The addition of high manganese to a copper-deficient diet further depresses copper status and growth of cattle

The influence of steroidal implants and manganese sulfate supplementation on growth performance, trace mineral status, hepatic gene expression, hepatic enzyme activity, and circulating metabolites in feedlot steers

Angus-cross steers (n = 144; 359 kg ± 13.4) were used to assess the effect of dietary Mn and steroidal implants on performance, trace minerals (TM) status, hepatic enzyme activity, hepatic gene expression, and serum metabolites. Steers (n = 6/pen) were stratified by BW in a 3 × 2 factorial. GrowSafe bunks recorded individual feed intake (experimental unit = steer; n = 24/treatment). Dietary treatments included (MANG; 8 pens/treatment; Mn as MnSO4): (1) no supplemental Mn (analyzed 14 mg Mn/kg DM; Mn0); (2) 20 mg supplemental Mn/kg DM (Mn20); (3) 50 mg supplemental Mn/kg DM (Mn50). Within MANG, steers received a steroidal implant treatment (IMP) on day 0: (1) no implant; NO; or (2) combination implant (Revalor-200; REV). Liver biopsies for TM analysis and qPCR, and blood for serum glucose, insulin, non-esterified fatty acids, and urea-N (SUN) analysis were collected on days 0, 20, 40, and 77. Data were analyzed as a randomized complete block with a factorial arrangement of treatments including fixed effects of Mn treatment (MANG) and implant (IMP) using PROC MIXED of SAS 9.4 using initial BW as a covariate. Liver TM, serum metabolite, enzyme activity, and gene expression data were analyzed as repeated measures. No MANG × IMP effects were noted (P ≥ 0.12) for growth performance or carcass characteristic measures. Dietary Mn did not influence final body weight, overall ADG, or overall G:F (P ≥ 0.14). Liver Mn concentration increased with supplemental Mn concentration (MANG; P = 0.01). An IMP × DAY effect was noted for liver Mn (P = 0.01) where NO and REV were similar on day 0 but NO cattle increased liver Mn from days 0 to 20 while REV liver Mn decreased. Relative expression of MnSOD in the liver was greater in REV (P = 0.02) compared to NO and within a MANG × IMP effect (P = 0.01) REV increased liver MnSOD activity. These data indicate current NASEM Mn recommendations are adequate to meet the demands of finishing beef cattle given a steroidal implant. Despite the roles of Mn in metabolic pathways and antioxidant defense, a basal diet containing 14 mg Mn/kg DM was sufficient for the normal growth of finishing steers. This study also provided novel insight into how implants and supplemental Mn influence genes related to arginine metabolism, urea synthesis, antioxidant capacity, and TM homeostasis as well as arginase and MnSOD activity in hepatic tissue of beef steers.

Trace Mineral Nutrition in Confinement Dairy Cattle

Veterinarians are often called upon to diagnose health-related issues on the farm that may be related to trace mineral deficiencies or toxicities. Trace mineral feeding rates are often not available due to the proprietary nature of the trace mineral premixes provided by nutritional consultants. The veterinarian needs to be aware of the common clinical signs of trace mineral deficiencies and toxicities, interactions between trace minerals that may result in deficiencies, clinical samples that are necessary for the proper diagnosis, and the recommended normal ranges of each trace mineral depending on the age of the animal.

Review: Bioavailability of trace elements in farm animals: definition and practical considerations for improved assessment of efficacy and safety

Currently, the authorisation procedure of trace elements as feed additives in the European Union according to Regulation (EC) No. 1831/2003 does not consider the bioavailability of trace element sources. This manuscript provides framework conditions for in vivo experiments that aim to estimate differences in the relative bioavailability between supplements of essential trace elements. Framework conditions encompass necessary technical information on the test substance, the experimental design and diet composition as well as the suitability of status parameters that allow for relative comparisons of regression variables. This manuscript evolves recommendations for researchers to conduct solid and reliable experiments on the matter as well as decision makers to interpret the value of studies submitted with authorisation applications regarding a certain trace element supplement.

