Journal article
Nitrogen partitioning and isotopic fractionation in dairy cows consuming diets based on a range of contrasting forages
L Cheng, EJ Kim, RJ Merry, RJ Dewhurst
Journal of Dairy Science | ELSEVIER SCIENCE INC | Published : 2011
Abstract
Nine multiparous Holstein-Friesian cows (initially 97 d in milk), were used in a 3×3 lattice square design experiment with 4-wk periods. All cows received 4kg/d concentrates and dietary treatments were based on silages offered ad libitum: perennial ryegrass (PRG); timothy (TIM); tall fescue (TF); red clover (RC); red clover/corn silage mixture [40/60 on a dry matter (DM) basis; RCC]; red clover/whole-crop oat silage mixture (40/60 on a DM basis; RCO); or red clover/whole-crop oat silage mixture (25/75 on a DM basis; ORC). The remaining treatments were based on RCO with feed intake restricted to the level of PRG (RCOr) or with a low protein concentrate (50/50 mixture of barley and molassed su..
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Funding Acknowledgements
The financial support of the Department for Environment, Food and Rural Affairs (United Kingdom; N partitioning study) and Ministry of Agriculture and Fisheries (New Zealand; stable isotope work) is gratefully acknowledged. The authors acknowledge the skilled technical assistance of the staff of Trawsgoed Research Farm and the analytical and nutrition research laboratories in Aberystwyth (United Kingdom). We are also grateful to Roger Cresswell and the stable isotope laboratory at Lincoln University (New Zealand) for help and advice with the <SUP>15</SUP>N analysis.