Nitrogen metabolism in dairy cows fed restricted amounts of grass–clover silage supplemented with seeds from narrow-leafed lupin or pea

摘要: Abstract Twelve dairy cows in mid to late lactation were fed iso-nitrogenous diets (161 g CP/kg DM, forage:concentrate ratio 65:35) where rolled barley and coarsely ground seeds from either narrow-leafed lupin or field pea supplemented grass–clover silage. Feed allowance was individually restricted fixed (18.8 ± 0.6 kg dry matter/day) throughout the experiment avoid refusals. The of 2 × 2 change-over design utilized a previous with 3 periods as covariate. Nitrogen balance assessed by quantitative urine sampling fecal spot eight whereas rumen metabolism studied four cannulated cows. Production energy corrected milk 24.3 kg/day diet 23.2 kg/day ( P  = 0.08) be higher diet. N lower Digestibilities organic matter, neutral detergent fiber crude protein did not differ between neither ruminal pools these constituents. In addition, there no differences respect concentrations NH -N total volatile fatty acids, only minor pH iso-acids α-amino-N. It is concluded that fat content lupins compared peas an advantage typical Scandinavian home-grown rations probably explains yield this experiment. Differences utilization are small magnitude when without thermal processing. practical feeding, ad libitum forage may create response observed