Effects of chromium on health status, blood neutrophil phagocytosis and in vitro lymphocyte blastogenesis of dairy cows.

The objective of this study was to determine the effects of supplemental dietary chromium (Cr) on health status and mastitis-related parameters, as well as neutrophil phagocytic activity of dairy cows during late pregnancy and early lactation. In addition, possible interactions and involvements of Cr with insulin, cortisol, somatotropin (rBST) and insulin-like growth factor-1 (IGF-1) were directly investigated in vitro based on blastogenic responses using peripheral blood lymphocytes (PBL) of eight cows fed the control diet. Forty pregnant Holsteins, 18 primiparous and 22 multiparous, at week (wk) 6 before the expected calving dates were randomly assigned to treatments: control and supplemental chelated Cr (0.5 ppm) in the diet. All cows were managed in a normal production operation and health status was assessed by recording the incidence of health problems during the experimental period of wks 6 before and 16 after calving (-6 to 16 wks). Mastitis-related parameters included somatic cell counts (SCC), bacterial colony counts of milk samples from each mammary gland quarter of all cows during wk 1 to wk 8 postpartum. Peripheral blood neutrophil phagocytic function of eight cows fed either control or supplemental Cr diet was determined by the ability to take up uniform fluorescent beads measured by flow cytometry. Supplemental Cr had no effect (P > 0.10) on health status of cows during late pregnancy and early lactation, or on SCC and bacterial colonies of quarter milk samples from early lactation (wks 1 to 8). Supplemental Cr also did not affect neutrophil phagocytic function of cows from 6 wks prepartum to 6 wks postpartum. However, in the in vitro study of PBL (from control animals, not fed Cr diet) blastogenesis with addition of insulin or cortisol at two levels (0.05 and 0.5 ng ml-1), insulin and cortisol enhanced or had no effect on PBL proliferations with or without concanavalin A (con A) simulation. However, further Cr addition in the culture medium containing supplemental insulin or cortisol, particularly CrCl3, additively increased (P < 0.05) BPL blastogenic activities with or without con a stimulation. Conversely, addition of rBST or IFG-1 (0.5 and 5.0 ng ml-1) in the culture medium enhanced PBL proliferation, but addition of Cr gave no additional effect. These results indicated that supplemental Cr had no beneficial effect on health status, mastitis-related parameters or neutrophil phagocytic activity of dairy cows. However, in vitro study confirmed and extended our previous observations that Cr has an effect on lymphocyte proliferation and this may associate with insulin or cortisol actions.

Immunomodulatory activity of blood serum from chromium-supplemented periparturient dairy cows.

Our previous research showed enhanced immune responses, including mitogen-induced blastogenesis of peripheral blood mononuclear cells from feedlot calves and periparturient dairy cows supplemented with dietary chromium (Cr). The objective of the present study were to test whether blood sera from Cr-supplemented periparturient cows contained immunomodulatory activity for mitogen-stimulated peripheral blood mononuclear cells and, if so, to determine if this activity was explicable by differences in blood profiles of some glucose-regulating hormones (insulin, cortisol, growth hormone, insulin-like growth factor I, and tumor necrosis factor-alpha) between Cr-supplemented and unsupplemented (control) animals. Blood sera from ten unsupplemented cows and nine Cr-supplemented cows (0.5 ppm day-1) were collected weekly from 2 weeks before to 6 weeks after parturition, and were used to supplement (1, 10, and 20% vol/vol) culture medium supporting concanavalin A (Con A) stimulated mononuclear cells enriched from blood of four nulliparous donor cows. Hormone concentrations were determined using radioimmunoassays. Con A-induced blastogenesis was enhanced when 1, 10, and 20% sera from Cr-supplemented cows was added to the mononuclear cell cultures, and this was particularly evident around parturition. Conversely, peripartum sera from unsupplemented cows depressed Con A-induced blastogenesis. Except for a marginal rise in blood cortisol 2-4 weeks after parturition, no significant effects of Cr supplementation on other hormones (insulin, growth hormone, insulin-like growth factor I, tumor necrosis factor-alpha) were observed. These observations suggest that factors in peripheral blood serum from Cr-supplemented cows, other than absolute concentrations of the glucose-regulating hormones studied, modulate Con A-induced blastogenesis of mononuclear leukocytes.

