Biomedical subjects

T H Elsasser

Publications and source records attributed to T H Elsasser.

At least 37 records · Page 2Linked to original sources

PubMed2000

Design and application of a polyclonal peptide antiserum for the universal detection of leptin protein.

An epitope-specific polyclonal antiserum was produced in rabbits immunized against a synthetic 15 amino acid peptide (QRVTGLDFIPGLHPV) derived from the coding sequence reported for the porcine leptin gene (GenBank Accession No. U59894). This peptide contains a core sequence comprised of eight amino acids (GLDFIPGL) that is totally conserved in all leptin proteins studied to date. Purified recombinant human, mouse, rat, pig, and chicken leptin proteins were separated by polyacrylamide gel electrophoresis (SDS-PAGE) and electro-blotted onto PVDF membranes. Western blots were developed employing the leptin-specific peptide antiserum with an alkaline-phosphatase-conjugated anti-rabbit IgG second antibody chromogenic system. The peptide antiserum was found to be highly specific for leptin which exhibited an estimated molecular weight of about 16 kDa for all species analyzed. The sensitivity of the Western blot assay was not sufficient to permit the direct detection of leptin in chicken serum or plasma. However, with this assay we were able to detect native leptin protein in an enriched fraction prepared from chicken plasma using a combination of gel filtration and ion exchange column chromatography. Slot blots indicated a potential application of the immunostaining technique for quantitative analysis of leptin protein. Finally, the peptide antiserum was successfully employed to localize leptin protein by immunohistochemical staining of thin sections prepared from adipose (chicken and pig) and liver (chicken) tissue samples. This study is the first to report a polyclonal peptide antiserum that apparently recognizes intact leptin protein, both native and recombinant, regardless of the species of origin.

Amino Acid Sequence↗

PubMed2000

Presence of immunoreactive adrenomedullin in human and bovine milk.

We examined by radioimmunoassay the presence of immunoreactive adrenomedullin (ir-AM) in human and bovine milk. Milk samples displaced (125)I-AM from the AM-antiserum in parallel to the standard curve. RP-HPLC revealed a main immunoreactive peak eluting as synthetic AM. Concentrations in human milk ranged between 140 and 404 pg/mL. In cow, the levels of AM were 73.5 +/- 3.8 pg/mL. Bovine milk products had AM levels similar to those found in fresh bovine milk. Human milk had growth promoting activity on the human intestinal cell line Int-407 that could be partially blocked with an anti-AM antibody.

Adrenomedullin↗

PubMed2000

Modulation of growth performance in disease: reactive nitrogen compounds and their impact on cell proteins.

During life, all animals encounter situations that challenge their capability for optimal growth. In reacting to immune challenges in the form of disease, homeostatic mechanisms attempt to overcome disharmony of the body's internal environment, or simply put, stress. The overall impact of stress revolves around a dynamic relationship between the level of challenge imparted on physiological systems and the degree of host response that is mounted in the process of detecting and reacting to the stress. In growing animals, the majority of milder stress encounters are manifest in terms of energetic inefficiencies and periods of reduced anabolism. In contrast, severe stress is often characterized by frank catabolism and tissue wasting. In some instances a level of stress (that might be termed a "stress breakpoint") is reached at which time the host response itself contributes to the cascade of negative effectors that further cause illness. These "breakpoint" responses are characterized by more intense acute responses to stress or a much more protracted duration of the response than would be expected given the nature of the stress. Key to understanding how growth in the young animal responds to infectious stresses is the recognition that (a) when immune responses that normally maintain health go awry, the reporters and effectors of the immune system (cytokines and the nitric oxide cascade) can contribute to stress disease processes and (b) reactive nitrogen compounds derived from the nitric oxide, as well as super oxide anion can modify intracellular proteins and block otherwise normal biochemical processes that regulate cell function. A key example of this is the loss of regulation of IGF-I by GH. As animals react more severely to disease stress, IGF-I concentrations in plasma decline progressively. Recent data derived from (LPS) challenges performed on young calves suggest that the prolonged decline in IGF-I is associated with the development of hepatic cytotoxicity localized to regions of protein nitration as identified by immunohistochemistry. Identifying biochemical criteria for disease processes provides needed guidance for the further development of intervention strategies to limit the impact of disease on growth.

Animals↗

PubMed2000

Effect of endotoxin challenge on hepatic 5'-deiodinase activity in cattle.

