Response to adrenocorticotropic hormone or corticotrophin-releasing hormone and vasopressin in lactating cows fed an immunomodulatory supplement under thermoneutral or acute heat stress conditions.

Adrenal responsiveness was tested in nonpregnant, lactating Holstein dairy cows fed diets supplemented with OmniGen-AF (OG; Phibro Animal Health Corp., Teaneck, NJ), an immune modulator, and in nonsupplemented control (CON) cows following bolus infusions of a combination of corticotropin-releasing hormone (CRH; 0.3 µg/kg of BW) and arginine vasopressin (VP; 1.0 µg/kg of BW) or ACTH (0.1 IU/kg of BW) in 2 environments: thermoneutral [TN; temperature-humidity index (THI) <60] for 24 h/d and heat stress (HS; THI >68 for 17 h/d). Cows (506) were initially fed OG (n = 254) or CON (n = 252) diets for 44 d before selection of a subgroup of cows (n = 12; 6 OG, 6 CON) for the study. The 2 subgroups were balanced for parity, milk yield, and days in milk. All cows were transported to and housed in 2 environmentally controlled rooms at the University of Arizona Agricultural Research Complex (Tucson). Cows were given 3 d to acclimate to the rooms and then underwent 12 d of TN conditions and then 8 d of HS conditions for a total of 24 d on experiment. Cows were infused with CRH-VP on d 9 of TN and on d 1 of HS and with ACTH on d 10 of TN and on d 2 of HS. Hormone infusions took place at 1000 h (0 h) on each infusion day. Blood samples, taken in 30-min intervals, were first collected at 0800 h (-2 h) and were drawn until 1800 h (8 h). Before infusion, serum progesterone was elevated in OG cows compared with CON cows. Infusion of releasing factors (CRH-VP or ACTH) caused increases in serum cortisol and progesterone, but cortisol release was greater in CON cows than in OG cows during HS, whereas progesterone did not differ between the 2 treatments. Serum ACTH increased following infusion of releasing factors, but this increase was greater following CRH-VP infusion than ACTH infusion. Serum bovine corticosteroid-binding globulin also increased following infusion of releasing factors in both treatment groups, but this increase was greater during HS in cows fed OG. The free cortisol index (FCI) increased following CRH-VP and ACTH and was higher in HS than in TN for both OG and CON cows. However, the FCI response was blunted in OG cows compared with CON cows during HS. Heat stress enhanced the adrenal response to releasing factors. Additionally, the adrenal cortisol and FCI response to releasing factors was reduced during acute heat stress in cows fed OG. Collectively, these data suggest that OG supplementation reduced the adrenal responsiveness to factors regulating cortisol secretion during acute HS.

Prion protein N1 cleavage peptides stimulate microglial interaction with surrounding cells.

Microglia act as the protective immune cell of the brain. By surveying the tissue to identify and rectify problems, they function to maintain the health of brain cells. The prion protein N-terminal cleavage fragment, N1, has demonstrated neuroprotective activities in vitro and in vivo. This study aimed to elucidate whether N1 could modulate microglial function and, if so, determine the consequences for the surrounding tissue. Using a mixed neuronal lineage and microglia co-culture system, we showed that N1 stimulation changed overall morphology and metabolism, suggesting enhanced cellular viability. Furthermore, N1 induced an increase in Cxcl10 secretion in the co-cultures. Recombinant Cxcl10, administered exogenously, mediated the changes in the mixed neuronal lineage culture morphology and metabolism in the absence of microglia, but no effect of Cxcl10 was observed on microglia cultured on their own. Direct cell-to-cell contact was required for N1 to influence microglia in the co-cultures, and this was linked with restructuring of microglial membrane composition to include a higher GM1 content at interaction sites with surrounding cells. Our findings show that N1 can play a regulatory role in microglial function in the context of an inter-connected network of cells by changing both cellular interaction sites and cytokine secretion.

Pre-weaning plane of nutrition and Mannheimia haemolytica dose influence inflammatory responses to a bovine herpesvirus-1 and Mannheimia haemolytica challenge in post-weaning Holstein calves.

The objectives of this study were to determine whether plane of nutrition (PON) of milk replacer previously provided to calves, and dosage level of Mannheimia haemolytica (MH), influenced inflammatory responses to a combined viral-bacterial respiratory challenge. Holstein calves (1 d of age; n = 30) were assigned to treatments in a 2 × 3 factorial with pre-weaning PON and MH dose as main effects (n = 5 per treatment). Calves were fed either a low (LPN; n = 15) or a high PON (HPN; n = 15) from birth through weaning. Calves fed LPN were fed 436 g of dry matter (DM) per day of milk replacer until weaning, and HPN calves were fed 797 g of DM per day of milk replacer from d 1 to 10 and 1,080 g of DM per day from d 11 until weaning. Calf starter and water were offered ad libitum. Calves were step-down weaned beginning at d 54 and moved into an enclosed barn at d 70. Indwelling rectal temperature (RT) recording devices and jugular catheters were inserted at d 80. Calves were challenged with 1.5 × 108 plaque-forming units (pfu) per mL of bovine herpesvirus-1 (BHV-1) in each nostril at d 81 and with either 106, 107, or 108 cfu of MH at d 84. Blood samples were collected at varying intervals relative to BHV-1 and MH challenges. Four LPN calves either died or were euthanized soon after the 144-h observation period, whereas all HPN calves survived the entire observation period. As dosage of MH administered increased, acute and systemic inflammatory responses increased. Higher doses of MH resulted in increased leukocyte, neutrophil, and haptoglobin concentrations in infected calves. Data from the current study suggest that the highest dose, 108 cfu, triggered weaned calves' acute disease response, whereas the lower doses, 106 and 107 cfu, caused more moderate inflammation and disease. The effects of PON on inflammation responses to the disease challenge indicated that calves previously fed the LPN diet had more severe pathophysiological responses. Calves fed LPN showed higher peripheral neutrophil and leukocyte counts and serum haptoglobin concentrations following the BHV-1 challenge. Additionally, following the MH challenge, LPN calves had higher peripheral neutrophil counts, neutrophil-to-lymphocyte ratios, and serum tumor necrosis factor-α concentrations. These data demonstrate that higher doses of MH increase the acute inflammatory response and prolong inflammation, and that calves previously fed LPN responded more severely to the combined viral-bacterial respiratory challenge.

