Comparing tryptophan:lysine ratios in dried distillers grains with solubles-based diets with and without a dried distillers grains with solubles withdrawal strategy on growth, carcass characteristics, and carcass fat iodine value of growing-finishing pigs.

A total of 6,240 finishing pigs (DNA 600 × PIC 1050; initially 22.5 ±â€…1.00 kg), divided into two groups, were used in a 119 or 120 d study comparing increasing Trp:Lys ratio in diets containing dried distillers grains with solubles (DDGS) or a DDGS withdrawal strategy (removing all DDGS from the last phase before marketing) on growth performance and carcass fat iodine value (IV). Pigs were randomly allotted to one of seven dietary treatments with 30 to 36 pigs per pen and 26 replications per treatment. Diets were fed in four phases, approximately 23 to 44, 44 to 71, 71 to 100, and 100 kg to market. Diets included a control corn-soybean meal-based diet (no DDGS) formulated to a 19% standardized ileal digestibility (SID) Trp:Lys ratio, four diets with 30% DDGS fed in all four phases and formulated to provide SID Trp:Lys ratios of 16%, 19%, 22%, or 25%, and two DDGS withdrawal strategy diets: 19% SID Trp:Lys with 30% DDGS in phases 1 through 3 and then 0% DDGS in phase 4 with either a 19% or 25% Trp:Lys ratio. Overall, body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and gain:feed ratio (G:F) increased (linear, P < 0.05) as SID Trp:Lys ratio increased in diets with 30% DDGS fed in all phases. Simultaneously, hot carcass weight (quadratic, P = 0.014), carcass yield (quadratic, P = 0.012), and backfat depth (linear, P = 0.040) increased with increasing Trp:Lys ratio. Pigs fed the 19% SID Trp:Lys ratio withdrawal strategy diet had similar ADG and ADFI as those fed the control diet, the 25% Trp:Lys withdrawal diet, or the 30% DDGS diets with 25% Trp:Lys ratio throughout the study. Pigs fed the control diet had decreased (P < 0.05) carcass fat IV compared to pigs fed the DDGS diets throughout the study, with pigs fed the two DDGS withdrawal strategy diets intermediate. In summary, increasing the SID Trp:Lys ratio in diets with 30% DDGS resulted in a linear increase in ADG, ADFI, G:F, and BW but did not influence carcass fat IV, with most of the benefits observed as diets increased from 16% to 19% Trp:Lys. Removing DDGS from the diet in the last period reduced carcass fat IV and increased growth rate during the withdrawal period compared to pigs fed with 30% DDGS throughout, indicating value in a withdrawal strategy.

Feeding high levels of dried distillers grains with solubles (DDGS) up to marketing has been found to have negative impacts on growth performance and carcass characteristics of finishing pigs, specifically carcass yield. High inclusion of DDGS has also been shown to increase iodine value (IV), a measurement of fat quality, due to increased deposition of unsaturated fatty acids. However, recent data suggested that when feeding finishing pigs diets containing DDGS, increasing the standardized ileal digestible Trp:Lys ratio well above the NRC requirement estimates can prevent or lessen some of these negative effects. This study compared removing DDGS from the final dietary phase with two levels of Trp:Lys ratio, commonly referred to as a withdrawal strategy, to increasing levels of Trp:Lys in diets containing 30% DDGS. The results of this study indicate that increasing the Trp:Lys ratio in diets containing DDGS to a 25% Trp:Lys ratio resulted in growth performance similar to the control diet and the withdrawal strategy, with most of the benefits observed when Trp:Lys is increased from a deficient to adequate status. However, feeding diets with DDGS up to market resulted in increased IV.

Effect of lactation and nursery diets supplemented with a feed flavor on sow feed intake and lactation performance and subsequent weaned pig nursery performance.

A total of 105 sows (Line 241, DNA, Columbus, NE) were used across four batch farrowing groups to evaluate the effects of feeding a feed flavor in lactation diets on sow and litter performance. Sow groups 1 and 2 farrowed in an old farrowing facility during the summer months and groups 3 and 4 farrowed in a new farrowing facility during the winter months. Sows were blocked by body weight (BW) within parity on days 110 of gestation and allotted to 1 of 2 dietary treatments. Dietary treatments were a standard corn-soy-based lactation diet (control) or the control diet with the addition of a feed flavor at 0.05% of diet (Krave AP, Adisseo, Alpharetta, GA, USA). Farrowing facility environment had a large impact and resulted in many interactions with the feed flavor treatment. From farrowing to weaning, sows fed the feed flavor in the old farrowing house tended to have a higher (P = 0.058) lactation feed intake, while no difference in average daily feed intake (ADFI) was observed in the new farrowing house. Pigs weaned from sows fed with the feed flavor in the old farrowing facility had a higher (P = 0.026) BW at weaning and piglet average daily gain (ADG) from day 2 to weaning (P = 0.001) compared to piglets from sows not fed with the feed flavor; whereas the opposite occurred in the new farrowing house. Progeny from one farrowing group in the old farrowing facility was followed into the nursery. A total of 360 weaned pigs (DNA 241 × 600: initially 5.7 kg) were used in a 2 × 2 factorial in the nursery portion of the study to evaluate the effects of previous sow feed flavoring treatment (control vs. flavor) and nursery diets formulated with or without a feed flavor on growth performance in a 38-d trial. Nursery treatments were either a control diet or a diet containing a feed flavor (Delistart #NA 21, Adisseo). Offspring from sows fed with the flavor diet were heavier at weaning (P < 0.001) which was maintained throughout the study. Overall, progeny from sows fed with a diet containing a feed flavor had greater (P < 0.05) ADG, ADFI, and final BW during the trial. The presence of a feed flavor in the nursery did not improve overall nursery performance. In conclusion, when sow lactation feed intake was increased in the old farrowing house, pigs weaned from sows fed with the flavor diet were heavier (P = 0.039) at weaning compared to pigs weaned from sows fed with the control diet. Adding the feed flavor increased sow feed intake and piglet ADG in a warm environment, but not in a cool environment.