Growth implant efficacy may be affected when administered to nutritionally stressed calves, whereas the procedure may alter health or the humoral immune response to respiratory vaccination. The study ...objective was to determine the effect of different administration times (d 0, 14, or 28) of a growth implant containing 200 mg progesterone and 20 mg estradiol benzoate on health, performance, and metabolic and immunologic variables in high-risk, newly received beef calves used in a 120-d receiving/grazing stocker system. Crossbred bull and steer calves ( = 203) were weighed (initial BW = 203 ± 2.7 kg), stratified by castrate status on arrival, and randomly assigned to experimental treatments consisting of 1) negative control (no growth implant administered), 2) growth implant administered on d 0, 3) growth implant administered on d 14, and 4) growth implant administered on d 28. There were no differences ( ≥ 0.16) in BW or ADG during the 42-d receiving period. However, ADG during the subsequent grazing period and overall was greater ( ≤ 0.01) for implanted calves versus the negative control. Growth implant timing did not affect the rate of clinical bovine respiratory disease morbidity ( = 0.52; 94% morbidity overall) or bovine viral diarrhea virus type 1a antibody titer concentration ( = 0.61). Indicative of an overall negative energy balance on arrival, NEFA decreased sharply subsequent to d 0 (day effect, < 0.001), but was not affected ( = 0.47) by the timing of growth implantation. Blood urea N concentrations increased transiently (day effect, < 0.001); however, no treatment effect was observed ( = 0.72). Therefore, under conditions of this study, the timing of growth implant administration did not affect growth implant efficacy, health, or metabolic or immunologic variables in newly received, high-risk beef stocker calves. Overall, our observations suggest that there is not a clear benefit to delaying growth implantation and that a growth implant does not affect health or vaccine response in newly received beef calves.
ABSTRACT
The objective of this research was to examine the effects of dexamethasone (DEX) treatment on various aspects of immunity following administration of a multivalent respiratory vaccine, using ...a model intended to mimic acute versus chronic stress. Angus × Hereford steers (n = 32; 209 ± 8 kg) were stratified by BW and randomly assigned to 1 of 3 treatments: 1) acute stress (ACU), in which 0.5 mg/kg BW DEX was intravenously administered at 1000 h only on d 0; 2) chronic stress (CHR), in which 0.5 mg/kg BW DEX was intravenously administered at 1000 h on d −3 to 0; or 3) control (CON), in which no DEX was administered. Steers were fitted with indwelling jugular catheters and rectal temperature (RT) recording devices on d −4 relative to vaccination and placed in individual stanchions in an environmentally controlled facility. Blood samples were collected and serum was isolated at −74, −50, and −26 h; at 0.5-h intervals from −4 to 6 h; and at 12, 24, 36, 48, and 72 h relative to multivalent respiratory vaccination at 1200 h on d 0. Additional blood samples were used to analyze complete blood cell count (CBC) and functional capacities of neutrophils. There was a treatment × time interaction (P < 0.01) for RT such that DEX treatment in CHR and ACU steers decreased RT on d −3 and 0, respectively. A treatment × time interaction (P < 0.01) was observed for total white blood cells (WBC), neutrophils, lymphocytes, and monocytes. Specifically, DEX increased WBC and neutrophils in CHR and ACU steers (P < 0.001) yet decreased lymphocytes in CHR steers (P = 0.02) compared with CON steers. Neutrophil concentration increased rapidly, within 2 h of the DEX infusion, in ACU steers. Monocytes transiently increased (P < 0.001) in response to DEX treatment in CHR and ACU steers. In contrast, eosinophils were greater (P < 0.01) in CON steers than in ACU and CHR steers. A treatment × time interaction (P = 0.004) was observed for interferon-γ, with CON cattle exhibiting greater concentrations than the ACU and CHR cattle at 5 h after vaccination, through d 3. Treatment also influenced (P ≤ 0.001) the expression of L-selectin on the surface of neutrophils. The percentage of neutrophils engaging in phagocytosis and the oxidative burst were suppressed (P ≤ 0.001) among only the CHR steers, whereas the intensity of the oxidative burst was suppressed (P ≤ 0.001) for both ACU and CHR steers. These data suggest that our model induced acute and chronic immunosuppression and defined the acute response to a multivalent vaccine in CON steers.
