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Crossbred steers (n = 20; 235 ± 4 kg) were fed for 53 d during a receiving period to determine if supplementing chromium (Cr; KemTRACE Chromium Propionate 0.04%, Kemin Industries, Des Moines, IA) would alter glucose or lipid metabolism of newly received cattle. Chromium premixes were supplemented to add 0 (Con) or 0.2 mg/kg of Cr to the total diet on a DM basis. Cattle were fitted with jugular catheters on d 52. A glucose tolerance test (GTT) and an insulin sensitivity test (1ST) were conducted on d 53. Blood samples were collected from -60 to 150 min relative to each infusion. Serum was isolated to determine glucose, insulin, and NEFA concentrations. Throughout GTT, no differences were detected in glucose concentrations, glucose clearance rates (k), or preinfusion insulin concentrations (P > 0.50), but insulin concentrations postinfusion tended (P = 0.06) to be greater for the Cr-supplemented steers. This caused an increase in the insulin to glucose ratio (I:G) from 0 to 150 min postinfusion for the Cr-supplemented steers (P = 0.03). In addition, NEFA concentrations during GTT were lower (P < 0.01) for Cr-supplemented steers both preinfusion and postinfusion. During 1ST, there was no treatment effect on glucose concentrations preinfusion (P = 0.38), but postinfusion glucose concentrations were greater (P< 0.01) in the Cr-supplemented steers. The k of Cr-supplemented steers tended (P = 0.06) to be faster than Con steers from 30 to 45 min postinfusion. During the same test, there was no treatment effect detected for insulin concentrations (P > 0.33). The I:G were not affected by treatment (P > 0.40).Concentrations of NEFA were reduced (P < 0.01) both preinfusion and postinfusion during 1ST for Cr-supplemented steers. Results of this study indicate that supplementation of Cr can significantly alter lipid metabolism. This suggests that these steers had less dependence on lipid metabolism for energy or sensitivity of adipose tissue to antilipolytic signals was reduced. Results of glucose and insulin metabolism were inconsistently modified after a GTT and an 1ST. [ABSTRACT FROM AUTHOR]

Crossbred steers (n = 180; 230 ± 6 kg) were fed during a 56-d receiving period to determine if supplementing chromium (Cr; KemTRACE Chromium Propionate 0.04%, Kemin Industries) would improve feedlot performance and health of newly-received cat-tle. A completely randomized block design (36 pens; 9 pens/treatment; 5 steers/pen) was used. Chromium pre-mixes were supplemented to add 0 (Con), 0.1, 0.2, or 0.3 mg/kg of Cr to the total diet on a DM basis. No differences were detected on d 0 or after the first 14 d on feed. From d 0 to d 28, DMI (P = 0.07) and ADG increased linearly (P = 0.04) as Cr concentrations increased. From d 0 to d 56, BW (P = 0.08) displayed a tendency to increase linearly, and consequently ADG and G:F increased linearly (P < 0.05) as Cr concentra-tions increased. The number of steers treated at least once for respiratory symptoms tended (P = 0.07) to lin-early decrease as Cr concentrations increased. Twenty additional steers (235 ± 4 kg) were fed 56 d to deter-mine if supplementing Cr (Con or 0.2 mg/kg Cr) would alter the metabolic response of newly-received cattle to a lipopolysaccharide (LPS) challenge. Cattle were samples were collected at 0.5-h intervals from -2 to 8 h, and again at 24 h relative to a LPS challenge (0.5 pg/ kg BW) at 0 h. Serum glucose, insulin, and NEFA con-centrations were determined from blood samples. Steer BW was also measured at cannulation, and 24 h and 8 d post-LPS. Steer BW did not differ at cannulation (P = 0.37), but 24 h post-LPS, Cr-supplemented steers had lost less BW (P = 0.03). Pre-LPS glucose concentra-tion did not differ (P = 0.97). Post-LPS, there was a time x treatment interaction (P <0.01) such that glucose concentration peaked earlier (0.5 h) and at a greater con-centrations in Cr-supplemented steers (P < 0.01). Insulin concentration did not differ between treatments pre- or post-LPS (P > 0.13). Concentration of NEFA did not dif-fer pre-LPS (P = 0.54); but 0.5 h post-LPS Cr-treated steers produced a greater peak NEFA concentration (P < 0.04). Results of this study indicate that supplementation of Cr to the basal diet can have beneficial effects on the performance and health of newly-received steers. These data also suggest that supplementation of Cr attenuated BW loss and allowed for a quicker recovery after a LPS challenge fitted with jugular catheters on d 52. On d 55, blood [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess changes in exit velocity (EV) of Brahman calves from 21 d of age (DOA) to 56 d postweaning (231.30 ± 1.23 DOA). Spring-born calves (n = 308) from 2006 to 2008 were sired by 18 bulls. Exit velocity (m/s) was determined as the rate of speed of a