Residual feed intake (RFI) is the difference between observed and predicted feed intake of an animal, based on growth and maintenance requirements. In Yorkshire pigs, divergent selection for increased (Low RFI) and decreased (High RFI) RFI was carried out over 10 generations (G) while feeding a corn- and soybean-meal-based, higher-energy, lower-fiber (HELF) diet. In G8 to G10, representing 4 replicates, barrows and gilts (n = 649) of the RFI lines were fed the HELF diet and a diet incorporating coproducts that were lower in energy and higher in dietary fiber (LEHF). The diets differed in ME, 3.32 vs. 2.87 Mcal/kg, and in neutral detergent fiber (NDF), 9.4% vs. 25.9%, respectively. The impact of the LEHF diet on 1) performance and growth, 2) diet digestibility, 3) genetic parameter estimates, and 4) responses to selection for RFI, when fed the HELF, was assessed. In general, the LEHF diet reduced the performance of both lines. When fed the HELF diet, the Low RFI pigs had lower (P < 0.05) ADFI (-12%), energy intake (-12%), ADG (-6%), and backfat depth (-12%); similar (P > 0.05) loin muscle area (LMA; +5%); and greater (P < 0.05) feed efficiency (i.e., 8% higher G:F and 7% lower RFI) than the High RFI line. These patterns of line differences were still present under the LEHF diet but differences for ADFI (-11%), energy intake (-10%), G:F (+2%), and RFI (-6%) were reduced compared to the HELF diet. Apparent total tract digestibility (ATTD) of the HELF and LEHF diets was assessed using 116 barrows and gilts from G8. When fed the HELF diet, ATTD of DM, GE, N, and NDF were similar between lines (P ≥ 0.27), but when fed the LEHF diet, the Low RFI pigs had greater digestibility (7%, 7%, 10%, and 32%) than the High RFI line (P ≤ 0.04). To measure responses to selection for RFI and estimate genetic parameters, data from all 10 generations were used (HELF; n = 2,310; LEHF, n = 317). Heritability estimates of performance traits ranged from 0.19 to 0.63, and genetic correlations of traits between diets were high and positive, ranging from 0.87 (RFI) to 0.99 (LMA). By G10, RFI in the Low RFI line was 3.86 and 1.50 genetic SD lower than in the High RFI line when fed the HELF and LEHF diets, respectively. Taken together, the results of this study demonstrate that responses to selection for RFI when fed a HELF diet are not fully realized when pigs are fed an extremely LEHF diet. Thus, feeding diets that differ from those used for selection may not maximize genetic potential for feed efficiency.

Journal Article 320 Effect of hot temperature and drinker type on growth performance of and water disappearance by growing-finishing pigs Get access K. Vande Pol, K. Vande Pol 1University of Illinois, Champaign-Urbana Search for other works by this author on: Oxford Academic PubMed Google Scholar N. S. Grohmann, N. S. Grohmann 1University of Illinois, Champaign-Urbana Search for other works by this author on: Oxford Academic PubMed Google Scholar T. E. Weber, T. E. Weber 2Elanco Animal Health, Greenfield, IN Search for other works by this author on: Oxford Academic PubMed Google Scholar M. J. Ritter, M. J. Ritter 2Elanco Animal Health, Greenfield, IN Search for other works by this author on: Oxford Academic PubMed Google Scholar M. Ellis M. Ellis 1University of Illinois, Champaign-Urbana Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Animal Science, Volume 94, Issue suppl_2, April 2016, Pages 150–151, https://doi.org/10.2527/msasas2016-320 Published: 01 April 2016

Thermal imaging can be used to monitor the thermal comfort of pigs. The objective was to establish the effect of room temperature on skin surface temperatures using thermal imaging of pigs kept under conditions similar to commercial practice. The study was performed as a RCBD; with 2 room temperature treatments: 1) Thermoneutral (TN constant 18°C); and 2) Hot (30°C from 0800–1900; 20°C from 2000–0700). There were 4 rooms of finishing pigs (2 on each temperature treatment). Rooms had fully-slatted concrete floors and there were 8 pens of 10 pigs in each room; floor space was 0.67 m2/pig. Images were taken on 20 randomly selected pigs from each room every 2 wk over an 8-wk period during which mean BW increased from 83.8 ± 11.21 to 129.1 ± 11.42 kg. Images were taken of the ear using 2 cameras (FLIR E6 and IRISYS IRI4010; sensitivity of 0.06°C and 0.15°C, respectively; resolution of 160 × 120 pixels). Emissivity on all images was set at 0.98. Images from each camera were processed with the respective program (FLIR Tools, IRISYS 4000 Series Imager) Surface temperature was measured at 5 points along the centerline of the ear: where the ear joins the head, near the tip of the ear, and 3 points equidistant between these 2 points. All observations for both cameras across the study period were averaged by temperature treatment for each point and an unpaired t test was used to compare the effects of room temperature. The average ear temperature across all 5 points for the Hot and TN treatments was 26.5 ± 3.3°C, and 23.0 ± 5.6°C, respectively (P = 0.11). Ear temperature was greater (P < 0.05) for the Hot than TN treatment the tip of the ear (23.96°C and 18.52°C, respectively) but not at the other measurement points (P > 0.05). The difference in ear temperature between the point closest to the head and the tip of the ear was greater for the TN than the Hot treatment (4.12 and 8.11°C, respectively; P < 0.0001). These results suggest that high environmental temperatures increase the surface temperature at the extremity of the ear due to increased vasodilation, and that the difference in temperature from the base to the tip of the ear may be the most appropriate measurement to assess the thermal comfort of the animal.