Supplementation of a Lactobacillus acidophilus fermentation product can attenuate the acute phase response following a lipopolysaccharide challenge in weaned pigs.

Lactobacillus acidophilus fermentation products have been used to improve the performance of nursery pigs. However, research on the influence of this supplement on health is lacking. This study was designed to determine if feeding a Lactobacillus acidophilus fermentation product to weaned pigs would reduce stress and acute phase responses (APR) following a lipopolysaccharide (LPS) challenge. Pigs (n=30; 6.4±0.1 kg) were individually housed in stainless steel pens with ad libitum access to feed and water. Pigs were weighed upon arrival, assigned to one of three groups (n=10/treatment), and fed for 18 days: (1) Control, fed a non-medicated starter diet; (2) Control diet with the inclusion of a Lactobacillus acidophilus fermentation product at 1 kg/metric ton (SGX1) and (3) Control diet with the inclusion of a Lactobacillus acidophilus fermentation product at 2 kg/metric ton (SGX2). On day 7 pigs were anesthetized for insertion of an i.p. temperature device, and similarly on day 14 for insertion of a jugular catheter. Pigs were challenged i.v. with LPS (25 µg/kg BW) on day 15. Blood samples were collected at 0.5 h (serum) and 1 h (complete blood cell counts) intervals from -2 to 8 h and at 24 h relative to LPS administration at 0 h. Pigs and feeders were weighed on days 7, 14 and 18. The supplemented pigs had increased BW and average daily gain before the challenge. In response to LPS, there was a greater increase in i.p. temperature in Control pigs compared with supplemented pigs. In addition, cortisol was reduced in SGX2 pigs while cortisol was elevated in SGX1 pigs at several time points post-challenge. White blood cells, neutrophils and lymphocytes were decreased in SGX1 and SGX2 compared with Control pigs. Furthermore, the pro-inflammatory cytokine response varied by treatment and dose of treatment. Specifically, serum TNF-α was greatest in SGX2, intermediate in Control, and least in SGX1 pigs, while the magnitude and temporal pattern of IFN-γ in SGX2 pigs was delayed and reduced. In contrast, IL-6 concentrations were reduced in both SGX treatment groups compared with Control pigs. These data demonstrate that different supplementation feed inclusion rates produced differential responses, and that feeding SynGenX to weaned pigs attenuated the APR to an LPS challenge.

Influence of Saccharomyces cerevisiae fermentation products, SmartCare in milk replacer and Original XPC in calf starter, on the performance and health of preweaned Holstein calves challenged with Salmonella enterica serotype Typhimurium.

This study was designed to investigate the effects of supplementing SmartCare (SC; Diamond V, Cedar Rapids, IA) in milk replacer and Original XPC (XPC; Diamond V) in calf starter on performance and health of preweaned calves following an oral challenge with Salmonella enterica. The study was performed in two 35-d periods with 30 Holstein bull calves (2 ± 1 d of age) per period. In each period, calves were blocked by location in the barn and randomly assigned to treatments that included control, base milk replacer and calf starter with no added Saccharomyces cerevisiae fermentation products; SC, milk replacer with 1 g of SC/calf per day and base calf starter; and SC+XPC, milk replacer with 1 g of SC/calf per day and calf starter with 0.5% XPC on a dry matter basis. Calves were fed 350 g of milk replacer solids at 14% dry matter twice daily at 0700 and 1700 h. Calf starter and water were offered ad libitum and intakes were recorded daily. Calves were challenged with 108 cfu of sulfamethazine-resistant Salmonella enterica serotype Typhimurium orally on d 14 of the study. Fecal Salmonella shedding was determined on d 14 to 21 (daily), 24, 28, and 35 using selective media. Blood samples were collected on d 0, 7, 14, 16, 18, 21, 24, 28, and 35 and analyzed for hematology; plasma were analyzed for haptoglobin concentrations. All data were reported as CON, SC, and SC+XPC, respectively. Calf starter intake was increased from d 22 to 35 among SC+XPC calves and from d 29 to 35 among SC calves. The SC+XPC calves had a lower neutrophil-to-lymphocyte ratio (0.81, 0.83, and 0.69 ± 0.051) throughout the study. The SC+XPC calves also had lower hematocrits (35.1, 35.3, and 33.4 ± 0.54%) and hemoglobin concentrations (10.8, 10.6, and 10.1 ± 0.16 mg/dL) throughout the study. We found a tendency for calves fed SC and SC+XPC to have more solid fecal scores during the week after the challenge. We observed no treatment or treatment × time differences on plasma haptoglobin concentrations (63, 48, and 60 ± 0.5 µg/mL). No treatment differences were observed in the fecal shedding of the Salmonella; however, we noted a tendency for a treatment difference in the percentage of calves positive for Salmonella present in the ileal tissue at d 21 after the challenge (25, 50, and 60%). Supplementing preweaned Holstein calves with both SC in milk replacer and XPC in calf starter improved starter intake and improved fecal consistency immediately after a mild Salmonella enterica challenge, but more data are needed to further understand how these yeast fermentation products influence the immune responses to Salmonella enterica.