Impact of Cell Culture and Copper Dose on Gene Expression in Bovine Liver

The objectives of these experiments were to investigate (1) the relative abundance of transcripts for Cu-responsive genes in whole bovine liver vs. cultured hepatocytes and (2) the influence of Cu dose on the relative abundance of transcripts for Cu-responsive genes in cultured bovine hepatocytes. Experiment 1: Liver samples were obtained immediately post-mortem from one healthy Angus steer. Half of the tissue samples were placed in RNAlater solution; the remaining half was used to isolate hepatocytes. Experiment 2: A subset of cultured hepatocytes was incubated in media containing: 0 mg/L, 0.10 mg/L, 1.0 mg/L, 10.0 mg/L, and 100 mg/L Cu for 1 h. Transcripts analyzed were aldehyde dehydrogenase (ALDH2), apolipoprotein A-1 (APOA1), antioxidant 1 (ATOX1), ATPase copper transporting alpha (ATP7A), ATPase copper transporting beta (ATP7B), betaine homocysteine methyltransferase (BHMT), flavin reductase (BLVRB), carbonic anhydrase II (CA2), copper chaperone for superoxide dismutase (CCS), cytochrome c oxidase copper chaperone (COX17), Cu transporter 1 (CTR1), glutamate dehydrogenase (GLUD1), glutathione synthetase (GSS), protein disulfide isomerase A3 (PDIA3), and superoxide dismutase (Cu-Zn) (SOD1). Β-Actin (ACTB) was selected as the endogenous control in both experiments. Experiment 1: Whole liver had greater (P < 0.01) relative abundance of mRNA for APOA1, ATOX1, ATP7A, ATP7B, COX17, CTR1, ALDH2, BHMT, BLVRB, CA2, GLUD1, and GSS when compared with cultured hepatocytes. Experiment 2: Copper dose impacted all identified transcripts. These results indicate that the relative abundance of Cu-responsive transcripts is different in whole vs. cultured hepatocytes and that the relative abundance of Cu-responsive genes is dependent on Cu dose in cultured hepatocytes.

Supplementing organic-complexed or inorganic Co, Cu, Mn, and Zn to beef cows during gestation: postweaning responses of offspring reared as replacement heifers or feeder cattle

One hundred and ninety nonlactating, pregnant beef cows (¾ Bos taurus and ¼ Bos indicus; 138 multiparous and 52 primiparous) were assigned to this experiment at 117 ± 2.2 d of gestation (day 0). Cows were ranked by parity, pregnancy type (artificial insemination = 102, natural service = 88), body weight (BW) and body condition score, and assigned to receive a supplement containing: (1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 95) or (2) an organic complexed source of Cu, Mn, Co, and Zn (AAC; Availa4; Zinpro Corporation, Eden Prairie, MN; n = 95). The INR and AAC provided the same daily amount of Cu, Co, Mn, and Zn, based on 7 g of the AAC source. From day 0 to calving, cows were maintained in a single pasture and segregated 3 times weekly into 1 of 24 individual feeding pens to receive treatments. Calves were weaned on day 367 (200 ± 2 d of age), managed as a single group for a 45-d preconditioning period (days 367 to 412), and transferred to a single oat (Avena sativa L.) pasture on day 412. Heifer calves were moved to an adjacent oat pasture on day 437, where they remained until day 620. Heifer puberty status was verified weekly (days 437 to 619) based on plasma progesterone concentrations. Steer calves were shipped to a commercial feedlot on day 493, where they were managed as a single group until slaughter (day 724). Plasma cortisol concentration was greater (P = 0.05) in AAC calves at weaning but tended to be less (P = 0.10) on day 370 compared with INR calves. Mean plasma haptoglobin concentration was greater (P = 0.03) in INR vs. AAC calves during preconditioning, and no treatment effects were noted (P = 0.76) for preconditioning average daily gain (ADG). Puberty attainment was hastened in AAC heifers during the experiment (treatment × day; P < 0.01), despite similar (P = 0.39) ADG between treatments from days 412 to 620. Expression of myogenin mRNA in the longissimus muscle was greater (P = 0.05) in INR vs. AAC heifers on day 584. No treatment effects were detected (P ≥ 0.24) for steer ADG from day 412 until slaughter, nor for carcass quality traits. Hepatic mRNA expression of metallothionein 1A was greater (P = 0.02) in INR vs. AAC steers on day 586. In summary, supplementing Co, Cu, Zn, and Mn as organic complexed instead of sulfate sources to beef cows during the last 5 mo of gestation did not improve performance and physiological responses of the steer progeny until slaughter, but hastened puberty attainment in the female progeny reared as replacement heifers.