Effect of supplemental chromium on whole-body kinetics of glucose, lactate, and propionate in rams fed a high grain diet.

The isotope dilution technique of [6-3H]glucose, [U-14C]lactate and [l-14C]propionate was used to evaluate the effect of dietary chromium (Cr) supplementation on whole-body kinetics of glucose, lactate, and propionate in rams. Rams were fed a high grain diet at 2% of body weight with or without 0.5 ppm of supplemental Cr from chelated Cr for the initial 14 days, and then intake was increased to 2.5% at body weight for the last 9 days. Weight gain was enhanced (P < 0.01) with Cr supplementation. Plasma concentrations of glucose, lactate, and propionate were not influenced by Cr supplementation. Turnover rates of glucose and lactate, and their interconversion were also not influenced. Propionate turnover rate tended to increase (P = 0.11) and the conversion of propionate to glucose increased (P < 0.05) with Cr supplementation, leading the increased proportional contribution of propionate to glucose turnover rate (P < 0.05). Chromium supplementation may influence the contribution of each glucogenic substrate for glucose production in rams fed a high grain diet.

Supplemental chromium for stressed and growing feeder calves.

The effects of supplemental chromium (Cr) from high-Cr yeast were investigated with steer calves fed corn silage diets. One hundred eight Charolais-crossed calves, weighing 245 kg after marketing and transport, were allotted to one of four treatments during the initial 28-d stress period: control, .4 ppm of Cr in the diet, long-acting injectable oxytetracycline (LAOTC), and Cr + LAOTC. Those fed Cr received 4 mg of Cr/d for the first 3 d sprinkled onto a small amount of hay over the silage. Chromium without LAOTC increased (P less than .05) ADG by 30% (.61 vs .79 kg/d) and ADG/DMI by 27% (.123 vs .156). Oxytetracycline alone increased (P less than .05) ADG by 30% and DMI by 15%. Chromium had no effect on morbidity. However, LAOTC tended (P less than .14) to reduce morbidity (26.0 vs 14.0%) after its administration. After d 28, steers were processed. Two weeks later, they were rerandomized within Cr groups to urea-corn vs soybean meal supplementation of corn silage during a 70-d growing period. Level of Cr was reduced to .2 ppm. Jugular blood was collected from eight steers on each treatment on two occasions. Chromium had no effect on ADG or ADG/DMI. However, Cr decreased (P less than .05) serum cortisol (75.0 vs 55.6 nmol/L). Furthermore, Cr increased (P less than .05) serum immunoglobulin M and total immunoglobulins in calves fed diets with soybean meal but had no effect in calves with urea-corn supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of level of supplemental chromium on performance, serum constituents, and immune status of stressed feeder calves.

The effects of level of supplemental Cr from high-Cr yeast on performance, blood chemistry profile, morbidity, and immune status were investigated using 84 Charolais-crossed steer calves in a completely randomized design. Calves of 236-kg average weight, after transportation from Saskatchewan to Ontario, were randomly assigned to four treatments; 0, .2, .5, and 1 ppm of supplemental Cr, incorporated into a corn-silage diet. Blood was collected via jugular venipuncture at d 0, 7, 14, 21, and 28 and analyzed for metabolites, minerals, immunoglobulins, hematocrit (Hct), and leucocyte counts. Hemagglutinating antibody titers to human red blood cells (HRBC) were quantified after immunizations on d 0 and 14. Contact sensitivity after sensitization and challenge with dinitrochlorobenzene was also measured. A 27% increase (P < .05) in ADG was observed at d 30 for calves that were fed .2 and 1 ppm of supplemental Cr. Dry matter intake also increased (P < .05) for the .2- and 1-ppm Cr treatments. A linear decrease (P < .05) in serum cortisol with increasing Cr level was observed at d 28. Chromium supplementation decreased (P < .05) morbidity, as well as rectal temperatures at d 2 and 5. Peak primary antibody titers to HRBC (P < .05) and immunoglobulin G1 concentrations (P = .06) at d 14 were higher for steers that received the Cr supplementation. However, Cr treatment had no effect on expression of contact sensitivity. Chromium supplementation increased (P < .05) Hct on d 14 and 21 and serum Ca and Mg on d 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of supplemental chromium on immune responses of periparturient and early lactation dairy cows.

