In vitro Solubility of Copper(II) Sulfate and Dicopper Chloride Trihydroxide for Pigs

Impacts of dietary copper on the swine gut microbiome and antibiotic resistome

Restrictions on antibiotic growth promoters have prompted livestock producers to use alternative growth promoters, and dietary copper (Cu) supplementation is currently being widely used in pig production. However, elevated doses of dietary Cu constitute a risk for co-selection of antibiotic resistance and the risk may depend on the type of Cu-based feed additives being used. We here report the first controlled experiment investigating the impact of two contrasting Cu-based feed additives on the overall swine gut microbiome and antibiotic resistome. DNA was extracted from fecal samples (n = 96) collected at four time points during 116 days from 120 pigs allotted to three dietary treatments: control, divalent copper sulfate (CuSO₄; 250 μg Cu g^-1 feed), and monovalent copper oxide (Cu₂O; 250 μg Cu g^-1 feed). Bacterial community composition, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) were assessed, and bioavailable Cu ([Cu]_bio) was determined using whole-cell bacterial bioreporters. Cu supplementation to feed increased total Cu concentrations ([Cu]_total) and [Cu]_bio in feces 8-10 fold and at least 670-1000 fold, respectively, but with no significant differences between the two Cu sources. The swine gut microbiome harbored highly abundant and diverse ARGs and MGEs irrespective of the treatments throughout the experiment. Microbiomes differed significantly between pig growth stages and tended to converge over time, but only minor changes in the bacterial community composition and resistome could be linked to Cu supplementation. A significant correlation between bacterial community composition (i.e., bacterial taxa present) and ARG prevalence patterns were observed by Procrustes analysis. Overall, results of the experiment did not provide evidence for Cu-induced co-selection of ARGs or MGEs even at a Cu concentration level exceeding the maximal permitted level for pig diets in the EU (25 to 150 μg Cu g^-1 feed depending on pig age).

Relative Bioavailability of Broiler Chickens Fed with Zinc Hydroxychloride and Sulfate Sources for Corn-Soybean Meal

This study was conducted to determine relative bioavailability (RBV) of basic zinc chloride (BZC) compared to zinc sulfate monohydrate (ZSM) for broilers. A randomized design involving a 2 × 3 factorial arrangement of the different treatment regimens plus one negative control was set up for this study. A total of 630 newly hatched male AA broiler chicks were randomly allocated to 42 different pens (15 chickens/pen) and assigned to 7 dietary treatments in a completely randomized design. The diet was supplemented with 0, 20, 40, or 80 mg of Zn mg/kg of feed in the form of ZSM or BZC. The results showed that zinc supplementation altered average daily gain (ADG) and feed conversion ratio (FCR) (P < 0.05) for both zinc sources. It was observed that the weight gain increased linearly (P < 0.01) and FCR decreased linearly as dietary BZC and ZSM concentration increased. Moreover, compared with chickens fed with ZSM, chickens fed with BZC had higher ADG and lower FCR from days 0 to 14 (P < 0.05), and higher activity of plasma alkaline phosphatase (ALP) (P < 0.05), total superoxide dismutase (T-SOD), and CuZn superoxide dismutase (CuZn-SOD) (P < 0.01) in the plasma of chickens fed with BZC at zinc level 80 mg/kg at day 14. The pancreas divalent metal-ion transporter-1 (DMT1) mRNA expression of chickens fed with BZC was found to be significantly enhanced at day 28, and the pancreas metallothionein (MT) mRNA expression for BZC fed group was also markedly increased at Zn levels of 20 and 40 mg/kg respectively. The relative bioavailability (RBV) of BZC (Zn sulfate 100%) based on ADG in the starter phase was 110.82%, whereas the tibia zinc content, as well as the activities of plasma ALP and CuZn-SOD, and the pancreas MT mRNA level were in the range between 108 and 119%. It was thus concluded that BZC was more efficacious than Zn sulfate and could serve as a potentially novel zinc source in the broilers.

