Effect of dietary linoleic acid concentration and vitamin E supplementation on cell desquamation and susceptibility to oxidative damage of pig jejunal mucosa

Linoleic acid stimulation results in TGF-β1 production and inhibition of PEDV infection in vitro

Linoleic acid (LA) is recommended to improve pork quality. However, whether it affects the intestinal immune response in pigs is still unclear. Our ex vivo experiments demonstrated that LA stimulation resulted in increased frequencies of Tregs in PBMCs but not in Peyer's Patches (PPs). The results of RT-qPCR, flow cytometry, and ELISA indicated that LA increased the TGF-β1 expression level in DCs isolated from PEDV infected pigs. Furthermore, RT-qPCR and flow cytometry results demonstrated that TGF-β1 was associated with higher frequencies of Tregs both in PBMCs and PPs. Additional investigations showed that TGF-β1 inhibited PEDV infection in vitro. Besides, knocking-out TGF-β1 in IPEC-J2 cells resulted in higher viral load. Taken together, our results demonstrated that LA stimulation resulted in enhanced production of TGF-β1 by DC, which resulted in higher frequencies of Tregs production and inhibition of PEDV infection.

Effects of dietary fiber content and different fiber-rich ingredients on endogenous loss of fat and fatty acids in growing pigs

Background

Determination of the endogenous loss of fat (ELF) is used to adjust for the estimation of true total tract digestibility (TTTD) of fat in diets and ingredients. Any factor which affected ELF may further affect the digestibility of fat, including sources and concentrations of fat and fiber in the diet. There are some reports of determining the ELF using regression methods based on different levels of fat intake, while reports on effects of dietary fiber content and different fiber-rich ingredients in pig diets on ELF are very limited. Therefore, the objective of this study was to determine the effects of dietary fiber content and different fiber-rich ingredients on endogenous losses of fat and fatty acids at the end of ileum and throughout the entire intestinal tract in growing pigs.

Methods

In Exp. 1, the effect of fiber content on endogenous loss of fat was determined using six growing pigs (Duroc × Landrace × Yorkshire; 27.6 ± 2.4 kg), fitted with a T-cannula at the end of ileum. The experimental design was a 6 × 6 complete Latin square design with six periods of feeding and six diets. The six experimental fat-free diets were formulated to include graded levels of neutral detergent fiber (NDF) (0, 40, 80, 120, 160 and 200 g/kg) and soybean hull (SH) was the only fiber source, providing 0, 75, 150, 225, 300 and 375 g/kg, respectively. Chromic oxide was included at 4 g/kg in all diets as an indigestible marker. In Exp. 2, six crossbred growing barrows (27.6 ± 1.6 kg) were used and the experimental design was the same as for Exp. 1. The six fat-free diets were formulated to include six common fiber-rich ingredients and the concentration of NDF was 100 g/kg. The six fiber-rich ingredients were defatted rice bran (DRB), sugar beet pulp (SBP), rice hull (RH), corn germ meal (CGM), SH and wheat bran (WB) and they were fed at represented 250, 270, 145, 250, 170 and 280 g/kg in the diet, respectively.

Results

In Exp. 1, the endogenous loss of fatty acids profile did not change as dietary NDF increased in growing pigs. The endogenous losses of fat, C16:0, C18:0, C18:1, C18:2, total unsaturated fatty acids (UFA) and total saturated fatty acids (SFA) in growing pigs at the end of ileum and throughout the entire intestinal tract increased linearly as NDF content of diets increased. The endogenous losses of fat, as well as C16:0 and C18:0 throughout the entire intestinal tract also increased quadratically as NDF content of diets increased. The ELF increased from 0.71 to 3.14 g/kg of dry matter intake (DMI) and 0.56 to 8.21 g /kg DMI at the end of ileum and throughout the entire intestinal tract in growing pigs, respectively. The ELF occurred in the hindgut except for the growing pigs fed 0 and 4% NDF in their diets. The endogenous losses of C16:0 and UFA occurred primarily in the upper regions of the gut and the greatest endogenous losses of C18:0 occurred in the hindgut. The endogenous losses of fat, individual SFA and total SFA throughout the entire intestinal tract were much greater than that at the end of ileum. However, the endogenous losses of individual UFA and total UFA were less throughout the intestinal tract than at the end of ileum. In Exp. 2, the endogenous losses of fat at the end of ileum were greater in growing pigs fed CGM or WB diets. The endogenous loss of fatty acids profile changed to a slight degree at the end of ileum that the endogenous loss of UFA (particularly C18:1 and C18:2) in growing pigs fed CGM or WB diets were greater (P <  0.01) than that for the other four diets. The greatest (P <  0.01) endogenous loss of SFA (particularly C18:0) was in growing pigs fed the RH diet. The endogenous losses of fat, C16:0, C18:0 and SFA over the entire intestinal tract were much greater in growing pigs fed CGM or WB diets, whereas the lowest values were in growing pigs fed DRB diet. The ELF at the end of ileum in growing pigs fed CGM or WB diets were 3.50 or 4.17 g/kg DMI, respectively, and the ELF over the entire intestinal tract was 7.23 or 7.38 g/kg DMI. The contribution in percentage of ELF in the upper gut was greater than that in the hindgut of growing pigs fed DRB and RH diets, while the ELF in the upper gut and hindgut were equal in growing pigs fed SBP, CGM and WB diets. On the whole, the endogenous losses of C18:1 and C18:2 throughout the entire intestinal tract in growing pigs fed the six fiber-rich ingredients diets were less than losses at the end of ileum, whereas the endogenous loss of fat, C16:0, C18:0 and SFA were greater throughout the intestinal tract than at the end of ileum.