Thyroid status is compromised in a variety of acute and chronic infections and toxin-mediated disease states. Conversion of thyroxine (T4) into the metabolically active hormone, triiodothyronine (T3), is catalyzed by 5'-deiodinase (5'D). Our objective was to determine the effect of endotoxin (LPS) challenge with and without L-arginine (Arg) infusion on hepatic activity of 5'D and plasma concentrations of T4 and T3. In a 2 x 2 factorial, beef heifers (275-310 kg b.wt.) were fed low (8% CP; 6.5 kg/d) or high (14% CP; 7.2 kg/d) isocaloric protein diets (1.96 Mcal/kg DM) for 10 d before LPS challenge. L-Arginine in saline (0.5 g/kg b.wt.) or saline alone was infused i.v. throughout an 8 hr period starting 2 hr before bolus LPS injection (Escherichia coli, 055: B5; 0.2 microg/kg; i.v.). Blood samples were collected at -2, 0, 3, 6, 12, and 24 hr relative to LPS injection. Liver samples were obtained 20 hr before, and then 6 and 24 hr after LPS challenge using a biopsy needle. Plasma T4 and T3 concentrations were not affected by dietary CP or Arg. Compared with levels at 0 hr, LPS challenge decreased plasma T4 (P < 0.01) and T3 (P < 0.001), respectively, 8.4% and 28.9% at 6 hr and 19.7% and 31.3% at 24 hr. Consistent with these changes, the T3:T4 ratio was lower than that at 0 hr (P < 0.001) 22.0% at 6 hr and 13.5% at 24 hr. Hepatic 5'D activities 20 hr before LPS injection were 2.80 +/- 0.11 nmol I- x hr(-1) x mg protein(-1) and decreased 24 hr after LPS, respectively, 45.4% (P < 0.01) and 17.6% (P < 0.05) in saline- and Arg-infused heifers. The results indicate that mild LPS challenge in cattle inhibits hepatic generation of T3 and decreases plasma concentrations of thyroid hormones. The data also suggest that the impact of LPS on 5'D activity in liver can be altered by Arg supplementation.

Animals↗

PubMed2000

Anti-inflammatory effects of ergotamine in steers.

The objective of this experiment was to investigate whether the ergot alkaloid, ergotamine (ET), an alkaloid used to model fescue toxicosis in cattle, modifies the response of cattle to endotoxin (LPS) challenge. Steers (n = 16) were divided into the following treatment groups: control (C), ergotamine (ET), endotoxin (LPS), and ET + LPS. ET and ET + LPS groups received a single bolus intravenous injection of ET (40 microg. kg. body wt(-1)), whereas C and LPS steers received a single bolus injection of sterile vehicle. Thirty minutes after ET/vehicle administration, a single bolus intravenous injection of LPS (0.2 microg. kg. body wt(-1)) was given. Blood was collected at various time points for 48 hr post. Endotoxin increased rectal temperature (RT) and the circulating levels of tumor necrosis factor-alpha (TNF-alpha), cortisol, haptoglobin (Hp), thromboxane B(2) (TXB(2)). The circulating Hp, TNF-alpha, and TXB(2) increases were blunted by pretreatment with ET compared with ET + LPS. Ergotamine by itself increased circulating cortisol and RT, whereas it decreased serum prolactin (PRL). Therefore, whereas administration of LPS at 0.2 microg/kg to steers resulted in an expected response, the combination of ET + LPS attenuated major effects of LPS alone. Thus, acute administration of ET appeared to be anti-inflammatory as it decreased the inflammatory response to LPS, an effect likely driven at least in part by the ET-caused cortisol increase.

Animal Feed↗

PubMed2000

Performance and carcass merit of growing beef steers with chlortetracycline-modified sensitivity to pituitary releasing hormones and fed two dietary protein levels.

This paper reports the effects of reduced sensitivity to growth hormone-releasing hormone and thyrotropin-releasing hormone through feeding a subtherapeutic level of chlortetracycline (CTC; 350 mg CTC/d) and two levels of dietary CP (10% and 13% of diet DM) on growth performance and carcass merit characteristics. Thirty-two steers (initial average BW, 286 kg) were adapted to a common 13% CP diet consisting primarily of grass hay, corn, and soybean meal fed to gain 1.25 kg/d. The steers were assigned to four treatments (with or without CTC and 10% or 13% dietary CP in a factorial arrangement) and fed ad libitum amounts of diet for 91 d. Feed intake was determined daily and steers were weighed weekly. Steers were killed at the end of the feeding period for carcass merit determinations. Efficiency of BW gain was greater (P < .05) for steers fed the 13% CP diet than for the 10% CP diet and tended to be less for CTC-steers when the 10% CP diet was fed and greater for the CTC-steers when the 13% CP diet was fed (CTC x dietary CP interaction, P < .10). Feeding CTC increased (P < .01) fat over the longissimus muscle and marbling. This study is interpreted to indicate that the sustained effect of subtherapeutic feeding of CTC to cattle appears to increase fat deposition consistent with a reduced growth hormone and thyroid status reported earlier for these same steers. This would tend to increase energy utilization but may not necessarily produce a measurable increase in BW gain.

