Effect of nitrogen and energy supplements on intake and digestion of oat straw by non-lactating dairy cows

Abstract

SummaryUrea with molasses and starch, casein, and fish meal with maize gluten meal were compared with a urea control as different nitrogen and energy sources in straw diets fed ad libitum to four mature non-lactating Swedish Red and White cows in a 4 × 4 latinsquare design. Cows fed fish meal with maize gluten meal had increased neutral detergent (ND) fibre intake, digestibility, and total digestion compared with those fed the urea control. When fed casein, cows tended to have higher ND fibre intake, lower ND fibre digestibility, and higher total ND fibre digestion than the urea control. Cows fed urea with molasses and starch had the same ND fibre intake, lower ND fibre digestibility, and lower total ND fibre digestion than the control. Treatments had no influence on rumen pH, rumen in sacco ND fibre kinetics, rumen residence times and median faecal particle size. Rumen ammonia concentrations were lower for the urea with molasses and starch as well as for the fish meal with maize gluten meal treatments when compared with the urea control. Rumen volatile fatty acid concentrations for supplemented diets were either unchanged or higher than for the control diet.