BACKGROUND: Beet vinasse (VIN), a by-product of sugar beet processing, is rich in non-protein nitrogen (NPN), potassium, and prebiotic compounds, offering potential as a feed additive to enhance dairy cow performance while reducing environmental waste. OBJECTIVES: This study investigates the effects of VIN supplementation at 0%, 1.5% (300 g/day) or 3% (600 g/day) on feed intake, feed efficiency (FE), milk production and composition, apparent nutrient digestibility, blood metabolites and ruminal fermentation in early-lactation Holstein dairy cows. METHODS: Twenty-four Holstein dairy cows (15 ± 3 days in milk, 30 ± 2.9 kg of milk/day) were used in a completely randomized design with three treatments: (1) control diet without beet VIN supplementation (0 g VIN/cow/day, 0% VIN; V0); (2) diet supplemented with 300 g VIN/cow/day (1.5% VIN; V1.5); and (3) diet supplemented with 600 g VIN/cow/day (3% VIN; V3). VIN was top-dressed over the total mixed ration. The experiment included a 15-day adaptation period and a 30-day sampling period. RESULTS: Dry matter intake (DMI) was unaffected by treatments, whereas FE and milk yield increased linearly with increasing VIN levels. Fat-corrected milk (FCM), energy-corrected milk (ECM) and yields of milk fat, true protein, lactose and solids non-fat (SNF) increased linearly from V0 to V3. Milk fat percentage exhibited a quadratic response, with highest milk fat observed at the V1.5 level. True protein and concentrations of de novo and saturated fatty acids increased linearly with VIN inclusion. Apparent digestibility of dry matter, organic matter and crude protein improved linearly with increasing VIN levels. Ruminal pH, acetate proportion and acetate to propionate ratio increased linearly, whereas the proportions of valerate and isovalerate decreased linearly. Plasma globulin, total protein and blood urea nitrogen concentrations increased linearly, whereas plasma glucose concentration decreased linearly with increasing VIN. CONCLUSIONS: VIN supplementation at 1.5% or 3% enhances milk production, FE and nutrient digestibility in early-lactating cows without affecting DMI. However, increased plasma globulin may suggest a mild inflammatory response, necessitating further investigation. IMPLICATIONS: VIN supplementation at 1.5%-3% enhances nutrient digestibility, ruminal fermentation and production efficiency in early-lactating Holstein cows, likely due to its NPN and mineral content. However, without rumen microbial or immune response data, long-term safety and efficacy require further study. VIN offers a cost-effective, environmentally sustainable feed additive pending validation.
Rahimi et al. (Fri,) studied this question.