Administration, Oral↗

PubMed1999

Is adrenomedullin a causal agent in some cases of type 2 diabetes?

The study of two populations with a recent onset of type 2 diabetes showed that a subset of the patients had higher levels of adrenomedullin (AM) than the rest of the diabetics. In this subset, physiological elevations of AM might have triggered the disease in predisposed individuals. Diabetics showed higher levels of AM than healthy controls. In addition, glycemia was measured in diabetic rats after injection of saline, AM, or antiAM antibody. AM elevated glycemia, whereas the antibody reduced circulating glucose to normal. These results suggest that manipulation of AM levels could represent a new approach in the management of diabetes for the appropriate individuals.

Adolescent↗

PubMed1999

A novel phenotype for Lardon dwarfism in miniature Bos indicus cattle suggests that the expression of growth hormone receptor 1A in liver is required for normal growth.

Mutations within the growth hormone receptor (GHR) gene that lead to an inactivated or truncated GHR protein cause abnormal growth and small adult size in a variety of species (Laron dwarfism). We studied a line of miniature Bos indicus cattle that have phenotypic (small mature size) and endocrine (increased blood growth hormone and decreased blood insulin-like growth factor-I concentrations) similarities to Laron dwarfs. Liver mRNA from miniature and control cattle was used to amplify a cDNA within the coding region of the GHR. The miniature cattle had GHR mRNA size (determined by Northern blot) and cDNA sequence that were similar to control cattle and, therefore, were unlike most Laron dwarf genotypes in which the GHR gene is mutated. Amounts of mRNA from liver as well as muscle (superficial neck and longissimus) were analyzed by ribonuclease protection assay for IGF-I, total GHR, GHR 1A (inducible, liver-specific GHR mRNA), and GHR 1B (constitutive GHR mRNA). Four control and five miniature bulls were tested. As expected, liver IGF-I mRNA was decreased in the miniature cattle (approximately 12% of control; P < 0.01). The amount of the total GHR as well as GHR 1A mRNA were also decreased in liver (17% and 19% of control, respectively; P < 0.01). Other GHR mRNA, including GHR 1B mRNA, were similar for miniature and control cattle. In muscle, there was a tendency (P < 0.10) for decreased IGF-I mRNA and increased GHR mRNA in miniature compared with control cattle. In summary, a novel phenotype for Laron dwarfism in Bos indicus cattle was associated with underexpression of GHR 1A mRNA, but not other GHR mRNA variants in liver. In addition to decreased GHR 1A mRNA, the miniature cattle had decreased liver IGF-I mRNA. Full expression of GHR 1A in liver, therefore, may be required for full liver IGF-I expression and normal growth.

Animals↗

PubMed1999

Adrenomedullin binding protein in the plasma of multiple species: characterization by radioligand blotting.

Frequently, peptide hormones circulate in plasma associated with specific binding proteins that modify the clearance and biochemical activities of the peptide. Our experimental approach was to use 125I-ligand blotting procedures to probe for the presence of specific adrenomedullin (AM) binding proteins (AMBPs). Plasma proteins from chick, calf, dog, goat, guinea pig, human, mouse, pig, rabbit and sheep blood were separated electrophoretically in 10% nonreducing SDS-polyacrylamide gels and transferred to nitrocellulose. Nonspecific binding of tracer was blocked on the nitrocellulose with a hydrolyzed casein matrix. Blots were probed with synthetic human 125I-AM. Autoradiogram scanning of blots revealed a mixture of 140- and/or 120- kD protein complexes that bound 125I-AM in all species tested. Binding of the ligand was specific as judged by a linear competitive displacement of the tracer binding from human, bovine and pig plasma AMBP bands with increasing concentrations of nonlabelled AM in the binding buffer. A series of peptide fragments of AM representing amino- and carboxyterminal regions of the hormone, or amylin, calcitonin gene-related peptide (CGRP), or insulin failed to displace intact 125I-AM from ligand blot bands. Bovine plasma proteins from healthy and parasitized calves with an infection-related stunting syndrome were separated electrophoretically, transferred to nitrocellulose and probed with 125I-AM; phosphoimage densitometry analysis revealed a 67% decrease in AMBP band intensity in the 120 and 140 kD proteins from infected calves. We conclude that a specific binding protein(s) for AM exists in mammalian and avian blood that might impact on the bioactivity and function of AM in health and disease.