Abstract
Three treatments were evaluated in feedlot heifers to determine the effects of zinc supplementation on the immune response to a combined viral-bacterial respiratory disease challenge. ...Thirty-two beef heifers (255 ± 15 kg) were subjected to a 30d period of Zn depletion, then randomly assigned to one of three treatment diets fed for 30d before the challenge: 1) Supplementation with 100 mg of Zn from Zn sulfate/kg of DM (Zn100), 2) Supplementation with 200 mg of Zn from Zn sulfate/kg of DM (Zn200), and 3) Supplementation with 80 mg of Zn/kg of DM from zinc methionine (ZinMet® Global Animal Products, Inc., Amarillo, TX) and 20 mg of Zn from Zn sulfate/kg of DM (ZinMet). All heifers were fitted with indwelling vaginal temperature (VT) devices and intra-nasally challenged with 1x108 PFU bovine herpesvirus-1 on d -3, and then allowed to rest in outdoor pens for 3d. On d0, each heifer was challenged intra-tracheally with an average dose of 2.38 × 107 CFU Mannheimia haemolytica (MH), fitted with an indwelling jugular catheter, then moved into individual stanchions in an environmentally-controlled enclosed barn. Whole blood samples were collected at 1-h (serum) or 2-h (complete blood counts) intervals from 0 to 8h, and at 12, 24, 36, 48, 60, 72, 168 and 360h relative to MH challenge. Data were analyzed using the MIXED procedure of SAS specific for repeated measures with fixed effects of treatment, time and their interaction. There was a treatment effect (P < 0.01) for VT such that Zn200 heifers had greater VT than Zn100 and ZinMet heifers. There was a trend (P = 0.10) for a serum cortisol treatment effect with Zn100 heifers having greater cortisol than ZinMet heifers. Total leukocytes and lymphocytes were greater (P ≤ 0.008) in Zn100 heifers than Zn200 and ZinMet heifers, while monocytes were less (P = 0.05) in ZinMet heifers than Zn100 and Zn200 heifers. Concentrations of IL-6 were greater (P = 0.02) in ZinMet heifers than Zn100 and Zn200 heifers. Concentrations of IFN-γ were greater in Zn200 heifers than ZinMet heifers at 0h, and Zn100 heifers from 0 to 12h post-MH challenge (trt × time P = 0.02). Serum haptoglobin was not affected by treatment or treatment × time (P ≥ 0.36), but increased over time (P < 0.001). There was a trend (P = 0.11) for ZinMet heifers to have less severe nasal lesion scores than Zn100 heifers. The observed differential physiological responses in this study indicate that zinc source and concentration may alter the response to a bovine respiratory challenge in heifers.