Supplementing organic-complexed or inorganic Co, Cu, Mn, and Zn to beef cows during gestation: physiological and productive response of cows and their offspring until weaning

One hundred and ninety non-lactating, pregnant beef cows (three-fourth Bos taurus and one-fourth Bos indicus; 138 multiparous and 52 primiparous) were assigned to this experiment at 117 ± 2.2 d of gestation (day 0). Cows were ranked by parity, pregnancy type (artificial insemination = 102 and natural service = 88), body weight (BW), and body condition score (BCS) and assigned to receive a supplement containing: 1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 95) or 2) an organic-complexed source of Cu, Mn, Co, and Zn (AAC; Availa 4; Zinpro Corporation, Eden Prairie, MN; n = 95). The INR and AAC provided the same daily amount of Cu, Co, Mn, and Zn, based on 7 g of the AAC source. From day 0 to calving, cows were maintained in a single pasture and were segregated three times weekly into 1 of the 24 individual feeding pens to receive treatments. Cow BW and BCS were recorded on days -30, 97, upon calving, and at weaning (day 367). Milk production was estimated at 42 ± 0.5 d postpartum via weigh-suckle-weigh (WSW) method. Liver biopsies were performed in 30 cows per treatment on days -30, 97, upon calving, and the day after WSW. Calf BW was recorded at birth and weaning. Liver and longissimus muscle (LM) biopsies were performed in 30 calves per treatment upon calving and 24 h later, the day after WSW, and at weaning. No treatment effects were detected (P ≥ 0.49) for cow BCS during gestation, despite AAC cows having greater (P = 0.04) BW on day 97. Liver Co concentrations were greater (P < 0.01) for AAC compared with INR cows, and liver concentrations of Cu were greater (P = 0.02) for INR compared with AAC cows on day 97. Upon calving, INR cows had greater (P ≤ 0.01) liver Cu and Zn concentrations compared with AAC cows. No other treatment differences were noted (P ≥ 0.17) for cow and calf liver trace mineral concentrations. Cows receiving AAC had greater (P = 0.04) hepatic mRNA expression of metallothionein 1A at calving, and their calves had greater (P = 0.04) hepatic mRNA expression of superoxide dismutase at weaning. Milk production did not differ between AAC and INR cows (P = 0.70). No treatment effects were detected (P ≥ 0.29) for mRNA expression of LM genes associated with adipogenic or muscle development activities in calves at birth and weaning. Calf birth and weaning BW also did not differ (P ≥ 0.19) between treatments. In summary, supplementing AAC or INR to beef cows during the last 5 mo of gestation yielded similar cow-calf productive responses until weaning.

Supplementing Trace Minerals to Beef Cows during Gestation to Enhance Productive and Health Responses of the Offspring

Simple Summary

During gestation, the fetus relies on the dam for the supply of all nutrients, including trace minerals, which are essential for developmental processes including organogenesis, vascularization, and differentiation. Alterations in maternal nutritional status may promote adaptations that permanently alter the trajectory of growth, physiology, and metabolism of the offspring. Supplementing trace minerals to gestating cows may be a strategy to enhance progeny performance and health. The purpose of this review is to highlight current information relevant to trace mineral supplementation during gestation, with an emphasis on Zn, Cu, Co, and Mn, and their impacts on offspring productive responses. Identifying nutritional strategies targeted at this period of development and understanding the implications of such provides an opportunity to enhance the productive efficiency of beef cattle systems.

Abstract

Nutritional management during gestation is critical to optimize the efficiency and profitability of beef production systems. Given the essentiality of trace minerals to fetal developmental processes, their supplementation represents one approach to optimize offspring productivity. Our research group investigated the impacts of supplementing gestating beef cows with organic-complexed (AAC) or inorganic sources (INR) of Co, Cu, Mn, or Zn on productive and health responses of the progeny. Calves born to AAC supplemented cows had reduced incidence of bovine respiratory disease and were >20 kg heavier from weaning until slaughter compared to unsupplemented cohorts. Complementing these findings, heifer progeny born to AAC supplemented cows had accelerated puberty attainment. Collectively, research demonstrates supplementing trace minerals to gestating beef cows may be a strategy to enhance offspring productivity in beef production systems.

