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dc.contributor.author A. R. J. en_US
dc.contributor.author Richard J. en_US
dc.contributor.author D. S. P. en_US
dc.contributor.author J. M. en_US
dc.contributor.author A. J. M. en_US
dc.date.accessioned 2012-01-23T13:37:09Z
dc.date.available 2012-01-23T13:37:09Z
dc.date.issued 2011-09 en_US
dc.identifier http://dx.doi.org/10.3168/jds.2010-4097 en_US
dc.identifier.citation Cabrita , A R J , Dewhurst , R J , Melo , D S P , Moorby , J M & Fonseca , A J M 2011 , ' Effects of dietary protein concentration and balance of absorbable amino acids on productive responses of dairy cows fed corn silage-based diets ' Journal of Dairy Science , vol 94 , no. 9 , pp. 4647-4656 . , 10.3168/jds.2010-4097 en_US
dc.identifier.other PURE: 175082 en_US
dc.identifier.other dspace: 2160/7756 en_US
dc.identifier.uri http://hdl.handle.net/2160/7756
dc.description.abstract A cyclical changeover design experiment (3-wk periods; 12-wk total) was conducted to evaluate whether improving the balance of absorbable AA would allow the feeding of less crude protein (CP) without compromising production, thereby reducing the potential environmental pollution from dairy farms. Sixteen multiparous Holstein cows were assigned to 1 of 8 dietary treatments as total mixed rations (TMR) containing [dry matter (DM) basis] 45% corn silage, 5% coarsely chopped wheat straw, and 50% concentrate mixture. The 8 treatments were formulated to differ in dietary CP (14 and 16%; DM basis) and in the balance of absorbable AA achieved by changing the main protein source (MPS) of the concentrate mixtures [replacing soybean meal (SBM) with corn byproducts (CBP), dried corn distillers grains (DDG), and some corn gluten meal], and by adding a mixture of rumen-protected Lys and Met (RPLM). Feeding lactating dairy cows corn silage-based diets with 16% CP promoted significantly higher DM intakes and milk yields, and lower feed N-use efficiency than feeding diets with 14% CP. Replacing SBM with CBP significantly increased milk yields and decreased milk fat and protein concentrations, but had no effect on the efficiency of conversion of feed N into milk N. With 16% CP diets, the addition of RPLM decreased feed N use efficiency. A significant effect was observed for the MPS × RPLM interaction on milk protein concentrations. Plasma Lys concentration was lower with diets based on CBP, and plasma Met increased with RPLM. We did not find clear benefits of RPLM in facilitating a reduction of dietary protein without loss of production. en_US
dc.format.extent 10 en_US
dc.relation.ispartof Journal of Dairy Science en_US
dc.title Effects of dietary protein concentration and balance of absorbable amino acids on productive responses of dairy cows fed corn silage-based diets en_US
dc.contributor.pbl Institute of Biological, Environmental and Rural Sciences en_US


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