Effects of dexamethasone treatment and respiratory vaccination on rectal temperature, complete blood count, and functional capacities of neutrophils in beef steers.

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 ( = 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 ( < 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 ( < 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 ( < 0.001) yet decreased lymphocytes in CHR steers ( = 0.02) compared with CON steers. Neutrophil concentration increased rapidly, within 2 h of the DEX infusion, in ACU steers. Monocytes transiently increased ( < 0.001) in response to DEX treatment in CHR and ACU steers. In contrast, eosinophils were greater ( < 0.01) in CON steers than in ACU and CHR steers. A treatment × time interaction ( = 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 ( ≤ 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 ( ≤ 0.001) among only the CHR steers, whereas the intensity of the oxidative burst was suppressed ( ≤ 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.

Evaluation of the influence of prenatal transportation stress on GnRH-stimulated luteinizing hormone and testosterone secretion in sexually mature Brahman bulls.

This study examined the relationship of prenatal transportation stress (PNS) with exogenous GnRH-induced LH and testosterone secretion in sexually mature Brahman bulls. Brahman cows (n = 96; 48 were stressed by transportation at 5 stages of gestation and 48 were controls) produced a calf crop of 85 calves. All bulls (n = 46) from this calf crop were electroejaculated every 2 wk beginning at a scrotal circumference of 24 cm until sexual maturity (SM; i.e., 500 million sperm/ejaculate). The initial 11 control and 12 PNS bulls to reach SM were selected for the experiment. Within 7-21 d after reaching SM, bulls were fitted with jugular cannulas, from which blood samples were collected at 15-min intervals for 6 h prior to exogenous GnRH administration (10 ng/kg BW; i.v.) and for 6 h after GnRH. Serum concentrations of LH, testosterone, and cortisol were determined by RIA. Age and body weight did not differ ( > 0.1) between PNS and control bulls at the time of the experiment. All bulls responded similarly to exogenous GnRH, indicating no influence of PNS on LH or testosterone response to GnRH. More ( < 0.01) PNS (9 of 11) than control (3 of 12) bulls exhibited an endogenous pre-GnRH LH pulse, and more ( = 0.02) PNS (9 of 11) than control bulls (4 of 12) exhibited a pre-GnRH testosterone response to LH. The average concentration of testosterone during the 60 min (time -60, -45, -30, -15, and 0 min relative to GnRH) immediately preceding GnRH, tended to be greater ( = 0.07) in PNS (1.46 ± 0.30 ng/mL) than control (0.68 ± 0.28 ng/mL) bulls. During that time span serum cortisol was lower ( < 0.01) in PNS (4.00 ± 0.91 ng/mL) than control (7.8 ± 0.87 ng/mL) bulls. A treatment by time interaction ( = 0.03) affected testosterone concentrations from time -240 to 360 min relative to GnRH. Results from this study indicate that PNS did not affect pituitary responsiveness to GnRH or testicular responsiveness to GnRH-induced LH secretion.

Use of a novel oleaginous microorganism as a potential source of lipids for weanling pigs.

Weanling pigs are at risk of succumbing to illness due to an immature immune system and insufficient supply of available energy at the time of weaning. This study was aimed at determining whether oleaginous bacteria could serve as a source of lipids to weanling pigs. Weanling pigs were provided a daily dose of 1×109 colony fomring unit (CFU) = kg-1 of the novel oleaginous Enterobacter cloacae strain JD6301 or JD8715 (which is a variant form of JD6301 capable of producing extracellular triglycerides) via oral gavage for 5 d. Serum was collected every 6 h and intestinal samples were collected at 6 d. Providing pigs with JD6301 or JD8715 significantly increased serum concentrations of triglycerides and non-esterified fatty acids (NEFA) within 72 h. Additionally, the JD6301 and JD8715 strains were able to survive within the gastrointestinal tract throughout the duration of the study. These results suggest that providing Enterobacter cloacae can increase the serum lipids in the pigs, thus potentially providing an additional source of energy to animals during times of stress. This could potentially help improve the metabolic response of animals during times of stress.

Serum blood metabolite response and evaluation of select organ weight, histology, and cardiac morphology of beef heifers exposed to a dual corticotropin-releasing hormone and vasopressin challenge following supplementation of zilpaterol hydrochloride.

