J. A. Carroll

Profile of the bovine acute-phase response following an intravenous bolus-dose lipopolysaccharide challenge.

Our objective was to characterize further the acute-phase response following endotoxin (i.e. lipopolysaccharide; LPS) exposure in the bovine. Nine pure-bred Angus castrated males (i.e. steers; average body weight = 299 ± 5 kg) were used in a randomized complete block design in environmentally controlled chambers, set at thermoneutral level, to characterize the acute physiological, endocrine, immune, and acute-phase protein responses following an i.v. bolus administration of 2.5 μg of LPS/kg body weight. One day before administration of LPS, all steers were fitted with an indwelling jugular vein catheter for serial blood collection. Blood samples were collected at 30-min intervals from -2 h to 8 h relative to the LPS challenge (time 0), and serum was harvested and stored at -80 °C until analyzed for concentrations of cortisol, pro-inflammatory cytokines, and acute-phase proteins. Indicators of thermal status (i.e. rectal temperature, ruminal temperature, respiration rate, sweat rate, and skin temperatures) were measured at 30-min intervals from -1 h to 6 h relative to the challenge. Endotoxin exposure increased (P<0.05) serum concentrations of cortisol, tumor necrosis factor-α (TNF-α), interleukin 1-β (IL-1β), IL-6, interferon-γ (IFN-γ), and serum amyloid A. Respiration rate, rectal temperature, and rump skin temperature also were increased (P<0.05) following LPS administration. Endotoxin exposure dramatically decreased ear skin temperature (P = 0.002), but tended to increase (P<0.10) ruminal temperature, shoulder skin temperature, and shoulder sweat rate. Serum concentrations of acid soluble protein, α-acid glycoprotein, IL-4 and IL-2, and rump sweat rate were not altered (P>0.24) by the challenge. To our knowledge, this report is the most complete characterization of the bovine acute-phase response to a bolus-dose endotoxin challenge conducted under thermoneutral conditions and should provide foundation data for future research.

Evaluation of physiological and blood serum differences in heat-tolerant (Romosinuano) and heat-susceptible (Angus) Bos taurus cattle during controlled heat challenge.

A study was performed to evaluate differences in thermoregulatory ability of 2 Bos taurus breeds with known differences in heat tolerance. Nine Angus (AG; 304 +/- 7 kg of BW) and 9 Romosinuano (RO; 285 +/- 7.5 kg of BW) steers were transported to the Brody Environmental Center at the University of Missouri. Steers were housed for 18 d at thermoneutrality (TN; 21 degrees C) before initiation of heat stress (HS), which consisted of daily cyclic air temperature (26 degrees C, night; 36 degrees C, day) for 14 d. Rectal temperature and respiration rate were measured 6 times daily throughout the study. Sweat rates at shaved skin sites were recorded on specific days. Blood samples were taken once per week. Angus steers maintained rectal temperature 0.5 degrees C greater than RO at TN (P < 0.001). Likewise, respiration and sweat rates were greater (P < 0.001) in AG than RO at TN (P < 0.05). Rectal temperature increased during HS for both breeds with AG maintaining greater temperatures (P < 0.001). Both breeds increased respiration rate during HS, with AG steers exhibiting the greater rate (P < 0.001). Sweat rate increased more than 4-fold during HS (P < 0.001), followed by reduction after 7 d. Even after HS acclimation, AG exhibited the greater sweat rate (P < 0.001). Breed differences for serum leptin, creatinine, and cholesterol were found throughout the study with AG being greater than RO. Although there were no breed differences (P = 0.21) at TN, only AG steers exhibited a HS-induced increase (P < 0.05) in prolactin, creatinine, and cholesterol concentrations to suggest that an increase in rectal temperature is required for this effect. Use of rectal temperature along with endocrine markers, such as prolactin, may aid in the identification of B. taurus sensitivity to heat.