Dietary manganese source does not affect Mn, Zn and Cu tissue deposition and the activity of manganese-containing enzymes in lambs

Manganese (Mn) is a trace element required for normal physiological processes in animals and humans. Organic forms of trace elements are expected to have higher bioavailability in comparison with inorganic sources. The effect of feeding a diet supplemented with different sources of manganese to lambs was studied in a 112-d feeding trial. The aim of this study was to investigate the deposition of Mn in relation to activities of superoxide dismutase (SOD), manganese superoxide dismutase (MnSOD) and arginase in the tissues of lambs fed the diet supplemented with an inorganic or an organic source of manganese up to the maximum total Mn content allowed in the European Union (150mg Mn/kg). A total of eighteen female lambs of the improved Valachian breed were randomly allocated to three dietary treatments and fed an unsupplemented basal diet (Control, 31mg Mn/kg) or the identical diet supplemented with manganese sulphate (MnSO₄) or manganese chelate of glycine hydrate (Mn-Gly) with a total Mn content up to 150mg/kg. Regardless of the source, feed supplementation with manganese increased Mn concentrations in plasma (P˂0.05) and the liver (P˂0.001) as well as the activity of liver MnSOD (P˂0.05) and arginase (P˂0.001) compared with the control lambs. In the kidney cortex, the concentration of Mn was greatest in lambs fed the diet supplemented with the chelated Mn source compared with animals receiving the inorganic Mn source (P˂0.05) and the unsupplemented diet (P˂0.001). The 112-d intake of feed enriched with manganese did not result in any change in Mn levels, SOD or MnSOD activity in pancreas and kidney tissues. Plasma Cu concentration was depressed in both supplemented treatments. No analyzed tissue showed a change in zinc and copper levels, except the greater Cu concentration in the liver of lambs fed the diet with Mn-Gly. The presented results did not indicate any differences between dietary Mn sources either in Mn tissue deposition or activity of SOD, MnSOD and arginase in lamb tissues; however, it seems that manganese intake of up to 150mg/kg in feed may decrease plasma Cu concentration in lambs.

Effects of wet corn distillers grains with solubles on visceral organ mass, trace mineral status, and polioencephalomalacia biomarkers of individually-fed cattle

Twenty-four steers (initial BW = 385 ± 1.1 kg) were blocked by BW and randomly assigned to 3 dietary treatments (0, 30, or 60% wet distillers grains with solubles [WDGS]; DM basis) and were fed individually to determine the effect of WDGS on live growth and carcass performance, visceral organ mass, trace mineral status, and polioencephalomalacia biomarkers. Steers were slaughtered at 125, 150, 164, and 192 d (2 blocks/slaughter date) when external fat depth was approximately 1.3 cm based on visual appraisal. Steers fed 30% WDGS had greater DMI than those fed 0 or 60% WDGS (P < 0.05), and steers fed 60% WDGS had the lowest carcass-adjusted ADG (P < 0.09) of the 3 treatments. Nonetheless, WDGS concentration did not alter feed efficiency (P > 0.41) on either live or carcass-adjusted basis. Steers fed 30% WDGS had greater liver S and Mn concentrations (DM basis) and lower liver Fe concentrations than control steers (P < 0.10; initial values used as a covariate), and feeding 60% WDGS decreased liver Cu and increased liver Fe (P < 0.10) compared with feeding 30% WDGS. Cytochrome c oxidase (COX) activity in brain tissue tended to be decreased with 60 vs. 30% WDGS (P = 0.12), and COX activity decreased linearly (P = 0.06) in lung tissue as dietary WDGS concentration increased. Likewise, gut fill linearly increased (P = 0.01) with increasing WDGS concentration. Feeding 30% WDGS increased fractional mass (g/kg of empty BW) of the small intestine (P < 0.10) compared with controls, whereas 60% WDGS increased fractional kidney mass (P < 0.10) compared with 30% WDGS. Overall, results suggest that gut fill, Cu status, and COX activity seem to be compromised by WDGS when fed at 60% of diet DM in diets based on steam-flaked corn, which suggests a greater susceptibility to polioencephalomalacia.

Effect of dietary copper and breed on gene products involved in copper acquisition, distribution, and use in Angus and Simmental cows and fetuses