Adrenomedullin↗

PubMed1999

Underlying disease stress augments plasma and tissue adrenomedullin (AM) responses to endotoxin: colocalized increases in AM and inducible nitric oxide synthase within pancreatic islets.

Rapid onset metabolic impairments accompany the initiation of the acute phase response to many disease stresses, whereas more chronic metabolic perturbations may prolong the recovery period. In the present experiment the application of a mild endotoxin challenge [lipopolysaccharide (LPS)] alone or additive to a chronic subclinical parasitic infection (Sarcocystis cruzi; LPS + PI) in calves was used as a model to investigate and define a dynamic axis coordinated between adrenomedullin (AM) and nitric oxide in response to immune challenge. Plasma AM and NO2/NO3 concentration responses after LPS (0.45 microg/kg, iv) were rapid in onset and of higher magnitude and longer duration in PI + LPS calves than in those challenged with LPS alone. The post-LPS increase in plasma insulin was significantly greater in PI + LPS than in LPS; following refeeding of calves, insulin secretion was most blunted in PI + LPS calves, consistent with the inhibitory effects of NO and AM on insulin secretion. A more chronic response to the immune challenge (organ specific) was in evidence in tissues harvested 24 h after LPS challenge. Where lung and liver showed no immunostaining for inducible nitric oxide (iNOS), iNOS immunostaining was present in the pancreas, localized to islets only. The percentages of iNOS-immunopositive cells in islets were 1.7%, 21%, 6.7%, and 24% for control (C; saline infused), PI, LPS, and PI + LPS calves, respectively. AM immunostaining was not evident in the liver and was present, but not differentially affected by treatment, in airway epithelium in the lung. The number of islet cells with positive immunostaining for AM was increased in LPS, PI, and PI + LPS calves. The percentages ofAM-immunopositive cells in islets were 8%, 27%, 20%, and 33% for C, PI, LPS, and PI + LPS, respectively. Immunostaining for AM and iNOS was colocalized with cells positive for pancreatic polypeptide. By triple label confocal fluorescence immunocytochemistry, colocalization of intense AM and iNOS immunostaining was confirmed in peripheral islet cells. A weaker, more diffuse iNOS signal was also apparent in insulin-containing cells in PI + LPS. We conclude that chronic low level infection potentiates the severity of metabolic perturbations that arise with additive sudden onset immune challenge, as can occur with bacterial toxins. These metabolic disturbances are reflected in and possibly mediated by early onset increases in plasma tumor necrosis factor-alpha, insulin, and AM and up-regulated iNOS activity. These acute complications rapidly progress into a more chronic state characterized by diminished insulin response to feeding stimulus and colocalized increases in pancreatic islet AM and iNOS. The pancreatic responses in AM and iNOS may play a major role in mediating prolonged disturbances in nutrient use by tissues through their influences on temporal patterns of pancreatic hormone secretion during chronic illness.

Adrenomedullin↗

PubMed1999

Neuropeptide Y restores appetite and alters concentrations of GH after central administration to endotoxic sheep.