How copper can impact pig growth: comparing the effect of copper sulfate and monovalent copper oxide on oxidative status, inflammation, gene abundance, and microbial modulation as potential mechanisms of action

The beneficial effect of elevated concentrations of copper (Cu) on growth performance of pigs has been already demonstrated; however, their mechanism of action is not fully discovered. The objective of the present experiment was to investigate the effects of including Cu from copper sulfate (CuSO₄) or monovalent copper oxide (Cu₂O) in the diet of growing pigs on oxidative stress, inflammation, gene abundance, and microbial modulation. We used 120 pigs with initial body weight (BW) of 11.5 ± 0.98 kg in 2 blocks of 60 pigs, 3 dietary treatments, 5 pigs per pen, and 4 replicate pens per treatment within each block for a total of 8 pens per treatment. Dietary treatments included the negative control (NC) diet containing 20 mg Cu/kg and 2 diets in which 250 mg Cu/kg from CuSO₄ or Cu₂O was added to the NC. On day 28, serum samples were collected from one pig per pen and this pig was then euthanized to obtain liver samples for the analysis of oxidative stress markers (Cu/Zn superoxide dismutase, glutathione peroxidase, and malondialdehyde, MDA). Serum samples were analyzed for cytokines. Jejunum tissue and colon content were collected and used for transcriptomic analyses and microbial characterization, respectively. Results indicated that there were greater (P < 0.05) MDA levels in the liver of pigs fed the diet with 250 mg/kg CuSO₄ than in pigs fed the other diets. The serum concentration of tumor necrosis factor-alpha was greater (P < 0.05) in pigs fed diets containing CuSO₄ compared with pigs fed the NC diet or the diet with 250 mg Cu/kg from Cu₂O. Pigs fed diets containing CuSO₄ or Cu₂O had a greater (P < 0.05) abundance of genes related to the intestinal barrier function and nutrient transport, but a lower (P < 0.05) abundance of pro-inflammatory genes compared with pigs fed the NC diet. Supplementing diets with CuSO₄ or Cu₂O also increased (P < 0.05) the abundance of Lachnospiraceae and Peptostreptococcaceae families and reduced (P < 0.05) the abundance of the Rikenellaceae family, Campylobacter, and Streptococcus genera in the colon of pigs. In conclusion, adding 250 mg/kg of Cu from CuSO₄ or Cu₂O regulates genes abundance in charge of the immune system and growth, and promotes changes in the intestinal microbiota; however, Cu₂O induces less systemic oxidation and inflammation compared with CuSO₄.

Inclusion of dicopper oxide instead of copper sulfate in diets for growing-finishing pigs results in greater final body weight and bone mineralization, but reduced accumulation of copper in the liver

An experiment was conducted to test the hypothesis that inclusion of Cu oxide (Cu2O) in diets for growing-finishing pigs improves body weight (BW) and bone mineralization, and reduces accumulation of Cu in the liver compared with pigs fed diets containing Cu sulfate (CuSO4). Two hundred growing pigs (initial BW: 11.5 ± 0.98 kg) were allotted to a randomized complete block design with 2 blocks of 100 pigs, 5 dietary treatments, 5 pigs per pen, and a total of 8 pens per treatment. Treatments included the negative control (NC) diet that contained 20 mg Cu/kg, and 4 diets in which 125 or 250 mg Cu/kg from CuSO4 or Cu2O were added to the NC diet. The experiment was divided into 4 phases and concluded when pigs reached market weight. Pig weights were recorded on day 1 and at the end of each phase and feed provisions were recorded throughout the experiment. On the last day of phases 1 and 4, 1 pig per pen was sacrificed to obtain samples of liver and spleen tissue, and the right metacarpal was collected. Results indicated that pigs fed diets containing 250 mg Cu/kg from CuSO4 had greater BW at the end of phases 1 and 2 than pigs fed NC diets. Pigs fed diets containing 250 mg Cu/kg from Cu2O had greater (P < 0.05) BW at the end of phases 1, 2, 3, and 4 compared with pigs fed NC diets, and these pigs also had greater BW at the end of phases 3 and 4 than pigs fed all other diets. Pigs fed the diets with 250 mg Cu/kg tended to have greater (P < 0.10) feed intake than pigs fed the NC diet at the end of phase 2, and for the overall experimental period, pigs fed diets containing 250 mg Cu/kg from Cu2O had greater (P < 0.05) feed intake than pigs on all other treatments. However, no differences in gain:feed ratio were observed among treatments. Copper accumulation in liver and spleen increased with Cu dose, but at the end of phase 1, pigs fed 250 mg Cu/kg from CuSO4 had greater (P < 0.05) Cu concentration in liver and spleen than pigs fed 250 mg Cu/kg from Cu2O. Pigs fed diets containing 250 mg Cu/kg from Cu2O had greater (P < 0.05) quantities of bone ash and greater (P < 0.05) concentrations of Ca, P, and Cu in bone ash than pigs fed NC diets or the 2 diets containing CuSO4, but Zn concentration in bone ash was less (P < 0.05) in pigs fed diets containing 250 mg Cu/kg from Cu2O. To conclude, supplementing diets for growing pigs with Cu2O improves growth performance and bone mineralization with less Cu accumulation in liver compared with pigs fed diets containing CuSO4.

