Crossbred pigs (n = 512) with an average initial BW of 22.1 +/- 0.54 kg were used to evaluate growth performance, carcass characteristics, and pork fat quality of grower-finisher pigs fed corn-soybean meal diets containing increasing content of distillers dried grains with solubles (DDGS). One of 4 dietary treatments was randomly assigned to each pen within sex. Dietary treatment and sex were the main factors in a 3-phase feeding program (BW = 22 to 53 kg, 53 to 85 kg, and 85 to 115 kg). Dietary treatments consisted of a corn-soybean meal control, or a corn-soybean meal diet containing 10, 20, or 30% DDGS. Overall, increasing the dietary DDGS content had no effect on ADG (P = 0.74), but ADFI was linearly reduced and G:F was linearly increased (P < 0.01). Dressing percentage, LM marbling and firmness, and belly firmness were linearly reduced (P < 0.01), but percentage of fat-free lean was linearly increased (P < 0.05) with increasing dietary DDGS. Subjective LM color score (P = 0.65), drip loss (P = 0.37), and ultimate pH of LM (P = 0.21) were not influenced by dietary DDGS. Japanese color scores for backfat (P = 0.41) and belly fat (P = 0.85) were similar among dietary treatments (P = 0.41). Feeding an increasing content of DDGS linearly increased (P < 0.05) PUFA concentration, particularly linoleic acid (C18:2), in belly fat, backfat, and LM intramuscular fat, but the increase in LM intramuscular fat was smaller in magnitude (P < 0.05) than in backfat and belly fat. Pigs fed an increasing content of DDGS had a linear increase (P < 0.05) in the iodine value of backfat, belly fat, and LM intramuscular fat of 58.4 to 72.4, 61.5 to 72.3, and 54.8 to 57.7, respectively. Oxidation of LM intramuscular fat measured on d 0, 14, 21, and 28 of storage was not affected by dietary treatment. Taste tests for LM showed no effects of diet on flavor, off-flavor (P = 0.36), tenderness (P = 0.66), juiciness (P = 0.58), and overall acceptability (P = 0.52) scores. Similarly, bacon flavor (P = 0.88), off-flavor, crispiness, and overall liking scores were not affected by increasing dietary DDGS, but bacon fattiness (P < 0.01) and tenderness (P < 0.05) scores were linearly reduced. These results showed no negative effects on growth performance or dressing percentage when growing-finishing pigs were fed diets containing up to 30% DDGS, but fat quality may not meet the standards of all pork processors when feeding diets containing more than 20% DDGS.

BackgroundThere are a variety of ways of increasing crop diversity to increase agricultural sustainability and in turn having a positive influence on nearby natural ecosystems. Competitive crops may provide potent management tools against invasive plants. To elucidate the competitive mechanisms between a sweet potato crop (Ipomoea batatas) and an invasive plant, mile-a-minute (Mikania micrantha), field experiments were carried out in Longchuan County of Yunnan Province, Southwest China, utilizing a de Wit replacement series. The trial incorporated seven ratios of sweet potato and mile-a-minute plants in 25 m2 plots.ResultsIn monoculture, the total biomass, biomass of adventitious root, leafstalk length, and leaf area of sweet potato were all higher than those of mile-a-minute, and in mixed culture the plant height, branch, leaf, stem node, adventitious root, flowering and biomass of mile-a-minute were suppressed significantly (P < 0.05). The relative yield (RY) of mile-a-minute and sweet potato was less than 1.0 in mixed culture, indicating that intraspecific competition was less than interspecific competition. The competitive balance index of sweet potato demonstrated a higher competitive ability than mile-a-minute. Except pH, other soil nutrient contents of initial soil (CK) were significantly higher than those of seven treatments. The concentrations of soil organic matter, total N, total K, available N, available P, available K, exchange Ca, exchange Mg, available Mn, and available B were significantly greater (P < 0.05) in mile-a-minute monoculture soil than in sweet potato monoculture soil, and were reduced by the competition of sweet potato in the mixture.ConclusionsEvidently sweet potato has a competitive advantage in terms of plant growth characteristics and greater absorption of soil nutrients. Thus, planting sweet potato is a promising technique for reducing infestations of mile-a-minute, providing weed management benefits and economic returns from harvest of sweet potatoes. This study also shows the potential value of replacement control methods which may apply to other crop-weed systems or invaded natural ecosystems.

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A study was conducted to determine the quantitative effects of feeding amount and withdrawal period of corn distillers dried grains with solubles (DDGS) from the diet on growth performance, carcass quality, and pork fat fatty acid profile. A total of 432 pigs (29.8 +/- 0.2 kg of BW) were randomly allotted to 1 of 9 dietary treatments in a completely randomized arrangement. The 9 treatments were the control (D0), D15-0 wk, D15-3 wk, D15-6 wk, D15-9 wk, D30-0 wk, D30-3 wk, D30-6 wk, and D30-9 wk, where D0, D15, and D30 indicate the dietary content of DDGS (0, 15, and 30%, respectively) and 0 wk, 3 wk, 6 wk, and 9 wk indicate the withdrawal period of DDGS from the diets before slaughter (0, 3, 6, and 9 wk, respectively). A dietary DDGS inclusion rate of 15 or 30%, without or with a withdrawal period, had no effect (P = 0.76) on ADG, ADFI, and G:F, except for a slight reduction (0.87 vs. 0.92 kg/d; P < 0.05) in ADG when pigs received the D30-0 wk treatment compared with the D0 treatment. Carcass quality, LM quality, and Japanese fat color scores for backfat and belly fat were not affected by dietary DDGS content (backfat, P = 0.47; belly fat, P = 0.17) or withdrawal period (backfat, P = 0.33; belly fat, P = 0.95). Compared with pigs fed the D0 diet, a smaller belly firmness score was observed (P = 0.04) in pigs that received the D30-0 wk treatment, but belly firmness in pigs fed the other treatments was not different (P = 0.26) from that of pigs fed the D0 diet. Linoleic acid content (C18:2; P < 0.001) and iodine value (IV; P < 0.001) of belly fat increased with increasing dietary DDGS content. Withdrawal of DDGS from the diet for 0 to 9 wk before slaughter resulted in a linear reduction in C18:2 content and the IV of belly fat in pigs fed the D15 diets (C18:2 content: 14.6, 13.3, 12.6, and 10.9%; P = 0.001; IV: 67.3, 64.4, 64.1, and 62.7; P = 0.02; for 0-, 3-, 6-, and 9-wk withdrawal, respectively) and the D30 diets (C18:2 content: 17.3, 16.1, 14.2, and 12.4%; P < 0.001; IV: 71.2, 68.2, 64.5, and 62.7; P < 0.001; for 0-, 3-, 6-, and 9-wk withdrawal, respectively). These results indicate that an inclusion rate of DDGS up to 30% in grower-finisher diets has minor effects on growth performance and that the desired effect of reducing the C18:2 content and IV of pork fat could be elicited in as little as 3 wk after withdrawing DDGS from the diet before slaughter.