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Five 43-kg barrows [(Dutch Landrace x Yorkshire) x Yorkshire] were fitted with steered ileocecal valve cannulas to compare the effects of K-diformate (KDF), a specifically conjugated salt vs its molecular constituents, namely, formic acid and K-formate, as acidifiers in lysine-deficient diets on the apparent ileal (ID) and fecal digestibility, retention of nutrients, and manure production. The animals were randomly assigned to five dietary treatments according to a 5 x 5 Latin square design as follows: 1) control-no acidifier; 2) 1% KDF (= 0.65% K-formate + 0.35% formic acid, or 0.7% [HCO[O.sup.-]] + 0.3% [[K.sup.+]]); 3) 0.65% K-formate (= 0.35% [HCO[O.sup.-]] + 0.3% [[K.sup.+]]); 4) 0.35% formic acid (= 0.35% [HCO[O.sup.-]]); and 5) 1.3% K-formate (= 0.7% [HCO[O.sup.-]] + 0.6% [[K.sup.+]]). Diets were formulated with barley, wheat, soybean meal, and canola meal as major ingredients, and provided all nutrients at adequate levels, except for lysine (24% less than estimated requirement). Feeding level was equal to 2.5 x maintenance requirement (MR) for ME (MR = 418 kJ ME*B[W.sup.-0.75), and daily rations were given in two portions after mixing with water in a ratio of 1:2.5. Chromic oxide was used as an indigestible marker. No clinical health problems due to the dietary treatments were observed. Irrespective of the additive, there were no differences (P [less than or equal to] 0.10) in the ID of DM, OM, CP, or essential amino acids compared to the control, except for phenylalanine (P [less than or equal to] 0.05). Among nonessential AA, only the ID of tyrosine tended (P = 0.092) to increase (up to 3.9 percentage units). The fecal digestibility of ash and K were greater (P [less than or equal to] 0.001) in pigs fed supplemental K, irrespective of its source. The greater intake and fecal digestibility of K corresponded with greater (P [less than or equal to] 0.05) losses of K in urine. Body retention of N, Ca, total P, and K was similar (P [greater than or equal to] 0.10) among treatments. As estimated from a separate nonorthogonal analysis, supplemental K improved (P [less than or equal to] 0.05) body N by 3.7 percentage units compared to the control. The results of this study do not provide a clear explanation for the improved growth performance reported previously with KDF and its molecular constituents, and further research on their in vivo mode of action will require methodological refinement, especially with regard to the efficiency of AA utilization. Key Words: Pigs, Digestibility, Retention

Four barrows of approximately 40 kg initial body weight, fitted with post-valvular T-cecum cannulas, were used to study the effect of lecithin as an external emulsifier on apparent ileal and overall digestibility of crude fat, fatty acids, and other dietary nutrients (DM, N, GE, crude fiber [CF], P, Ca, and Mg), as well as the utilization of N, GE, Ca, P, and Mg. Two levels of lecithin (0 and .24%) and two levels of rendered fat (0 and 6%) in cereal-soybean meal-based diets were investigated according to a 4 x 4 Latin square design. No significant interactions were found between lecithin and rendered fat for apparent digestibility of crude fat as estimated at the end of the small intestine and the total digestive tract. Lecithin decreased the apparent ileal digestibility of C16:0 fatty acid (P [is less than] .1) and the apparent overall digestibility of C14:0 fatty acid (P [is less than] .05) and C18:2 fatty acid (P [is less than] .1). The apparent ileal and overall digestibility of crude fat (P [is less than] .001) and total fatty acids (P [is less than] .05) increased with the inclusion of rendered fat in diets. Furthermore, rendered fat increased the apparent ileal and overall digestibility of C14:0 (P [is less than] .01), C16:1 (ileal, P [is less than] .001; overall, P [is less than] .1), and C18:1 (P [is less than] .05) fatty acids and the apparent overall digestibility of C18:0 (P [is less than] .001) fatty acid. Lecithin had no impact on the apparent digestibility and retention (percentage of intake) of GE, N, total P, Ca, and Mg. Rendered fat increased the apparent digestibility of DM (ileal, P [is less than] .1; overall, P [is less than] .05), N (P [is less than] .05), and GE (P [is less than] .05) at the terminal ileum and total tract. Also, the apparent ileal digestibility of Ca (P [is less than] . 1) and the retention (percentage of intake) of N, ME, and [ME.sub.n] were improved (P [is less than] .05) by the addition of rendered fat. Dietary lecithin had no influence on the apparent ileal or overall digestibility of rendered fat as estimated in the small intestine and the whole digestive tract of pigs.