Digestibility and metabolism of copper in diets for pigs and influence of dietary copper on growth performance, intestinal health, and overall immune status: a review

The current contribution reviews absorption and metabolism of copper (Cu), Cu deficiency, Cu toxicity, Cu bioavailability, and effects of pharmacological levels of Cu on growth performance and intestinal health of pigs. Copper is a micro mineral involved in metabolic reactions including cellular respiration, tissue pigmentation, hemoglobin formation, and connective tissue development. Copper is mostly absorbed in the upper gastrointestinal tract, particularly in the duodenum, but some Cu is absorbed in the stomach. One way to evaluate the efficacy of sources of Cu is to measure relative bioavailability where responses include tissue concentrations of Cu, concentrations of metalloproteins, and enzymatic activity of animals fed test diets containing graded levels of Cu. The requirement for Cu by pigs is 5 to 10 mg/kg diet, however, Cu can be included at growth-promoting levels (i.e., 75 to 250 mg/kg diet) in diets for weanling and growing pigs to reduce post-weaning diarrhea and improve growth performance. The consistently observed improvement in growth performance upon Cu supplementation is likely a result of increases in lipase activity, growth hormone secretion, and expression of genes involved in post-absorptive metabolism of lipids. The growth-promoting effects of dietary Cu have also been attributed to its bacteriostatic and bactericidal properties because Cu may change bacterial populations in the intestine, and thereby reduce inflammation caused by pathogens. However, further research is needed to determine potential interactions between Cu and non-nutritive feed additives (e.g., enzymes, probiotics, phytobiotics), and the optimum quantity of Cu as well as the optimum duration of feeding supplemental Cu in diets for pigs should be further investigated. These gaps needs to be addressed to maximize inclusion of Cu in diets to improve growth performance while minimizing diseases and mortality.

Effects of two zinc supplementation levels and two zinc and copper sources with different solubility characteristics on the growth performance, carcass characteristics and digestibility of growing-finishing pigs

The present study was conducted to evaluate the effect of two Zn supplemented levels and two Zn and Cu sources (sulphate and hydroxychloride) on growing-finishing pigs. An in vitro study and an in vivo study were conducted. In the in vitro study, Zn solubility from each source at different Zn supplementation levels was evaluated, as well as the phytic phosphorus (PP) solubility derived from the interaction or not with phytic acid at similar conditions to those found in digestive tract. The most critical interaction of Zn with phytic acid was at pH 6.5 and with Zn sulphate, resulting in the reduction in PP solubility. In the in vivo experiment, a total of 444 pigs ([Duroc × Landrace]×Pietrain; initial BW: 18.7 ± 0.20 kg) were allotted to 36 pens in a randomized complete block design (2 × 2) factorial arrangement with two Zn and Cu sources and two Zn supplemental levels (20 and 80 mg/kg). The Cu supplementation was fixed at 15 mg/kg for all diets. There was no effect of the interaction between mineral source × Zn level or Zn level on growth performance or carcass characteristics (p > .10). Apparent total digestibility of Zn and Cu along with carcass yield was higher for pigs fed hydroxychloride than pigs fed the sulphate counterparts (p < .05). Feeding low levels of Zn decreased Zn (45.5%; p < .0001) and Cu(18.5%; p = .018) faecal excretion. In conclusion, under commercial conditions, feeding growing-finishing pigs with Zn levels below those established by the European Union regulation did not affect growth performance and carcass characteristics. Reducing dietary mineral (Zn and Cu) diet content resulted in a lower faecal mineral excretion. Pigs fed sulphate minerals had an improved performance during grower period, while pigs fed hydroxychloride minerals showed an improved performance during finishing period and a greater carcass yield and mineral digestibility than those fed sulphates.