Effect of dietary supplementation of n-3 fatty acids and elevated concentrations of dietary protein on the performance of sows

A study was conducted to determine the effect of dietary supplementation of n-3 fatty acids (O3FA) with or without elevated concentrations of protein on the performance of sows during the first and the subsequent parity. Sixty-four pregnant gilts with BW of 195.0 +/- 2.1 kg and backfat (BF) thickness of 12.9 +/- 0.2 mm were assigned to 4 dietary treatments from d 60 of gestation (late gestation) to d 21 of lactation. Dietary treatments were 1) a control diet; 2) a high-protein diet (HP); 3) the control diet + 0.2% O3FA (O3); and 4) the HP diet + 0.2% O3FA (HPO3). For the control and O3 treatments, CP contents were 12.3% for late gestation and 17.9% for lactation, and for the HP and HPO3 treatments, CP contents were 18.4% for late gestation and 19.5% for lactation. On d 60 and 110 of gestation and after farrowing (within 12 h postfarrowing), on d 10 and 21 of lactation, BW, BF thickness, and blood samples were obtained. The total number of piglets and the number of piglets born alive and their birth weights were measured within 12 h postfarrowing. Colostrum and milk samples were obtained on d 2 and 21 of lactation, respectively. All piglets were weaned at 21 d. The wean-to-estrus interval and ADFI were recorded. The same measurements were obtained from the control and O3 groups during the subsequent parity. Dietary treatment did not affect BW, BF thickness, ADFI, and the wean-to-estrus interval of sows during their first reproductive cycle. Supplementation of O3FA increased both eicosapentaenoic acid and docosahexaenoic acid contents (P < 0.05) in colostrum and mature milk. First-parity litter size and piglet birth weight did not differ among treatment groups. Piglet BW was greater (P < 0.05) for the O3 group compared with both the control and HPO3 groups at d 10 and 21 of lactation. The same pattern was also noted for overall piglet BW gain. Both piglet and litter characteristics of the HP group did not differ from those of other groups throughout lactation. During the subsequent parity, both total and live piglet birth weights tended (P < 0.07) to be greater for the O3 group than for the control group. Compared with the control group, piglet BW and BW gain in the O3 group showed a pattern similar to the previous parity. Results indicated that O3FA alone during lactation improved the growth of nursing piglets, regardless of parity. However, the O3FA diet, with or without elevated protein, did not affect first-parity gestation performance, although O3FA alone may have improved piglet birth weight in the subsequent litter.

Citrus Products Decrease Growth of E. coli O157:H7 and Salmonella Typhimurium in Pure Culture and in Fermentation with Mixed Ruminal Microorganisms In Vitro

Orange peel and orange pulp are by-products that are included in feedlot and dairy cattle diets because of their low cost and high nutritional quality. The antimicrobial activity of citrus oils has been reported previously. The present study was carried out to determine whether these citrus by-products exert antimicrobial effects on Escherichia coli O157:H7 and Salmonella Typhimurium populations that are found in cattle gastrointestinal tracts. The growth of pure cultures (n = 3) of E. coli O157:H7 and Salmonella Typhimurium were reduced (p < 0.05) by addition of 2% (w/v) orange pulp and orange peel. Ruminal fluid was collected from cattle (n = 2) and E. coli O157:H7 or Salmonella Typhimurium were added. The addition of orange pulp and peel to in vitro mixed ruminal microorganism fermentations (n = 3) demonstrated that both orange pulp and peel reduced E. coli O157:H7 and Salmonella Typhimurium populations at least 2 log(10) in mixed ruminal fluid fermentations. Addition of orange pulp reduced (p < 0.05) E. coli O157:H7 populations from 10(5) to 10(2) colony-forming units (CFU)/mL and Salmonella Typhimurium populations (p < 0.05) from 10(4) to 10(2) CFU/mL. These results indicate that orange pulp and/or peel included in ruminant diets could decrease ruminal populations of foodborne pathogenic bacteria. Further research is needed to determine whether the antimicrobial activity of orange products against E. coli O157:H7 or Salmonella Typhimurium is expressed in the lower gastrointestinal tract.

Early weaning alters the acute-phase reaction to an endotoxin challenge in beef calves.