Lecithin was investigated in diets for growing-finishing pigs. Diets were based on corn and soybean meal and contained a constant ME:lysine level. The use of lecithin as an emulsifier on utilization of soy oil by the pig was investigated in Exp. 1. Diets were arranged in a 2 x 2 factorial structure with two levels of lecithin (0 and 2%) and two levels of soy oil (0 and 6%). There were no interactions between lecithin and soy oil for any measurements of growth performance. In general, the inclusion of lecithin or soy oil did not affect (P |is greater than~ .1) ADG but did improve (P |is less than~ .01) gain/feed during the finishing period and during the entire experiment. During the finishing period, gain/ME intake was improved (P |is less than~ .01) by both lecithin and soy oil. The use of lecithin as an energy source for pigs was investigated in Exp. 2. Dietary treatments were corn and soybean meal diets with 0, 1, 2, or 3% lecithin. There were no significant differences in performance of pigs as measured by ADG, ADFI, gain/feed, and gain/ME intake among the four lecithin levels. Lecithin did not improve utilization of soy oil by growing-finishing pigs. Furthermore, lecithin was not an efficacious source of supplemental dietary fat for growing-finishing pigs in this study.

One digestibility experiment (Exp. 1) and two growth experiments (Exp. 2 and 3) were conducted to evaluate the use of lecithin as an emulsifier of soy oil and(or) an energy source in a two-phase starter diet program. Phase 1 consisted of d 0 to 14 postweaning, and Phase 2 consisted of d 14 to 35 postweaning. Diets were based on corn, soybean meal, and 20% dried whey and contained a constant ME:lysine level. In Exp. 1 and 2, two levels of lecithin (0 and 2%) at two levels of soy oil (0 and 6%) were investigated. In both experiments, there was no interaction between lecithin and soy oil for any traits measured. In Exp. 1, the apparent digestibility of fat increased significantly with increased fat level in the diets. Addition of lecithin to diets improved (P |is less than~ .05) nitrogen retention, and the addition of soy oil significantly improved apparent digestibility of DM, GE, fat, and CP. In Exp. 2, there was no significant effect of lecithin or soy oil on ADG. In Phase 2 and overall, the inclusion of lecithin and soy oil to diets significantly increased gain/feed but did not significantly improve gain/ME intake. In Exp. 3, pigs were fed diets containing 0, 1, 2, or 3% lecithin. The addition of lecithin to diets did not affect ADG, ADFI, gain/feed, or gain/ME intake during Phases 1, 2, or overall. These results fail to demonstrate that the addition of lecithin to diets for young pigs improves utilization of soy oil or growth performance.

The aim of this investigation was to study the effect of K-diformate on the intraluminal pH, microbial composition in digesta and feces, organic acids along the digestive tract, and alterations of the gastric epithelium of pigs. Pigs (n = 36) weaned at 28 d of age were allotted to two groups and fed without (control diet) or with 1.8% supplemental K-diformate. Fecal samples were taken from the rectum on d 0, 1, 3, 5, 7, 14, 21, and 28 postweaning. Half of the animals from each group were killed on d 7 and the other half on d 29 postweaning. Growth performance was not different for both groups (P [is greater than or equal to] 0.73). The gastric epithelium was not negatively affected by K-diformate (P = 0.25). Potassium-diformate decreased (P [is less than or equal to] 0.04) or tended to decrease (P [is less than or equal to] 0.10) the counts of total anaerobic bacteria, lactic acid bacteria, and yeasts in feces and digesta samples from the stomach, distal small intestine, cecum, and middle segment of the colon. The pH along the gastrointestinal tract of piglets was not affected by K-diformate (P [is greater than or equal to] 0.30). On d 7, the concentration of lactic acid along the gastrointestinal tract was similar with both diets (P = 0.15). On d 29, the concentrations of lactic acid tended to be lower along the small intestine (P [is less than or equal to] 0.08) and the stomach (P = 0.11) of the pigs fed K-diformate. Formic acid in digesta was detected at significant levels only in the distal segment of the small intestine of the control pigs (from 4 to 11 mmol/kg of wet digesta), whereas considerable amounts were measured in the stomach (from 23 to 40 mmol/kg of wet digesta) and all segments of the small intestine (from 7 to 25 mmol/kg of wet digesta) in the K-diformate-fed pigs on both days. On d 7, pigs fed the K-diformate diet had a tendency (P [is less than or equal to] 0.08) to have higher concentrations of organic acids (acetic + propionic + butyric) in the digesta of the distal small intestine, cecum, and proximal colon. On d 29, both groups had similar concentrations of these acids, irrespective of the segment of the gastrointestinal tract (P = 0.95). Our study showed that the addition of K-diformate to a starter diet for piglets decreased total anaerobic bacteria, lactic acid bacteria, coliforms, and yeasts in feces and in digesta from various segments of the gastrointestinal tract, without affecting the gastric or intestinal pH. Key Words: Formates, Microbial Flora, pH, Pigs, Short Chain Fatty Acids