To evaluate the effect of feeding thermally oxidized vegetable oils and animal fats on growth performance, liver gene expression, and liver and serum fatty acid and cholesterol concentration in young pigs, 102 barrows (6.67 ± 0.03 kg BW) were divided into 3 groups and randomly assigned to dietary treatments in a 4 × 3 factorial arrangement. The main factors were lipid source (n = 4; corn oil [CN], canola oil [CA], poultry fat [PF], and tallow [TL]) and lipid peroxidation level (n = 3; original lipids [OL], slow oxidation [SO] through heating at 95°C for 72 h, or rapid oxidation [RO] through heating at 185°C for 7 h). Pigs were provided ad libitum access to diets in group pens for 28 d followed by controlled feed intake in metabolism crates for 10 d. On d 39, all pigs were euthanized for liver samples to determine liver weight, lipid profile, and gene expression patterns. Lipid oxidation analysis indicated that compared with the OL, SO and RO of lipids had a markedly increased concentrations of primary and secondary peroxidation products, and the increased lipid peroxidation products in CN and CA were greater than those in PF and TL. After a 28-d ad libitum feeding period, pigs fed RO lipids tended to have reduced ADFI (P = 0.09) and ADG (P < 0.05) compared with pigs fed OL, and pigs fed CA had reduced G:F (P < 0.05) compared with pigs fed all other lipids. Pigs fed RO lipids tended to have increased relative liver weight (P = 0.09) compared with pigs fed OL. Liver triglyceride concentration (LTG) in pigs fed OL was greater (P < 0.05) than in pigs fed SO lipids and tended to be greater (P < 0.07) than in pigs fed SO. The reduced LTG were consistent with increased (P < 0.05) mRNA expression of PPARα factor target genes (acyl-CoA oxidase, carnitine palmitoyltransferase 1, and mitochondrial 3-hydroxy-3-methylglutary-CoA synthase) in pigs fed SO and RO lipids compared with pigs fed OL. Pigs fed CN or CA tended to have increased LTG (P = 0.09) compared with pigs fed TL. Liver cholesterol concentration in pigs fed CN was less (P < 0.05) than in pigs fed PF and tended to be less (P = 0.06) than in pigs fed TL, whereas pigs fed CA had a reduced (P < 0.05) liver cholesterol compared with pigs fed PF or TL. In conclusion, feeding thermally oxidized lipids negatively affected growth performance and LTG of young pigs, which was associated with an upregulation of fatty acid catabolism pathways.

A total of 108 barrows (6.67 ± 0.03 kg BW) were assigned to 12 dietary treatments in a 4 × 3 factorial design plus a corn-soybean meal control diet to evaluate the effect of lipid source and peroxidation level on DE, ME, and apparent total tract digestibility (ATTD) of DM, GE, ether extract (EE), N, and C in young pigs. Main effects were lipid source (corn oil [CN], canola oil [CA], poultry fat [PF], and tallow [TL]) and peroxidation level (original lipids [OL], slow oxidation [SO] of lipids heated for 72 h at 95°C, or rapid oxidation [RO] of lipids heated for 7 h at 185°C). Pigs were provided ad libitum access to diets for 28 d followed by an 8-d period of controlled feed intake equivalent to 4% BW daily. Diets were formulated based on the ME content of CA with the standardized ileal digestible Lys, Met, Thr, Trp, total Ca, and available P:ME balanced relative to NRC (1998) recommendations. Lipid peroxidation analysis indicated that compared with the OL, SO and RO had a markedly increased concentrations of lipid peroxidation products, and the increase of peroxidation products in CN and CA were greater than those in PF and TL. Addition of lipids to diets increased (P < 0.05) ATTD of EE and tended to improve (P = 0.06) ATTD of GE compared with pigs fed the control diet. Feeding CN or CA increased (P < 0.05) ATTD of DM, GE, EE, N, and C compared with feeding TL, while feeding PF improved (P < 0.05) ATTD of GE and EE and tended to increase (P = 0.06) ATTD of C compared with TL. Pigs fed CN had increased (P = 0.05) percentage N retention than pigs fed TL. No peroxidation level effect or interaction between lipid source and peroxidation level on DE and ME was observed. Lipid source tended (P = 0.08) to affect DE but not ME values of experimental lipids (P > 0.12). Digestible energy values for CA (8,846, 8,682, and 8,668 kcal/kg) and CN (8,867, 8,648, and 8,725 kcal/kg) were about 450 kcal/kg greater than that of TL (8,316, 8,168, and 8,296 kcal/kg), with PF being intermediate (8,519, 8,274, and 8,511 kcal/kg), for OL, SO, and RO lipids, respectively, respectively. In conclusion, lipid source affected ATTD of dietary DM, GE, EE, N, and C, and N retention and tended to influence the DE value of the lipid but did not significantly affect their ME value. Rapid and slow heating of lipids used in this study increased lipid peroxidation products but had no detectable effects on nutrient and energy digestibility as well as DE and ME values of the various lipids.

