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This study evaluated the impact of different vitamin D supplementation strategies to pre- and post-weaning piglets on vitamin D, calcium and phosphorous metabolism and immune status. Sixty piglets were selected at d 2 of age [body weight (BW) = 1.71 ± 0.03 kg] and orally supplemented with saline (CTR) or a solution of 25(OH)D3at d 2, d 8, and d 21 (0.1, 0.2 and 0.3 mg, respectively) along with UVB exposure every second day from d1 4 up to d 21 (HD). From weaning (d 21) until d 42, CTR animals were supplemented with 2,000 UI of vitamin D3/kg of feed and HD animals were supplemented with 2,000 UI 25(OH)D3/kg. Piglets were sacrificed at d 21, d 28, and d 35 (n = 10/treatment/d) for the collection of blood, jejunum, liver, and kidney samples. Serum 25(OH)D3concentrations were determined by HPLC and the mRNA expression of genes implicated in vitamin D, calcium and phosphorous metabolism and immune status were assessed by quantitative real-time PCR. Data were analyzed using a 2x3 factorial design. Serum 25(OH)D3concentrations were 2.8, 3.6, and 2.2-fold greater in HD piglets at d 21, 28, and 35 (P≤ 0.01), respectively (Table 1). No treatment or treatment x time interaction was detected on the expression of genes related to vitamin D metabolism in the jejunum mucosa and liver (P≥ 0.19). In kidney, HD piglets had greater expression of CYP27B1 (P= 0.09) and decreased expression of CYP24A1 (P= 0.06). Renal EGR1 expression was greater in HD piglets (P= 0.01). No treatment effect was detected on the expression of genes directly implicated in phosphate or calcium reabsorption (P≥ 0.16). No treatment or treatment x time interaction was detected on the mRNA expression of selected genes related to immune response in the jejunum mucosa, liver, and kidney (P≥ 0.14). Independently of vitamin D treatments, time effects were detected for gene expression. The mRNA expression of CYP27B1 increased and that of CYP24A1 decreased from d 28 to 35 (P≤ 0.04) in kidney. Genes related to calcium (TRPV5) and phosphate (NPT2c) reabsorption in kidney had reduced mRNA expression on d 35 compared with d 21 (P≤ 0.01). Overall, the mRNA expression of genes related to immune response in all studied tissues was lower at d 35 compared with d 21 (P≤ 0.08). Bodyweight at slaughter was not affected by treatments at d 21, 28, and 35 (P≥ 0.29). In conclusion, pre-weaning vitamin D supplementation enhanced vitamin D status at weaning and the use of dietary 25(OH)D3supplementation was more effective in increasing the vitamin D status post-weaning. The mRNA expression results suggest that greater vitamin D status at weaning and during the first 2 wk post-weaning do not affect calcium and phosphate reabsorption in kidney and the immune defense of pre- and post-weaning piglets.

This study evaluated the impact of different dietary zinc/copper ratios on the gene expression of zinc (Zn), copper (Cu), and iron (Fe) transporters in jejunum and liver of weaned pigs. Piglets (n = 160) were weaned at 21 days of age (d 21; 7.81 ± 0.25 kg) and fed a basal post-weaning diet (without antibiotics) supplemented (n = 40/treatment) with 100 (LZn) or 3,000 (HZn) mg/kg of Zn as ZnO in combination with 6 (LCu) or 130 (HCu) mg/kg of Cu as CuSO4 until d 42. Piglets were sacrificed at d 21, d 28, d 35, and d 42 (n = 10 animals∙treatment -1∙day-1) for harvesting jejunum and liver samples. The mRNA expression of Zn, Cu, and Fe transporters was evaluated by quantitative real-time PCR. Data were analyzed using a 2x2x3 factorial design (two Zn levels, two Cu levels, and three slaughter days) and results are presented as fold-change relative to pre-treatment values (d 21). For Zn-related genes, jejunum Zip4 expression was least for HZn from d 28 (Zn effect; P≤ 0.01; Table 1) and Zip5 was greatest for HZn at d 28 (Zn effect; P= 0.04). On d 42, the greatest values for jejunal Zip4 were observed with LZnHCu (interaction Zn x Cu x time; P= 0.05). For Znt1 in jejunum and liver, mRNA expression was greatest for HZn from d 28 (Zn effect; P≤ 0.01) whereas Zip5 was greatest in liver for HZn at d 28 and d 35 (Zn effect; P≤ 0.04). On d 35, the least values for hepatic Zip5 were observed with LZnHCu (interaction Zn x Cu x time; P= 0.04). For Cu-related genes, no treatment effect (P≥ 0.12) was detected for Crt1 and Atox1 in jejunum and liver. In both tissues, Mt3 expression was greatest for HZn from d 28 (Zn effect; P≤ 0.01). No treatment effect was detected (P= 0.53) for Atp7a expression in jejunum. However, for Atp7b in liver, values were greatest for HZn from d 35 (Zn effect; P≤ 0.01). For Fe-related genes, no treatment effect (P≥ 0.18) was detected for Heph, Tfrc and Fpn1 in jejunum and for Dmt1, Tfrc and Hamp in liver. In jejunum, Dmt1 was greatest for LZn at d 28 and d 42 (Zn effect; P≤ 0.01) whereas Fth1 was greatest in HZn groups from d28 (Zn effect; P ≤ 0.01) and for HCu at d42 (Cu effect; P= 0.04). In liver, Fth1 and Fpn1 were greatest for HZn from d28 (Zn effect; P≤ 0.02). In conclusion, among the present different dietary zinc/copper ratios, most treatment effects on intestinal and hepatic Zn, Cu and Fe transporters originated from dietary ZnO levels suggesting a major contribution of Zn in modulating the metabolism of these trace minerals in post-weaning piglets.