Abstract
Our objective was to examine immunosuppression induced by dexamethasone (DEX) administration in cattle on immunological responses to a multivalent respiratory vaccine containing replicating ...and nonreplicating agents. Steers (n = 32; 209 ± 8 kg) seronegative to infectious bovine rhinotracheitis virus (IBRV), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), and parainfluenza-3 virus (PI3V) were stratified by BW and randomly assigned to 1 of 3 treatments: 1) acute immunosuppression (ACU; 0.5 mg/kg BW DEX intravenously at 1000 h only on d 0), 2) chronic immunosuppression (CHR; 0.5 mg/kg BW DEX intravenously at 1000 h on d −3 to 0), or 3) a control (CON; no DEX). On d −4, steers were fitted with intravenous catheters in the jugular vein and placed into individual stanchions. At 1200 h on d 0, steers were administered a respiratory vaccine containing modified-live virus (MLV) isolates of IBRV, BVDV, BRSV, and PI3V and a Mannheimia haemolytica (MH) toxoid. On d 4, cattle were transported (177 km) and housed in an isolated outdoor pen. Serum was harvested on d 0, 7, 14, 21, 28, 35, 42, and 56 to determine IBRV-, BVDV-, BRSV-, and PI3V-specific antibody titers and MH whole cell and leukotoxin antibody concentrations. Sera from d −2, 0, 1, 3, 7, and 14 were used to quantify haptoglobin (Hp) concentration and ceruloplasmin (Cp) activity. Nasal swab specimens were collected on d 0, 3, and 14 to determine the presence of IBRV, BVDV, BRSV, and PI3V via PCR analysis. There was a treatment · day interaction (P < 0.01) such that CHR steers had a greater (P ≤ 0.07) BVDV antibody titer on d 14, 21, and 28. Moreover, IBRV-specific antibodies increased beginning on d 14 for CHR and on d 28 for ACU and remained greater through d 56 compared with CON (P ≤ 0.03). Conversely, serum MH whole cell antibody concentration was least (P ≤ 0.06) for CHR from d 7 to 28 and greatest for CON (P ≤ 0.04) on d 56. Treatment altered Hp such that CON exhibited a greater (P < 0.01) Hp concentration than CHR but was not different from ACU (P = 0.16). On d 3, Cp was greatest for CON, intermediate for ACU, and least for CHR (treatment · day; P ≤ 0.01). The prevalence of IBRV and BVDV in nasal swabs on d 14 was 67 and 56%, respectively, for CHR; 10 and 10%, respectively, for CON; and 9 and 0%, respectively, for ACU (P ≤ 0.006). Results suggest that CHR allowed increased replication of MLV vaccine agents. Conversely, DEX-induced immunosuppression blunted the acute phase protein and antibody response against the nonreplicating MH toxoid.
Exposure to animals persistently infected (PI) with bovine viral diarrhea virus (BVDV) results in immunomodulation in cohorts. It is hypothesized that the extent of modulation differs for low-risk, ...preconditioned (PC) vs. high-risk, auction market (AM) beef cattle. Our objective was to compare immune responses of PC or AM calves in the presence (PI) or absence (CON) of a PI-BVDV pen mate. Crossbred PC steers (n = 27) from a single ranch origin were weaned, dewormed, vaccinated against respiratory and clostridial pathogens, tested for PI-BVDV, and kept on the ranch for 61 d. Subsequently, PC steers were transported to a receiving unit (RU), weighed, stratified by d -1 BW, and assigned randomly to treatment (PCPI or PCCON) with no additional processing. Simultaneously, crossbred AM calves (n = 27) were assembled from regional auction markets and transported to the RU. The AM calves were weighed, stratified by gender and d -1 BW, processed under the same regimen used for PC steers at their origin ranch, except bull calves were castrated, then assigned randomly to treatment (AMPI or AMCON). Treatment pens were arranged spatially so that PI did not have fence line contact with CON. Blood samples were collected on d 0, 1, 3, 7, and 14 to determine serum concentrations of haptoglobin (Hp), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-4, and IL-6. Rectal temperature (RT) was recorded concurrent with blood sampling. In AM calves, RT and Hp increased (management effect; P < 0.001) sharply on d 1; however, exposure to a PI-BVDV pen mate did not affect either variable (P ≥ 0.79) during the 14-d evaluation period. Serum concentrations of TNF-α tended to increase (P = 0.09) for the PI cohort. A treatment × day interaction (P ≤ 0.05) was observed for IFN-γ on d 7 and 14 and IL-6 on d 14; these indices were greatest for AMPI. Results indicate weaning management and PI-BVDV exposure alter the immune status of newly received beef cattle. These main effects may be additive because proinflammatory cytokine concentrations were greatest for AMPI. Therefore, results further indicate that potential health or growth consequences in cohorts exposed to a PI-BVDV pen mate are impacted by previous management and health history.
We investigated the independent and in- teractive effects of dietary starch concentration and feed- ing management regimen on growth performance, carcass characteristics, and prevalence of liver ...abscesses in finish- ing beef cattle.