Copper (Cu) deficiency is a widespread problem in cattle across the United States and breed differences in Cu metabolism may contribute to this issue. Intracellular Cu is tightly regulated by transport and chaperone proteins, and to date, these mechanisms have not been elucidated to address breed differences in Cu metabolism, nor have these proteins been characterized in bovine fetal liver. Mature, pregnant Angus (n = 8) and Simmental (n = 8) cows (∼4 mo into gestation) were used in a 2 × 2 factorial arrangement of treatments. All cows were bred to Angus sires resulting in an Angus vs. Simmental × Angus comparison for fetuses. Cows were randomly assigned to corn silage-based diets that were either adequate (+Cu) or deficient (-Cu; 6.6 mg Cu/kg DM) in Cu. Diets were individually fed for 112 d. At the end of the study, cows were harvested to collect duodenal mucosa scrapes, liver samples, and fetal liver samples for mineral analysis and also for mRNA and protein analysis of Cu transport and chaperone proteins. Placentomes were also obtained for mineral analysis. Plasma Cu and liver Cu were affected by Cu, breed, and Cu × breed. Both of these Cu indices were less (P ≤ 0.05) in-Cu Simmentals (-CuS) than in-Cu Angus (- uA), but were similar among +Cu Simmental (+CuS) and +Cu Angus cows (+CuA). Duodenal Cu was less (P = 0.01) in-Cu vs. +Cu cows. Placentome Cu was less (P = 0.003) in-Cu vs. +Cu cows, and was also less (P = 0.03) in Simmentals vs. Angus. Fetal liver Cu was less (P = 0.002) in-Cu vs. +Cu fetuses, and was also less (P = 0.05) in Simmental × Angus vs. Angus. Abundance of Cu transporter1 (CTR1) protein and transcripts for Cu transporters and chaperones were not affected by Cu or breed in liver and were not affected by Cu in the intestine. Duodenal Ctr1 was less (P = 0.04) and CTR1 tended (P = 0.10) to be less in Simmentals vs. Angus. Expression of Atp7a tended (P = 0.08) to be less in Simmentals than in Angus. In fetal liver, expression of antioxidant 1 (Atox1), cytochrome c oxidase assembly protein 17 (Cox17), and Cu metabolism MURR1 domain 1 (Commd1) were up-regulated (P ≤ 0.05) in-Cu vs. +Cu fetuses. In conclusion, less expression of duodenal Ctr1 and a tendency for less CTR1 (P = 0.10) and Atp7a (P = 0.08) suggest that Simmentals have a lesser ability to absorb and utilize dietary Cu, and may explain why Simmentals are more prone to Cu deficiency than Angus. Up-regulation of fetal liver Atox1, Cox17, and Commd1 in-Cu fetuses may reflect the great Cu demand by the fetus.

Early postnatal kinetics of colostral immunoglobulin G absorption in fed and fasted piglets and developmental expression of the intestinal immunoglobulin G receptor

The transport of IgG across the epithelial barrier and into the circulation is achieved in part by the neonatal Fc receptor (FcRn), and this provides passive immunity to the neonate. The objective of this study was to determine the effect of time and feeding state on IgG absorption, intestinal morphology, and expression of IgG receptors in the first 24 h postbirth. Twenty newborn pigs were obtained immediately after birth and fitted with umbilical arterial catheters. Colostrum was manually collected from 12 lactating sows and centrifuged to produce defatted colostrum. Piglets were orally gavaged with 32 mL defatted colostrum per kilogram of BW (given in 2 doses 1 h apart) either at birth (0 h) or at 12 h postbirth under either fed (milk replacer) or fasted (saline solution) condition (n=5 per treatment). A fifth reference group (n=5) was euthanized at birth. Blood was collected every hour for the first 2 h immediately after the catheter was inserted and then every 4 h until 12 h (i.e., 0, 1, 2, 4, 8, and 12 h) for the treatment in which the defatted colostrum was given right after birth. For the treatment gavaged at 12 h postbirth, the sampling schedule was at 12, 13, 14, 16, 20, and 24 h. At 12 h postgavage, pigs were euthanized and jejunum tissues were collected for measurement of villi height, width, crypt depth, and gene expression of FcRn and β2-microglobulin (β2M) via reverse transcription PCR. Pig serum IgG concentration was determined by radial immunodiffusion. Data were analyzed according to a 2×2 factorial arrangement of treatments (0 h-fed, 0 h-fasted, 12 h-fed, and 12 h-fasted). There was no interaction between the time (age) of offering defatted colostrum (0 vs. 12 h) and nutritional state (fed vs. fasted) for any of the measurements, and there were no differences between fed and fasted pigs. Serum IgG concentrations increased progressively with time. Piglets offered defatted colostrum at 0 h had greater (P<0.05) overall IgG absorption and greater (P<0.05) villi height than those offered defatted colostrum at 12 h postbirth. Abundance of mRNA of FcRn and β2M were normalized to glyceraldehyde-3-phosphate dehydrogenase. Abundance of FcRn transcript was lower (P=0.006) in pigs euthanized at birth compared with those euthanized at 12 h of age. In conclusion, the effects of delayed offering of defatted colostrum and age-dependent changes in IgG receptor were modest over the first 24 h of life.