Three experiments were conducted to evaluate the effect of adding salts of formic acid to diets for growing-finishing pigs. In Exp. 1, 72 pigs (23.1 kg and 104.5 kg initial and final BW) were used to evaluate the effect of Ca/Na-formate and K-diformate on performance and carcass traits. Treatments were organized in a 2 x 3 factorial arrangement with two feeding regimens (limit and semi-ad libitum feeding) and three diets (control, .85% Ca/Na-formate, and .8% K-diformate). No significant feeding regime x diet interaction was found. The K-diformate diet increased overall ADG of pigs compared with the control and Ca/Na-formate diets, but had no effect on ADFI or gain/feed (G/F) ratio. Neither K-diformate nor Ca/Na-formate had any effect on carcass lean or fat content. In Exp. 2, 10 limit-fed pigs (24.3 kg and 85.1 kg initial and final BW) were used to study the effect of K-diformate on performance and sensory quality of pork. Adding .8% K-diformate to diets increased ADG (P [is less than] .13) and G/F (P [is less than] .04), but had no effect on sensory quality of the pork or content of formate in liver, kidney, or muscle tissue of pigs. In Exp. 3, 96 limit-fed pigs (27.1 kg and 105 kg initial and final BW) were used to determine the effect of adding K-diformate to diets on performance, carcass traits, and stomach keratinization and(or) lesions. Adding K-diformate (0, .6, or 1.2%) to diets increased ADG and ADFI (linear P [is less than] .01). The K-diformate reduced the percentage of carcass fat (linear P [is less than] .03) and fat area in the cutlet (linear P [is less than] .09) and increased percentage lean in the ham (linear P [is less than] .01), flank (linear P [is less than] .02), loin (linear P [is less than] .09), and neck and shoulder (linear P [is less than] .09). The K-diformate had no negative effect on stomach alterations. In Exp. 3, the concentration of coliform bacteria in the gastrointestinal tract was evaluated in eight control and eight 1.2% K-diformate-fed pigs. The K-diformate reduced the number of coliforms in the duodenum (P [is less than] .03), jejunum (P [is less than] .02), and rectum (P [is less than] .10) of pigs. In conclusion, K-diformate improved growth performance and carcass quality of growing-finishing pigs, whereas Ca/Na-formate had no effect. K-diformate had no adverse effect on sensory quality of pork or on stomach alteration scores. Key Words: Carcass Traits, Formate, Growth Performance, Pigs, Sensory Quality

Two growth experiments and one digestibility experiment were conducted to study the effect of trimethylamine oxide (TMAO) and betaine in swine diets. In Exp. 1, 36 limit-fed pigs averaging 19.1 kg in initial weight were used to study the effect of adding TMAO at 10 g/kg of feed or betaine at an equivalent level of methyl groups (10.5 g/kg feed) to a high-fat (11.3% ether extract) basal diet. Dietary addition of TMAO increased ADG by 61 g/d, reduced number of days to market by 8.3 d (P < .02), and tended (P < .09) to improve gain/feed (G/F) compared with the control diet. Betaine had no effect on growth performance of pigs. Adding TMAO or betaine to diets had no effect on percent carcass fat, percent carcass lean, or dressing percentage. Dietary supplementation of TMAO reduced (P < .05) plasma triacylglycerol level (TAG) compared with the control diet. There was no effect of dietary TMAO or betaine on sensory quality characteristics of pork. In Exp. 2, 48 ad libitum-fed pigs averaging 21.7 kg initial BW and 104.7 kg final BW were used to determine the effect of adding low and intermediate levels of TMAO (1, 2, or 5 g/kg) to diets. Adding I g of TMAO increased G/F (P < .01) compared with control pigs. When using orthogonal contrasts, adding 2 g of TMAO reduced (P < .05) P2 backfat thickness and tended to increase (P < .09) lean percentage compared with the control diet. Trimethylamine oxide gave a quadratic effect (P < .05) on plasma TAG levels. Adding 1 and 2 g of TMAO increased plasma TAG, but 5 g of TMAO decreased it compared with the control diet. In Exp. 3, 12 barrows of 42.3 kg average initial BW and 50.0 kg final BW were used to investigate the effect of supplementing diets with I g of TMAO and 1.27 g of betaine/kg of feed on apparent total tract nutrient digestibility. The addition of TMAO increased (P < 0.03) apparent total tract digestibility of fat (HCl-EE). Betaine had no such effect. Adding TMAO to diets influenced growth performance and carcass quality in a dose-dependent manner. Key Words: Pigs, Trimethylamine oxide, Betaine, Animal Fat, Sensory Evaluation