Diet supplementation with canola meal improves milk production, reduces enteric methane emissions, and shifts nitrogen excretion from urine to feces in dairy cows

The objective of this study was to examine the effect isonitrogenous substitution solvent-extracted soybean meal (SBM) with canola (CM) on enteric CH4 production, ruminal fermentation characteristics (including protozoa), digestion (in situ and apparent total-tract digestibility), N excretion, milk production dairy cows. For purpose, 16 lactating Holstein cows, which 12 were ruminally cannulated, used in a replicated 4 × Latin square (35-d periods; 14-d adaptation). cows averaged (mean ± SD) 116 23 d milk, 692 60 kg body weight, 47.5 4.9 kg/d production. experimental treatments control diet (no CM; 0%CM) diets supplemented [dry matter (DM) basis] 7.9% CM (8%CM), 15.8% (16%CM), or 23.7% (24%CM) DM basis. forage:concentrate ratio 52:48 (DM basis) similar among diets. Canola included at expense SBM hulls, whereas percentages other ingredients same. Intake increased linearly, digestibility DM, crude protein, neutral detergent fiber, gross energy (GE) declined linearly as inclusion increased. Total volatile fatty acids concentration butyrate molar proportion decreased propionate that acetate unaffected by diet. Ruminal ammonia not affected Energy-corrected (ECM) yield (up 2.2 kg/d) increasing percentage diet, efficiency 1.63 ECM/kg intake Daily (489, 475, 463, 461 g/d for 0%CM, 8%CM, 16%CM 24%CM diets, respectively). As consequence, emission intensity (g CH4/kg ECM) also up 10% amount Methane when expressed relative GE (5.7, 5.2, 5.1, 4.9% Quantity manure excretion replacing however, shifted from urine feces dietary increased, suggesting reduced potential volatilization. Results show protein source cow emissions (g/d, % intake, adjusted production) indicates can successfully, partially fully, replace positive effects animal productivity environment (i.e., less urinary excreted). We conclude compared SBM, play key role reducing environmental footprint