Previous research indicates that early weaning before shipment can reduce transportation-induced increases in acute-phase proteins (APP) and can increase feedlot performance in beef calves. These data suggest that the combination of weaning and transport stress may compromise the immune system of calves, thus hindering subsequent performance and health. Therefore, our objective was to determine if the innate immune response of early weaned calves (EW; 80 d of age) differed from normal-weaned calves (NW; 250 d of age) in response to an endotoxin challenge. Eighteen Brahman x Angus calves (8 and 10 EW and NW, respectively; 233 +/- 5 kg of BW) were used. Calves were maintained on pasture with supplement and then moved into individual pens for 1 wk of acclimation before the start of the study. Calves were fitted with an indwelling jugular catheter 1 d before LPS challenge (0 h; 1.0 microg/kg of BW, intravenously). Blood samples were collected at 30-min intervals from -2 to 8 h. Serum samples were stored at -80 degrees C until analyzed for cortisol, tumor necrosis factor-alpha (TNF), IL-1 beta, IL-6, interferon-gamma (IFN), ceruloplasmin, and haptoglobin. Whereas LPS increased serum cortisol (P <or= 0.001), no weaning age effect (P >or= 0.15) was observed. A weaning age x time interaction (P <or= 0.04) was observed for TNF, IL-1, IL-6, and ceruloplasmin such that concentrations of these indices were greater in the NW compared with EW calves. For haptoglobin, a weaning age effect (P <or= 0.03) was observed with NW calves having greater average haptoglobin concentrations compared with EW calves. Interestingly, the weaning age x time interaction (P <or= 0.001) for IFN revealed greater IFN in EW compared with NW calves. Based upon these data, the innate immune system of EW calves appears to be more competent in responding to immune challenge compared with that of NW calves. Additionally, the differential IFN response indicates that the immune system of EW calves may be more effective at recognizing and eliminating endotoxin. These data suggest that an altered innate immune system may be one of the factors responsible for the improved feedlot performance previously reported in EW calves.

Temporal pattern and effect of sex on lipopolysaccharide-induced stress hormone and cytokine response in pigs

The temporal pattern and sex effect of immune and stress hormone responses to a lipopolysaccharide (LPS) challenge were assessed using a pig model. Secretion of the pro-inflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 increased in a time-dependent manner following LPS infusion. There was also a time-dependent increase in secretion of the stress-related hormones cortisol, epinephrine (E), and norepinephrine (NE) following LPS, with peak concentrations attained within 30 min. The magnitude of the TNF-alpha and IL-1beta responses were both positively associated (P < 0.05) with the magnitude of cortisol response following LPS, whereas serum IL-1beta and IL-6 were positively correlated with the magnitude of E and NE responses following LPS. Acute-phase protein production was also time-dependently increased following LPS. The concentration of immune cells in circulation was decreased (P < 0.05) at 5.5h post-LPS and negatively correlated with pro-inflammatory cytokine production. By 24h post-LPS, immune cell counts increased (P < 0.05) and were positively associated with both pro-inflammatory cytokine and stress hormone production. The amplitude of pro-inflammatory cytokine response following LPS was affected (P < 0.05) by sex classification; however, the magnitude of elevated cytokine concentrations was not. The magnitude of the NE response, but not of the E and cortisol responses, to LPS was influenced by sex (P < 0.05). Similar to the pro-inflammatory cytokines, the magnitude of exposure to the stress hormones following LPS was not influenced by sex. The production of serum amyloid A (SAA) was influenced by sex, with barrows producing more SAA than gilts at 24h post-LPS (P < 0.05). Collectively, these results demonstrate sex-specific, concomitant temporal changes in innate immune- and stress-related hormones.

Technical note: Development of a self-contained, indwelling rectal temperature probe for cattle research

A device was developed to monitor rectal temperature automatically in cattle for application in research settings. Compared with manual measurement of rectal temperature, this device decreases labor and time requirements and allows data collection without the influence of animal handling or restraint. The device consists of a custom-fabricated aluminum tail harness that supports an indwelling rectal temperature data logger. Materials cost approximately US

Effects of changing milk replacer feedings from twice to once daily on Holstein calf innate immune responses before and after weaning

300 per unit, and units are completely reusable. Use of this device would increase the conditions under which accurate rectal temperature measurements can be obtained in experiments with cattle.

Effects of supplementing Saccharomyces cerevisiae fermentation product in sow diets on performance of sows and nursing piglets.