The present study compared the net intestinal absorption of zinc (Zn) and copper (Cu) after meals containing different dietary ratios among these trace elements. Ten 46-kg pigs were used in a cross-over design to assess the 10-h net portal-drained viscera (PDV) flux of serum Cu and Zn after ingestion of boluses containing ZnSO4 and CuSO4 in different Zn:Cu ratios (mg:mg): 120:20; 200:20; 120:8; and 200:8. Arterial Zn concentrations peaked within the first hour post-meal and responses were greater with 200 (0.9 to 1.8 mg/L) than with 120 mg (0.9 to 1.6 mg/L) of dietary Zn (dietary Zn × time, P = 0.05). Net PDV flux of Zn was greater (P = 0.02) with 200 than with 120 mg of dietary Zn and tended to be greater (P = 0.10) with 20 than with 8 mg of dietary Cu. The cumulative PDV appearance of Zn (% of dietary intake) was greater with 120 than 200 mg of dietary Zn from 8 h post-meal (P ≤ 0.04) and with 20 than 8 mg of dietary Cu from 7 h post-meal (P ≤ 0.05). At the end of the postprandial period (10 h), estimated PDV appearance of Zn was 16.0%, 18.4%, 12.0%, and 15.3% of Zn intake for 120:8, 120:20, 200:8, and 200:20 ratios, respectively. For Cu, irrespective of treatment, arterial values varied (P < 0.01) by less than 5% across postmeal times. Net PDV flux was not affected by treatments (P ≥ 0.12), but the value for ratio 120:20 was different from zero (P = 0.03). There was an interaction dietary Zn × dietary Cu on cumulative PDV appearance of Cu (% of dietary intake) at 30 min post-meal (P = 0.04) and thereafter at 3 h post-meal (P = 0.04). For the whole postprandial period (10 h), estimated PDV appearance of Cu was 61.9%, 42.1%, -17.1%, and 23.6% of Cu intake for 120:8, 120:20, 200:8, and 200:20 ratios, respectively. In conclusion, the present dietary amounts and ratios of Zn and Cu can affect the metabolic availability of both trace minerals for pigs. Ratios with 120 mg of dietary Zn maximized the postintestinal availability of both Zn and Cu.

Besides being incorporated into proteins, Trp, an indispensable AA, is involved in numerous metabolic pathways. Previous data showed that Trp conversion into kynurenine (Kyn) and nicotinamide (Nam) differs among studies, and such differences cannot be explained by different dietary niacin supplies. We hypothesized that pig genotype influences Trp metabolism and thus the conversion of Trp into its metabolites. The objective of this study was to compare plasma appearance of Trp and related metabolites in 12 Duroc and 12 Piétrain crossbred postweaning pigs fed 2 contrasting dietary Trp levels. Within each genotype, 6 pigs were fed a basal (B-Trp: 17% and 15% standardized ileal digestible [SID] Trp:Lys for starter and prestarter diets) or supplemented (S-Trp: 24% and 23% SID Trp:Lys for starter and prestarter diets) Trp diet. Growth was monitored, and plasma fasted concentrations were measured over 4 wk, and then pigs were fitted with a jugular catheter for frequent blood samplings. After overnight fasting, 350 g of the experimental diets were offered to each pig, and plasma concentrations of Trp, Kyn, Nam, and 5-hydroxytryptamine (5-HT) were measured for 6 h. The activities of Trp-degrading enzymes were measured in different tissues collected after pig slaughtering. Plasma Trp fasted concentrations did not differ between B-Trp and S-Trp diets and increased from weaning to 2 and 4 wk after weaning for Piétrain but not for Duroc crossbred pigs (time × genotype, P= 0.001). Plasma Kyn concentrations were greater 4 wk after weaning (P= 0.002) than at weaning and for Piétrain compared to Duroc genetics (P= 0.008). Plasma Nam concentrations were greater for pigs fed the S-Trp diet than for those fed the B-Trp diet (P= 0.0001) and for Duroc than for Piétrain genetic lines (P= 0.001); this difference tends to be greater at weaning than after (P= 0.055). Our data showed an increase in plasma concentrations of Trp, Kyn, Nam, and 5-HT according to time after a meal and to the dietary Trp content. However, postprandial plasma concentrations of Trp metabolites and enzyme activities were not significantly different between Duroc and Piétrain crossbred pigs. In conclusion, our results suggest that Nam endogenous synthesis capacity from Trp is greater in Duroc than in Piétrain crossbred pigs, but this was apparent only at weaning.