Copper imbalances in ruminants and humans: unexpected common ground

Ruminants are more vulnerable to copper deficiency than humans because rumen sulfide generation lowers copper availability from forage, increasing the risk of conditions such as swayback in lambs. Molybdenum-rich pastures promote thiomolybdate (TM) synthesis and formation of unabsorbable Cu-TM complexes, turning risk to clinical reality (hypocuprosis). Selection pressures created ruminant species with tolerance of deficiency but vulnerability to copper toxicity in alien environments, such as specific pathogen-free units. By contrast, cases of copper imbalance in humans seemed confined to rare genetic aberrations of copper metabolism. Recent descriptions of human swayback and the exploratory use of TM for the treatment of Wilson's disease, tumor growth, inflammatory diseases, and Alzheimer's disease have created unexpected common ground. The incidence of pre-hemolytic copper poisoning in specific pathogen-free lambs was reduced by an infection with Mycobacterium avium that left them more responsive to treatment with TM but vulnerable to long-term copper depletion. Copper requirements in ruminants and humans may need an extra allowance for the "copper cost" of immunity to infection. Residual cuproenzyme inhibition in TM-treated lambs and anomalies in plasma copper composition that appeared to depend on liver copper status raise this question "can chelating capacity be harnessed without inducing copper-deficiency in ruminants or humans?" A model of equilibria between exogenous (TM) and endogenous chelators (e.g., albumin, metallothionein) is used to predict risk of exposure and hypocuprosis; although risk of natural exposure in humans is remote, vulnerability to TM-induced copper deficiency may be high. Biomarkers of TM impact are needed, and copper chaperones for inhibited cuproenzymes are prime candidates.

Amount and source of dietary copper affects small intestine morphology, duodenal lipid peroxidation, hepatic oxidative stress,and mRNA expression of hepatic copper regulatory proteins in weanling pigs

Thirty weanling, crossbred barrows (SUS SCROFA) were used to determine the effects of amount and source of dietary Cu on small intestinal morphology and lipid peroxidation, Cu metabolism, and mRNA expression of proteins involved in hepatic Cu homeostasis. At 21 d of age, pigs were stratified by BW (6.33 ± 0.23 kg) and allocated to 1 of the following dietary treatments: i) control (no supplemental Cu; 6.7 mg Cu/kg), ii) 225 mg supplemental Cu/kg diet from Cu sulfate (CuSO(4)), or iii) 225 mg supplemental Cu/kg diet from tribasic Cu chloride (TBCC). Pigs were housed 2 pigs per pen and were fed a 3-phase diet regimen until d 35 or 36 of the study. During harvest, bile and liver were obtained for mineral analysis, and liver samples were also obtained for analysis of liver glutathione (GSH) and mRNA expression of Cu regulatory proteins. Segments of duodenum, proximal jejunum, and ileum were obtained for mucosal morphology, and duodenal mucosal scrapings were collected from all pigs for analysis of malondialdehyde (MDA). Duodenal villus height was reduced in CuSO(4) pigs compared with control (P = 0.001) and TBCC (P = 0.03) pigs. Villus height in the proximal jejunum of CuSO(4) pigs was reduced (P = 0.03) compared with control pigs, but ileal villus height was not affected (P = 0.82) by treatment. Duodenal MDA concentrations were greater (P = 0.03) in CuSO(4) pigs and tended to be greater (P = 0.10) in pigs supplemented with TBCC compared with control pigs. Liver Cu was greater (P = 0.01) in CuSO(4) vs. control pigs, and tended (P = 0.07) to be greater in TBCC pigs than control pigs. Bile Cu concentrations were greater (P < 0.001) in CuSO(4) and TBCC pigs vs. controls and were also greater (P = 0.04) in TBCC vs. CuSO(4) pigs. Total liver GSH concentrations were less (P = 0.02) in pigs fed diets supplemented with CuSO(4) vs. pigs fed control diets but total liver GSH did not differ (P = 0.11) between control and TBCC pigs. Hepatic mRNA of cytochrome c oxidase assembly protein 17 was less (P = 0.01) in CuSO(4) and tended to be less (P = 0.08) in TBCC pigs vs. control pigs. Expression of antioxidant 1 mRNA was greater (P = 0.04) in TBCC pigs and tended to be greater (P = 0.06) in CuSO(4) pigs compared with control pigs. Results of this study indicated that, when fed at 225 mg Cu/kg diet, TBCC may cause less oxidative stress in the duodenum than CuSO(4). Feeding weanling pigs increased Cu resulted in modulation of certain Cu transporters and chaperones at the transcription level.

