TECHNOLOGY 72 FEED & ADDITIVE MAGAZINE September 2025 Time After Ensiling Well Preserved Silage (Good Anaerobic Fermentation) Poorly Preserved Silage (Aerobic Spoilage) Table 3. Typical Brix and ph patterns in well preserved vs. poorly preserved silage Pre ensiling (0 h) 24 h 48 h 7 days Additional signs Brix: ~12 % pH: 6.0–6.5 Brix: 8–10 % pH: 4.8–5.2 Brix: 5–8 % pH: 4.4–4.8 Brix: 3–5 % pH: ≤4.2 (stable) Cool temperature (<30 °C), pleasant acidic smell, stable over time Brix: ~12 % pH: 6.0–6.5 Brix: 8–10 % pH: 5.8–6.2 Brix: 5–8 % pH: 5.5–6.0 Brix: 3–5 % pH: ≥5.0 (unstable) Heating (>35–40 °C), musty/alcohol smell, visible mold within weeks • Squeeze juice from ~200 g of forage and place a few drops on the prism. • Calibrate the refractometer with distilled water at ~20 °C before use; allow samples to reach temperature equilibrium before reading. Take an initial reading before ensiling, then repeat at 24–48 h, and if possible, at one week. Comparing inoculated vs. untreated silage over time shows how quickly sugars are used. PAIRING BRIX WITH A QUICK FIELD PH CHECK Brix shows sugar supply, but not whether it’s being converted into lactic acid. A simple field pH test help correct that misinterpretation: 1. Collect a small silage sample, either freshly chopped forage or material from a mini silo/bale. 2. Make “silage tea”, chop finely, place a handful in a clean jar, add 4 parts clean water to 1 part forage, stir, and let sit a few minutes. 3. Measure pH by using narrow range (3–6) pH strips or a pocket pH meter. Interpreting Brix + pH together: • High Brix + High pH → Sugars available but fermented slowly or stopped. • Low Brix + Low pH → Good fermentation. • Low Brix + High pH → Sugar loss from spoilage, not beneficial fermentation. Target pH: • Grass silage: <5.0 by day 2–3; ≤4.2 when stable. • Maize silage: often stabilizes closer to 3.8. ECONOMIC VALUE OF PAIRING A BRIX REFRACTOMETER WITH A PH METER A good handheld Brix refractometer and a reliable Photo: Dellait Animal Nutrition and Health
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