This study investigates the effects of oil quality and trace mineral source on the growth performance, antioxidant activity, and meat quality of growing–finishing pigs. A total of 180 crossbred pigs (Duroc × Landrace × Large White [64.4 ± 1.95]) were randomly allocated five dietary treatments based on body weight (BW) and sex in a 30 d trial. Pigs were fed five diets: (i) fresh soy oil + inorganic trace minerals (ITMs) + inorganic selenium (FISI), (ii) oxidized soy oil + ITMs + inorganic selenium (OISI), (iii) fresh soy oil + ITMs + selenium yeast (FISY), (iv) oxidized soy oil + ITMs + selenium yeast (OISY), and (v) oxidized soy oil + organic trace minerals (OTMs) + selenium yeast (OOSY). Each dietary treatment included six replicates and six pigs per replicate (three barrows and three gilts). Feeding OISI resulted in lower average daily gain (ADG) and dressing percentage (p < 0.05). The OOSY group had a higher dressing percentage and activities of serum CAT and GSH-Px in growing–finishing pigs (p < 0.05). In addition, the relative abundance of Campylobacterota in the colonic digesta varied with the quality of soy oil and source of trace minerals (p < 0.05), but no significant differences in short-chain fatty acid concentrations were observed among all dietary groups. In conclusion, adding oxidized soy oil to the diet negatively impacted the ADG and dressing percentage of growing–finishing pigs, and replacing ITMs with OTMs and SY alleviated these negative impacts. A combination of OTMs and SY can support antioxidant capacity to mitigate the negative impacts of oxidized oil on the growth performance and dressing percentage of growing–finishing pigs.

Dietary nutrient digestion and utilization patterns influence pig performance and intestinal health. This study aimed to evaluate the effects of protein digestion and fiber fermentation speed among different feed ingredients on growth performance and fecal short-chain fatty acid (SCFA) concentrations in weaned pigs. A total of 192 weaned pigs (Duroc × Landrace × Yorkshire [6.87 ± 0.14 kg]) were selected and randomly divided into four dietary groups: fast-digesting protein with fast-fermenting fiber, fast-digesting protein with slow-fermenting fiber, slow-digesting protein with fast-fermenting fiber, and slow-digesting protein with slow-fermenting fiber. The results showed that cottonseed and wheat protein powders exhibited faster protein digestion than potato protein powder (p < 0.05). In vitro microbial fermentation of hawthorn powder and orange pomace resulted in greater and faster gas production and SCFA concentrations than sugarcane bagasse (p < 0.05). Orange pomace increased the abundance of Klebsiella and Escherichia–Shigella, whereas sugarcane bagasse increased the abundance of Rikenellaceae_RC9_gut_group and norank_f__Muribaculaceae. In addition, the fast-fermentation fiber tended to increase the daily weight gain and feed intake of piglets (p < 0.10), and the slow-fermentation fiber significantly reduced diarrhea incidence in pigs (p < 0.05). Fast fermentation increased acetate and valerate concentrations, and slow-digestion protein increased branched-chain SCFA and valerate contents (p < 0.05). In conclusion, there were large variations in protein digestion and fiber fermentation speed among the different common feed ingredients. Dietary protein digestion and fiber fermentation speed would affect growth performance and diarrhea incidence in weaned pigs.