The objective of this experiment was to evaluate peroxidation in 4 lipids, each with 3 levels of peroxidation. Lipid sources were corn oil (CN), canola oil (CA), poultry fat, and tallow. Peroxidation levels were original lipids (OL), slow-oxidized lipids (SO), and rapid-oxidized lipids (RO). To produce peroxidized lipids, OL were either heated at 95°C for 72 h to produce SO or heated at 185°C for 7 h to produce RO. Five indicative measurements (peroxide value [PV], p-anisidine value [AnV], thiobarbituric acid reactive substances [TBARS] concentration, hexanal concentration, 4-hydroxynonenal [HNE] concentration, and 2,4-decadienal [DDE]) and 2 predictive tests (active oxygen method [AOM] stability and oxidative stability index [OSI]) were performed to quantify the level of oxidation of the subsequent 12 lipids with varying levels of peroxidation. Analysis showed that a high PV accurately indicated the high level of lipid peroxidation, but a moderate or low PV may be misleading due to the unstable characteristics of hydroperoxides as indicated by the unchanged PV of rapidly oxidized CN and CA compared to their original state (OL). However, additional tests, which measure secondary peroxidation products such as AnV, TBARS, hexanal, HNE, and DDE, may provide a better indication of lipid peroxidation than PV for lipids subjected to a high level of peroxidation. Similar to PV analysis, these tests may also not provide irrefutable information regarding the extent of peroxidation because of the volatile characteristics of secondary peroxidation products and the changing stage of lipid peroxidation. For the predictive tests, AOM accurately reflected the increased lipid peroxidation caused by SO and RO as indicated by the increased AOM value in CN and CA but not in poultry fat and tallow, which indicated a potential disadvantage of the AOM test. Oxidative stability index successfully showed the increased lipid peroxidation caused by SO and RO in all lipids, but it too may have disadvantages similar to AnV, TBARS, hexanal, DDE, and HNE because OSI directly depends on quantification of the volatile secondary peroxidation products. To accurately analyze the peroxidation damage in lipids, measurements should be determined at appropriate time intervals by more than 1 test and include different levels of peroxidation products simultaneously.

To evaluate the effect of feeding thermally oxidized lipids on metabolic oxidative status, gut barrier function, and immune response of young pigs, 108 barrows (6.67 ± 0.03 kg BW) were assigned to 12 dietary treatments in a 4 × 3 factorial arrangement in addition to a corn-soybean meal control diet. Main effects were 4 lipid sources (corn oil [CN], canola oil [CA], poultry fat [PF], and tallow [TL]) and 3 oxidation levels (original lipids [OL], slow oxidation [SO] of lipids heated for 72 h at 95°C, or rapid oxidation [RO] of lipids heated for 7 h at 185°C). Pigs were provided ad libitum access to diets for 28 d followed by controlled feed intake for 10 d. After a 24-h fast on d 38, serum was collected and analyzed for α-tocopherol (α-T), thiobarbituric acid reactive substances (TBARS), endotoxin, haptoglobin, IgA, and IgG. On the same day following serum collection, lactulose and mannitol were fed and subsequently measured in the urine to evaluate gut permeability. There was a source × peroxidation interaction for serum α-T concentration where pigs fed SO or RO had decreased (P < 0.05) serum α-T concentration compared with pigs fed OL in CA and CN diets but not in pigs fed PF and TL diets. There was no source × peroxidation interaction for serum TBARS, but among all lipid sources, pigs fed SO or RO lipids had increased (P < 0.05) serum TBARS compared with pigs fed OL. In addition, pigs fed CN or CA had greater (P < 0.05) serum TBARS compared with pigs fed PF or TL diets. There were no lipid source × peroxidation level interaction or lipid source or peroxidation level effects on serum endotoxin, haptoglobin, IgA, or IgG. Pigs fed lipid supplemented diets tended to have increased serum endotoxin (P = 0.06), IgA (P = 0.10), and IgG (P = 0.09) compared with pigs fed the control diet. There were no lipid source × peroxidation level interaction or lipid source or peroxidation level effects on urinary TBARS and lactulose to mannitol ratio. Compared with pigs fed the control diet, pigs fed diets containing lipids had a lower lactulose to mannitol ratio (P < 0.01). In conclusion, feeding weaning pigs diets containing 10% thermally oxidized lipids for 38 d, especially vegetable oils containing greater concentrations of PUFA, appeared to impair oxidative status but had little influence on gut barrier function or serum immunity parameters.

