Use of fresh cheese whey as an additive for Lucerne silages: Effects on chemical composition, conservation quality and ruminal degradation of cell walls

The objective was to determine effects of use of fresh whey at different levels as an additive to lucerne silages relative to conservation and rumen plant cell wall degradability. Forage from one paddock of lucerne was used without wilting to produce 16 silages with 4 treatments: silages without additives (control) and silages with 20, 50 or 100g of fresh whey/kg forage (fresh basis). The fermentation quality, measured as the pH, losses of dry matter (DMₗₒₛₛ), organic matter (OMₗₒₛₛ), crude protein (CPₗₒₛₛ), neutral detergent fibre (NDFₗₒₛₛ) and the increase of soluble CP with respect to the original forage (SPᵢₙcᵣₑₐₛₑ) of the silages, was determined. Fresh and ensiled materials were incubated in situ to study rumen degradability of DM, NDF and ADF of the forage and silages. Use of whey led to a linear reduction of pH (P=0.03) and SPᵢₙcᵣₑₐₛₑ (P<0.01). DMₗₒₛₛ, OMₗₒₛₛ, and NDFₗₒₛₛ increased at an increasing rate (linear P≤0.04; quadratic P<0.01) with increasing whey doses, whereas CPₗₒₛₛ increased linearly with whey dose (P<0.01). The increase of whey addition level led to a linear increase (P=0.05) of DM degradability and a quadratic response of NDF (P<0.01) and ADF (P≤0.04) degradability. The highest values of NDF and ADF degradability were at 50g/kg of whey addition level. Addition of fresh whey at up to 100g/kg had positive effects evidenced by a decrease of CP solubilisation and pH of silages and it contributed to preservation of the degradable fractions of plant cell walls. However, the increase in the dose of whey above 50g/kg led to a general increase in nutrient losses. Fresh whey can be useful as an additive for lucerne silage production at up to 50g of fresh whey per kg of fresh forage.