The objective of the present study was to determine the effects of supplemental dietary chromium on immune responses of dairy cows subjected to physical and metabolic stresses associated with late pregnancy, calving, early lactation, and peak milk yield. Nine periparturient dairy cows were supplemented with chelated Cr (.5 ppm/d) from 6 wk prepartum (wk -6) through 16 wk postpartum (wk 16), and 10 cows were unsupplemented controls. To assess humoral immune responses, all cows were immunized with ovalbumin (OVA; s.c.) and human erythrocytes (HRBC; i.v.) on wk -2 and 2, and sera from weekly blood samples were assayed for content of antigen-specific antibody. Cell-mediated immunity was assessed in vitro using antigen (OVA)- and mitogen-stimulated peripheral blood mononuclear cell (PBMC) blastogenesis of cells collected biweekly from wk -2 and 6. Supplemental Cr caused anti-OVA antibody responses (P < .01) and mitogen-stimulated blastogenic responses of PBMC (P = .05) to be elevated, was associated with lowered OVA-stimulated blastogenic responses of PBMC (P < .01), and had no overall effect on antibody responses to HRBC (P > .10) relative to responses of control cows. These results confirmed and extended our previous observations that supplemental Cr can alter specific immune responses of stressed cattle.

Effects of supplemental chromium on antibody responses of newly weaned feedlot calves to immunization with infectious bovine rhinotracheitis and parainfluenza 3 virus.

The objective of this study was to determine the effect of supplemental dietary chromium (Cr) on antibody responses of feedlot calves. Fifty-five newly weaned calves were divided into two groups, 28 that received supplemental Cr and 27 that did not, and were immunized with a commercial vaccine against bovine infectious rhinotracheitis virus (IBR) and bovine parainfluenza virus type 3(PI-3). Sera harvested from blood sampled preimmunization, and at days 14 and 28 postimmunization (PI), were assayed for anti-IBR and anti-PI-3 antibody titers. Individual calves were also scored as seroconverters if day 14 or 28 PI titers were > or = 3 times the value of the preimmunization titer. Thirty-five calves did not seroconvert to either antigen. Of 20 IBR seroconverters, 15 calves were from the Cr-supplemented group while only five calves were controls (p = 0.007). There was no treatment difference in the number of PI-3 seroconverters. Least squares analysis of actual antibody titers revealed that Cr supplementation increased the magnitude of the peak antibody response to the IBR (p = 0.003), but had no effect on anti-PI-3 antibody titers. These data confirmed and extended our previous observations that supplemental Cr can be immunomodulatory in cattle.

The influence of supplemental chromium and vaccines on the acute phase response of newly arrived feeder calves.

