ABSTRACT: Two hundred sixteen crossbred barrows
and gilts (84.3 kg BW) were used to test the effects
of dietary energy density and lysine:energy ratio
(Lys:ME) on the performance, carcass characteristics,
and pork quality of finishing pigs fed 10 ppm ractopamine.
Pigs were blocked by BW and gender, allotted
to 36 pens (six pigs per pen), and pens were assigned
randomly within blocks to dietary treatments (as-fed
basis) arranged in a 2 × 3 factorial design, with two
levels of energy (3.30 or 3.48 Mcal/kg) and three Lys:ME
(1.7, 2.4, or 3.1 g lysine/Mcal) levels. Pigs were fed experimental
diets for 28 d, and weights and feed disappearance
were recorded weekly to calculate ADG,
ADFI, and G:F. Upon completion of the feeding trial,
pigs were slaughtered and carcass data were collected
before fabrication. During carcass fabrication, hams
were analyzed for lean composition using a ham electrical
conductivity (TOBEC) unit, and loins were collected,
vacuum-packaged, and boxed for pork quality data collection.
Energy density had no (P > 0.22) effect on ADG
or ADFI across the entire 28-d feeding trial; however,
pigs fed 3.48 Mcal of ME were more (P < 0.02) efficient
than pigs fed 3.30 Mcal of ME. In addition, ADG and
G:F increased linearly (P < 0.01) as Lys:ME increased