Feed supplementation with arginine and zinc on antioxidant status and inflammatory response in challenged weanling piglets

Effects of Organic Zinc on the Growth Performance of Weanling Pigs: A Meta-analysis

Supplementation of feed with organic zinc (Zn) has long been discussed as an alternative to inorganic Zn in pigs, but its effects on growth performance are mixed. This meta-analysis was conducted to provide a comprehensive evaluation of the influence of organic Zn on the growth performance of weanling pigs, on the basis of average daily gain (ADG), average daily feed intake (ADFI), and feed to gain ratio (F/G). We screened the PubMed and Web of Science databases (published before December 31, 2022; limited to English) systematically and contrasted organic Zn supplementation with inorganic Zn supplementation. There were 680 retrievals of studies, of which 16 (1389 pigs, 37 records) were eligible to analyze. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated using a random-effects model. The subgroup analysis was classified as organic Zn source (Zn-amino acid (Zn-AA), Zn-glycine (Zn-Gly), Zn-methionine (Zn-Met), Zn-Lysine (Zn-Lys), proteinate complex Zn (Zn-Pro), chitosan-Zn (Zn-CS) or Zn-lactate (Zn-Lac)) and Zn additive dose (low, medium, or high, i.e., lower than, equal to or higher than the requirement of NRC). Organic Zn addition in the weaning phase increased the ADG (P < 0.001) and the ADFI (P = 0.023) and decreased the F/G (P < 0.001). Specifically, for the organic sources, only Zn-CS supplementation presented significant effects on the ADG (P < 0.001), ADFI (P = 0.011), and F/G (P < 0.001). Moreover, medium-dose organic Zn supplementation had positive effects on ADG (P = 0.012), ADFI (P = 0.018), and F/G (P < 0.001). Our results indicate that organic Zn added to diets greatly improves the growth performance of weanling pigs.

Fucoidan Supplementation Improves Antioxidant Capacity via Regulating the Keap1/Nrf2 Signaling Pathway and Mitochondrial Function in Low-Weaning Weight Piglets

Fucoidan (FC) is known for its antioxidant properties, but it has unclear effects and mechanisms on weaned piglets. Two experiments were conducted to determine the optimal FC dosage in piglet diets and its protective effect against lipopolysaccharide (LPS)-induced oxidative stress. In experiment one, 24 low weight weaned piglets were randomly assigned to four dietary treatments: a basal diet (FC 0), or a diet supplemented with 150 (FC 150), 300 (FC 300), or 600 mg/kg FC (FC 600). In experiment two, 72 low-weaning weight piglets were randomly allocated into four treatments: a basal diet (CON), or 300 mg/kg of fucoidan added to a basal diet challenged with LPS (100 µg LPS/kg body weight) or not. The results showed that FC treatments increased the G:F ratio, and dietary FC 300 reduced the diarrhea incidence and increased the plasma IGF-1 concentrations. In addition, FC 300 and FC 600 supplementation increased the plasma SOD activity and reduced the plasma MDA concentration. LPS challenge triggered a strong systemic redox imbalance and mitochondrial dysfunction. However, dietary FC (300 mg/kg) supplementation increased the activity of antioxidant enzymes, including SOD, decreased the MDA concentration in the plasma and liver, down-regulated Keap1 gene expression, and up-regulated Nrf2, CAT, MFN2, SDHA, and UQCRB gene expression in the liver. These results indicated that dietary fucoidan (300 mg/kg) supplementation improved the growth performance and antioxidant capacity of low-weaning weight piglets, which might be attributed to the modulation of the Keap1/Nrf2 signaling pathway and the mitochondrial function in the liver.