The objectives of this study were to determine the effects of switching Holstein calves to once-daily feeding during the fourth week of life (24 ± 2.3 d of age; once-fed n=22; twice-fed n=22) on innate immune responses, and to evaluate whether carry-over effects occurred when the calves were weaned during the seventh week of life. Peripheral blood samples were taken immediately before the change in feeding strategy (24 d of age) and at 27, 31, 45, 48, 52, and 66 d of age and were analyzed for circulating cortisol, haptoglobin, total leukocyte counts, neutrophil:mononuclear cells, and hematocrit percentage. Heparinized whole blood was also stimulated with lipopolysaccharide (LPS) for 24h and the concentration of tumor necrosis factor-α (TNF-α) in the supernatant was analyzed. Neutrophil L-selectin and β(2)-integrin expression were analyzed by flow cytometry. Simultaneous neutrophil phagocytic and oxidative burst responses to a heat-killed Escherichia coli were quantified by dual-color flow-cytometry. Treatment (once-daily or twice daily feeding) had no effect on pre- or postweaning performance. Once-fed calves tended to have more circulating neutrophils at 27 d of age, greater expression of L-selectin on neutrophils at 31 and 45 d of age, and greater intensity of phagocytosis at 45 d of age. Once-fed calves secreted less TNF-α in LPS-stimulated whole blood cultures at 45 d of age compared with twice-fed calves and this tended to persist through the immediate postweaning period. None of the other immune parameters differed after weaning between the preweaning feeding strategies. Consolidating calf milk replacer into one feeding during the fourth week of life was likely a mild and acute stressor, as evidenced by transient neutrophilia in the absence of suppressed functional capacities of neutrophils. Future research should address the mechanism and immunological significance of the persistent decreased TNF-α response in once-fed calves.

Effect of maternal restraint stress during gestation on temporal lipopolysaccharide-induced neuroendocrine and immune responses of progeny

Forty-two sows were used to determine the effects of adding a Saccharomyces cerevisiae fermentation product (SCFP) to the gestation and lactation diets on the performance of sows and their progeny. At 5 d before breeding, sows were allotted to 2 dietary treatments representing 1) sows fed a diet with 12.0 g of fermentation product/d through gestation and 15.0 g of fermentation product/d through lactation (SCFP treatment, n=22), and 2) sows fed a diet with equal amounts of a mixture of corn and soybean meal instead of the SCFP (CON treatment, n=20). Sow BW and backfat thickness were recorded. Blood was collected from sows, as well as piglets, for the measurement of cell numbers, plasma urea nitrogen (PUN), and IgG. Fecal samples from d 7 to 9 of lactation were collected to determine apparent total tract nutrient digestibility. The composition of colostrum and milk was also measured. No difference (P > 0.10) in reproductive performance was observed between treatments. However, sows in the SCFP treatment tended to have increased total litter weaning weight (P=0.068) and litter BW gain (P=0.084) compared with sows in the CON treatment. Neutrophil count was decreased (P < 0.05) by adding the fermentation product on d 110 of gestation and d 17 of lactation, whereas a decreased (P < 0.05) white blood cell count was observed only on d 110 of gestation. Concentration of PUN tended to be greater (P=0.069) for sows in the CON treatment compared with sows in the SCFP treatment on d 110 of gestation. Apparent total tract nutrient digestibility values of ash, CP, DM, and ether extract were not affected (P > 0.10) by adding the fermentation product. Protein and fat contents in colostrum and milk did not differ (P > 0.10) between treatments. Colostrum from sows in the SCFP treatment contained a greater (P < 0.05) amount of ash than colostrum from sows in the CON treatment. Immunoglobulin G measured in the colostrum, milk, and plasma of piglets did not differ (P > 0.10) between sows in the CON and SCFP treatments. This study indicates that adding the SCFP in the gestation and lactation diets has the potential to 1) improve litter BW gain during lactation, possibly by improving maternal protein utilization, as shown in a tendency to reduce PUN; 2) improve the maternal health status, as shown by the reduced neutrophil cell count; and 3) increase milk production, as shown in a tendency to improve litter BW gain without affecting nutrient composition of the colostrum and milk.