Beef steers (n = 720) were assigned to 48 pens in a randomized complete block de- sign, with treatments arranged in a 2 × 2 factorial (12 pens per treatment). Factors were finishing diets with ei- ther low (49.1%; CON) or high (64.4%; HOT) starch con- centrations and feeding management regimens designed for consistent feed delivery (REG) or randomized varia- tions (ERR) in both feed quantity (85% followed by 115% of the previous 4-d average randomly once per week) and delivery time (randomly delayed for 1, 2, 3, or 4 h twice per week).
No interactions between diet and feeding management regimen were detected for growth performance, carcass outcomes, or liver abscess prevalence. Steers fed HOT had greater liver abscess fre- quency (55.1% vs. 33.4%) and a greater proportion of liver scars (46.7% vs. 34.0%) compared with CON. Steers consuming HOT also had less final BW, ADG, DMI, hot carcass weight, marbling score, and calculated YG versus CON. Feeding management regimen did not affect liver abscess frequency, growth performance, or carcass merit.
Feeding a high- starch diet increased liver abscess prevalence and de- creased growth and affected carcass outcomes. In contrast, erratic feeding management did not affect liver or produc- tion outcomes.
Exposure to animals persistently infected (PI) with bovine viral diarrhea virus (BVDV) results in immunomodulation of cohorts that may have health and growth consequences; however, effects may differ ...in low-risk, preconditioned (PC) vs. high-risk, auction market (AM) beef cattle. Our objective was to compare health and performance of PC or AM management systems with (PI) or without (CON) presence of a PI-BVDV pen mate using a 2 x 2 factorial arrangement. Four shipment blocks of crossbred PC steers (n = 236) from 3 ranch-origins were weaned, dewormed, vaccinated, tested for PI-BVDV, and kept on the ranch for ≥42 d. Subsequently, PC steers were transported to a stocker receiving unit (RU), weighed (251 ± 2 kg), blood sampled, stratified by d -1 BW, and assigned randomly to treatment (PCPI or PCCON) with no additional processing. Simultaneously, 4 blocks of crossbred AM calves (n = 292) were assembled from regional auction markets and transported to the RU ± 36 h from PC arrival. The AM calves were weighed (245 ± 1.3 kg), stratified by gender and d -1 BW, processed under the same regimen used for PC steers at their origin ranch except bull calves were castrated, and then assigned randomly to treatment (AMPI or AMCON). Treatment pens (0.45 ha) were arranged spatially such that PI did not have fence-line or water source contact with CON. Calves were fed identically and followed the same antibiotic treatment protocol. Daily BW gain for the entire 42-d receiving trial was greater (P < 0.001) for PC (1.2 kg) compared with AM (0.85 kg). There was an exposure effect (P = 0.002) on ADG from d 28 to 42; CON gained 1.12 kg vs. 0.90 kg BW for PI cohort. Morbidity was markedly greater (P < 0.001) in AM (70%) vs. PC (7%), resulting in (P < 0.001) an antibiotic treatment cost of $20.52 and $2.48/animal, respectively. Treatment with a third antibiotic occurred more often (P = 0.04) for PI cohort, and the percentage of chronically ill cattle was greatest (P = 0.06) for AMPI. Upon arrival, BVDV type 1a, 1b, and 2a titers were greater for PC (treatment x day, P < 0.001), and the percentage seropositive to BVDV type 1a on d 0 was 100% for PC vs. 23% in AM. Platelets increased transiently (P < 0.001) with greater platelets observed in AM (P < 0.001). Results indicate that PC calves gain faster and require fewer antibiotic treatments during the receiving period. Exposure to PI reduced BW gain from d 28 to 42, increased the number of calves treated thrice, and increased chronically ill cattle for AM. PUBLICATION ABSTRACT
This study evaluated the effects of starch dilution with different sources of dietary fiber from terminal implant to slaughter on growth performance, energy utilization, and carcass characteristics ...of feedlot cattle.