Dietary Arginine Supplementation Improves Intestinal Mitochondrial Functions in Low-Birth-Weight Piglets but Not in Normal-Birth-Weight Piglets

Our previous studies revealed that _L-arginine supplementation had beneficial effects on intestinal barrier functions of low-birth-weight (LBW) piglets, which were associated with the enhanced antioxidant capacity. Moreover, mitochondrial functions are closely related to the redox state. This study was to explore potential mechanisms of _L-arginine-induced beneficial effects against intestinal dysfunction by regulating mitochondrial function of LBW piglets. Twenty 4-day-old normal birth weight (NBW) piglets (BW: 2.08 ± 0.09 kg) and 20 LBW siblings (BW: 1.16 ± 0.07 kg) were artificially fed either a basal diet or a basal diet supplemented with 1.0% _L-arginine for 21 d, respectively. Growth performance, intestinal morphology, redox status, mitochondrial morphology, and mitochondrial functions were examined. Data were subjected to two-way analysis of variance. LBW piglets presented lower (p < 0.05) ADG, shorter (p < 0.05) intestinal villus height, lower (p < 0.05) jejunal adenosine triphosphate (ATP) content and higher (p < 0.05) concentrations of Ca²⁺ and 8-OH-dG in jejunal mitochondria, compared with NBW piglets. Supplementation with 1.0% _L-arginine significantly increased (p < 0.05) ADG, the activities of CAT, SOD, and GPx, intestinal villus height and mRNA abundances of ZO-1 (2-fold) in the jejunum of LBW piglets, but not in NBW piglets. Furthermore, the concentrations of ATP and the transcription of COX IV, COX V genes were up-regulated (p < 0.05) and the concentration of Ca²⁺ and 8-OH-dG were decreased (p < 0.05) in arginine-treated LBW piglets. The results suggest that mitochondrial morphology is affected, and mitochondrial functions are impaired in the jejunum of LBW piglets. While supplementation with 1.0% _L-arginine relieved intestinal dysfunction through enhancing antioxidant capacity and improving mitochondrial functions via repairing mitochondrial morphology, normalizing mitochondrial calcium, and increasing ATP concentration in the jejunum of LBW piglets. However, supplementation with _L-arginine has no significant beneficial effects on intestinal health in NBW piglets.

Functional Amino Acids in Pigs and Chickens: Implication for Gut Health

In pigs and broiler chickens, the gastrointestinal tract or gut is subjected to many challenges which alter performance, animal health, welfare and livability. Preventive strategies are needed to mitigate the impacts of these challenges on gut health while reducing the need to use antimicrobials. In the first part of the review, we propose a common definition of gut health for pig and chickens relying on four pillars, which correspond to the main functions of the digestive tract: (i) epithelial barrier and digestion, (ii) immune fitness, (iii) microbiota balance and (iv) oxidative stress homeostasis. For each pillar, we describe the most commonly associated indicators. In the second part of the review, we present the potential of functional amino acid supplementation to preserve and improve gut health in piglets and chickens. We highlight that amino acid supplementation strategies, based on their roles as precursors of energy and functional molecules, as signaling molecules and as microbiota modulators can positively contribute to gut health by supporting or restoring its four intertwined pillars. Additional work is still needed in order to determine the effective dose of supplementation and mode of administration that ensure the full benefits of amino acids. For this purpose, synergy between amino acids, effects of amino acid-derived metabolites and differences in the metabolic fate between free and protein-bound amino acids are research topics that need to be furtherly investigated.

Influence of Dietary Supplementation with an Amino Acid Mixture on Inflammatory Markers, Immune Status and Serum Proteome in LPS-Challenged Weaned Piglets