The objective of this study was to determine whether neuropeptide Y (NPY) and recombinant human interleukin-1 receptor antagonist (IL-1ra) would: first, increase food intake; secondly, decrease concentrations of GH; thirdly, reduce GHRH-induced release of GH; and fourthly, reduce changes to concentrations of IGF-I in plasma during experimental endotoxemia in sheep. Six treatments were given to six castrated male sheep in a 6x6 Latin square treatment order. Osmotic mini-pumps were implanted at 0 h and a jugular vein was cannulated. Each sheep was continuously infused with saline (0.9%) or lipopolysaccharide (LPS) (20 micrograms/kg per 24 h, s.c.) at 10 microliters/h for 72 h via the osmotic mini-pumps. Blood samples (3 ml) were collected at 15-min intervals from 24 to 33 h. At 26 h, one of three treatments (artificial cerebrospinal fluid, NPY or IL-1ra) was injected i.c.v. within 30 s (0.3 microgram/kg), then infused i.c.v. from 26 to 33 h (600 microliters/h) at 0.3 microgram/kg per h. GHRH was injected i.v. (0.075 microgram/kg) at 32 h after which blood samples were collected at 5, 10, 15, 30, 45 and 60 min. Feed intake was reduced up to 50% for 48 h in LPS-treated compared with non-LPS-treated sheep. NPY restored feed intake in LPS-treated sheep and induced hyperphagia in non-LPS-treated sheep from 24 to 48 h. In contrast, IL-1ra did not affect appetite. Injection of NPY increased concentrations of GH from 26 to 27 h, while IL-1ra had no effect. Infusion of NPY suppressed GHRH-induced release of GH. However, no treatment altered pulse secretion parameters of GH. Concentrations of IGF-I were 20% higher at 72 h in LPS-treated sheep given NPY than in sheep treated with LPS alone, and this may reflect increased appetite from 24 to 48 h. We concluded that reduced appetite during endotoxemia is due to down-regulation of an NPY-mediated mechanism. Furthermore, NPY stimulates release of GH in healthy sheep, does not reduce pulse secretion parameters of GH, but does suppress GHRH-induced release of GH in endotoxic sheep. Therefore, NPY may be an important neurotransmitter linking appetite with regulation of GH during endotoxemic and healthy states in sheep.

Animals↗

PubMed1999

Increased responsiveness to intravenous lipopolysaccharide challenge in steers grazing endophyte-infected tall fescue compared with steers grazing endophyte-free tall fescue.

Fescue toxicosis in cattle occurs as a result of consumption of ergot alkaloids in endophyte-infected (E+, Neotyphodium coenophialum) tall fescue (Festuca arundinacea). The condition is characterized by pyrexia, decreased weight gains, rough hair coats, and decreased calving rates. The objective of this experiment was to investigate whether steers grazing E+ fescue have altered host response to lipopolysaccharide (endotoxin, LPS) challenge compared with steers grazing endophyte-free (E-) fescue. Angus steers (n=8) had continuously grazed either E+ (n=4) or E- (n=4) tall fescue grass for 8 months prior to the experiment. The E+ steers had lower body weight, depressed average daily gain, and decreased basal serum prolactin compared with the E- steers prior to LPS administration. Each steer received a single bolus i.v. injection of LPS (0.2 microgram/kg body weight; Escherichia coli; 026:B6) dissolved in sterile saline, and blood was serially collected every 30 min for 4 h and at 24 h post LPS administration. LPS increased serum tumor necrosis factor-alpha (TNF-alpha), cortisol, and haptoglobin but decreased plasma glucose and IGF-I. Importantly, however, TNF-alpha, cortisol, and IGF-I responses to LPS were greater in E+ compared with E- steers. These results indicated that animals grazing E+ fescue had altered integrated metabolic host response compared with animals grazing E- fescue. Potentially, combined exposure to E+ fescue and a bacterial LPS could have greater deleterious effects on the animal compared with exposure to only one of the two and would likely lead to increased catabolism.

Animals↗

PubMed1999

Responses to an estrogenic growth promoter in beef steers fed varying nutritional regimens.

