Crude glycerin as an alternative energy feedstuff for dairy cows

The intent of this study was to demonstrate the potential of biodiesel derived crude glycerin as a good alternative for an energy feedstuff in dairy cow diets. Eight multiparous Jersey cows with 85 ± 20 days in milk were used. The following treatments were evaluated: 0, 40, 80, and 120 g crude glycerin (containing 814.4 g glycerol/kg) dietary inclusion/kg dry matter. The experimental diets contained equal protein and energy levels. A replicated Latin square experimental design was applied. Crude glycerin intake did not influence average daily milk yield, energy corrected milk yield, or crude fat, lactose, and total milk solids average daily yield and concentration. Milk protein concentration was higher when 120 g crude glycerin was included in the diet when compared with the control group (37.2 vs. 36.1 g/kg, respectively, P<0.05). Crude glycerin intake also increased average daily crude protein yield at the dietary inclusion levels of 80 g/kg (0.77 vs. 0.71 kg by the control group, P<0.05). None of the evaluated treatments influenced dry matter or organic matter intake. Dry matter, organic matter, and neutral detergent fiber digestibility, and serum concentrations of non-esterified fatty acids and urea were not influenced by crude glycerin intake. Glycemia showed a quadratic response to crude glycerin intake (P<0.05), and was lower at the intermediate levels of dietary inclusion (40 and 80 g/kg). Crude glycerin is a good alternative energy feedstuff for dairy cows at a dietary inclusion levels of up to 120 g/kg dry matter in partial substitution of ground corn in dairy cow rations, and may even improve milk protein concentration.