Abstract The objective of this study was to determine the effects of feeding different net energy (NE) levels on growth performance and carcass characteristics of PIC 337 or PIC 800 sired grow-finish pigs from 30- to 135-kg. A total of 2,016 barrows and gilts (PIC 337 or 800×Camborough, initial BW 32.1 ± 4.2 kg) were used in a 91-d growth trial with 16 mixed sex pens (21 pigs per pen) per treatment in a 2 × 3 factorial arrangement. Two factors were sire lines (PIC 337 or PIC 800) and dietary energy levels (Control: 2.43 Mcal NE/kg, Medium: 3.2% less NE than Control, Low: 6.4% less NE than Control) throughout the experiment. NRC (2012) Digestible Energy and analyzed nutrient composition were used to calibrate ingredient NE. Reduced dietary energy was achieved by increasing the inclusion levels of barley, canola meal, and faba beans, and reducing the usage of wheat, soybean expeller, and canola oil. The Low diet contains 2.5% greater Neutral Detergent Fiber than the Control diet. Growth performance, carcass traits, and removals and mortality were recorded. Data were analyzed using mixed models in R with pen as the experimental unit for performance traits and individual carcasses for carcass traits. Overall, no significant interaction between sire lines and dietary energy levels was observed. There was no difference in average daily feed intake (ADFI), average daily gain (ADG), and final weight (Table 1) between PIC 337 and 800 sired pigs. PIC 337 pigs had improved feed efficiency and a greater hot carcass weight (HCW, both P 0.05) as compared to PIC 800 pigs. PIC 337 pigs tended to have a lower backfat depth (P 0.10), having a greater loin depth (P 0.05), and greater lean percentage (P 0.05) as compared to PIC 800 pigs. Decreasing dietary energy levels reduced feed efficiency by increasing ADFI (both P 0.05) without affecting final market weight. Compared to pigs which fed 2.43 Mcal NE/kg diet (energy equivalent to a corn-SBM diet), each 1% reduction in NE reduced the feed efficiency by 1.14% for PIC 337 sired pigs, and 1.21% for PIC 800 sired pigs, respectively. Reducing dietary NE by 6.4% decreased ADG, and HCW, decreased backfat thickness, subsequently increased the lean yield (all P 0.05). Removal and mortality rate was not affected by either sire lines or dietary energy levels. In summary, PIC 337 sired pigs have an enhanced feed efficiency and lean yield as compared to PIC 800 sired pigs. Reducing dietary energy resulted in comparable reductions in feed efficiency and hot carcass weight across both sire lines.
Guo et al. (Wed,) studied this question.