We investigated the influence of DM and(or) energy intake and dietary CP levels on the performance and nitrogen (N) retention of beef steers with and without growth promoter implants. In Exp. 1, four implanted (Synovex-S, 200 mg of progesterone plus 20 mg of estradiol benzoate) Angus steers and four Angus steers that were not implanted were assigned to concurrent 4 x 4 Latin squares. Initial BW averaged 296 kg. Each square consisted of moderate and moderately high DM intake treatments (4 and 6 kg/d) and low and adequate CP intake treatments (450 and 600 g/d) in a 2 x 2 factorial arrangement. Periods were 2 wk of adaptation, 5 wk of growth, and 1 wk of balance collection. Experiment 2 consisted of two replicates of 32 Hereford steers each (initial BW 324 kg). Each replicate was a 4 x 2 factorial in which steers were individually fed for 63 d. All steers had ad libitum access to a 60% corn-based concentrate diet containing either 7.9, 10.0, 12.1, or 14.6% CP (DM basis), and steers were either implanted or not implanted with Synovex-S. Experiment 3 was similar to Exp. 2 except that all steers (initial BW 315 kg) received a low-protein diet (7.6% CP) with calculated energy densities of either 1.86, 2.04, 2.22, or 2.42 Mcal ME/kg DM, and steers were limited to an equalized DM intake of 9.5 kg daily. In Exp. 1, gains for the low CP, moderate and moderately high DM intakes and the adequate CP, moderate and moderately high DM intakes were 240, 555, 208, and 730 g/d, respectively, for steers not implanted and 333, 643, 488, and 988 g/d, respectively, for implanted steers (SEM = 102 g/d). Respective values for retained N were .13, .18, .16, and .26 g/kg BW.75 and .13, .15, .22, and .29 g/kg BW.75 (SEM = .04 g/kg BW.75). Implant response was greater (CP x implant, P < .01) for both gain and retained N when adequate CP compared to low CP diets were fed. For Exp. 2, the lowest CP diet reduced ADG (.97 vs 1.27 kg/d) and efficiency of gain (100 vs 120 g gain/kg DM). Synovex-S was less effective in improving efficiency for the lowest protein diet than for the other diets (11.7 vs 20.2%). During Exp. 3, neither Synovex-S nor dietary energy influenced gain and efficiency. We concluded that adequate dietary protein is necessary to optimize the response to estrogenic growth promoters and that the low response under inadequate protein and energy intake is not improved by increasing the energy density of the diet.

Animal Nutritional Physiological Phenomena↗

PubMed1999

Performance and digestibilities of beef cattle fed diets supplemented with either soybean meal or roasted soybeans and implanted with Synovex.

Two 160-d feedlot experiments, each consisting of 20 Angus-Hereford steers (216 +/- 5 kg BW, Exp. 1; 258 +/- 5 kg BW, Exp. 2) and 20 Angus-Hereford heifers (208 +/- 5 kg BW, Exp. 1; 236 +/- 5 kg BW, Exp. 2), were used to investigate the effects of supplementing diets with either roasted soybeans (RSB, roasted at 127 degrees C for 10 min) or soybean meal (SBM) and implanting or not implanting with an estrogenic growth promoter (SYN; Synovex-S, 20 mg of estradiol benzoate plus 200 mg of progesterone or Synovex-H, 20 mg of estradiol benzoate plus 200 mg of testosterone) on performance. The cattle were fed a basal diet of 15% orchardgrass silage, 15% corn silage, and 70% corn-based concentrate. Treatments were 1) no SYN and fed a SBM-supplemented diet, 2) no SYN and fed a RSB-supplemented diet, 3) SYN and SBM, and 4) SYN and RSB. Cattle in the SYN groups were reimplanted at 80 d. Four additional Angus-Hereford steers were used in a digestion and nitrogen balance experiment conducted during the first half of Exp. 1. For the total 160-d feedlot experiments, DMI for RSB compared with SBM was lower (P < .01; 8.5 vs 9.2 kg/d, SEM = .07) and ADG/DMI tended to be higher (P < .10; 165 vs 157 g/kg, SEM = 1.3). Final BW of steers fed RSB was similar (P > .10) to that of steers fed SBM (473 vs 478 kg, SEM = 5.6), as was ADG (1.39 vs 1.43 kg/d, SEM = .02). Dry matter intake for SYN-implanted steers was higher (P < .01) than for steers not implanted (9.2 vs 8.5 kg/d). Likewise, final BW (491 vs 460 kg) and ADG (1.49 vs 1.33 kg/d) were higher (P < .01), and ADG/DMI (166 vs 157 g/kg) tended to be higher (P < .10), for SYN-implanted steers than for steers not implanted. During the more rapid muscle growth period (0 to 80 d), DMI for RSB compared with SBM was lower (P < .01; 7.8 vs 8.6 kg/d, SEM = .07) and ADG/DMI was similar (P > .10; 181 vs 172 g/kg, SEM = 1.8). Dry matter intake for SYN-implanted steers was higher (P < .05) than for steers not implanted (8.4 vs 8.0 kg/d), as was ADG/DMI (P < .01, 182 vs 171 g/kg). During this more rapid growth period, the supplement x implant interaction for ADG was significant (P < .05; 1.35, 1.36, 1.59, and 1.44 kg/d for Treatments 1, 2, 3, and 4, respectively, SEM = .04). There were no differences in digestibilities or N balance. The results suggest that there is no improvement in performance under feedlot conditions when RSB replaces SBM in the diet of beef cattle, and, in young cattle, RSB may reduce the response expected by an estrogenic growth promoter.