Steers (n = 416; initial BW = 372 ± 2.67 kg) were allocated to 48 pens in a randomized complete block design. Pens of cattle (n = 12 per treatment) were assigned to 1 of 4 treatments consisting of diets based on steam-flaked corn, containing (1) 7.50% corn stalks on a DM basis fed for the entire feeding period (CON), (2) 14.75% corn stalks on a DM basis fed from terminal implant to slaughter (CS), (3) 9.50% wet distillers grains with solubles and 7.50% corn stalks on a DM basis fed from terminal implant to slaughter (WD), and (4) 19.00% wet distillers grains with solubles and 0.0% corn stalks on a DM basis fed from terminal implant to slaughter (NR). Six days before administration of the terminal implant, steers were transitioned to their treatment diets using a 2-ration system, whereas CON consumed the same diet throughout the entire feeding period.
As expected, performance (BW, DMI, ADG, G:F) was not different from d 0 of the study to dietary transition. Dry matter intake and calculated ME intake from dietary transition to slaughter were greatest for cattle consuming CS, intermediate for WD and CON, and least for NR. Final BW and ADG did not differ among treatments from dietary transition to slaughter; G:F was greatest for NR, intermediate for WD, and least for CS and CON. There was no difference in hot carcass weight, DP, marbling score, QG, YG, or percentage KPH among treatments. Steers consuming CS had greater 12th-rib s.c. fat thickness. The proportion of abscessed livers did not differ among treatments.
Increasing the proportion of corn stalks in the diet after terminal implant administration increased DMI and ME intake with no effect on G:F. In contrast, removing corn stalks from the diet and increasing the proportion of wet distillers grains with solubles to provide an equivalent starch concentration reduced DMI and improved G:F.
Abstract
One hundred eighty bulls (BW = 337 ± 10.9 kg) were blocked by BW and assigned randomly to 1 of 3 treatments on d 0: 1) INJ; received 1 mL (100 mg Zn) of a Zn solution in each testis, 2) BAN; ...received blood-restrictive rubber band placed around the dorsal aspect of the scrotum, 3) BUL; bulls with testicles remaining. Cattle were harvested by block on three separate dates (d 155, 176, and 197) when blocks reached similar BW (656 ± 4.4 kg) and visual adipose accretion. Striploins were removed from the left side of the carcass, wet-aged 14 d, and frozen at -20°C. Frozen striploins were sliced into 2.54-cm-thick steaks and remained frozen until analyses. Data were analyzed as a randomized complete block design (3 treatment pens/block and 10 cattle/pen) using the MIXED and GLIMMIX procedures of SAS with pen as the experimental unit for all dependent variables. Hot carcass weights were greater (P < 0.01) in INJ and BUL treatments compared to BAN. Similarly, longissimus muscle area was greater (P < 0.01) in INJ and BUL compared to BAN. Numeric yield grade was not different between treatments (P = 0.12). Percentage of USDA Choice carcasses was greater (P < 0.01) in BAN compared to INJ and BUL. Consumer panelists (n = 152) perceived greater (P = 0.02) tenderness from BAN steaks as compared to BUL whereas INJ was intermediate. Panelists scored BAN steaks with greater (P < 0.01) juiciness ratings than either BUL or INJ. Beef flavor was rated by panelists as greater (P = 0.01) in BAN and BUL compared to INJ. Overall acceptability was greater (P < 0.01) in BAN compared to INJ whereas BUL was intermediate. Percentage cook loss of striploin steaks (P = 0.47) and Warner-Bratzler shear force values (P = 0.11) were not different between treatments. Cooked color lightness values (L*) and redness values (a*) were not affected (P ≥ 0.23) by treatment. Yellowness values (b*) of striploin steaks were greater (P = 0.02) in BAN and BUL compared to INJ. Cooked steaks from INJ cattle displayed a greater (P = 0.05) ratio of red-to-brown (630:580 nm) compared to either BAN or BUL. Compositionally, INJ steaks were more similar to BUL than BAN, suggesting limiting efficacy of INJ as a castration method in older beef bulls. Compared to BAN, INJ increased HCW and LM area, yet quality grade and consumer acceptability were reduced.
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