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Effect of dietary lysine on carcass dressing percentage and lean cut yield in late finishing pigs
Although the lysine requirement of pigs at late finishing stage is lower than that of younger pigs, it is the last production stage for producers to provide optimal levels of dietary lysine to maximize carcass yield and quality. The objective of this study was to evaluate the effect of dietary lysine on growth performance and carcass characteristics of late finishing pigs. A total of 9 crossbred barrows (Yorkshire × Landrace; initial BW 94.4±6.7 kg) were randomly allotted to 3 treatments, and each treatment consisted of three pen replicates with one pig per pen. Three corn and soybean-meal based diets were formulated according to the NRC (2012) requirements for nutrients except for lysine. The total lysine concentrations were 0.43, 0.71, and 0.98% (as-fed basis) for Diets 1 (D1, lysine-deficient), 2 (D2, lysine-adequate), and 3 (D3, lysine-excess), respectively. The feeding trial lasted 5 weeks, during which time the pigs were allowed ad libitum access to the respective diets and water. Pigs receiving D1 had lower ADG than those receiving D2 or D3 (p < 0.05), but no difference was found between the D2 and D3 pigs. Although there were no significant differences (p > 0.08) in the hot carcass weights among the 3 treatment groups, the loin eye area of the D1 group was reduced by 15% (6.2 cm2) when compared to the D2 group (p < 0.05), but no difference (p = 0.77) were detected between the D3 and D2 groups. Both the trimmed and untrimmed ham weights of the D1 group were decreased by approximately 17% (4.0 kg) compared to the D2 or D3 group (p < 0.05). The dressing percentage and the total lean cut weight were both linearly increased (p < 0.05) with the dietary lysine concentrations. The carcass shrinkage, the back-fat thickness, and the visual scores for loin color, loin marbling, and ham color were not affected by dietary lysine level (p > 0.15). In conclusion, while the lysine-deficient diet reduced the loin eye area and the ham weights, the lysine-excess diet linearly increased the dressing percentage and the total lean cut weight. Data from this study confirmed the importance of dietary lysine supply for the overall carcass yield and quality of late finishing pigs and indicated that there is still some room for improving dressing percentage and lean cut yield via more dietary lysine supply. This research was supported by USDA-NIFA Hatch/Multistate Project 233803.
Keywords:
lean cut yield, dressing percentage, lysine, late finishing pigs