PSVI-4 Harvest yields and carcass performance data association with increasing finished weights of market hogs.

Abstract The US hog industry has experienced increased hog inventory and dressed carcass weights. This provides ample opportunity for industry improvement in efficiency via animal growth metrics. Our study evaluated carcass growth associations among increasing finished weights of gilts, with specific objectives to identify models predicting organ weights and estimate carcass performance. Genetically similar cull gilts (n = 72) were procured from a commercial swine farm and transported to the Caviness Meat Science and Innovation Center for harvest the subsequent day. Hogs were restricted from feed, but allowed ad libitum water access. Hogs were serially slaughtered on one of four harvest dates and allowed 72 to 144 h chill time. Live weights (LW) were collected immediately following electrical stunning. Post-exsanguination (~3 min), scalding/dehairing (~5 min), and evisceration, organs (heart, lung, liver, stomach, small intestine [SI], and large intestine [LI]) were separated, cleaned of contents, and weighed. Hot carcass weights (HCW) and dressing percentage (DP) were calculated. Post-chilling, cold side weights (CSW) were noted alongside carcass data, including dorsal fat thickness (FT) measurements (first rib [FRFT], last rib [LRFT], last lumbar vertebra [LLFT]), and 10th-rib FT (10FT) upon ribbing between the 10th and 11th ribs, where the 10th-rib interface Longissimus m. area (LMA) and Longissimus m. depth (LMD) were also recorded. Standardized fat free lean (procedure 1) was calculated using HCW, 10FT, and LMA. Outliers (>3 SD from the mean) were eliminated. Best-fit regression equations were determined using the highest R2 value among models per variable; α = 0.05. Live weights ranged from 75.3 to 199.6 kg (mean = 155.9 kg), whereas HCW ranged from 54.7 to 155.1 kg (mean = 116.1 kg), with an average DP of 74.97%. Model equations for predicting numerous variables were all significant (P < 0.01), except for percentage liver and large intestine (P ≥ 0.18). Quadratic models were developed for percentage heart (R2 = 0.511), stomach (R2 = 0.485), and small intestine (R2 = 0.275), with mild to moderate association. Percentage lung was the only exponential model (R2 = 0.321) within the study. As expected, all organ weights expressed as percentage of LW, decreased as LW increased. All individually measured carcass performance traits were power curves, with moderate to strong associations (R2 ≥ 0.569). Fat thickness measurements all increased at an increasing rate as LW increased. Both LMA and LMD increased as LW increased, but at a much slower rate than FT. Calculated SFFL was best predicted via a quadratic model (R2 = 0.685), decreasing as LW increased. The pork industry will likely continue to maximize efficiency and production. Animal growth data, such as these, will assist industry stakeholders in production and economic decision making.