The objectives of this study were 1) to determine if supplementation of zilpaterol hydrochloride (ZH) altered select organ weights, histology, and cardiac anatomical features at harvest and 2) to determine if administration of a corticotropin-releasing hormone (CRH) and vasopressin (VP) challenge following 20 d of ZH supplementation altered the blood chemistry profile in cattle. Crossbred heifers ( = 20; 556 ± 7 kg BW) were randomized into 2 treatment groups: 1) control (CON), without ZH, and 2) zilpaterol (ZIL; ZH at 8.33 mg/kg [DM basis] for 20 d). On d 20 of supplementation, heifers were fitted with indwelling jugular catheters. On d 24, starting at 0800 h and continuing until 1600 h, blood samples were collected at 60-min intervals. At 1000 h, heifers received an i.v. bolus of CRH (0.3 µg/kg BW) and VP (1.0 µg/kg BW) to activate the stress axis. Serum was separated and stored at -80°C until analyzed for a large-animal chemistry panel. Following the CRH/VP challenge, heifers were harvested on d 25, 26, and 27 (5, 6, and 7 d after ZH supplementation); BW, HCW, select organ weights, and histology were measured, and a total heart necropsy was performed. A treatment effect ( ≤ 0.02) was observed for Ca, K, creatinine, alkaline phosphatase, and sorbitol dehydrogenase. Zilpaterol-fed heifers had decreased ( ≤ 0.02) concentrations of Ca and K and increased concentrations ( 0.01) of creatinine ( = 0.02) during the CRH/VP challenge when compared to control heifers. Control heifers had greater ( ≤ 0.05) alkaline phosphatase and sorbitol dehydrogenase concentrations when compared with ZIL heifers. A treatment × time interaction ( = 0.02) was observed for P; concentrations were similar between treatments from -2 to 6 h postchallenge, and 7 h postchallenge CON heifers had decreased P. Liver ( = 0.06) and kidney ( = 0.08) weights as a percentage of BW tended ( ≤ 0.08) to be reduced in ZIL heifers. Gross liver weights tended ( = 0.08) to be lower in ZIL heifers. Other organ (heart, lung, adrenals) to BW ratios remained similar ( ≥ 0.41). These data suggest that there are some variations observed between treatments in terms of response to ZH supplementation and the CRH/VP challenge; however, in the environmental conditions of this study, limited variation in blood metabolic responses and organ weights suggests that the supplementation of ZH did not detrimentally alter the physiology of cattle.

Exposure to lipopolysaccharide in utero alters the postnatal metabolic response in heifers.

This study was designed to determine the effect of prenatal lipopolysaccharide (LPS) exposure on the postnatal metabolic response to an LPS challenge in beef heifers. Pregnant, crossbred cows ( = 50) were assigned to a prenatal immune stimulation (PIS; = 25; administered 0.1 µg/kg BW LPS subcutaneously 233 ± 15d of gestation) or saline treatment group (Control; = 25). Birth and weaning BW of calves were collected. There was not (> 0.05) a treatment × gender interaction for birth weight or 205-d adjusted weaning BW. Treatment did not affect (> 0.05) birth BW, but steers and heifers of PIS cows had greater ( < 0.02) 205-d adjusted weaning BW than offspring from Control cows. From the 2 prenatal treatment groups, heifer calves ( = 12 PIS, 11 Control) were identified at weaning (238 ± 15 d of age) to subsequently receive an LPS challenge. On d 0, heifers were fitted with indwelling jugular catheters and were moved into individual pens. On d 1, heifers (fed at 0600 h) were challenged i.v. with LPS (0.5 µg/kg BW) at 0 h (1000 h). Blood samples were collected at 30-min intervals from -2 to 8 h and again at 24 h relative to the LPS challenge. There was a treatment × time interaction ( < 0.01) for cortisol; PIS heifers had greater cortisol from 4 to 6.5 h post-LPS challenge ( < 0.001). There was a treatment × time interaction ( = 0.04) for serum glucose such that glucose was greater ( = 0.01) in PIS than Control heifers at 0.5 h, but was greater in Control than PIS heifers at 2, 4.5, and 7 h post-LPS challenge. This resulted in overall time ( < 0.01) and treatment ( < 0.01) effects such that Control heifers had greater glucose concentrations than PIS heifers. There was a tendency ( = 0.10) for a treatment × time interaction for serum NEFA, such that NEFA was greater in Control than PIS heifers at -2, -1.5, and 7 h relative to the LPS challenge ( ≤ 0.02). Also, there were time ( < 0.01) and treatment effects ( < 0.01) for NEFA with Control heifers having greater NEFA than PIS heifers. Serum BUN was affected by a treatment × time interaction ( < 0.01). Concentrations of BUN were greater in PIS heifers from -1.5 to -1 h, 1 to 2 h, at 4 h, and from 5 to 24 h relative to the LPS challenge. These results demonstrate postnatal growth and the metabolic responses of weaned beef calves can be significantly altered with a single exposure to LPS in utero.

Dexamethasone treatment differentially alters viral shedding and the antibody and acute phase protein response after multivalent respiratory vaccination in beef steers.

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 ( = 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 (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 ( < 0.01) such that CHR steers had a greater ( ≤ 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 ( ≤ 0.03). Conversely, serum MH whole cell antibody concentration was least ( ≤ 0.06) for CHR from d 7 to 28 and greatest for CON ( ≤ 0.04) on d 56. Treatment altered Hp such that CON exhibited a greater ( < 0.01) Hp concentration than CHR but was not different from ACU ( = 0.16). On d 3, Cp was greatest for CON, intermediate for ACU, and least for CHR (treatment × day; ≤ 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 ( ≤ 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.

