Pigs fed the FLys diet performed in a
similar manner and showed similar carcass characteristics
to the control pigs. Pigs fed the –50% FLys diet
had the lightest BW (P < 0.01) as well as the lightest
carcass (P = 0.02) and trimmed thigh (P = 0.04)
weights. Pigs fed the –80% MLys diet showed growth
performance and carcass characteristics similar to the
control pigs The N balance study was conducted with
8 barrows arranged in a double replicated 4 × 4 Latin
square design. The control pigs had greater (P < 0.01)
N intake and urinary and total N excretion compared
with pigs fed the low-protein diets. The reduction of
the dietary protein concentration by 3% units decreased
total N excretion by an average of 24.5% and the greatest
reduction of total N excretion was obtained by the
–80% MLys diet (26.12%) compared with the control
diet throughout the trial. No effect of dietary treatment
was observed on the plasma concentrations of ammonia,
urea, and total AA in the 80-kg pigs. Decreased
plasma ammonia (P < 0.01) and urea (P = 0.03) concentrations
were detected in the 120-kg pigs fed the
low-protein diets. The 160-kg pigs fed the –80% MLys
pigs had less total AA, indispensable AA in particular
(P < 0.01), than pigs fed the other diets and decreased
ammonia (P < 0.01) and urea (P = 0.05) concentrations
than the control pigs. The results showed that the use of
microencapsulated Lys, compared with both Lys HCl
and dietary protein-bound Lys, can save CP and synthetic
AA in diet formulation and can reduce N excretion
in manure without adversely affecting the growth
performance and carcass quality of heavy growing–finishing
pigs.
Key words: carcass characteristics, growth performance, heavy