The acute phase response as indicated by serum haptoglobin and total haemolytic complement activity (CH50) was measured in 72 cross-bred steer calves purchased at sales in Ontario. During the 28 day (d) trial, 18 steers were randomly assigned to each of the following groups: 1) control; 2) vaccinated (Infectious Bovine Rhinotracheitis, Parainfluenza-3, Bovine Viral Diarrhea, Bovine Respiratory Synctial Virus vaccine plus Pasteurella haemolytica vaccine); 3) supplemental chelated Cr (0.14 mg/kg); and 4) Cr plus vaccines. Haptoglobin concentrations were low at arrival, increased (P < 0.05) on day 7, and returned to near initial levels (P > 0.05) by day 14. Supplemental Cr reduced (P < 0.05) haptoglobin on day 7 when morbidity was highest. Following antibiotic treatment for respiratory disease haptoglobin was lower (P < 0.05) than during morbidity; however, during morbidity, haptoglobin concentrations were not greater in sick calves (P > 0.05) than in healthy calves. Complement activity was lowest on day 7 (P < 0.05) and peaked on day 14 (P < 0.05). Complement activity tended to be lower on day 7 for vaccine, Cr, and Cr+ vaccine groups; however, the difference from controls was not significant (P > 0.10). Complement activity did not increase on day 14 (P > 0.05) with Cr supplementation as in other treatments. Morbid calves had lower (P < 0.05) CH50 activity than healthy calves on day 14. Following antibiotic treatment, the Cr-supplemented group had higher (P < 0.05) CH50 than during morbidity. In general, chromium supplementation reduced the acute phase response in newly arrived feeder calves.

Effect of supplemental chromium on antibody responses of newly arrived feeder calves to vaccines and ovalbumin.

Two trials were conducted to investigate the effects of supplemental chromium (Cr) from organic sources (Cr chelate and high Cr yeast) on antibody responses of newly arrived feeder calves following vaccination with infectious bovine rhinotracheitis (IBR), para-influenza-3 (PI3), bovine respiratory syncytial virus (BRSV), bovine viral diarrhea (BVD) and Pasteurella haemolytica and ovalbumin (OVA). Using cross bred steer calves purchased at sales in Ontario, vaccines and OVA were given on d 0 and 21 after arrival in the feedlot. Immune responses of calves were measured as serum specific antibody titres against all antigens on d 0 and 28 or d 35. The anti-OVA antibody responses (trial 2) were further investigated by measuring antibody concentrations of calves weekly until d 55 after arrival in the feedlot. Supplemental Cr (0.14 ppm) from an amino acid-chelated source had no effect on antibody responses to IBR, P13 and BRSV, but enhanced (P < 0.05) antibody titres of calves in response to the BVD vaccine on d 28 or d 35. Supplemental Cr from Cr yeast had no effect on antibody titres of calves to any vaccines. Chromium from both sources (trial 1 and 2) had no effect on antibody responses of calves following vaccination with P. haemolytica. However, supplemental Cr (0.75 ppm) from Cr yeast enhanced (P < 0.05) serum antibody responses of calves to OVA during the primary response (d 14) and secondary response (d 35) following immunization. These data confirmed our previous finding that supplemental Cr can enhance humoral immune response of market-transit stressed calves, but its enhancement on vaccine efficacy was antigen-dependent and variable.

Metabolite and hormonal responses to glucose or propionate infusions in periparturient dairy cows supplemented with chromium.

Two studies were conducted to evaluate the effects of Cr supplementation on blood metabolite and hormonal responses of Holstein cows to glucose challenges during late pregnancy and early lactation and to propionate challenges during early lactation. Eight multiparous and 4 primiparous cows (Experiment 1) and 12 primiparous cows (Experiment 2) were assigned to one of two treatments: control and 0.5 ppm of supplemental Cr. The glucose challenges were performed at 2 wk prepartum and at 2 wk postpartum, and the propionate challenges were conducted at wk 2 and 6 postpartum. During glucose tolerance tests, Cr supplementation reduced the ratio of insulin to glucose and reduced plasma concentrations of insulin and triglycerides of primiparous cows during the prepartum period. Chromium supplementation decreased plasma Cr of primiparous cows following glucose challenge. With supplemental Cr, insulin sensitivity was reduced postpartum, particularly for primiparous cows, but insulin sensitivity was increased prepartum. Results of this study suggested that primiparous cows experienced Cr deficiency during late pregnancy and possibly during early lactation. Following propionate infusion, Cr supplementation increased the serum glucose peak, increased the area under the response curve for serum glucose, and tended to increase IGF-I concentrations. Chromium supplementation tended to reduce the ratio of insulin to glucagon. Supplementation might have enhanced gluconeogenesis or glycogenolysis. Supplemental Cr also resulted in reduced variability of most parameters during both experiments.