UNASSIGNED: This study investigated the effect of metabolizable protein (MP) supply and rumen-protected (RP) Lys and Met supplementation on productivity, nutrient digestibility, urinary N losses, apparent total-tract digestibility of dietary AA, and the efficiency of AA utilization for @entity6155 protein synthesis in dairy @entity291 . The experiment was conducted with 8 ruminally cannulated Holstein @entity291 in a replicated 4 * 4 Latin square design trial with 21-d periods. Treatments were (1) MP-adequate diet (AMP; MP balance of -24 g/d); (2) @entity1131 diet (DMP; MP balance of -281 g/d); (3) DMP supplemented with 100 g of RPLys/ @entity291 per day (estimated digestible Lys supply = 24 g/d; DMPL; MP balance of -305 g/d); and (4) DMPL supplemented with 24 g of RPMet/ @entity291 per day (estimated digestible Met supply = 15 g/d; DMPLM; MP balance of -256 g/d). Diet had no effect on total-tract nutrient digestibility, @entity6155 production, and @entity6155 composition, but the DMP diets decreased urinary N excretion and the ammonia emitting potential of manure. Plasma Met concentration was increased by DMPLM compared with AMP. Supplementation with RPLys had no effect on plasma Lys. Concentration of most AA in @entity6155 protein was increased or tended to be increased by DMPLM compared with DMPL. Except for the AA supplemented as RPAA (i.e., Met and Lys), apparent total-tract digestibility of all dietary AA was generally greater for the DMP diets and ranged from 33% (Arg, AMP diet) to 67% (Thr, DMPL diet). Apparent recovery of dietary AA in @entity6155 protein followed the same trends, being greater for the DMP diets than AMP and generally lower for Lys and Met with the RPAA-supplemented diets versus AMP and DMP. The RPAA were apparently not used for @entity6155 protein synthesis in the conditions of this experiment. The AA recoveries in @entity6155 protein varied from around 17% (Ala) to 70% (Pro). @entity6155 protein recoveries of essential AA (EAA) were around 54% for the DMP diet and 49% for AMP. The estimated efficiency of utilization of digestible EAA for @entity6155 protein synthesis was generally greater for the DMP diets compared with AMP. In this trial, blood plasma Lys and Met were labeled by abomasal pulse-dose of (15)N-Lys and (13) @entity68737 (respectively). Analysis of the (15)N-Lys and (13) @entity68737 decay curves in plasma indicated trends for a faster extraction of Lys and Met from plasma for the @entity1131 diets, compared with AMP. Overall, this study confirmed conclusions from previous analyses that the efficiency of utilization of dietary EAA will increase with decreasing MP-AA supply.

Effect of dietary protein level and rumen-protected amino acid supplementation on amino acid utilization for milk protein in lactating dairy XXXX .

@entity1131 :: ('MESH:D011488', 'Disease') :: ['MP-deficient'] @entity291 :: ('9913', 'Species') :: ['cows', 'cow'] @entity68737 :: ('280855(Tax:9913)', 'Gene') :: ['C-Met'] @entity6155 :: ('100532204', 'Gene') :: ['Milk', 'milk']
@entity291 :: (9913,Species) :: ['cows']