The metabolic, stress axis, and hematology response of zilpaterol hydrochloride supplemented beef heifers when exposed to a dual corticotropin-releasing hormone and vasopressin challenge.

The objective of this study was to determine the metabolic, stress, and hematology response of beef heifers supplemented with zilpaterol hydrochloride (ZH) when exposed to an endocrine stress challenge. Heifers ( = 20; 556 ± 7 kg BW) were randomized into 2 treatment groups: 1) control (CON), no ZH supplementation, and 2) zilpaterol (ZIL), supplemented with ZH at 8.33 mg/kg (DM basis). The ZIL group was supplemented ZH for 20 d, with a 3-d withdrawal period. On d 24, heifers received an intravenous bolus of corticotropin-releasing hormone (CRH; 0.3 µg/kg BW) and arginine vasopressin (VP; 1.0 µg/kg BW) to activate the stress axis. Blood samples were collected at 30-min intervals for serum and 60-min intervals for plasma and whole blood, from -2 to 8 h relative to the challenge at 0 h (1000 h). Samples were analyzed for glucose, insulin, NEFA, blood urea nitrogen (BUN), cortisol, epinephrine, norepinephrine, and complete blood cell counts. Following the challenge, cattle were harvested over a 3-d period. Liver, LM, and biceps femoris (BF) samples were collected and analyzed for glucose, lactate, and glycolytic potential (GP). There was a treatment ( ≤ 0.001) effect for vaginal temperature (VT), with ZIL having a 0.1°C decrease in VT when compared with CON. A treatment × time effect ( = 0.002) was observed for NEFA. A treatment effect was observed for BUN; ZIL had decreased BUN concentrations compared with CON ( < 0.001) prior to the challenge; however, no treatment × time effect was observed. There was also a treatment effect for cortisol ( ≤ 0.01) and epinephrine ( = 0.003); ZIL had decreased cortisol and epinephrine during the CRH/VP challenge when compared with CON. There was a time effect for total white blood cells, lymphocytes, and monocytes; each variable increased ( ≤ 0.01) 2 h postchallenge. Additionally, neutrophil counts decreased ( ≤ 0.01) in response to CRH/VP challenge in both treatment groups. Glucose concentrations within the LM were greater ( = 0.03) in CON when compared with ZIL. Lactate concentrations and GP within the BF were greater in CON ( = 0.05) when compared with ZIL. These data suggest there are some variations observed between treatments in terms of response to the CRH/VP challenge; however, in the environmental conditions of this trial, none of the variations observed suggest that the supplementation of ZH detrimentally alters the ability of cattle to effectively respond to stressful stimuli.

Cattle temperament influences metabolism: metabolic response to glucose tolerance and insulin sensitivity tests in beef steers.

Cattle temperament, defined as the reactivity of cattle to humans or novel environments, can greatly influence several physiological systems in the body, including immunity, stress, and most recently discovered, metabolism. Greater circulating concentrations of nonesterified fatty acids (NEFAs) found in temperamental cattle suggest that temperamental cattle are metabolically different than calm cattle. Further, elevated NEFA concentrations have been reported to influence insulin sensitivity. Therefore, the objective of this study was to determine whether cattle temperament would influence the metabolic response to a glucose tolerance test (GTT) and insulin sensitivity test (IST). Angus-cross steers (16 calm and 15 temperamental; 216 ± 6 kg BW) were selected based on temperament score measured at weaning. On day 1, steers were moved into indoor stanchions to allow measurement of individual ad libitum feed intake. On day 6, steers were fitted with indwelling rectal temperature probes and jugular catheters. At 9 AM on day 7, steers received the GTT (0.5-mL/kg BW of a 50% dextrose solution), and at 2 PM on day 7, steers received the IST (2.5 IU bovine insulin/kg BW). Blood samples were collected and serum isolated at -60, -45, -30, -15, 0, 10, 20, 30, 45, 60, 90, 120, and 150 min relative to each challenge. Serum was stored at -80°C until analyzed for cortisol, glucose, NEFA, and blood urea nitrogen concentrations. All variables changed over time (P < 0.01). For the duration of the study, temperamental steers maintained greater (P < 0.01) serum NEFA and less (P ≤ 0.01) serum blood urea nitrogen and insulin sensitivity (calculated using Revised Quantitative Insulin Sensitivity Check Index) compared with calm steers. During the GTT, temperamental steers had greater (P < 0.01) serum glucose, yet decreased (P = 0.03) serum insulin and (P < 0.01) serum insulin: serum glucose compared to calm cattle. During the IST, temperamental steers had greater (P < 0.01) serum insulin and a greater (P < 0.01) serum insulin: serum glucose as compared with calm steers. These data demonstrate that differences exist in the manner in which temperamental steers respond to glucose and insulin, potentially a result of elevated serum NEFA concentrations, which may result in changes in utilization and redistribution of energy in temperamental vs calm cattle.

Prenatal transportation stress alters temperament and serum cortisol concentrations in suckling Brahman calves.

