Branched-chain amino acids for growing @entity291 limit-fed XXXX hull-based diets.

@entity5066 @entity598 @entity1460 @entity2596 @entity3918 @entity291
Five ruminally cannulated Holstein steers (176 kg) were used in a 5 x 5 Latin square to evaluate the effects of branched-chain @entity5066 supplementation on N retention and plasma @entity5066 concentrations of steers. Steers were limit-fed (3.0 kg/d of @entity3918 ) twice daily diets low in ruminally undegradable protein (72% @entity1460 hulls, 19% alfalfa, 5% molasses, and 4% vitamins and minerals). @entity598 (400 g/d) was continuously infused into the rumen. Treatments were continuous abomasal infusions of 1) 115 g/d of a mixture of 10 essential @entity5066 designed to exceed the steers' requirements (10AA), 2) 10AA with Leu removed, 3) 10AA with Ile removed, 4) 10AA with @entity2596 removed, and 5) 10AA with all three branched-chain @entity5066 removed. Experimental periods were 7 d, with 3 d for adaptation to treatments and 4 d for total fecal and urinary collections for N balance. Blood samples were collected 5 h after feeding on d 7. Retained N decreased in response to removal of Leu (P < 0.06), @entity2596 (P < 0.05), or all three branched-chain @entity5066 (P < 0.05). Plasma Leu concentrations decreased (P < 0.05) in response to removal of Leu and all three branched-chain @entity5066 . Plasma Ile concentrations decreased (P < 0.05) in response to removal of Ile and all three branched-chain @entity5066 but increased (P < 0.05) in response to removal of Leu. Plasma @entity2596 concentrations decreased (P < 0.05) in response to removal of @entity2596 and all three branched-chain @entity5066 but increased (P < 0.05) in response to removal of Leu. Responses in N balance and plasma @entity5066 concentrations of growing @entity291 limit-fed @entity1460 hull-based diets demonstrate limitations in the basal supply of Leu and @entity2596 but not Ile provided that supplies of all other essential @entity5066 are met.