In order to investigate the effect of a dietary amino acid mixture supplementation in lipopolysaccharide (LPS)-challenged weaned piglets, twenty-seven 28-day-old (8.2 ± 1.0 kg) newly weaned piglets were randomly allocated to one of three experimental treatments for five weeks. Diet 1: a CTRL treatment. Diet 2: an LPS treatment, where piglets were intraperitoneally administered LPS (25 μg/kg) on day 7. Diet 3: an LPS+MIX treatment, where piglets were intraperitoneally administered LPS on day 7 and fed a diet supplemented with a mixture of 0.3% of arginine, branched-chain amino acids (leucine, valine, and isoleucine), and cystine (MIX). Blood samples were drawn on day 10 and day 35, and serum was analysed for selected chemical parameters and proteomics. The LPS and LPS+MIX groups exhibited an increase in haptoglobin concentrations on day 10. The LPS group showed an increased cortisol concentration, while this concentration was reduced in the LPS+MIX group compared to the control group. Similarly, the LPS+MIX group showed a decreased haptoglobin concentration on day 35 compared to the two other groups. Immunoglobulin concentrations were affected by treatments. Indeed, on day 10, the concentrations of IgG and IgM were decreased by the LPS challenge, as illustrated by the lower concentrations of these two immunoglobulins in the LPS group compared to the control group. In addition, the supplementation with the amino acid mixture in the LPS+MIX further decreased IgG and increased IgM concentrations compared to the LPS group. Although a proteomics approach did not reveal important alterations in the protein profile in response to treatments, LPS-challenged piglets had an increase in proteins linked to the immune response, when compared to piglets supplemented with the amino acid mixture. Overall, data indicate that LPS-challenged piglets supplemented with this amino acid mixture are more protected against the detrimental effects of LPS.

Metagenomics of antimicrobial and heavy metal resistance in the cecal microbiome of fattening pigs raised without antibiotics

This study aimed to detect the cecal microbiome, antimicrobial resistance (AMR) and heavy metal resistance genes (MRGs) in fattening pigs raised under antibiotic-free (ABF) conditions compared with ordinary industrial pigs (control, C) using whole-genome shotgun sequencing. ABF pigs showed the enrichment of Prevotella (33%) and Lactobacillus (13%), whereas Escherichia coli (40%), Fusobacterium and Bacteroides (each at 4%) were notably observed in the C group. Distinct clusters of cecal microbiota of ABF and C pigs were revealed; however, microbiota of some C pigs (C1) appeared in the same cluster as ABF and were totally separated from the remaining C pigs (C2). For AMR genes, the highest abundance tet(Q) (35.7%) and mef(A) (12.7%) were markedly observed in the ABF group whereas tet(Q) (26.2%) and tet(W) (10.4%) were shown in the C group. tet(Q) was positively correlated to Prevotella in ABF and C1 samples. In the C2 group, the prominent tet(W) was positively correlated to Fusobacterium and Bacteroides Pigs have never received tetracycline but pregnant sows used chlortetracycline once 7 d before parturition. Chromosomal Cu and Zn resistance genes were also shown in both groups regardless the received Cu and Zn feed additives. A higher abundance of multi-metal resistance genes was observed in the C group (44%) compared with the ABF group (41%). In conclusion, the microbiome clusters in some C pigs were similar to that in ABF pigs. High abundant tetracycline resistance genes interrelated to major bacteria were observed in both ABF and C pigs. MRGs were also observed.IMPORTANCE: Owing to the increased problem of AMR in farm animals, raising farm animals without antibiotics is one method that could solve this problem. Our study showed that only some tetracycline and macrolide resistance genes, tet(Q), tet(W) and mef(A), were markedly abundant in ABF and C groups. The tet(Q) and tet(W) genes interrelated to different predominant bacteria in each group, showing the potential role of major bacteria as reservoirs of AMR genes. In addition, chromosomal Cu and Zn resistance genes were also observed in both pig groups, not depending on the use of Cu and Zn additives in both farms. The association of MRGs and AMR genotypes and phenotypes together with the method to re-sensitize bacteria to antibiotics should be studied further to unveil the cause of high resistance genes and solve the problems.

