30 and analyzed using linear mixed-effects models with cow as a random effect. Compared with corn stover silage, sweet sorghum silage increased dry matter intake (p < 0.05) and improved the digestibility of fibre fractions, including crude fibre, NDF and ADF (p ≤ 0.003), while crude protein- and nitrogen-free extract digestibility were not different (p > 0.05). Milk yield, 4% fat-corrected milk, energy-corrected milk, and feed-use efficiency indices were unaffected by silage source (p > 0.05). Milk protein concentration was higher with sweet sorghum silage (treatment effect p < 0.05), whereas milk fat and lactose were unchanged. Sweet sorghum silage can therefore replace corn stover silage in tropical dairy diets, improving intake and fibre utilization without compromising milk output.