Effects of abrupt introduction and removal of high and low digestibility corn distillers dried grains with solubles from the diet on growth performance and carcass characteristics of growing-finishing pigs.

Two experiments were conducted to evaluate the effects of feeding continuously a diet containing 40% dried distillers grains with solubles (DDGS) or intermittently diets containing 20 or 40% DDGS on growth performance and carcass quality of pigs. Responses of the pigs to abrupt introduction and removal of dietary DDGS with differing concentrations of standardized ileal digestible (SID) AA were also evaluated. In Exp. 1, crossbred pigs (n=216; initial BW=51.3±3.1 kg) were assigned randomly to 1 of 4 treatments, which included a corn-soybean meal control (CON), a 20% DDGS diet (D20), a switch between D20 and CON (D20-CON), and a switch between a 40% DDGS diet and CON (D40-CON) with 6 pens per treatment. Pigs abruptly introduced and removed from a 20% DDGS diet (D20-CON) exhibited no differences in growth performance or carcass quality compared with CON pigs. However, intermittently feeding a 40% DDGS diet (D40-CON) resulted in lighter HCW (P<0.05) compared with all other treatments. In Exp. 2, crossbred pigs (n=324; initial BW=33.2±3.0 kg) were assigned randomly to 1 of 6 treatments, including a corn-soybean meal control (CON), a 40% low SID AA DDGS diet (LD), a 40% high SID AA DDGS diet (HD), LD and CON diets alternated (LD-CON), HD and CON diets alternated (HD-CON), or HD and LD diets alternated (HD-LD) with 6 pens per treatment. Final BW and ADG were less (P<0.05) for LD and HD-LD pigs compared with CON pigs, but HD pigs tended to have reduced (P<0.10) final BW and ADG. Loin muscle area was smaller for LD and HD-LD pigs compared with CON pigs (P<0.05). Percentage carcass lean was not affected by dietary treatment. Backfat of DDGS-fed pigs was more unsaturated than CON pigs, but AA digestibility of DDGS did not affect this response. Digestibility of AA in DDGS can influence pig performance and carcass quality when fed at high concentrations (40% or more). The use of a high SID AA DDGS source may diminish some of the negative responses observed for growth performance and carcass characteristics when feeding high concentrations of DDGS if accurate values of SID AA are used in diet formulation. Periodic inclusion and removal of 40% DDGS from diets did not adversely affect growth performance or carcass quality regardless of the SID AA digestibility of the DDGS used. These results indicate that it is possible to abruptly incorporate and remove DDGS from grower-finisher swine diets without meaningful detrimental effects on growth performance or carcass quality.

Impact of distillers dried grains with solubles particle size on nutrient digestibility, DE and ME content, and flowability in diets for growing pigs.

A study was conducted to determine the effect of particle size of distillers dried grains with solubles (DDGS) on DE and ME content, diet DM, energy, N, P digestibility, and diet flowability for growing pigs. One DDGS source was processed through an Urshel Commitrol mill or a hammer mill to achieve mean particle sizes of 818, 595, and 308 µm. The basal control diet consisted of 96.8% corn with supplemental minerals and vitamins. Three experimental diets were formulated by replacing 30% of corn from the basal diet with DDGS of different particle sizes. Thirty-six growing pigs (initial BW of 40 ± 1.13 kg) were assigned to 1 of 4 treatments in a randomized complete block design according to their BW block and housed in individual metabolic crates for a 9-d adaptation period followed by a 4-d total collection of feces and urine. Pigs were provided ad libitum access to water and fed an amount of their respective experimental diets equivalent to 3% of the initial BW of each pig. Feed, feces, and urine samples were analyzed for DM, GE, N, and P and used to calculate diet apparent total tract digestibility (ATTD). Gross energy was also used to calculate DE and ME of diets as well as the DE and ME content of corn and DDGS with different particle sizes. Diet drained and poured angles of repose were measured using a modified Hele-Shaw cell method to evaluate the diet flowability. Inclusion of 30% DDGS with an average particle size of 308 µm improved (P < 0.05) dietary ATTD of DM and GE as well as DE (4,006 vs. 3,783 kcal/kg DM) and ME (3,861 vs. 3,583 kcal/kg DM) compared with 818 µm DDGS. No differences (P > 0.05) were found in N and P digestibility among the 3 DDGS diets. The DDGS particle size of 595 µm had greater (P < 0.05) DE but not ME compared with 818 µm DDGS, and DE and ME were not different between 308 and 595 µm. Compared with a 595 or 818 µm DDGS, grinding DDGS to 308 µm reduced diet flowability as indicated by a greater (P < 0.05) drained angle of repose. These results suggested that for each 25 µm decrease in DDGS particle size from 818 µm to 308 µm, the ME contribution of DDGS to the diet is 13.46 kcal/kg DM, but diet flowability will be reduced.