This experiment examined the relationship between prenatal stress and subsequent calf temperament through weaning. The prenatal stressor used was repeated transportation of pregnant Brahman cows for 2 h at 60 ± 5, 80 ± 5, 100 ± 5, 120 ± 5, and 140 ± 5 d of gestation. Prenatally stressed calves ( = 41) were compared with controls ( = 44; dams did not undergo transportation during pregnancy) from 2 wk of age until weaning (average age at weaning = 174.8 ± 1.3 d). Temperament was defined by pen score (PS; 1 = calm and 5 = excitable), exit velocity (EV; m/sec), and temperament score (TS; (PS + EV)/2) and was recorded for each calf on d -168, -140, -112, -84, -56, -28, and 0 relative to weaning (d 0 = weaning). Cortisol concentrations were determined in serum samples obtained on d -168, -140, -28, and 0 relative to weaning. Birth weight and weaning weight were not different between treatment groups ( > 0.1). Pen score was greater ( = 0.03) in prenatally stressed calves (2.84 ± 0.21) relative to controls (2.31 ± 0.21). Exit velocity was greater ( < 0.01) in prenatally stressed calves (2.1 ± 0.14 m/sec) than in controls (1.61 ± 0.14 m/sec). Exit velocity was affected by a treatment × calf sex interaction ( = 0.04) and was greater in prenatally stressed females. Exit velocity was also affected by day ( < 0.0001). Temperament score was greater ( = 0.01) in prenatally stressed calves (2.45 ± 0.16) than in controls (1.95 ± 0.16). Temperament score was affected by day ( < 0.01). Basal cortisol concentrations were greater ( = 0.04) in prenatally stressed calves (15.87 ± 1.04 ng/mL) than in controls (13.42 ± 1.03 ng/mL). Basal cortisol concentrations were greater ( < 0.01) in females (16.61 ± 1.06 ng/mL) than in males (12.68 ± 1.02 ng/mL). Cortisol concentrations were positively correlated ( < 0.01) with PS ( = 0.55, < 0.01), EV ( = 0.4, < 0.01), and TS ( = 0.55, < 0.01). Overall, suckling Brahman calves that were prenatally stressed were more temperamental and had greater circulating serum concentrations of cortisol than control calves.

Dehydrated citrus pulp alters feedlot performance of crossbred heifers during the receiving period and modulates serum metabolite concentrations before and after an endotoxin challenge.

English × Continental heifers ( = 180) were sourced in 2 loads (219.3 ± 16.0 and 221.4 ± 16.4 kg, respectively) from commercial auction barns to study the effects of feeding dehydrated citrus pulp (DCP) on feedlot performance of newly received heifers. A completely randomized block design was used with BW nested within arrival load and blocked by BW into 3 dietary treatments (36 pens, 5 heifers/pen, 12 blocks, 3 pens/block, and 12 pens/treatment). Treatment diets contained 1) 0% DCP (control diet [CON]), 2) 10% DCP, or 3) 20% DCP on a DM basis. Diets containing DCP were exchanged with steam-flaked corn on a 1:1 basis. Cattle were fed a 63, 73, and 83% concentrate diet from d 0 to 28, d 28 to 42, and d 42 to 56, respectively. Over the 56-d trial period, as the amount of dietary DCP increased, DMI decreased ( = 0.01), ADG decreased ( < 0.01), and G:F decreased ( = 0.02). From d 0 to 28, there was no difference in the observed minus the predicted NEg of the diet ( = 0.73); from d 28 to 42, there was a linear increase in NEg favoring DCP treatments ( < 0.01); and from d 42 to 56, there was a linear decrease in NEg against the DCP treatments ( < 0.01). At the conclusion of the trial, a subset of heifers ( = 22; 307.89 ± 3.32 kg on d 63) were used to evaluate blood metabolite concentrations before and after a lipopolysaccharide (LPS) challenge. On d 63, heifers were fitted with jugular catheters and moved into individual stalls. On d 64, heifers were intravenously challenged with LPS (0.5 µg/kg BW), and blood samples were collected every 0.5 h from -2 to 8 h and at 24 h relative to the LPS challenge (0 h). Serum glucose, serum urea nitrogen (SUN), and NEFA concentrations were determined. Cattle lost less weight at both 24 and 72 h after the LPS challenge with increasing DCP percentage ( < 0.01). Glucose ( = 0.12) and NEFA ( = 0.13) concentrations did not differ before the LPS challenge; however, there was a treatment effect for SUN, with elevated concentrations of SUN in CON cattle ( < 0.01). After the LPS challenge, DCP-fed cattle had reduced glucose, elevated NEFA, and reduced SUN concentrations ( ≤ 0.01). Results indicate that dietary DCP modulated metabolite concentrations in heifers following an endotoxin challenge and affected feedlot performance when incorporated in receiving diets in replacement of corn. Future studies will need to address strategies to increase DMI or explore levels of DCP less than 10% in the diet of newly received heifer calves.

Effect of surgical castration with or without oral meloxicam on the acute inflammatory response in yearling beef bulls.