This study compared the effects of different dietary zinc/copper ratios on zinc (Zn) and copper (Cu) metabolism in weaned pigs. One hundred and sixty piglets (7.81 ± 0.25 kg; 21 d of age) were used in a completely randomized 2 × 2 factorial design composed with high (H) and low (L) levels of added dietary Zn (100 and 3,000 mg/kg) and dietary Cu (6 and 130 mg/kg). Piglets were slaughtered at 21, 28, 35, and 42 d of age for blood and tissues collection. Serum, jejunum mucosa, liver, and kidney concentrations of Zn and Cu were analyzed as well as tissues mRNA abundance of genes related to their metabolism. Serum and liver Zn concentrations increased at days 28, 35, and 42 in HZn groups compared to pre-treatment levels (day 21; P≤ 0.01) but for LZn animals, values decreased at days 28, 35, and 42 in liver (P≤ 0.01) but remained stable vs. day 21 levels in serum (P≥ 0.37). Serum, jejunum mucosa, liver, and kidney Zn concentrations were greater in HZn groups from day 28 (P≤ 0.01). In jejunum mucosa, the mRNA expression of ZIP4 was lower in HZn piglets at day 28 (P≤ 0.01) and at day 42 whereas HCu supplementation increased ZIP4 expression in LZn but not in HZn diets (P= 0.05). For ZNT1, MT3, and MT1, values of relative mRNA expression were greater for HZn animals in jejunum mucosa, liver, and kidney (P≤ 0.01) from day 28. In kidney (P< 0.01) at day 42, HZn supplementation increased MTs expression in both LCu or HCu groups. Serum and liver Cu concentrations decreased at days 35 and 42 in all treatments compared to day 21 (P≤ 0.04), except LZnHCu in liver that was not different from day 21 (P≥ 0.17). Serum Cu concentrations were lower in HZn and greater in HCu groups at days 35 and 42 (P≤ 0.01) whereas hepatic Cu was reduced by HZn diets in both LCu and HCu groups at days 35 and 42 (P≤ 0.01). Jejunum Cu concentrations were increased by HCu diets in HZn but not in LZn groups at days 28 and 42 (P≤ 0.04). Renal Cu concentrations were greater in HZn groups at day 28 (P< 0.01) whereas at day 42 HZn diets increased Cu values in both LCu and HCu groups (P≤ 0.01). The expression of ATP7A in kidney at day 42 was greater for HZn groups (P= 0.02). In conclusion, high dietary Zn levels were not efficiently regulated by homeostatic mechanisms and significantly impaired Cu homeostasis. Low dietary Zn/Cu ratios allow a more efficient regulation of the metabolism of these trace minerals in post-weaning piglets. The current official recommendations for Zn and Cu to post-weaning piglets apparently do not fulfill their requirements.Optimal dietary zinc/copper ratios in diets for post-weaning piglets are necessary not only to address environmental and public health (antibiotic resistance) issues but also to improve piglets’ health. This study shows the disturbed homeostasis of zinc and copper metabolism in post-weaning piglets fed high dietary zinc/copper ratios and suggests that current official recommendations for zinc and copper to post-weaning piglets do not fulfill their requirements.Zinc oxide and copper sulfate are commonly used as growth promoters and alternatives to antibiotics to prevent diarrhea in weaned piglets but their use in post-weaning pigs diets has been challenged due to environmental issues and concerns related to bacterial resistance to antibiotics and heavy metals. Recently, it was reported that high dietary zinc levels interfere with copper status and may be detrimental to post-weaning piglets’ health. In fact, the optimal dietary zinc/copper ratios need to be determined. Therefore, this experiment was conducted to evaluate the effects of different dietary zinc/copper ratios (3,000/130, 3,000/6, 100/130, and 100/6 mg/kg) on zinc and copper metabolism in weaned piglets. This study demonstrated that high dietary zinc/copper ratios impaired zinc and copper homeostasis but also that 100 mg/kg of dietary zinc and 6 mg/kg of dietary copper are apparently not sufficient to fulfill the piglets’ requirements during the first weeks post-weaning.