calf traversing 1.83 m after being released from a working chute. Temperament score was determined as the average of EV and pen score 28 d before and at weaning (2006: 173 ± 2 DOA; 2007: 174 ± 2 DOA; 2008: 163 ± 2 DOA). Pen score was determined by separating calves into groups of 3 to 5 animals and scoring their reactivity to a human observer on a scale of 1 (calm, docile, approachable) to 5 (aggressive, volatile, crazy). The number of calves that switched temperament group was determined by ranking calves based on their EV at 21 to 24 DOA, 90 DOA, weaning, and at 56 d postweaning. The GLIMMIX procedure of SAS was used to analyze EV with DOA, birth year and sex as fixed effects, and sire and calf nested within sire included as random effects. Temperament classification (calm, intermediate, temperamental) was modeled as a fixed effect, and the linear regression of traits on DOA investigated. Spearman rank order correlations were determined between EV at 21 to 24 DOA, 90 DOA, weaning, and 56 d postweaning and correlations decreased as the number of days between EV measurements increased. Differences in EV were observed between the 2006 (2.23 ± 0.057 m/s) compared with the 2007 (1.90 ± 0.059 m/s) and 2008 (1.83 ± 0.057 m/s) calves (P < 0.001), but the 2007 and the 2008 calves did not differ (P = 0.75). The random effect of sire approached significance (P = 0.07) and accounted for some of the variation observed. Exit velocity increased as days of age increased (P < 0.001). Exit velocity of temperamental calves increased at a faster rate with age (P < 0.001; estimate of slope = 0.005 ± 0.0004 m/s daily) compared with intermediate (slope = 0.003 ± 0.0005 m/s daily; P < 0.001) and calm calves (slope = 0.0007 ± 0.0005 m/s daily; P < 0.001). Exit velocity is a useful and viable indicator of temperament classification. Results suggest that temperamental calves increase their EV at a faster rate and may be identified before weaning, which may enhance the ability of producers to select against temperamental animals. [ABSTRACT FROM AUTHOR]

Interrelationships among growth, endocrine, immune, and temperament variables were assessed in neonatal Brahman calves. The velocity upon exiting a working chute (exit velocity) of an animal was measured and used as an objective indicator of temperament to classify calves as calm, intermediate, or temperamental. Calves (n = 116) were weighed weekly between d 0 and 21 to 24, and blood samples were collected for plasma and serum on d 0, 1, 2, 7, 14, and 21 to 24 after birth to measure concentrations of immunoglobulins, cortisol, and epinephrine (EPI). Body weight increased from d 0 through d 21 to 24 (P < 0.001) with bulls (n = 60) having greater BW than heifers (n = 56; P = 0.02). Serum concentrations of cortisol were greatest on d 0 before declining (P < 0.001) over the ensuing 21 to 24 d and were not related to temperament (P = 0.89) or sex (P = 0.97). Concentrations of EPI were affected by time, with an increase in EPI concentrations in temperamental bulls between 2 and 14 d of age (P < 0.008). Concentrations of EPI were not affected by temperament (P = 0.44) or sex (P = 0.68). Serum immunoglobulin concentrations peaked on d 1 before dedining (P < 0.01) but were not related to temperament (P = 0.40 to 0.68). Of the stress hormones measured (cortisol and EPI), only cortisol was associated with the early performance of the calf. Calf BW at d 21 to 24 and BW gain were positively associated with serum immunoglobulin concentrations, yet negatively associated with concentrations of cortisol. Serum immunoglobulin concentrations were negatively correlated with cortisol concentrations (r = -0.28; P= 0.003), yet positively associated with EPI concentrations (r = 0.51; P = 0.003). During the neonatal period in this study, there was no relationship of temperament with passive immunity or stress hormone concentrations; however, growth was positively associated with passive immunity and negatively associated with stress hormones. Measuring exit velocity as early in life as d 21 to 24 fails to accurately predict temperament at weaning in over 40% of Brahman calves. Our conclusion is that measurement of exit velocity should be done nearer to the time of weaning than to birth. These data can be beneficial in developing best management practices for young calves. [ABSTRACT FROM AUTHOR]