Conclusion

The profile of loss in endogenous fatty acids did not change as dietary NDF increased in growing pigs and the endogenous losses of fatty acids (C16:0, C18:0, C18:1 and C18:2) fat, UFA and SFA increased linearly as NDF content increased in the diets of pigs. The endogenous losses of fat or fatty acids at the end of ileum were greater in growing pigs fed RH, CGM or WB diets. The endogenous losses of fat, fatty acids (C16:0 and C18:0) and SFA were greater over the entire intestinal tract in pigs fed CGM or WB diet, while these values were the lowest in growing pigs fed the DRB diet. The contribution in percentage losses of fat in the upper gut were greater than in the hindgut of growing pigs fed DRB and RH diets, while the contribution of losses of fat in the upper gut and hindgut were equal in growing pigs fed SBP, CGM and WB diets. In addition, the endogenous loss of individual or total UFA was less over the entire intestinal tract of growing pigs fed fiber diets than that at the end of ileum, and the greatest endogenous losses of fat, individual or total SFA were over the entire intestinal tract. Therefore, differences in fiber content and the nature of fiber-rich ingredients in diets of pigs have different effects to the endogenous losses of fat or fatty acids. Considering the requirement of fat or fatty acids of pigs, careful attention must be paid that the endogenous losses of fat and fatty acids when fiber ingredients are used in diets of pigs.

Determination of net energy content of dietary lipids fed to growing pigs using indirect calorimetry

The objective of this experiment was to determine the NE content of different dietary lipids fed to growing pigs using indirect calorimetry. Thirty-six growing (initial BW: 41.1 ± 3.1 kg) barrows were allotted to 6 diets based on completely randomized design with 6 replicate pigs per diet. Diets included a corn-soybean meal basal diet and 5 test diets each containing 10% palm oil, poultry fat, fish oil, corn oil, or flaxseed oil at the expense of corn and soybean meal. During each period, pigs were individually housed in metabolism crates for 14 d, which included 7 d for adaptation to feed, metabolism crates, and environmental conditions. On day 8, pigs were transferred to the open-circuit respiration chambers and fed 1 of the 6 diets at 2.3 MJ ME/kg BW0.6/day. Total feces and urine were collected and daily heat production (HP) was also calculated from day 9 to day 13. On the last day of each period (day 14), pigs were fasted and the fasting heat production (FHP) was measured. The results show that the FHP of pigs averaged 809 kJ/kg BW0.6·day-1 and was not affected by diet characteristics. The DE values were 35.98, 36.84, 37.11, 38.95, and 38.38 MJ/kg DM, the ME values were 35.79, 36.56, 36.92, 37.73, and 38.11 MJ/kg DM, and the NE values were 32.42, 33.21, 33.77, 34.00, and 34.12 MJ/kg DM, for the palm oil, poultry fat, fish oil, corn oil, and flaxseed oil, respectively. Based on our result, we concluded that the DE content of dietary lipid varied from 91% to 98% of its GE content, the ME content of dietary lipid was approximately 99% of its DE content, and the NE content of dietary lipid was approximately 90% of its ME content in growing pigs.

Determination of net energy content of soybean oil fed to growing pigs using indirect calorimetry

The objectives of this experiment were: (i) to determine the net energy (NE) of soybean oil (SBO) fed to growing pigs using indirect calorimetry (IC); and (ii) to evaluate the effects of inclusion rate of SBO on heat production, oxidative status and nutrient digestibility in growing pigs. Eighteen growing barrows were allotted to three diets based on completely randomized design with six replicate pigs (period) per diet. Diets included a corn-soybean meal basal diet and two test diets containing 5% or 10% SBO at the expense of corn and soybean meal. During each period, pigs were individually housed in metabolism crates for 14 days, including 7 days to adapt to feed, metabolism crate and environmental conditions. On day 8, pigs were transferred to the open-circuit respiration chambers for measurement of daily O₂ consumption and CO₂ and CH₄ production. During this time, pigs were fed one of the three diets at 2.4 MJ metabolizable energy/kg body weight (BW)^0.6 /day. Total feces and urine were collected and daily total heat production (THP) was measured from days 9 to 13 and fasted on day 14 to evaluate their fasting heat production (FHP). The results show that trends of decreased apparent total tract digestibility of neutral detergent fiber (linear, P = 0.09) and acid detergent fiber (linear, P = 0.07) were observed as the content of dietary lipids increased. The average THP for the three diets were 1326, 1208 and 1193 kJ/kg BW^0.6 /day, respectively. The FHP of pigs averaged 843 kJ/kg BW^0.6 /day and was not affected by diet characteristics. A reduction of the respiratory quotients in the fed state as the inclusion level of SBO increased was observed. In conclusion, the NE values of SBO we determined by indirect calorimetry were 33.45 and 34.05 MJ/kg dry matter under two inclusion levels. THP could be largely reduced when SBO is added in the feed, but the THP of SBO included at 5% in a corn-soybean meal diet is not different from the THP of SBO included at 10%.