Lipid peroxidation in animal feed can negatively affect growth performance and meat quality. Weanling pigs (n = 432; BW = 6.6 ± 0.4 kg) were used to evaluate the effects of feeding peroxidized distillers dried grains with solubles (DDGS) with 3 levels of vitamin E (α-tocopheryl acetate) on growth performance, carcass composition, fatty acid composition of pork fat, and lipid peroxidation in LM. The DDGS source used in this study contained the highest thiobarbituric acid reactive substances (TBARS) value, peroxide value, and total S content (5.2 ng malondialdehyde/mg oil, 84.1 mEq/kg oil, and 0.95%, respectively) among 30 DDGS sources sampled. Pens within blocks were assigned randomly to 1 of 6 diets in a 2 × 3 factorial arrangement of treatments with 8 pens per treatment and 9 pigs per pen. Pigs were fed a corn-soybean meal (CON) or 30% peroxidized DDGS (Ox-DDGS) diets with 3 levels of vitamin E: none supplemented (No-E), NRC (1X-E), or 10X NRC (10X-E). Compared to CON, inclusion of 30% Ox-DDGS in diets reduced (P < 0.001) final BW (110 vs. 107 kg), overall ADG (0.76 vs. 0.74 kg/d), and G:F (0.39 vs. 0.37). Increasing dietary vitamin E concentrations improved G:F (P = 0.03) of pigs fed 10X-E and 1X-E vs. No-E diets (0.39 and 0.39 vs. 0.38, respectively). Hot carcass weight, dressing percentage, backfat depth, and LM area were reduced (P < 0.01) in pigs fed Ox-DDGS compared to CON, but percentage of fat-free carcass lean was not affected. Feeding Ox-DDGS increased (P < 0.001) PUFA concentration, particularly linoleic acid (P < 0.001), and iodine value (P < 0.001) in belly fat and backfat compared to pigs fed CON. Dietary vitamin E levels did not affect fatty acid profiles in belly or back fat. Loin muscle TBARS were measured to determine the lipid peroxidation level in pork loins. Although pigs were fed a Ox-DDGS source in this study, TBARS in LM were similar between Ox-DDGS and CON treatments. There was no interaction between Ox-DDGS and dietary vitamin E concentration in LM TBARS. Alpha-tocopherol concentration in LM was greater (P < 0.001) in 10X-E than No-E or 1X-E dietary treatments. Compared to CON, feeding Ox-DDGS increased α-tocopherol concentration in LM of pigs fed No-E (1.0 vs. 3.1 mg/kg; P = 0.005) but not in those fed 1X-E or 10X-E. These results indicate that feeding diets containing 30% Ox-DDGS to wean-finish pigs may negatively affect growth performance, but supplementation of additional vitamin E in the diet did not counteract these effects.

Humic acid (MFG) and fat-protected butyric acid (BA) has been shown to modulate energy metabolism and inflammation. Therefore, the objectives of this study were to determine the effects of MFG and BA, alone and in combination, on growth performance and response to lipopolysaccharide (LPS)-induced inflammation in young pigs. An experiment was conducted using 448 crossbred weanling pigs, which were stratified by gender and BW and were randomly assigned to 1 of 4 dietary treatments in a 2 × 2 factorial arrangement consisting of control and MFG with or without BA. The pigs were housed at a density of 8 pigs/pen and with 14 pens/dietary treatment. Growth performance and feed intake were assessed for 35 d. To assess the inflammation-related properties of MFG and BA, on d 36 a subset of 48 pigs from each treatment was intramuscular injected with either sterile saline or Escherichia coli LPS (20 μg/kg BW; E. coli serotype O55:B5) for 4 h in a 2 × 2 × 2 factorial arrangement (± LPS, ± MFG and ± BA; n = 6 pigs/treatment group) to assess their febrile response as well as serum, liver, and muscle cytokine responses. Results from this study showed that neither BA nor MFG alone or in combination altered pig ADG, ADFI, and G:F. Moreover, in the presence of LPS, the combination of MFG and BA resulted in a 62% decrease (P = 0.08) in serum cortisol compared to when neither compound was added to the diet. In contrast, serum IGF-I was increased (P < 0.01) by 59% from the use of both MFG and BA, as opposed to when neither was added, with pigs subjected to LPS. However, both MFG and BA inclusion appear to have a complex role in modulating different aspects of the immune response to LPS, particularly when both are fed in combination. Humic acid also appeared to play a role in decreasing oxidative stress.

The ability of enzymes, direct-fed microbials, or yeast to enhance nutrient utilization or growth performance in nursery or finishing pigs fed diets containing increased levels of fiber from corn distillers dried grains with solubles is largely unknown. A total of 192 nursery (11.9kg initial BW) and 96 finishing (98.4kg initial BW) pigs were allotted to individual pens and fed their respective diets for 5 wk. Diets containing corn, soybean meal, and 30% corn distillers dried grains with solubles were adequate in all nutrients and were offered ad libitum in meal form. Additives were included at the recommended rates and were assumed to contain the active ingredients and activity level listed on the product label. In the starter experiment, Allzyme and Releezyme decreased GE, N, C, P, ADF, and NDF digestibility (P<0.05), whereas Econase decreased S, P, and NDF digestibility (P<0.05). In the finisher experiment, Allzyme increased P digestibility (P<0.05), BactoCel decreased N digestibility (P=0.05), BioPlus2B decreased ether extract digestibility (P<0.05), Hemicel decreased ADF digestibility (P<0.05), Porzyme decreased GE, N, C, S, P, ADF, and NDF digestibility (P<0.05), Releezyme decreased GE, N, C, S, P, ADF, and ether extract digestibility (P<0.05), and XPC yeast decreased GE and C digestibility (P=0.05). No effect on nursery- or finishing-pig growth performance because of any feed additive was noted (P>0.10). In conclusion, even though some of the feed additive products evaluated had small effects on nutrient digestibility, none of the products affected starter- and finishing-pig growth performance when fed nutritionally adequate corn-soy diets containing 30% corn distillers dried grains with solubles.