This study compared different dietary zinc oxide (ZnO) levels on zinc (Zn) and copper (Cu) metabolism in weaned pigs. One hundred twenty weaned piglets (7.96 ± 1.17 kg; 21 d of age) were used in a completely randomized 3 × 4 factorial design composed with three levels of dietary ZnO at 100 (100Zn), 1,000 (1,000Zn), or 3,000 mg/kg (3,000Zn) and four ages at slaughter at 21 (day 21), 23 (day 23), 35 (day 35), and 42 d (day 42). Dietary Cu levels were constant at 130 mg/kg. Serum, jejunum, liver, and kidney levels of Zn and Cu as well as mRNA abundance of genes related to Zn and Cu metabolism were analyzed. Zinc levels were greatest in 3,000Zn piglets from day 35 in all tissues (P ≤ 0.01). In 3,000Zn piglets, mRNA expression of ZIP4 was reduced in jejunum whereas ZnT1 and MT3 were stimulated in jejunum and liver and MT1 in kidney (P≤ 0.04) from day 35. Copper levels were greatest in jejunum (P= 0.06) and kidney (P≤ 0.01; days 35 and 42 only) and lowest in liver and serum (P≤ 0.01) of 3,000Zn piglets. In conclusion, the treatment containing 3,000 mg ZnO/kg triggered Zn homeostatic mechanisms in weaned pigs and impaired Cu metabolism through high enterocyte and kidney Cu sequestration.Supranutritional levels of zinc oxide (ZnO) in piglets post-weaning diets are related to environmental concerns and antibiotic resistance issues but the effects on trace minerals metabolism are less explored. This study shows the disturbed homeostasis of zinc and copper in post-weaning piglets fed high levels of ZnO, with a potential risk of Cu deficiency under long-term supranutritional supplementation and detrimental impacts on piglets growth.Zinc oxide (ZnO) is commonly used in post-weaning pig diets as growth promoter alternative to antibiotics to prevent diarrhea. The use of supranutritional levels of ZnO in post-weaning pigs diets has been challenged due to environmental issues and concerns related to bacterial resistance to antibiotics and heavy metals. However, the limited knowledge of the consequences of high levels of dietary ZnO on the metabolism of trace minerals has hampered advances to replace this nutritional strategy without compromising piglets health. Therefore, this experiment was conducted to evaluate the effects of increasing levels of dietary ZnO (i.e., 100, 1,000, and 3,000 mg/kg) on Zn and Cu metabolism in weaned piglets. In this experiment, it was demonstrated that systemic Zn levels were not effectively regulated with supplementation levels at 3,000 mg of ZnO/kg of diet. In addition, this level of dietary ZnO increased the intestinal intracellular sequestration of Cu and impaired its renal reabsorption, negatively impacting hepatic, and systemic serum Cu concentrations. These results emphasize the potential risk of Cu deficiency under long-term supranutritional supplementation of dietary ZnO during the post-weaning period, with potentially detrimental impacts on piglets growth.