Effects of copper and zinc sources and inclusion levels of copper on weanling pig performance and intestinal microbiota

A 42-d experiment was conducted to evaluate the effect of Cu and Zn source and Cu level on pig performance, mineral status, bacterial modulation, and the presence of antimicrobial-resistant genes in isolates of Enterococcus spp. At weaning, 528 pigs (5.9 ± 0.50 kg) were allotted to 48 pens of a randomized complete block design in a 2 × 2 factorial arrangement with two Cu and Zn sources (SF: sulfate and HCl: hydroxychloride) and two Cu levels (15 and 160 mg/kg). As a challenge, the pigs were reared in dirty pens used by a previous commercial batch. Two-phase diets were offered: the pre-starter (PS) phase from day 1 to 14 and the starter phase (ST) from day 14 to 42. At days 14 and 42, pigs were individually weighed and blood samples from one pig per pen were taken. At the end of the experiment, one pig per pen was euthanized to collect the samples. Feeding high levels of Cu increased body weight (BW) from 16.6 to 17.7 kg (P < 0.001). Furthermore, average daily gain, gain to feed (G:F) ratio, average daily feed intake (ADFI), and mineral status were enhanced with Cu at 160 mg/kg (P < 0.05) compared with Cu at 15 mg/kg. There was no effect of the interaction between source × level on any of the growth performance responses except for ADFI (P = 0.004) and G:F (P = 0.029) at the end of the ST period and for G:F (P = 0.006) for entire nursery period (day 0 to 42). At the end of the ST period, pigs fed Cu at 160 mg/kg as HCl had not only higher ADFI but also lower G:F than those fed Cu as SF at 160 mg/kg. Meanwhile, for the entire nursery period, G:F did not differ between pigs fed Cu at 160 mg/kg as HCl or SF. In colonic digesta, the relative abundance of Streptococcus, Enterobacter, Escherichia, among others, decreased (P-adjust < 0.05), while Lachnospira and Roseburia tended (P-adjust < 0.10) to increase in pigs fed Cu at 160 mg/kg as HCl compared with those fed Cu SF at 160 mg/kg. An increase (P-adjust < 0.05) in Methanosphaera and Roseburia was observed in pigs fed Cu at 160 mg/kg. From colon digesta, Enterococcus spp. was isolated in 40 samples, being E. faecalis the most dominating (65%) regardless of the experimental diet. Genes of ermB (7.5%) and tetM (5%) were identified. No genes for Cu (tcrB) or vancomycin (vanA, vanB, vanC1, and vanC2) were detected. In conclusion, European Union permissible levels of Cu (160 mg/kg), of both sources, were able to increase performance, mineral status, and bacterial modulation compared with nutritional level. Different effects on growth performance, mineral tissue content, and microbial modulation were observed between Cu and Zn sources.

The differences between copper sulfate and tribasic copper chloride on growth performance, redox status, deposition in tissues of pigs, and excretion in feces

OBJECTIVE

The objective of this experiment was to compare the effects of adding 130 mg/kg Cu from either copper sulfate (CS) or tribasic copper chloride (TBCC) on growth performance, mineral deposition in tissues, and the excretion in feces of pigs as well as changes in the mineral contents in tissues and feces when the supplemental Cu level was decreased from 130 mg/kg to 10 mg/kg.

METHODS

A total of 72 pigs (32.6±1.2 kg) were randomly assigned to a CS diet or a TBCC diet with 6 pens per treatment. The trial lasted 102 d and included 3 phases (phase 1, 1 to 30 d; phase 2, 31 to 81 d; and phase 3, 82 to 102 d). The supplemental levels of Cu in the 2 treatments were 130 mg/kg in phase 1 and 2 and 10 mg/kg in phase 3.

RESULTS

The results showed that pigs fed the CS diet tended to have higher average daily gain than pigs fed the TBCC diet during d 1 to 81 (p<0.10). Compared with CS, TBCC increased the activities of aspartate transaminase (AST), ceruloplasmin, and superoxide dismutase in serum on d 30 (p<0.05). The TBCC decreased the Cu level in the liver on d 81 (p<0.05) and increased the Mn level in the liver on d 102 (p<0.05). The concentration of Cu in feces sharply decreased when the supplemental Cu level in diet changed from 130 mg/kg to 10 mg/kg in both diets (p<0.05).

CONCLUSION

The result suggested that TBCC and CS had no significant difference on growth performance but TBCC had higher activities of AST and antioxidant enzymes and lower liver Cu than CS when pigs fed diets with 130 mg Cu/kg diet.