Pain management and welfare are increasingly prevalent concerns within animal agriculture. Analgesics may alleviate pain and inflammation associated with castration of beef cattle. This study was conducted to elucidate the effects of surgical castration on the acute inflammatory response and immunomodulation and whether concurrent oral administration of meloxicam (1 mg/kg BW) would alter these responses. On d -1, crossbred bull calves ( = 30; initial BW = 227.4 ± 10.3 kg) were fitted with indwelling jugular catheters and rectal temperature (RT) recording devices, placed into individual stanchions, and randomly assigned to 1 of 3 treatments. Treatment application occurred at h 0 and consisted of 1) intact bull calves treated with sham castration (CON), 2) bulls surgically castrated without meloxicam administration (CAS), and 3) bulls surgically castrated with oral meloxicam (1 mg/kg BW) administration (MEL). Blood samples were collected at 0.5-h intervals from h -2 to 4, 1.0-h intervals from h 4 to 8, and 12-h intervals from h 12 to 72. Serum was analyzed for cortisol and haptoglobin (Hp) concentrations using ELISA. Whole blood was analyzed for complete blood counts at -2, 0, 2, 4, 6, 8, 12, 24, 36, 48, 60, and 72 h, and RT was recorded in 5-min intervals. Postcastration RT was greatest for MEL (39.04), intermediate for CAS (38.99), and least for CON (38.93°C; ≤ 0.01). Serum cortisol was increased ( < 0.001) for CAS (12.3) and MEL (11.3) compared with CON (6.7 ng/mL) during the postcastration period. At 0.5 and 1.5 h, cortisol concentration was greater in CAS and MEL than CON, whereas at 2 and 2.5 h, cortisol concentration was greatest for CAS, intermediate for MEL, and least for CON (treatment × time, < 0.001). Total white blood cell ( ≤ 0.04), lymphocyte ( ≤ 0.02), and monocyte ( ≤ 0.002) counts were greatest for CAS, intermediate for MEL, and least for CON. Administration of MEL reduced ( ≤ 0.002) eosinophil counts during the postcastration period when compared with CON and CAS. The change in serum Hp, relative to baseline values, was reduced for MEL at 36 ( < 0.01) and 60 h ( ≤ 0.03), and the overall Hp concentration was least for MEL ( < 0.001). Oral administration of meloxicam at the time of castration reduced the acute inflammatory response in castrates, as evidenced by a reduction in Hp and certain leukocyte concentrations; it also caused a delayed increase in RT. Further research is needed to determine if this reduced acute inflammatory response would equate to improved health and/or performance after castration.

Effect of castration timing and oral meloxicam administration on growth performance, inflammation, behavior, and carcass quality of beef calves.

Beef bull calves (n = 62) were assigned randomly, within sire breed, to 1 of 4 treatments at birth. Treatments were 1) surgical castration near birth, 2) surgical castration near birth with oral administration of meloxicam (1 mg/kg BW), 3) surgical castration at weaning (WNG), or 4) surgical castration at weaning with oral administration of meloxicam (1 mg/kg BW; WMX). A subset of calves (n = 7/treatment group) were selected randomly near birth for blood collection, behavioral analyses, and rectal temperature (RT) records for a 7-d postcastration period on d 0 (birth), 1, 3, and 7, and on d 214 (weaning), 214 + 6 h, 215, 217, 221, and 228. Calf standing and lying activity were monitored from the same subsets by recording x- and y-axis positions of an accelerometer attached to the right metatarsus for 7 d postcastration. Calf BW was recorded throughout the entire production cycle, and carcass data were collected at slaughter. For statistical analyses, bulls left intact at birth were considered a positive control (BUL) for observations that occurred before their treatment application at weaning; likewise, bulls castrated at birth were considered a negative control (STR) during postweaning observations. No difference (P > 0.88) occurred in ADG between treatments throughout the preweaning period (d 0 to 214); however, 56-d postweaning ADG was greatest ( P= 0.02) in STR, intermediate in WMX, and least in WNG. At weaning, haptoglobin (Hp) was greater (P ≤ 0.005) for WNG and WMX compared to STR on d 214+6 h, 215, and 217, and Hp was greater (P = 0.05) in WNG compared to WMX on d 217. Neutrophils increased (P < 0.001) and red blood cells decreased (P ≤ 0.03) for WNG and WMX on d 214+6 h and 217, respectively. Postweaning behavior observations indicated that STR calves spent the least proportion of time standing (P = 0.002) when compared to WNG and WMX. Furthermore, WMX calves exhibited a greater proportion of time spent standing (P = 0.03) compared to WNG. Grazing and finishing phase ADG and carcass measurements did not differ (P ≥ 0.24) across treatments. In this study, surgical castration at weaning, but not near birth, altered the acute phase response, behavior, and growth performance. Oral meloxicam reduced serum Hp and improved ADG briefly when administered to calves castrated at weaning. Oral administration of meloxicam may be efficacious for mitigating some of the stress and inflammation associated with castration of weaning-age bull calves.

Physiological and metabolic responses of gestating Brahman cows to repeated transportation.

