Effects of dietary vitamin E and fat supplementation in growing-finishing swine fed to a heavy slaughter weight of 150 kg: I. Growth performance, lean growth, organ size, carcass characteristics, primal cuts, and pork quality

The study aimed to assess the effect of vitamin E (VE) supplementation and fat source on growth performance, lean growth, organ size, carcass characteristics, and pork quality of pigs at a heavy slaughter weight of 150 kg. A total of 64 pigs (32 barrows and 32 gilts; 28.41 ± 0.83 kg) were blocked by sex and body weight, and randomly assigned to one of eight dietary treatments (n = 8 per treatment) in a 4 × 2 factorial arrangement with main effects of fat source (corn starch [CS; no fat added], 5% tallow [TW], 5% distiller's corn oil [DCO], and 5% coconut oil [CN]) and VE supplementation level (11 and 200 ppm). Five-phase diets were formulated to meet requirement estimates of NRC and fed to pigs with each period of 25 kg from 25 to 150 kg. Increasing dietary VE supplementation from 11 to 200 ppm tended to increase average daily gain (ADG) in phase 5 (P = 0.08), and gain to feed ratio (G/F) in phase 4 (P = 0.06) and phase 5 (P = 0.06) resulting in increased G/F in the overall period (P = 0.10). Compared with the pigs fed the CS diet in the overall period, the pigs fed DCO diets had greater ADG (P < 0.05), the pigs fed the TW and CN diets had lower average daily feed intake (P < 0.05), and the pigs fed the fat-added diets had greater G/F (P < 0.05). Belly firmness was greatest in the pigs fed the CN diet and lowest in those fed the DCO diet (P < 0.05). Increasing dietary VE level from 11 to 200 ppm increased absolute and relative liver weight, absolute ham yield (P < 0.05), and tended to increase the relative yield of picnic shoulder (P = 0.07) and ham (P = 0.06) and the pigs fed the corn oil diet tended to have greater belly yield (P = 0.08) than the other fat treatments. Increasing dietary VE level increased 45-min pH and ΔpH at slaughter but decreased a∗ value, chroma (P < 0.10), and belly depth (P < 0.05). However, no effects of VE supplementation and fat source were observed on the other carcass traits and meat quality measurements. In conclusion, increasing dietary VE level from 11 to 200 ppm slightly increased growth rate and feed efficiency in the late finishing periods, and the addition of fat increased feed efficiency and backfat thickness, decreased lean content, and altered belly firmness. While there were some effects of VE supplementation and fat source observed on organ weight, primal cuts, carcass traits, and meat quality, there was no strong evidence that VE supplementation and fat source materially affected these measurements except for belly firmness.