Animal Feed↗

PubMed1999

The effect of roasted soybeans in the diet of feedlot steers and Synovex-S ear implants on carcass characteristics and estimated composition.

Beef steer carcasses from three 2 x 2 factorial feeding experiments (Exp. 1, 20 carcasses; Exp. 2 and 3, 19 carcasses each) were evaluated to study the influence of supplementing with roasted soybeans (RSB; 127 degrees C for 10 min) vs soybean meal (SBM) and implanting with the estrogenic growth promoter Synovex-S (SYN, 20 mg estradiol benzoate and 200 mg progesterone) on carcass merit, composition of dissected 9-10-11th rib section, estimated edible carcass composition, and cooking characteristics of strip loin steaks. In all experiments, steers were fed diets consisting of 15% corn silage, 15% orchardgrass silage, and 70% corn-based concentrate. There were no treatment interactions found in this study. Final BW averaged 480.4, 498.5, and 500.7 kg for Exp. 1, 2, and 3, respectively, and hot carcass weights averaged 288.4, 296.4, and 309.1 kg. Across experiments, hot carcass weight was 8.3 kg less (P < .03) for RSB steers than for SBM steers. Fat weight (P < .01) and percentage of fat (P < .01) were less and percentage of bone (P < .04) was greater in the 9-10-11th rib section of RSB steers than of SBM steers. Estimated percentage of fat (P < .02) was less and percentage of bone (P < .04) was greater in edible carcass of RSB steers than in that of SBM steers. Total 9-10-11th rib section weight tended to be less for RSB steers (P < .08) than for SBM steers. Carcass merit measurements were not affected (P > .10) by supplement, but numerically the percentage of kidney, pelvic, and heart fat was 11% greater for RSB steers than for SBM steers in Exp. 2 and 3. Final BW and carcass weight were 38.7 and 22.6 kg greater (P < .01), respectively, for SYN-implanted steers than for steers not implanted. Longissimus muscle area was greater (P < .01), percentage of kidney, pelvic, and heart fat (P < .02) was less, USDA quality grade tended to be less (P < .09), and shear force of strip loin was greater (P < .01) for SYN-implanted steers than for steers not implanted. The 9-10-11th rib section and estimated carcass compositions were not different (P > .10) between SYN-implanted steers and steers not implanted but reflected a somewhat leaner carcass. The authors conclude from this study that in feedlot steers, either implanted or not implanted, there is no benefit from supplementing with RSB in place of SBM, and that the use of RSB in place of SBM in feedlot diets may reduce the amount of edible carcass.

Adipose Tissue↗

PubMed1999

Effects of oral chlortetracycline and dietary protein level on plasma concentrations of growth hormone and thyroid hormones in beef steers before and after challenge with a combination of thyrotropin-releasing hormone and growth hormone-releasing hormone.

The objective of this study was to determine the effect of a subtherapeutic level of chlortetracycline (CTC) fed to growing beef steers under conditions of limited and adequate dietary protein on plasma concentrations of GH, thyroid-stimulating hormone (TSH), and thyroid hormones before and after an injection of thyrotropin-releasing hormone (TRH) + GHRH. Young beef steers (n = 32; average BW = 285 kg) were assigned to a 2x2 factorial arrangement of treatments of either a 10 or 13% crude protein diet (70% concentrate, 15% wheat straw, and 15% cottonseed hulls) and either a corn meal carrier or carrier + 350 mg of CTC daily top dressed on the diet. Steers were fed ad libitum amounts of diet for 56 d, and a jugular catheter was then placed in each steer in four groups (two steers from each treatment combination per group) during four consecutive days (one group per day). Each steer was injected via the jugular catheter with 1.0 microg/kg BW TRH + .1 microg/kg BW GHRH in 10 mL of saline at 0800. Blood samples were collected at -30, -15, 0, 5, 10, 15, 20, 30, 45, 60, 120, 240, and 360 min after releasing hormone injection. Plasma samples were analyzed for GH, TSH, thyroxine (T4), and triiodothyronine (T3). After 84 d on trial, the steers were slaughtered and the pituitary and samples of liver were collected and analyzed for 5'-deiodinase activity. Feeding CTC attenuated the GH response to releasing hormone challenge by 26% for both area under the response curve (P<.03) and peak response (P<.10). Likewise, CTC attenuated the TSH response to releasing hormone challenge for area under the response curve by 16% (P<.10) and peak response by 33% (P<.02), and attenuated the T4 response for area under the curve by 12% (P<.08) and peak response by 14% (P<.04). Type II deiodinase activity in the pituitary was 36% less (P<.02) in CTC-fed steers than in steers not fed CTC. The results of this study are interpreted to suggest that feeding subtherapeutic levels of CTC to young growing beef cattle attenuates the release of GH and TSH in response to pituitary releasing hormones, suggesting a mechanism by which CTC may influence tissue deposition in cattle.