This study examined the effects of maternal stress on the response of the pig to acute restraint stress and in vitro measures of immune function. Pregnant sows were assigned by parity to one of two treatments and managed per current industry standards (Control; n=2) or subjected to a daily 5 min acute restraint stress from d 85 to 110 of gestation (Stressed; n=2). After farrowing, pigs (n= 12 from control sows; MC; and n=15 from stressed sows; MS) were weighed and tattooed for permanent identification and managed similarly throughout the remainder of the study. At 35 d of age, pigs were restrained and blood collected initially (t = 1.5 ± 0.1 min), and at 3 and 6 min. Plasma was collected and analyzed for cortisol (C), epinephrine (E), norepinephrine (NE) and dopamine (D). To assess immune function, lymphocytes were isolated using density gradient centrifugation. Cells were plated in DME/F12 media containing Concanavalin A (ConA; 0 to 10 ug/mL) and cultures incubated for 96 hours (37C and 5% CO2). Following incubation, IgM production and the extent of proliferation were determined. Plasma C did not differ (P > 0.05) between MS and MC pigs, and increased (P < 0.01) with duration of restraint (40±5 vs. 75±5 ng/mL for 1.5 vs. 6 min). Plasma E and NE increased with duration of restraint, (P < 0.05) and MS pigs had lower (P < 0.05) E and NE than MC pigs. In MC pigs, D increased (P < 0.05) with duration of restraint. In contrast, in MS pigs D was not affected (P > 0.05) by restraint, and D was lower in MS relative to MC (1.6 ± 0.2 vs. 2.9 ± 0.3, respectively). ConA induced dose-dependent increases (P < 0.01) in lymphocyte proliferation and IgM production. The extent of proliferation was not affected (P > 0.05) by duration of restraint. In contrast, IgM production by cultures decreased (P < 0.05) with increasing time of restraint. Regardless of duration of restraint, cultures established from MS pigs had a reduced (P < 0.05) proliferative and IgM response to ConA than MC pigs. These results indicate that maternal stress affects the stress response of the progeny which may have a negative impact on immune function. [ABSTRACT FROM AUTHOR]

This study examined the effects of maternal stress on offspring behavior in relationship to changes in the stress response. Pregnant sows were assigned by parity to one of two treatments and managed either per current industry standards (Control; n=2) or subjected to a daily 5 min acute restraint stress from d 85 to 110 of gestation (Stressed; n=2). After farrowing, pigs (n= 12 from control sows; MC; and n=17 from stressed sows; MS) were weighed, tattooed for identification and managed similarly throughout the study. On d 18 of age, pigs were subjected to a social confrontation test by placing 3 MC and 3 MS pigs in a 1.5 x 1.5 m open field. Each pig was numbered and the test was videotaped. The behavioral elements measured per pig included: (1) sniffing; (2) threat; (3) biting; (4) fighting; (5) chasing; (6) fleeing; and (7) withdrawal. An aggression score (AS) was calculated as the sum of elements 2 through 5. To assess pig stress response, pigs were subjected to an acute restraint test and blood samples collected at 1.5, 3 and 6 min. Plasma was analyzed for cortisol (C), epinephrine (E), norepinephrine (NE), and dopamine (D). All data was subjected to ANOVA using split-plot design. Sources of variation included treatment, time of bleed, and individual interactions. MS pigs displayed more (P < 0.05) sniffing than MC pigs. MS pigs had decreased (P < 0.05) incidents of biting and fighting, and increased (P < 0.05) incidents of fleeing. The AS score for MS pigs was lower (P = 0.03) than MC (10.9 ± 2.3 vs. 23.8 ± 6.2, respectively). The MS pigs had similar (P > 0.05) plasma concentrations of C, but had lower (P < 0.05) E, NE, D than MC pigs. For both MC and MS pigs there was a positive correlation between AS and E (r=0.76; P < 0.01), but no (P > 0.05) correlation between AS and NE and D. MC pigs showed a positive correlation between AS and C (r=0.78; P < 0.01). In contrast, in MS pigs there was a negative relationship between AS and C (r=-0.61; P < 0.01). Collectively, these data indicate that maternal stress reduces the normal aggressive behavior of pigs. In addition, the results suggest that the role of C in normal aggression in the pig is dependent upon concentrations of the E. [ABSTRACT FROM AUTHOR]

Although livestock experience many stressors throughout their life, one of the most commonly experienced, and most difficult to control, is stress caused by fluctuations in environmental temperatures that extend beyond the thermoneutral (TN) zone for an animal. In swine, cold stress has long been recognized as a main cause of neonatal morbidity and mortality. A possible explanation for this increased morbidity and mortality may be related to their inability to generate a febrile response. Previously, we reported that the acute phase immune response, including the generation of fever, after exposure to lipopolysaccharide (LPS; Escherichia coli O111: B4; Sigma-Aldrich, St Louis, MO, USA) is substantially altered in neonatal pigs maintained in a cold environment (ie, 18°C). Neonatal pigs that were maintained in a cold environment and administered LPS experienced a period of hypothermia coupled with altered endocrine