Impact of zinc and arginine on antioxidant status of weanling piglets raised under commercial conditions

The effects of dietary zinc and L-arginine supplements on the weight gain, feed efficiency, antioxidant capacity and oxidative status of weanling piglets raised under commercial conditions were examined. A total of 288 piglets aged 21 d were fed for 15 d a diet supplemented or not with 2,500 mg/kg of zinc (provided as zinc oxide) and 1% L-arginine·HCl. The 4 treatments were distributed in a randomized complete block design with 6 initial body weight categories (12 animals per pen). Access to feed and water was ad libitum. Data were analyzed as a 2 × 2 factorial experiment using the SAS MIXED procedure, with zinc and arginine as the main independent variables. Blood collection day (d 8 and 15, samples were collected from the same 2 piglets in each pen before the morning feeding) was included as a third factor. The zinc supplement increased the average daily gain (ADG) from d 0 to 7, d 8 to 15 and d 0 to 15 (0.289 vs. 0.217 kg/d), average daily feed intake (ADFI) from d 8 to 15 and d 0 to 15 (0.338 vs. 0.279 kg/d) and the gain to feed (G:F) ratio from d 0 to 7 and d 0 to 15 (0.86 vs. 0.77) (P < 0.001). Both supplements significantly decreased the malondialdehyde concentration (zinc: 4.37 vs. 3.91 μmol/L, P = 0.005; arginine: 4.38 vs. 3.89 μmol/L, P = 0.002). Total antioxidant capacity and reduced glutathione (GSH) increased from d 8 to 15 (0.953 vs. 1.391 μmol/L, 2.22 vs. 3.37 μmol/L, P < 0.05) regardless of dietary treatment. Total and oxidized GSH concentrations on d 8 were higher in response to the combined supplements (zinc × arginine interaction, P < 0.05). Piglets fed either Zn-supplemented diet had a lower haptoglobin serum concentration (509 vs. 1,417 mg/L; P < 0.001). In conclusion, the zinc supplement improved piglet growth performance (ADG and ADFI) and oxidative status (based on malondialdehyde concentration). The arginine supplement had a limited effect on growth performance and oxidative status under these conditions.

Effects of zinc sources and levels of zinc amino acid complex on growth performance, hematological and biochemical parameters in weanling pigs

Objective

The objective of the study was to investigate the effects of zinc amino acid complex (ZnAA) on growth performance, hematological and biochemical parameters in weanling pigs.

Methods

In Exp. 1, a total of 216 Duroc×Landrace×Large White weanling pigs were assigned randomly to 6 dietary treatments. Each treatment had 6 replicates (pens) with 6 pigs each. The diets were corn-soybean meal based with supplementation of 0, 20, 40, 80, 120 mg Zn/kg from ZnAA or 40 mg Zn/kg from feed-grade zinc sulfate. The experiment lasted 42 days. In Exp. 2, a total of 180 weanling pigs were assigned randomly to 3 dietary treatments supplemented with 0, 80, or 800 mg Zn/kg from ZnAA.

Results

In Exp. 1, pigs fed 40 to 80 mg Zn/kg from ZnAA had higher (p<0.05) average daily gain (ADG) than the unsupplemented group during d 0 to 14. During d 0 to 42, the pigs fed 20 to 120 mg Zn/kg from ZnAA had increased (p<0.05) ADG. Pigs fed 20 to 120 mg/kg Zn from ZnAA had lower feed:gain (p<0.05), increased the activity of serum Cu-Zn superoxide dismutase on d 14, and increased serum Zn levels on d 42 (p<0.05). In Exp. 2, pigs fed diets with 800 mg Zn/kg had increased average daily feed intake during d 15 to 28 (p<0.05) compared to the unsupplemented group. During d 0 to 28, the pigs fed supplemental Zn had increased ADG (p<0.05). On d 14 and d 28, pigs fed supplemental Zn had higher the serum alkaline phosphatase activities (p<0.05). No significant differences were observed in the hematological parameters and organ indices.

Conclusion

Supplementation with 20 to 80 mg/kg Zn from ZnAA improved the growth performance in weaned pigs. The piglets can tolerate up to 800 mg/kg Zn from ZnAA with limited potential health effects.