A feeding experiment was conducted to demonstrate similar growth performance and carcass quality in grow-finish pigs fed diets containing ”Bt” corn as compared to ”non-Bt” corn. Bt corn resists the European Corn Borer by expressing the Cry1Ab selective insecticidal protein from Bacillus thuringiensis. Pigs (n=180; DeKalb EB x 45; 30 5.2 kg BW) were randomly assigned to one of three dietary treatments: diets containing 1) Bt corn (Bt); 2) the near isogenic control to the Bt corn (NIC); or 3) commingled conventional, non-genetically modified, corn hybrids (CC). The experimental diets were fed in four phases, and were formulated to contain equal percentages of each corn source within each phase. Pig growth rates were similar between corn sources (P>.10) at all time points. Barrows had greater overall ADG, ADFI, and lower feed efficiency (G:F) than gilts (P<.01). Pigs were harvested at 121 kg and carcass data collected. Pigs fed CC had greater HCW and dressing percentage (P<.05) than pigs fed NIC or Bt. Pigs fed NIC had greater 10th rib fat depth than either Bt or CC fed pigs (P<.05). Pigs fed the NIC corn had lower predicted percent lean than CC fed pigs (P<.05), but similar percent lean to Bt fed pigs. Pigs fed NIC had greater visible loin marbling than CC fed pigs (P<.05) and barrows had greater visible loin marbling than gilts (P<.05). Gilts had greater loin eye area and less backfat at the 10th and last rib (P<.05) and greater predicted percent lean than barrows (P<.05). DNA was extracted from loins of 12 pigs fed Bt and 12 pigs fed NIC diets. Southern blot analysis of PCR products was performed to screen for the presence of specific fragments of the cry1Ab and the endogenous corn protein Shrunken-2 (sh-2) genes. None of the extracted DNA samples were positive for cry1Ab or sh-2 genes. Also, using a competitive immunoassay cryIAb protein was not detected in the extracts of loin samples from pigs fed Bt corn. Results indicate pig growth performance and carcass characteristics are similar in pigs fed diets containing ”Bt” or ”non-Bt” corn. Furthermore, no evidence of passage of the transgene from the corn to the pigs tissue was found.

Some sources of corn dried distillers grains with solubles (DDGS) contain relatively high amounts of oxidized lipids produced from PUFA peroxidation during the production process. These oxidized lipids may impair metabolic oxidation status of pigs. The objective of this study was to understand the effects of feeding corn-soybean meal diets (CON) or diets containing 30% highly oxidized DDGS with 1 of 3 levels of supplemental vitamin E (dl-α-tocopheryl acetate), none, the 1998 NRC level (11 IU/kg), and 10x the 1998 NRC level (110 IU/kg), on oxidative status of nursery pigs. The DDGS source used in this study contained the greatest thiobarbituric acid reactive substances (TBARS) value, peroxide value, and total S content (5.2 ng/mg oil, 84.1 mEq/kg oil, and 0.95%, respectively) relative to 30 other DDGS sources sampled (mean values = 1.8 ng/mg oil, 11.5 mEq/kg oil, and 0.50%, respectively). Barrows (n = 54) were housed in pens and fed the experimental diets for 8 wk after weaning and transferred to individual metabolism cages for collection of feces, urine, blood, and liver samples. Total S content was greater in DDGS diets than in CON (0.39 vs. 0.19%). Dietary inclusion of 30% DDGS improved apparent total tract digestibility of S (86.8 vs. 84.6%; P < 0.001) and S retained (2.94 vs. 2.07 g/d; P < 0.01) compared with CON. Although pigs were fed highly oxidized DDGS in this study, serum TBARS were similar between DDGS and CON treatments. There was an interaction between DDGS and dietary vitamin E level for serum concentrations of α-tocopherol. Serum α-tocopherol concentrations were greater (P < 0.001) in pigs fed DDGS diets than those fed CON when dl-α-tocopheryl acetate was not provided or provided at the NRC level but were similar when dl-α-tocopheryl acetate was supplemented at the 10x NRC level. Pigs fed DDGS diets had greater serum concentrations of S-containing AA, particularly Met (P < 0.001) and taurine (P = 0.002), compared with those fed CON. Liver glutathione concentration was greater in pigs fed DDGS diets than CON (56.3 vs. 41.8 nmol/g). Dietary inclusion of DDGS (P < 0.001) and vitamin E (P = 0.03) increased enzyme activity of glutathione peroxidase. The elevated concentrations of S-containing antioxidants (Met, taurine, and glutathione) in vivo may protect pigs against oxidative stress when feeding highly oxidized DDGS. Therefore, the increased S content in DDGS may be beneficial, and increasing concentrations of vitamin E in diets may not be necessary to protect pigs against metabolic oxidative stress when feeding high S and highly peroxidized DDGS.

