- To evaluate the immunologic and metabolic effects of OmniGen-AF® (Phibro Animal Health corporation, Quincy, IL; OG) supplementation in growing beef cattle, we designed three studies using replacement beef heifers (8.5 and 10.5 months of age) and steers supplemented across backgrounding, transition, and finishing periods. In Study 1, the effect of OmnniGen-AF (OG) supplementation on expression of cytokines, chemokines, and associated receptors involved in the inflammatory response in whole blood cells of eight healthy purebred Angus heifers was evaluated during the priming phase (first 28d of supplementation). Heifers were trained to eat behind a Calan Broadbent system and then randomly assigned to control or supplemented daily with 56 g/hd/d OG group (n=4/group) to a basal diet consisting of grass hay, alfalfa hay, and ground corn. Blood was collected from the jugular vein before the study started (d0) and on days 3, 5, 10, 14, 21, and 28 of supplementation (priming phase). Genes coding for chemokine receptors (CX3CR1, CXCR1), stress
response (NAMPT), osteoclastogenesis (TNFRSF11B), and angiogenesis (VEGFA) were affected by treatment x time. Thirteen genes coding for interleukins and interleukin receptors (IL1B, IL9, IL1RN, IL1R1, IL10RB, IL10RA), chemokine ligand and receptors (CCR2, CXCL2, CXCR1, CCL26, CCR1), macrophage function (CSF1), and secondary immune response (BMP2) were down-regulated and CCL1 was up-regulated by OG supplementation. Of the 20 receptors evaluated, 7 (35%) were influenced by OG supplementation, and both decoy receptors (IL1RN and TNFRSF11B) were regulated by OG supplementation. Results of Study 1 suggest that OG supplementation may induce a broad, regulatory effect on genes associated with immune cell communication in whole blood during the priming phase.
In Study 2, our objective was to evaluate the effect of OmniGen-AF® supplementation on immune, physiological and carcass ultrasound parameters in steers during backgrounding, transition and finishing periods. Nine purebred Angus half-sibling steers were divided into one of two treatment groups, Control (CNTL n=4) and OmniGen-AF® (OG; n=5), based on the mean of two consecutive fill body weights. Cattle were offered 0 g/hd/d (CNTL) or 56 g/hd/d of OG through a 28-d backgrounding period (limit-fed a predominantly forage diet), a 14-d transition period, and a 56-d finishing period on a high concentrate diet (104 days total). Whole blood was collected on days -4, 14, 21 and 28 of supplementation to evaluate markers of immune function in mRNA during the OG priming phase. Serum was collected on days 0, 14, 21, 28 (OG priming phase), 35, 43, 56, 70, 84, 98 and 104 (OG action phase) to assess markers of physiology. Body weights, average daily gain (ADG), and dry matter intake (DMI) were measured through the all phases; feed efficiency was calculated bi-weekly; no difference was found between groups for any production parameter. Rib eye area (REA), 12th rib fat thickness (FT), rump fat (RF), REA/cwt and percent intramuscular fat (%IMF) were measured at 30-d intervals by ultrasound during the finishing phase. Predicted yield grade was completed using FT, REA, live body weight x 62% dressing percent and 2.5% Kidney Pelvic Heart fat (KPH); predicted quality grade was calculated using %IMF data. OG-supplemented cattle had a tendency to scan leaner over the 12th rib (P=0.06), had less rump fat (P=0.04), larger REA (P=0.009) and larger REA/cwt (P=0.03) which facilitated for a lower predicted numerical yield grade (P=0.03). %IMF and predicted quality grade were not significantly different between groups. IL10RB and CD80 were downregulated (P=0.02 and P=0.04, respectively), and CXCR2 and MAPK8 had a tendency to be downregulated during the backgrounding phase (P=0.08 and P=0.09, respectively). OG supplementation during the entire experiment increased serum chloride and haptoglobin concentrations and decreased serum NEFA concentrations. OG supplementation also attenuated the decrease in serum paraoxonase concentrations and ameliorated the increase in serum markers of liver cell damage (AST and GGT) at the end of the finishing period (compared to control cattle). Combined, these data suggest that OG may regulate immune system components during the OG priming phase and may act on the IMA during OG priming and action phases. During a high concentrate diet metabolic challenge, OG supplementation may prevent liver damage and improve predicted carcass grades by decreasing fat deposition and increasing REA.
In Study 3, we supplemented 8 purebred replacement Angus heifers (273.70 ± 8.88 kg) with 56 g/hd/day of OmniGen-AF® to a basal diet consisting of grass hay and alfalfa hay. The supplementation period was 28 days long (OG priming phase), during which body weights and blood collected on day 0, 7, 14, 21, and 28 of supplementation. Blood samples were collected for gene expression in whole blood (CD80, CD62L, CXCR2, IL10RA, IL10RB, MAPK8, NOD2, TLR1) and serum analysis of inflammatory markers (globulin, serum amyloid A, haptoglobin), markers of kidney function (BUN, creatinine), liver activity and liver cell damage (total protein, albumin, AST, GGT), metabolic markers (glucose, cholesterol, BHBA, NEFA) and serum mineral concentrations (Na, P, Cl, CA K). OmniGen-AF supplemented heifers (OG) were compared to non-supplemented controls (271.70±.88 kg; n=8) for each sample collection. Orts were collected daily and dry matter analysis was conducted twice per week for dry matter intake (DMI). No difference between groups was present in body weight, DMI, average daily gain, or feed efficiency. No differences in inflammatory markers, kidney function, liver activity, liver cell damage, or metabolism were observed between groups. The interaction of OG supplementation and time had an effect on serum albumin concentrations (P=0.003), such that OG heifers had increased serum albumin on day 7 and decreased serum albumin on day 28 (compared to controls, analyzed as change from baseline). Serum Na, P, Cl and Ca concentrations were not different between groups; however, OG supplemented heifers had lower phosphorus concentrations (control 0.69 ± 0.15 mg/dL vs. OG 0.10 ± 0.20 mg/dL; P=0.03), higher magnesium concentrations (control -0.08 ± 0.02 mg/dL from baseline vs. OG -0.17 ± 0.2 mg/dL from baseline; P=0.005) and a treatment x time interaction was present for Na (P=0.0001), K (P=0.02), Cl (P=0.003), Ca (P=0.0002), P (P<0.0001) and Magnesium (P<0.0001). OG supplemented heifers had higher serum Na concentrations on day 7 (change from baseline) and lower serum Ca and Mg concentrations than controls on day 28 (change from baseline). OG supplementation did not influence CD80, CD62L, CXCR2, IL10RB, MAPK8 or TLR1 expression in whole blood. Conversely OG supplementation increased IL10RA and NOD2 expression (P=0.02 and P=0.005) in whole blood and OG supplemented heifers had increased IL10RA expression on day 14 (P<0.001). When compared to previous results in beef cattle (using other sexes or animals in different stages of maturity), OG supplementation did not have consistent results on whole blood gene expression or serum indicators of animal health, suggesting that the effect OG supplementation on beef cattle may differ among ages and sexes.
The results of all three studies indicate OG supplementation may have a regulatory effect on markers of immune function during the OG priming phase, but these markers may not be consistent across sexes and/or stages of maturity. OG supplementation may also regulate serum mineral concentrations during the OG priming phase, but again these results are inconsistent. When cattle are subjected to a metabolic challenge, OG supplementation may support animal health through improved liver function and influencing the immune-metabolic axis. Additionally, OG supplementation during the finishing phase may improve potential carcass grades without altering body weight, average daily gain, dry matter intake or feed efficiency.