ABSTRACT: Two studies were conducted to assess
the effects of dietary protein and Lys reduction on
growth performance, carcass quality, N excretion, and
plasma N profile in growing–finishing pigs from 35 to
180 kg. The growing trial was conducted with 72 gilts
and 72 barrows with 6 pens per treatment and 6 gilts
or 6 barrows per pen. Four diets with the same DE and
NE were compared: 1) control diet, 2) diet with protein
content reduced by 3% units compared with the
control diet and supplemented with Lys HCl to match
the requirements according to the 2012 NRC (FLys),
3) diet similar to FLys for protein level but supplemented
with only 50% of the Lys HCl provided with
FLys (–50% FLys), and 4) diet similar