Heat stress can compromise intestinal integrity and induce leaky gut in a variety of species. Therefore, the objectives of this study were to determine if heat stress (HS) directly or indirectly (via reduced feed intake) increases intestinal permeability in growing pigs. We hypothesized that an increased heat-load causes physiological alterations to the intestinal epithelium, resulting in compromised barrier integrity and altered intestinal function that contributes to the overall severity of HS-related illness. Crossbred gilts (n=48, 43±4 kg BW) were housed in constant climate controlled rooms in individual pens and exposed to 1) thermal neutral (TN) conditions (20°C, 35-50% humidity) with ad libitum intake, 2) HS conditions (35°C, 20-35% humidity) with ad libitum feed intake, or 3) pair-fed in TN conditions (PFTN) to eliminate confounding effects of dissimilar feed intake. Pigs were sacrificed at 1, 3, or 7 d of environmental exposure and jejunum samples were mounted into modified Ussing chambers for assessment of transepithelial electrical resistance (TER) and intestinal fluorescein isothiocyanate (FITC)-labeled lipopolysaccharide (LPS) permeability (expressed as apparent permeability coefficient, APP). Further, gene and protein markers of intestinal integrity and stress were assessed. Irrespective of d of HS exposure, plasma endotoxin levels increased 45% (P<0.05) in HS compared with TN pigs, while jejunum TER decreased 30% (P<0.05) and LPS APP increased 2-fold (P<0.01). Furthermore, d 7 HS pigs tended (P=0.06) to have increased LPS APP (41%) compared with PFTN controls. Lysozyme and alkaline phosphatase activity decreased (46 and 59%, respectively; P<0.05) over time in HS pigs, while the immune cell marker, myeloperoxidase activity, was increased (P<0.05) in the jejunum at d 3 and 7. These results indicate that both HS and reduced feed intake decrease intestinal integrity and increase endotoxin permeability. We hypothesize that these events may lead to increased inflammation, which might contribute to reduced pig performance during warm summer months.

Microbes and microbial components potentially impact the performance of pigs through immune stimulation and altered metabolism. These immune modulating factors can include endotoxin from gram negative bacterial outer membrane component, commonly referred to as lipopolysaccharide (LPS). In this study, our objective was to examine the relationship between intestinal barrier integrity, endotoxin and inflammation with feed efficiency (FE), using pig lines divergently selected for residual feed intake (RFI) as a model. Twelve gilts (62 ± 3 kg BW) from the low RFI (LRFI, more efficient) and 12 from the high RFI (HRFI, less efficient) were used. Individual performance data was recorded for 5 wk. At the end of the experimental period, ADFI of LRFI pigs was less (P < 0.001), ADG not different between the 2 lines (P = 0.72) but the G:F of LRFI pigs was greater than for HRFI pigs (P = 0.019). Serum endotoxin concentration (P < 0.01) and the acute phase protein haptoglobin (P < 0.05) were greater in HRFI pigs. Transepithelial resistance of the ileum, transport of fluorescein isothiocyanate labeled-Dextran and-LPS in ileum and colon, as well as tight junction protein mRNA expression in ileum, did not differ between the lines, indicating the 2 lines did not differ in transport characteristics at the intestinal level. Ileum inflammatory markers, myeloperoxidase (P < 0.05) and IL-8 (P < 0.10), were found to be greater in HRFI pigs. Alkaline phosphatase (ALP) activity was significantly increased in the LRFI pigs in ileum and liver tissues and negatively correlated with blood endotoxin (P < 0.05). Lysozyme activity in the liver was not different between the lines; however, the LRFI pigs had a twofold greater lysozyme activity in ileum (P < 0.05). Despite the difference in their activity, ALP or lysozyme mRNA expression was not different between the lines in either tissue. Decreased endotoxin and inflammatory markers and the enhanced activities of antimicrobial enzymes in the LRFI line may not fully explain the difference in the FE between the lines, but they have the potential to prevent the growth potential in HRFI pigs. Further studies are needed to identify the other mechanisms that may contribute to the greater endotoxin and acute phase proteins in the HRFI pigs and the greater FE in the LRFI pigs.

High ambient temperature exposure can cause major reductions in intestinal function, pig performance, and, if severe enough, mortality. Therefore, our objective was to examine how acute heat stress (HS) alters growing pig intestinal integrity and metabolism. Individually penned crossbred gilts and barrows (46 ± 6 kg BW) were exposed to either thermal neutral (TN; 21°C; 35 to 50% humidity; n = 8) or HS conditions (35°C; 24 to 43% humidity; n = 8) for 24 h. All pigs had ad libitum access to feed and water. Rectal temperature (Tr), respiration rates (RR), BW, and feed intake (FI) were measured. Pigs were killed after 24 h of environmental exposure and freshly isolated ileum and colon samples were mounted into modified Ussing chambers. Segments were analyzed for glucose and glutamine nutrient transport and barrier integrity [transepithelial electrical resistance (TER) and fluorescein isothiocyanate-labeled dextran transport]. As expected, pigs exposed to HS had an increase in Tr (39.3 vs. 40.9°C; P < 0.01) and RR (52 vs. 119 breaths per minute; P < 0.05). Heat stress decreased FI (53%; P < 0.05) and BW (-2.2 kg; P < 0.05) compared to TN pigs. Compared to TN pigs, mucosal heat shock protein 70 increased (101%; P < 0.05) whereas intestinal integrity was compromised in the HS pigs (ileum and colon TER decreased 52 and 24%, respectively; P < 0.05). Furthermore, serum endotoxin concentrations increased 200% due to HS (P = 0.05). Intestinal glucose transport and blood glucose were elevated due to HS (P < 0.05). However, ileal sucrase and maltase activities decreased in HS pigs (30 and 24%, respectively; P < 0.05). Altogether, these data indicate that high ambient heat loads reduce intestinal integrity and increase circulating endotoxin and stress in pigs. Furthermore, glucose transport and digestive capacity are altered during acute HS.

