Effects of birth weight and paylean inclusion level on the growth performance, carcass characteristics, and fresh pork quality parameters of pigs

The effects of birth weight and dietary Paylean inclusion level on the growth performance, carcass characteristics, and fresh pork quality parameters of pigs were evaluated using 72 barrows in a 2 part study. Part I was carried out from 3 wk post-weaning to 110 ?? 2.0 kg BW as a RCBD with 1 treatment: Birth weight [Heavy, Medium, Light (average 1.5, 1.2, 0.9 kg, respectively)]. Pigs from the 3 birth weight classifications were selected from within the same birth litter. Part II was carried out from 110 ?? 2.0 to 134 ?? 3.2 kg BW as a RCBD using a 3 ?? 2 factorial arrangement of treatments: 1) Birth weight (Heavy, Medium, Light), and 2) dietary Paylean inclusion level (0 and 5 ppm). Pigs were housed in individual pens and were weighed at birth, weaning, and every two weeks thereafter in Part I and weekly during Part II. All feed additions and feed left in the feeder at the time of pig weighing were recorded and used in the calculation of average daily feed intake and gain:feed ratio. At 134 kg BW, pigs were shipped to the University of Illinois Meat Science Laboratory and harvested according to standard procedures. Standard carcass and meat quality measurements (subjective color, firmness, and marbling, Minolta color, and drip loss) were taken ~24 hr post-mortem, and Warner-Bratzler shear force was measured on cooked Longissimus muscle chops. The right side of each carcass was separated into skin, bone, and soft tissue, each tissue was weighed, and the soft tissue was ground. In Part I, light birth weight pigs had lower (P 0.05) ADFI and G:F as medium and heavy birth weight pigs. In Part II, there were no treatment interactions for growth traits; the effects of birth weight on growth performance were similar to Part I. There was no effect (P > 0.05) of birth weight on HCW, carcass yield, or Longissimus muscle area, however, tenth rib backfat was greater (2.8 vs. 2.5 vs. 2.5 cm, respectively; SEM 0.13; P < 0.05), and predicted fat-free lean was lower (49.0 vs. 50.5 vs. 51.2%, respectively; SEM 0.57; P < 0.01) for light than medium and heavy birth weight pigs. In Part II, feeding Paylean at 5 ppm increased ADG (1.06 vs. 1.25 kg; SEM 0.033; P < 0.001), G:F (0.300 vs. 0.358; SEM 0.0065; P < 0.001) and carcass yield (76.5 vs. 77.0%; SEM 0.16; P < 0.05), but had no effect on tenth rib back fat thickness, Longissimus muscle area, or predicted fat-free lean. Results of this study confirm previous research on the effects of birth weight and Paylean on growth and carcass characteristics and suggest that the response to Paylean is similar across the birth weights evaluated