Animal Nutritional Physiological Phenomena↗

PubMed1999

Field method for monitoring blood glucose in beef cattle.

The purpose of this study was to determine the applicability of the Accu-Chek Easy (ACE) human self-monitoring system for monitoring glycemic status in cattle. The ACE method was compared with the Yellow Springs Instrument (YSI) analytical laboratory method in two studies. A preliminary study (62 samples) and a primary study (434 samples) involved a nine-fold range and a 10-fold range, respectively, of glucose concentrations obtained during the acute phase response of growing beef cattle to injections of varying dosages of endotoxin. The ACE monitoring method compared with the YSI analytical method resulted in similar patterns of glucose concentration change, similar ranking of glucose means across endotoxin dosages during hyper-and hypoglycemia, and a close relationship between paired YSI and ACE concentrations from common samples. The ACE method identified all nine animals that displayed hypoglycemic distress during the acute phase response to endotoxin injection. The relationship between the YSI analytical method and the ACE monitoring method was found to be nonlinear (YSI = -38.2+13.6.ACE.50; R2 = .99; Sy.x = 7.3 mg/dL), and the use of this equation to predict YSI values from ACE values in an independent data set resulted in linearity when YSI was regressed on the predicted YSI values (YSI = -.78+1.00. Predicted YSI; R2 = .87; Sy.x = 6.9 mg/dL). Even though variation seemed greater for ACE than for YSI, we concluded that a system developed for human self-monitoring of blood glucose, such as the ACE, can be used to monitor the glycemic status of cattle.

Animals↗

PubMed1998

Changes in somatotropic axis response and body composition during growth hormone administration in progressive cachectic parasitism.

A multistage protozoan parasitic disease was used as a cachexia model to study the effects of daily administration of bovine growth hormone (GH) on endocrine and body composition changes of young calves from the onset of the acute phase response (APR). Male calves averaging 127.5 +/- 2.0 kg body weight were assigned to control, ad libitum fed, noninfected (C); ad libitum fed, infected (250,000 oocysts Sarcocystis cruzi, per os, I); noninfected, pair-fed (PF) to matched I-treatment calves and these respective same treatments in calves injected daily with GH (USDA-bGH-B1), 12.5 mg/calf/day, im) designated as CGH, IGH and PFGH. GH injections were initiated on Day 20 postinfection (PI), 3 to 4 d before the onset of clinical signs of APR, and continued to Day 56 PI, at which time animals were euthanized for tissue collections. Abrupt increases in rectal temperature commensurate with up to 70% reduction in voluntary feed intake were observed in I and IGH beginning 23-25 d PI. For the trial period between Days 20 and 56 PI, average daily carcass protein gains were 123, 52, 109, 124, 48, and 67 g/d and average daily carcass fat gains were 85, 11, 43, 71, -23, and 29 g/d for C, I, PF, CGH, IGH, and PFGH, respectively. Effects of GH were significant for fat accretion and plasma urea depression. Rectus femoris was highly refractory to catabolic effects of infection while psoas major was significantly catabolized during infection. Plasma concentrations of insulin-like growth factor-I (IGF-I) increased significantly in all GH-treated calves between Day 20 and 23 PI. Plasma IGF-I declined well below Day 20 values in all infected calves from the onset of the APR through the end of the study. The decrease in plasma IGF-I concentrations in I and IG was highly correlated with the magnitude of the fever response. Hepatic mRNA for GH receptor and IGF-I was decreased in infected calves. Hepatic microsomal membrane binding of 125I-GH did not differ between groups. The data suggest that effects of GH and parasitism on tissue metabolism during disease may vary among different specific tissue pools. The data demonstrate that daily GH administration in young calves does not prevent lean tissue losses and may accelerate fat depletion associated with cachectic parasitism. Furthermore, the onset of APR overrode the capacity for GH to maintain elevated plasma concentrations of IGF-I, an effect not readily explained through changes of GH-receptor binding.

Acute-Phase Reaction↗