THE INFLUENCE OF GENOTYPE, SEX, AND DIETARY LYSINE ON PORK SUBPRIMAL CUT YIELDS AND CARCASS QUALITY OF PIGS FED TO EITHER 104 OR 127 KILOGRAMS

One hundred twenty pigs (initially 44 kg BW) were used to determine th e effects of genotype, sex, and dietary lysine on subprimal cut yields and carcass quality. Within genotype (high or medium potential for le an tissue gain), barrows and gilts were fed separately either a .90 or .70% lysine diet until the mean weight of each pen of three pigs reac hed 104 kg. Then one pig was removed and dietary lysine for the remain ing two pigs was decreased to .75 or .55%, respectively. At both 104 a nd 127 kg BW, carcasses from high-lean genotype (HLG) pigs and gilts h ad (P < .01) higher percentages of boneless closely trimmed ham, loin, and shoulder than carcasses from medium-lean genotype (MLG) pigs and barrows, respectively. At 104 kg BW HunterLab values indicated (P < .0 1) that HLG longissimus muscle (LM) was redder, more yellow, and more intense in color than MLG LM. The LM from HLG gilts had (P < .05) high er Warner-Bratzler shear values (less tender) than LM from HLG barrows and MLG pigs at 104 kg BW. At 127 kg BW, HLG LM was visually firmer ( P < .05) and more reddish-pink (P < .01); had HunterLab values (P < .0 1) that indicated a darker, redder color; had less moisture exudate (P < .05), thaw loss (P < .01), and percentage of lipid (P < .01); and h ad a higher pH (P < .05) than MLG LM. Barrow LM had more marbling (P < .05), a higher percentage of lipid (P < .01), less moisture exudate ( P < .05), and less thaw loss (P < .01) than LM from gilts. The LM from HLG barrows had higher (P < .05) Warner-Bratzler shear values than th e LM from HLG gilts and MLG pigs at 127 kg BW. Overall, the dietary re gimens used in this trial resulted in minimal differences in either ca rcass quality or cutability. The production option of feeding HLG gilt s to 127 kg can be used to optimize carcass cutability and quality tra its.