Short Communication: Antioxidant capacity in the intestinal mucosa of weanling piglets fed diets containing Fusarium mycotoxins and the efficacy of commercial supplements sold as detoxifiers

Le Thanh, B. V., Lessard, M., Chorfi, Y. and Guay, F. 2015. Short Communication: Antioxidant capacity in the intestinal mucosa of weanling piglets fed diets containing Fusarium mycotoxins and the efficacy of commercial supplements sold as detoxifiers. Can. J. Anim. Sci. 95: 569–575. The ability of commercial feed additives to prevent oxidative damage due to deoxynivalenol (DON) in piglets was studied. Sixty piglets (6.0±0.5 kg) were assigned randomly to six wheat–corn–soybean diets: control (<0.5 mg kg−1 DON), DON-rich diet (4 mg kg−1 DON), and four DON-rich diets supplemented with either glucomannan (DON+GLUC), yeast, live bacteria, enzymes and plant extract (DON+YBP), aluminosilicate (DON+ALS), or a mixture of preservatives (DON+PV). Malondialdehyde concentration (MDA), glutathione peroxidase activity (GPx), catalase activity (CAT) and superoxide dismutase activity (SOD) in the small intestine were measured after 14 d. The DON-rich diet increased MDA in the jejunum while decreasing CAT in the jejunum and SOD in the ileum and increasing GPx in the ileum (P<0.05). The DON+GLUC diet decreased GPx and SOD (P<0.05) and tended to decrease MDA in the jejunum (P<0.10). The DON+YBP, DON+PV and DON+ALS diets all decreased CAT in the jejunum, while DON+YBP and DON+PV also did so in the ileum (P<0.05). DON+GLUC decreased SOD in the jejunum, while DON+YBP increased it (P<0.05). In the ileum, DON+PV decreased SOD, while DON+ALS increased GPx (P<0.05). No significant differences in total antioxidant capacity (TAC) in intestinal tissues were found. This study demonstrates that the mycotoxin DON and anti-mycotoxin additives modify oxidative status, including the antioxidant enzyme activities (CAT, SOD or GPx) in the intestinal mucosa of piglets. However, it was not possible to identify a specific antioxidant enzyme involved in counteracting the effect of DON.

Net energy of soybean oil and choice white grease in diets fed to growing and finishing pigs

The objectives of this experiment were 1) to determine the NE of soybean oil (SBO) and choice white grease (CWG) fed to growing and finishing pigs, 2) to evaluate the effects of inclusion rate of SBO on the NE by growing and finishing pigs, and 3) to determine if there is a difference in the NE of SBO and CWG between growing and finishing pigs. Forty-eight growing (initial BW: 22.13 ± 1.78 kg) and 48 finishing (initial BW: 84.17 ± 5.80 kg) barrows were used, and they were housed and fed individually. Within each stage of growth, pigs were allotted to 8 outcome groups of 6 barrows based on BW. Within each outcome group, pigs were randomly allotted to 1 of 6 groups. Two groups at each stage of growth served as an initial slaughter group. Pigs in the remaining groups were assigned to 4 dietary treatments and slaughtered at the conclusion of the experiment. The basal diet contained corn, soybean meal, and no supplemental lipids. Three additional diets were formulated by mixing 95% of the basal diet and 5% SBO, 90% of the basal diet and 10% SBO, or 90% of the basal diet and 10% CWG. Average daily gain and G:F for finishing pigs and apparent total tract digestibility of energy for growing and finishing pigs increased (linear, P < 0.05) with lipid content, but was not affected by lipid source. The lipid gain:protein gain ratio and the energy retention also increased (linear, P ≤ 0.05) with lipid content in growing and finishing pigs. There were no interactive effects between lipid content and stage of growth or between lipid source and stage of growth on the NE of diets and the NE of dietary lipids. The NE of diets increased (linear, P < 0.01) with increasing SBO (2,056, 2,206, and 2,318 kcal/kg for diets containing 0, 5, or 10% SBO). The NE of the diet containing 10% CWG (2,440 kcal/kg) was greater (P < 0.05) than the NE of the diet containing 10% SBO. The NE of diets was greater (P < 0.05) for finishing pigs than for growing pigs regardless of lipid content or source. The NE of SBO included at 5% (5,073 kcal/kg) was not different from the NE of SBO included at 10% (4,679 kcal/kg), but the NE of CWG (5,900 kcal/kg) was greater (P < 0.05) than the NE of SBO. The stage of growth had no impact on the NE of SBO or CWG. In conclusion, the NE of lipids is not affected by the content of dietary lipids, but the NE of CWG is greater than the NE of SBO.