Endotoxin, also referred to as lipopolysaccharide (LPS), can stimulate localized or systemic inflammation via the activation of pattern recognition receptors. Additionally, endotoxin and inflammation can regulate intestinal epithelial function by altering integrity, nutrient transport, and utilization. The gastrointestinal tract is a large reservoir of both gram-positive and gram-negative bacteria, of which the gram-negative bacteria serve as a source of endotoxin. Luminal endotoxin can enter circulation via two routes: 1) nonspecific paracellular transport through epithelial cell tight junctions, and 2) transcellular transport through lipid raft membrane domains involving receptor-mediated endocytosis. Paracellular transport of endotoxin occurs through dissociation of tight junction protein complexes resulting in reduced intestinal barrier integrity, which can be a result of enteric disease, inflammation, or environmental and metabolic stress. Transcellular transport, via specialized membrane regions rich in glycolipids, sphingolipids, cholesterol, and saturated fatty acids, is a result of raft recruitment of endotoxin-related signaling proteins leading to endotoxin signaling and endocytosis. Both transport routes and sensitivity to endotoxin may be altered by diet and environmental and metabolic stresses. Intestinal-derived endotoxin and inflammation result in suppressed appetite, activation of the immune system, and partitioning of energy and nutrients away from growth toward supporting the immune system requirements. In livestock, this leads to the suppression of growth, particularly suppression of lean tissue accretion. In this paper, we summarize the evidence that intestinal transport of endotoxin and the subsequent inflammation leads to decrease in the production performance of agricultural animals and we present an overview of endotoxin detoxification mechanisms in livestock.

ABSTRACT: Endotoxin, also referred to as lipopolysaccharide (LPS), can stimulate localized or systemic infl ammation via the activation of pattern recognition receptors. Additionally, endotoxin and infl ammation can regulate intestinal epithelial function by altering integrity, nutrient transport, and utilization. The gastrointestinal tract is a large reservoir of both gram-positive and gram-negative bacteria, of which the gram-negative bacteria serve as a source of endotoxin. Luminal endotoxin can enter circulation via two routes: 1) nonspecifi c paracellular transport through epithelial cell tight junctions, and 2) transcellular transport through lipid raft membrane domains involving receptor-mediated endocytosis. Paracellular transport of endotoxin occurs through dissociation of tight junction protein complexes resulting in reduced intestinal barrier integrity, which can be a result of enteric disease, infl ammation, or environmental and metabolic stress. Transcellular transport, via specialized membrane regions rich in glycolipids, sphingolipids, cholesterol, and saturated fatty acids, is a result of raft recruitment of endotoxin-related signaling proteins leading to endotoxin signaling and endocytosis. Both transport routes and sensitivity to endotoxin may be altered by diet and environmental and metabolic stresses. Intestinal-derived endotoxin and infl ammation result in suppressed appetite, activation of the immune system, and partitioning of energy and nutrients away from growth toward supporting the immune system requirements. In livestock, this leads to the suppression of growth, particularly suppression of lean tissue accretion. In this paper, we summarize the evidence that intestinal transport of endotoxin and the subsequent infl ammation leads to decrease in the production performance of agricultural animals and we present an overview of endotoxin detoxifi cation mechanisms in livestock.

An experiment was conducted to determine the effects of feeding a moderate level of 2 different fiber sources on energy metabolites; mitochondrial biogenesis in the intestine, liver, and muscle; and the expression of some genes that regulate energy metabolism in intestine, liver, muscle, and adipose tissue. Female pigs (n = 36; BW = 15.0 ± 0.7 kg) were fed diets containing no added fiber, 12.5% sugar beet pulp (SBP), or 12.5% wheat bran (WB) for 24 d. Blood samples were collected on d 7 and 24 for cholesterol, glucose, NEFA, and triglyceride analyses. At completion of the experiment, ileum, colon, subcutaneous adipose, and LM samples were obtained from a subset (n = 6) of pigs fed each diet for analysis of tissue mitochondrial DNA (mtDNA) content and mRNA abundance by quantitative real-time reverse-transcription PCR. Glycogen and triglyceride content of liver and LM were determined, and colon content VFA was also determined. The addition of SBP or WB to the diet had no effect (P > 0.55) on ADG, ADFI, or G:F. Serum NEFA and triglycerides were increased (P < 0.05) in pigs fed SBP compared with pigs fed the control diet or WB on d 7, and NEFA remained increased (P < 0.05) on d 24 in pigs fed SBP. Dietary fiber had no effect (P > 0.24) on glycogen and triglyceride content of liver or LM, but colonic acetate concentrations were increased (P < 0.05) in pigs fed either SBP or WB. Pigs fed WB had an increased (P < 0.05) mtDNA content in ileum tissue and increased (P < 0.05) citrate synthase mRNA in colon tissue. In the liver, feeding either SBP or WB led to a decrease (P < 0.05) in mtDNA content, whereas feeding WB decreased (P < 0.05) mtDNA abundance in the LM, and feeding either SBP or WB decreased (P < 0.05) expression of citrate synthase mRNA. Quantitative reverse-transcription PCR revealed that feeding WB increased (P < 0.05) proliferating cell nuclear antigen mRNA abundance in the ileum and colon. Feeding WB increased (P < 0.05) mRNA abundance of a regulator of mitochondrial biogenesis, PPAR coactivator 1 α, in ileum tissue, and increased (P < 0.05) mRNA abundance of another mediator of mitochondrial biogensis, sirtuin 1, in colon tissue. Colonic mRNA expression of fasting-induced adipose factor was increased (P < 0.05) in pigs fed either SBP or WB, and adipose triglyceride lipase mRNA abundance was increased (P < 0.05) in adipose tissue of pigs fed SBP. These data indicate that increasing dietary fiber can increase the capacity of the intestine for oxidative metabolism and induce a repartitioning of energy metabolites depending on fiber source.