The present experiment aimed to determine if Trp metabolism and growth responses to dietary Trp are modulated by dietary niacin (B3) in weanling piglets. Piglets weaned at 3 wk of age were distributed 1 wk later (7.6 kg of BW, SEM = 0.1) in 52 pens of 2 animals each. Pens were assigned to factorial dietary treatments with 2 additions of B3, 15 mg/kg (LB3) vs. 45 mg/kg (HB3) and 2 additions of Trp, 0 mg/kg (-Trp) vs. 1 mg/kg (+Trp) for Trp to Lys ratios of 0.16 vs. 0.24, respectively. Growth performance was recorded every week from 4 to 10 wk of age. Fasting blood samples were taken at 4, 6, 8, and 10 wk of age. From 4 to 10 wk of age, ADFI tended to be greater (P= 0.10) in HB3 than in LB3 (1,031 vs. 1,003 g, SEM = 7), and this was reflected (P= 0.06) by ADG (642 vs. 623 g, SEM = 7). No treatment effect was observed on plasma Trp or kynurenine (Kyn), an intermediate metabolite of Trp catabolism. The response of plasma nicotinamide (Nam), a product of Trp catabolism and an indicator of B3status, to dietary B3differed according to treatments (interaction Trp × B3, P< 0.01) with values of 1.4, 3.3, 4.1, and 5.3 μM (SEM = 0.1) in LB3-Trp, HB3-Trp, LB3+Trp, and HB3+Trp, respectively. At 11 wk of age, postprandial blood samples were collected from 6 piglets per treatment for measurements of Trp and insulin metabolism. Postprandial plasma Trp (96.4 vs. 72.2 μM, SEM = 3.4) and Kyn (1.7 vs. 1.3 μM, SEM = 0.1) were greater (P< 0.01) in +Trp vs. -Trp. Postprandial plasma Nam was greater (P< 0.01) in +Trp vs. -Trp (3.4 vs. 1.9 µM, SEM = 0.3) and in HB3 vs. LB3 piglets (3.4 vs. 1.9 µM, SEM = 0.3). Postprandial peaks and areas under curves of C-peptide and glucose were not affected by treatments. However, for insulin, the postprandial peak was lower in +Trp vs. -Trp piglets in the LB3 group (interaction Trp × B3, P< 0.05); values were 1.3, 1.0, 0.7, and 1.0 nM(SEM = 0.1) in LB3-Trp, HB3-Trp, LB3+Trp, and HB3+Trp, respectively. The peak value of the molar ratio insulin:C-peptide was lower (P< 0.02) in +Trp vs. -Trp piglets (0.56 vs. 0.73, SEM = 0.05). The responses observed on growth performance and plasma Nam suggest that the LB3 level was suboptimal. According also to plasma Nam, it appears that supplemental dietary B3can attenuate Trp oxidation toward niacin metabolites. Postprandial profiles of insulin and C-peptide indicate that Trp action is exerted on insulin clearance rather than on insulin secretion in piglets, without apparent consequences on glucose utilization.

Homocysteine (Hcy), an intermediary sulfur AA, is recognized as a powerful prooxidant with deleterious effects on physiological and immune functions. In piglets, there is an acute 10-fold increase of plasma concentrations of homocysteine (pHcy) during the first 2 wk of life. This project aimed to maximize pHcy variations within physiological ranges using typical supplies of folates and vitamin B12(B12) to sows and piglets. Growth, immune response, and Hcy metabolism of piglets were studied until piglets reached 56 d of age. Third-parity sows were randomly assigned to a 2 × 2 split-plot design with 2 dietary treatments during gestation and lactation, S−(1 mg/kg folates and 20 µg/kg B12, n= 15) and S+(10-fold S−levels, n= 16), and 2 treatments to piglets within each half litter, intramuscular injections (150 µg) of B12(P+) at d 1 and 21 (weaning) and saline (P−). Within each litter of 12 piglets, 3 P+and 3 P−piglets were studied for growth and Hcy metabolism, and the others were studied for immune responses. During lactation, plasma B12decreased and was transiently greater in S+vs. S−piglets on d 1 and P+vs. P−piglets on d 7 (sow treatment × age and piglet treatment × age; P< 0.05). From 14 to 21 d of age, pHcy was 33% lower in S+P+vs. S−P−piglets (sow treatment × piglet treatment interaction; P< 0.05). At 56 d of age, hepatic B12was greater and pHcy was lower for P+vs. P−piglets (P< 0.05). No treatment effect was observed on growth except for a lower postweaning G:F in S+P−piglets than in others (sow treatment × piglet treatment interaction; P< 0.05). Positive correlations were observed between pHcy and growth (r> 0.29, P< 0.05) before and after weaning. Antibody responses to ovalbumin and serum tumor necrosis factor-α were not affected by treatments, but postweaning serum IL-8 peaked earlier in S−P−vs. S+P+piglets (piglet treatment × age; sow treatment × piglet treatment interaction, P< 0.05). Proliferation of lymphocytes in response to the mitogen concanavalin A tended to be lower in culture media supplemented with sera from S−vs. S+piglets (P= 0.081) and P−vs. P+piglets (P= 0.098), and the reduction of response was more marked (P <0.05) with high (>21 µM) compared to medium (17 to 21 µM) or low (<17 µM) pHcy. In conclusion, the present vitamin supplements to sows and/or piglets produced variations of pHcy that were not apparently harmful for growth performance of piglets. The greater pHcy, particularly prevalent in S−and/or P−piglets, had negative effects on some indicators of immune responses, suggesting that these young animals may be immunologically more fragile.