Grazing as an alternative for utilization of saline-sodic soils in the San Joaquin Valley: selenium accretion and performance of beef heifers

Two experiments were conducted to evaluate Se accumulation and health of non-pregnant, non-breeding beef cattle grazing on forages with a high Se content due to irrigation with saline drainage water. Heifers grazed experimental pastures of "Jose" tall wheatgrass (TWG; Thinopyrum ponticum var. "Jose") and creeping wildrye (CWR; Leymus triticoides var. "Rio") for 190 days in Experiment 1 (2007) and for 165 days in Experiment 2 (2008). In experiment 1, mean Se concentrations were similar in TWG and CWR herbage (4.0 versus 3.7 ± 0.26 mg/kg dry weight; p=0.34) as was crude protein (113 versus 114 ± 7.9 g/kg dry weight; p=0.94). Concentrations of Se in blood increased by 300% during the grazing period, and were similar for heifers grazing the TWG or CWR pastures (0.94 versus 0.87 ± 0.03 mg/kg; p=0.89). Heifers grazing on TWG gained more body weight than did heifers grazing on CWR (0.59 versus 0.27 ± 0.07 kg/days; p<0.01). In experiment 2, concentration of Se (4.0 versus 2.8 mg/kg ± 0.19 mg/kg dry weight; p<0.01) and crude protein (79 versus 90 ± 5.6 g/kg dry weight; p<0.01) differed, for TWG and CWR, respectively. Within 20 days, Se concentrations in blood had increased by 300% and by nearly 200% in heifers grazing on TWG or CWR. All data cited are least square means ± standard error of the mean. Data from our two grazing seasons are consistent in demonstrating the safety of grazing beef cattle for a period of up to 6 months on TWG and CWR forages having high levels of Se due to irrigation with saline drainage water. This suggests that forage production using saline drainage water is a viable alternative for saline soils with limited potential for producing high value, salt-sensitive, crops.

Investigation of breed and sex effects on cytochrome P450 gene expression in cattle liver

Many cytochrome P450 enzymes are involved in xenobiotic metabolism and elimination. In humans, genetic variation in some of these enzymes contributes to inter-individual drug responses, sometimes having significant clinical effects. Transcript levels of eight P450 genes were evaluated in liver to investigate potential differences in breed and sex in cattle. In Angus calves, heifers appeared to have higher gene expression than steers for two of the eight genes. In Angus and Simmental pregnant cows, Angus appeared to have higher gene expression for three of the eight genes. Transcript evaluation is just the first step toward determining if differences exist between breeds and sexes in enzyme catalytic activity. However, others (Giantin et al., 2008) have shown correlations between transcript levels and catalytic activity in other cattle breeds. Therefore breed and/or sex of an animal may need to be considered before administering a dose of a xenobiotic due to the potential for harmful drug residues in foodstuffs as well as improper treatment of disease conditions.

Proteins involved in iron metabolism in beef cattle are affected by copper deficiency in combination with high dietary manganese, but not by copper deficiency alone

A 493-d study was conducted to determine the impact of a severe, long-term Cu deficiency on Fe metabolism in beef cattle. Twenty-one Angus calves were born to cows receiving one of the following treatments: 1) adequate Cu (+Cu), 2) Cu deficient (-Cu), and 3) Cu deficient plus high Mn (-Cu+Mn). Copper deficiency was induced through the addition of 2 mg of Mo/kg of DM. After weaning, calves remained on the same treatment as their dam through growing (basal diet analyzed 7 mg of Cu/kg of DM) and finishing (analyzed 4 mg of Cu/kg of DM) phases. Plasma Fe concentrations were positively correlated (P < 0.01; r = 0.49) with plasma Cu concentrations. Liver Fe concentrations were greater (P = 0.05) in -Cu vs. +Cu calves and further increased (P = 0.07) in -Cu+Mn vs. -Cu calves. There was a negative relationship (P < 0.01; r = -0.31) between liver Cu and Fe concentrations. This relationship is likely explained by less (P < 0.01) plasma ceruloplasmin activity in -Cu than +Cu calves. As determined by real-time reverse transcription-PCR, relative expression of hepatic hepcidin was significantly downregulated (>1.5 fold) in -Cu compared with +Cu calves (P = 0.03), and expression of hepatic ferroportin tended (P = 0.09) to be downregulated in -Cu vs. +Cu. In the duodenum, ferritin tended to be upregulated in -Cu. vs. +Cu calves (P < 0.06). No significant change (P > 0.2) due to Cu-deficiency was detected at the transcriptional level for either isoform of divalent metal transporter 1 (DMT1 mRNA with or without an iron responsive element; dmt1IRE and dmt1-nonIRE) in liver or intestine. Duodenal expression of hephaestin and ferroportin protein was not affected by dietary treatment (P > 0.20). However, duodenal expression of DMT1 protein was less (P = 0.04) in -Cu+Mn steers vs. -Cu steers. In summary, Cu deficiency alone did affect hepatic gene expression of hepcidin and ferroportin, but did not affect duodenal expression of proteins important in Fe metabolism. However, the addition of 500 mg of Mn/kg of DM to a diet low in Cu reduced duodenal expression of the Fe import protein DMT1.