Little is known of the consequences of divergent selection for residual feed intake (RFI) on intestinal digestion capacity, particularly during immune system stimulation (ISS). Our objective was to evaluate the impact of ISS and divergent selection for RFI on apparent ileal digestibility (AID) and apparent fecal digestibility (AFD) of nutrients and intestinal nutrient active transport and barrier function. Twenty-eight gilts (63 ± 4 kg BW) from low RFI (LRFI; n = 14) and high RFI (HRFI; n = 14) Yorkshire lines were randomly selected from the Iowa State University RFI herd. Following adaptation, 8 pigs in each line were injected intramuscularly and every 48 h for 7 d with increasing amounts of Escherichia coli lipopolysaccharide (ISS+). Remaining pigs were injected with saline (ISS-). Pigs were then euthanized and ileal digesta was collected for measuring AID of nutrients. Fecal samples were collected on a daily basis and pooled for measuring AFD of nutrients. A segment of ileum was used to measure nutrient transport and transepithelial resistance (TER) and/or barrier integrity by Ussing chambers. No effects of line or its interaction with ISS on AID of CP (N × 6.25) and OM, TER, and active nutrients transport were observed. However, ISS decreased (P < 0.05) and tended to (P < 0.1) decrease AID of CP and OM, respectively. Decrease in AFD of CP as result of ISS was greater in the LRFI line compared to the HRFI line (P < 0.05). Relative to ISS-, active glucose and P transport was greater in ISS+ pigs (P < 0.05). Genetic selection for LRFI increases the AFD but has no effect on AID of nutrients. It also reduces the total tract digestive capacity of growing pigs during ISS. Immune system stimulation affects both AID and AFD of dietary CP.

Twenty corn coproducts from various wet- and dry-grind ethanol plants were fed to finishing pigs to determine DE and ME and to generate equations predicting DE and ME based on chemical analysis. A basal diet comprised corn (97.05%), limestone, dicalcium phosphate, salt, vitamins, and trace minerals. Twenty test diets were formulated by mixing the basal diet with 30% of a coproduct, except for dried corn solubles and corn oil, which were included at 20 and 10%, respectively. There were 8 groups of 24 finishing gilts (n = 192; BW = 112.7 ± 7.9 kg). Within each group, gilts were randomly assigned to 1 of 5 test diets or the basal diet for a total of 4 replications per diet per group. Two groups of gilts were used for each set of coproducts, resulting in 8 replications per coproduct and 32 replications of the basal diet. The experiment was conducted as a completely randomized design. Gilts were placed in metabolism crates and offered 3 kg daily of their assigned test diet for 13 d, with total collection of feces and urine during the last 4 d. Ingredients were analyzed for DM, GE, CP, ether extract, crude fiber, NDF, ADF, total dietary fiber (TDF), ash, AA, and minerals, and in vitro OM digestibility was calculated for each ingredient. The GE was determined in the diets, feces, and urine to calculate DE and ME for each ingredient. The DE and ME of the basal diet were used as covariates among groups of pigs. The DE of the coproducts ranged from 2,517 kcal/kg of DM (corn gluten feed) to 8,988 kcal/kg of DM (corn oil), and ME ranged from 2,334 kcal/kg of DM (corn gluten feed) to 8,755 kcal/kg of DM (corn oil). By excluding corn oil and corn starch from the stepwise regression analysis, a series of DE and ME prediction equations were generated. The best fit equations were as follows: DE, kcal/kg of DM = -7,471 + (1.94 × GE) - (50.91 × ether extract) + (15.20 × total starch) + (18.04 × OM digestibility), with R(2) = 0.90, SE = 227, and P < 0.01; ME, kcal/kg of DM = (0.90 × GE) - (29.95 × TDF), with R(2) = 0.72, SE = 323, and P < 0.01. Additional equations for DE and ME included NDF in the instance that TDF data were not available. These results indicate that DE and ME varied substantially among corn coproducts and that various nutritional components can be used to accurately predict DE and ME in corn coproducts for finishing pigs.