This study characterized physiological responses to repeated transportation (TRANS) of gestating cows of differing temperaments. Cows were classified as Calm (C; = 10), Intermediate (I; = 28), or Temperamental (T; = 10). Based on artificial insemination date and pregnancy confirmation, cows were TRANS for 2 h on d 60 (TRANS1), 80 (TRANS2), 100 (TRANS3), 120 (TRANS4), and 140 (TRANS5) ± 5 d of gestation. Indwelling vaginal temperature (VT) monitoring devices were inserted 24 h before each TRANS with VT recorded from 2 h before TRANS and averaged into 5-min intervals through 30 min after TRANS. Serum samples were collected before loading and on unloading from the trailer to determine concentrations of cortisol, glucose, and nonesterified fatty acids (NEFA). Data were analyzed by repeated measures analysis in SAS. Serum cortisol concentrations were affected by temperament ( < 0.001), with T cows having the greater concentrations of cortisol before each TRANS event. All cows (100%) regardless of temperament exhibited elevations in cortisol following each TRANS event. Peak VT was greater ( < 0.001) at TRANS1 relative to all other TRANS events regardless of cow temperament. During TRANS, the T cows tended ( < 0.09) to have greater peak VT (39.86 ± 0.15°C) compared to C (39.41 ± 0.16°C) and I cows (39.55 ± 0.08°C). Area under the VT curve decreased ( = 0.002) from TRANS1 through TRANS5. Pre-TRANS serum glucose concentration at TRANS1 was greater ( < 0.03) for T (68.13 ± 4.31mg/dL) compared to I (53.42 ± 2.78 mg/dL) and C cows (52.76 ± 4.60 mg/dL). The C and I cows had greater changes in NEFA concentration between pre- and post-transport, and T cows showed the least change ( < 0.001). Cow VT and serum glucose concentration decreased in all temperaments ( < 0.01) with repeated TRANS; however, serum NEFA concentration post-TRANS did not vary ( > 0.10) with repeated TRANS events. Serum glucose concentrations were affected ( < 0.02) by a TRANS event by temperament interaction with T cows taking more TRANS events to decrease their change in glucose concentration compared to C and I cows. These results demonstrate that temperament influences physiological responses to stress in gestating Brahman cows. Although repeated transport in our study is confounded with day of gestation, seasonal changes, and learning from repeated handling and transport, repeated transport is a useful model of repeated stress in studying the effects of temperament.

Plane of nutrition influences the performance, innate leukocyte responses, and resistance to an oral Salmonella enterica serotype Typhimurium challenge in Jersey calves.

Two experiments investigated how plane of nutrition influences performance, leukocyte responses, and resistance to an oral Salmonella enterica serotype Typhimurium challenge. In experiment 1, 46 (2±1 d of age) calves were randomly assigned to 2 diets: a low (LPN; n=23) and high plane of nutrition (HPN; n=23). The LPN calves were fed 409 g/d of dry matter (DM) of a 20% crude protein and 20% fat milk replacer, whereas HPN calves were fed 610 and 735 g/d of DM of a 28% crude protein and 25% fat milk replacer during wk 1 and 2 to 6, respectively. In experiment 2, 20 bull calves (LPN; n=11 and HPN; n=9) were orally challenged on d 80 with 1.5×10(7) cfu of Salmonella Typhimurium (ATCC #14028). The HPN calves had a greater incidence (87.5 vs. 45.5%) and duration of days with high fecal scores (5.5 vs. 3.5 d). The LPN calves had greater neutrophil surface expression of L-selectin on d 7, 21, and 42. Following the Salmonella Typhimurium challenge, calf starter DM intake was greater among the HPN calves. The percentage of neutrophils producing an oxidative burst was also greater among HPN calves on d 1 to 5 after the challenge. Similarly, the intensity of the oxidative burst tended to be greater among the HPN calves on d 2 and 3 postchallenge. The secretion of tumor necrosis factor-α from whole-blood cultures stimulated with lipopolysaccharide tended to be greater on d 1 and was greater on d 5 and 6 among HPN calves. The median ranks of haptoglobin concentrations were greater and plasma zinc concentrations tended to be decreased among LPN calves. These data indicate that feeding a HPN to Jersey calves improved average daily gain and feed efficiency, but increased the incidence of high fecal scores during the first few weeks of life; however, the HPN Jersey calves may be more resistant to Salmonella Typhimurium after weaning.

Associations between endotoxin-induced metabolic changes and temperament in Brahman bulls.

The influence of temperament on the alteration of metabolic parameters in response to a lipopolysaccharide(LPS) challenge was investigated. Brahman bulls were selected based on temperament score. Bulls (10 months; 211±5kg BW; n = 6, 8 and 7 for Calm, Intermediate and Temperamental groups, respectively) were fitted with indwelling jugular catheters to evaluate peripheral blood concentrations of glucose, blood urea nitrogen (BUN),non-esterified fatty acids (NEFA), insulin, epinephrine and cortisol before and after LPS administration (0.5 µg/kg BW LPS). Feed intake was also recorded. Intermediate bulls consumed more feed than the Temperamental bulls during the challenge (p = 0.046). Pre-LPS glucose (p = 0.401) and BUN (p = 0.222) did not differ among the temperament groups. However, pre-LPS insulin (p = 0.023) was lower, whereas pre-LPS NEFA (p < 0.001),cortisol (p < 0.001) and epinephrine (p < 0.001) were greater in Temperamental than in Calm and Intermediate bulls. Post-LPS glucose was increased in Calm and Intermediate bulls but not in Temperamental bulls(p < 0.001). Insulin concentrations post-LPS were greater in Calm than in Intermediate and Temperamental bulls (p < 0.001). Concentrations of NEFA post-LPS were greater in Temperamental than in Calm and Intermediate bulls (p < 0.001). Serum BUN concentration increased post-LPS, with values being greater in Calm and Intermediate than in Temperamental bulls (p = 0.012). Collectively, these data demonstrate that animal temperament is related to the metabolic responses of Brahman bulls following a provocative endotoxin challenge.Specifically, Temperamental bulls may preferentially utilize an alternate energy source (i.e. NEFA) to a greater degree than do bulls of Calm and Intermediate temperaments. The use of circulating NEFA from lipolysis may reduce the negative metabolic consequences of an immune response by allowing for a prompt answer to increasing energy demands required during immunological challenge, compared with the time required for glycogenolysis and gluconeogenesis.