and proinflammatory cytokine responses that could prove detrimental. In cattle, we previously reported differences in the acute phase immune response of two diverse breeds of Bos taurus cattle (Angus and Romosinuano) when maintained under TN conditions and exposed to LPS. More recently we have reported that differences in the stress and immune responses of Angus and Romosinuano heifers varies, depending on whether the cattle were housed at either TN or heat stress air temperatures. Our data clearly show that even intermittent periods of heat stress similar to that experienced in production environments can have significant effects on the stress and innate immune responses of cattle. Understanding the effect of thermal stress on livestock is critical to developing and implementing alternative management practices to improve their overall health and well-being., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Our primary objective of this experiment was to evaluate potential genetic differences between two diverse Bos taurus breeds [Angus (AG) and Romosinuano (RO)] in response to an endotoxin challenge. Eighteen steers (n = 9 steers/breed; 299.4 ± 5.2 kg BW) were acclimated to environmentally controlled chambers maintained at thermoneutrality (19.7 °C) and then fitted with indwelling jugular catheters and rectal temperature (RT) recording devices 1 d before the endotoxin challenge. The next day, blood samples were collected at 30-min intervals from -2 to 8 h, and RT was measured continuously at 1-min intervals throughout the study. At time 0, all steers received an intravenous bolus injection of lipopolysaccharide (LPS; 2.5 μg/kg BW). Serum samples were stored at -80 °C until analyzed for cortisol, proinflammatory cytokines [tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, and interferon gamma (IFN-γ)], and acute phase proteins (serum amyloid A, acid soluble protein, ceruloplasmin, and α-acid glycoprotein). Rectal temperatures increased in both breeds within 1 h after LPS, with RO producing a greater increase in RT than AG steers (P < 0.001). Serum cortisol and TNF-α increased (P < 0.01) in both breeds within 1 h after the LPS challenge. For cortisol, an overall breed effect (P < 0.02) was detected, such that AG steers had a higher cortisol response than RO steers. A breed × time interaction (P < 0.01) was observed for TNF-α, such that the response was delayed and extended in the RO steers compared with the AG steers. At 2 and 2.5 h after LPS, TNF-α concentrations were greater (P < 0.03) in RO steers than in AG steers. For IL-1β, a breed × time interaction (P < 0.04) was also observed. At 3 h after LPS, IL-1β concentrations were greater (P < 0.01) in RO steers than in AG steers. Serum IL-6 and IFN-γ increased (P < 0.01) in a similar manner in both groups after the LPS challenge. These data show differences in the innate immune response between two diverse Bos taurus breeds which may provide insight about differences observed in productivity, heat tolerance, disease resistance, and longevity among cattle breeds., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The present study tested the hypothesis that the oral administration of DHEAS enhances the in vitro and the in vivo immune response of young pigs. Crossbred, female pigs (80 days of age; 49+/-2 kg) were separated into two treatment groups (n=4/treatment) receiving either 0mg/kg (control) or 1mg/kg DHEAS twice daily (DHEAS) for 5 weeks. On day 7 pigs were immunized against KLH and ovalbumin. Body weight increased weekly throughout the study but did not differ between treatment groups. While white blood cell counts increased in response to immunization but did not differ between treatments, the neutrophil:lymphocyte ratio was enhanced (P<0.05) in DHEAS-supplemented pigs. Concanavalin A (ConA) induced an in vitro dose-dependent increase (P<0.05) in lymphocyte proliferation, but treatment did not affect proliferation prior to immunization. However, lymphocytes isolated from DHEAS-supplemented pigs displayed a greater increase in proliferation following immunization relative to control pigs (P<0.05). Dexamethasone (DEX) attenuated ConA-induced lymphocyte proliferation, with DHEAS-supplemented pigs retaining a greater proliferative response relative to control pigs (P<0.05). Serum IgG concentrations and relative concentrations of antigen-specific IgG increased after immunization with maximum values attained at 21 and 28 days for control and DHEAS-supplemented pigs, respectively. The DHEAS-supplemented pigs had greater (P<0.05) concentrations of IgG and relative concentrations of antigen-specific IgG compared to control pigs. Collectively these data suggest DHEAS supplementation increases the responsiveness of young pigs to antigenic challenge, and may be beneficial for improving their immune function.