Pigs Fed 15 Ppm Skycis® (narasin) Have Similar Viscera Weight, Carcass Composition and Lean Quality Compared to Controls, but Prominent Gender Differences Exist in Carcass Composition: II

The objective of this study was to evaluate inclusion of Skycis^® (NAR) in the diets of pigs and determine the source of carcass yield, specifically dressing percentage, improvements observed in previous studies. Barrows (n = 50) and gilts (n = 50) of PIC C22 x 337 genetics were randomly assigned to a diet containing 0 (CON) or 15 ppm NAR initiated at 39.5 kg of body weight and continued until slaughter. Pigs (n = 47 barrows, n = 46 gilts) were slaughtered in two groups at which time individual organ weights were recorded. At 24 h postmortem carcass composition and carcass quality data was obtained. At 48 h postmortem, one side of each carcass was fabricated into wholesale cuts according to North American Meat Institute specifications. Data points three standard deviations from the mean as determined by PROC UNIVARIATE were removed and remaining data was analyzed by using the PROC MIXED procedure of SAS 9.3. Gilts were higher cutability as evidenced by many gender differences (P < 0.05) observed in the fabrication phase of the study. Gilts were leaner at the last rib (P < 0.01), and 10^th rib (P < 0.01) and also had larger LM (P < 0.01) compared to barrows. Unsurprisingly, gilts had heavier boneless loins (P < 0.01) and heavier muscled hams (P < 0.01), specifically heavier biceps femoris (P < 0.01) and knuckles (P < 0.01). Therefore, boneless loins and hams constituted a greater portion (P < 0.01) of HCW in gilts than barrows. Barrows, however, contained more IMF (P = 0.01) than gilts. Regardless of NAR treatment, gilts were leaner and heavier muscled than barrows. The exact cause of increased HCW and DP in pigs fed NAR observed in other studies cannot be determined with these results. However, findings related to improving muscle quality, specifically, IMF, should be pursued further to improve pork export potential.