Technical note: copper chaperone for copper, zinc superoxide dismutase: a potential biomarker for copper status in cattle

Copper chaperone for Cu, Zn superoxide dismutase (CCS) has been shown to be reflective of Cu status in mice and rats. The objective of this study was to evaluate liver and erythrocyte CCS as an indicator of Cu status in beef cattle (Exp. 1), and to test the acute-phase properties of CCS under conditions of inflammation (Exp. 2). In Exp. 1, samples of whole blood and liver were collected at slaughter (492 d of age) from 15 Cu-deficient and 6 Cu-adequate Angus calves. At the time of tissue collection, severe Cu deficiency had been achieved and differences (P < 0.0001) in plasma and liver Cu among Cu-adequate and Cu-deficient calves were extreme (1.26 vs. 0.19 mg/L and 208.4 vs. 6.3 mg/kg for plasma and liver Cu, respectively). Protein levels of CCS were greater in liver (40%; P = 0.02) and erythrocytes (65%; P < 0.0001) of Cu-deficient vs. Cu-adequate calves. In Exp. 2, inflammatory responses were elicited in beef heifers by administration of a Mannheimia hemolytica vaccine. Four days after vaccination, plasma concentrations of the Cu-dependent protein ceruloplasmin and the Cu-independent protein haptoglobin were increased (P < 0.001) by 71 and 83%, respectively. In contrast, detection of CCS protein in samples of liver and erythrocytes did not differ (P >or= 0.45) between baseline (d 0) and d 4 after vaccination. These data demonstrate that bovine erythrocyte and liver CCS protein levels increase in Cu-deficient cattle. Furthermore, levels of CCS protein do not change after a vaccine-induced inflammatory response, suggesting that unlike ceruloplasmin, CCS may be a reliable indicator of Cu status in cattle.

Iron transporters are differentially regulated by dietary iron, and modifications are associated with changes in manganese metabolism in young pigs

To investigate the effects of dietary iron (Fe) on manganese (Mn) metabolism, 24 weaned pigs (21 d old) were blocked by litter and weight and randomly assigned to the following treatments: 1) no supplemental Fe [low Fe (L-Fe)]; 2) 100 mg supplemental Fe/kg [adequate Fe (A-Fe)]; and 3) 500 mg supplemental Fe/kg [high Fe (H-Fe)]. The basal diet was analyzed to contain 20 mg Fe/kg. Tissues were harvested after 32 d of feeding. Daily gain (least square means +/- SEM) was greater in A-Fe pigs (328.3 +/- 29.9 g/d) than in L-Fe pigs (224.0 +/- 11.2 g/d). Hemoglobin concentrations on d 32 were lower in L-Fe pigs (62 +/- 3.5 g/L) than in A-Fe pigs (128 +/- 5.6 g/L) and did not differ between pigs fed A-Fe and H-Fe (133 +/- 12.0 g/L). Liver Fe increased with increasing dietary Fe. Relative hepatic hepcidin expression was greater in pigs fed A-Fe and H-Fe than in those fed L-Fe. Relative expressions of duodenal divalent metal transporter 1 (DMT1) and solute carrier family 39 member 14 (ZIP14) were increased in L-Fe pigs compared with H-Fe pigs. Liver copper (Cu) was higher in L-Fe (0.56 +/- 0.04 mmol/kg) and H-Fe (0.58 +/- 0.04 mmol/kg) pigs than in A-Fe pigs (0.40 +/- 0.04 mmol/kg). Liver Mn was lower in H-Fe pigs (0.15 +/- 0.01 mmol/kg) than in A-Fe (0.23 +/- 0.02 mmol/kg) or L-Fe pigs (0.20 +/- 0.02 mmol/kg). Duodenal Mn concentrations were greater in L-Fe pigs than in A-Fe or H-Fe pigs. Fe deficiency in pigs increased gene expression of duodenal metal transporters (DMT1 and ZIP14) and supplementation with H-Fe reduced expression of DMT1 and ZIP14, which may have decreased absorption of Mn.