首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 250 毫秒
1.
Crossbred calves (n = 572; initial BW = 186 +/- 27 kg) purchased from northern Texas, Arkansas, and southeast Oklahoma auction markets were delivered to the Willard Sparks Beef Research Center, Stillwater, OK, and used to study the effects of dietary energy and starch concentrations on performance and health of newly received feedlot calves during a 42-d receiving period. On arrival, calves were assigned randomly to one of two dietary energy levels (0.85 or 1.07 Mcal NEg/kg DM) and one of two dietary starch levels (34 or 48% of ME from starch) in a 2 x 2 factorial arrangement of treatments. Cattle were weighed and serum samples were collected on d 0, 7, 14, 28, and 42. Individual animal records of morbidity were kept for all cases of respiratory and other disease. Nasal swabs were collected from each morbid animal and cultured for upper-respiratory pathogens. There were no energy x starch level interactions for performance or health response variables. Daily gain (1.14 kg/d) and gain efficiency (ADG:DMI = 0.179) were not affected by increasing dietary energy or starch concentrations. Calves fed low-energy diets consumed (P < 0.05) more DM. No difference (P = 0.54) was detected in morbidity for calves fed high-energy (62.4% calves treated) compared with low-energy (65.8% calves treated) diets; however, calves fed the high-starch diets had numerically (P = 0.11) greater morbidity than calves fed low-starch diets (68.8 vs. 59.4% calves treated, respectively). There were no energy or starch effects on Mannheimia haemolytica or Pasteurella multocida antibody titers; however, day effects (P < 0.02) occurred. On d 7, 14, and 28, calves had antibody titers for P. multocida that were greater (P < 0.05) than titers on d 0. In addition, calves had greater antibody titers to M. haemolytica on d 7 and 14 than on d 0. Nasal swabs revealed that calves fed the high-energy diets tended (P = 0.06) to have a lower percentage of morbid calves with P. multocida during the first antimicrobial treatment and a lower percentage of Haemophilus somnus isolates during the first (P = 0.01) and second (P = 0.06) antimicrobial treatments than calves fed the low-energy diets. Although animal performance was not influenced, the present data suggest that feeding the high-energy diet decreased the percentage of P. multocida and H. somnus pathogens in calves that received one or more antimicrobial treatments.  相似文献   

2.
Lecithin:cholesterol acyltransferase (LCAT), the enzyme responsible for esterification of cholesterol in plasma, is reported to be implicated in the regulation of inflammation in laboratory animals. The purpose of the present study was to elucidate the possible relevance of LCAT in the pathogenesis of calf pneumonia induced by inoculations of Pasteurella haemolytica and bovine herpes virus-1 into the calf lung. Serum LCAT activity was significantly (P < 0.01) reduced in calves inoculated with Pasteurella haemolytica. The concentration of cholesteryl esters (CE), the product of the LCAT reaction, was also decreased in the inoculated group. Decreases in LCAT activity and the CE concentration were similarly observed in calves in which bovine herpes virus-1 was inoculated. In both bacteria- and virus-inoculated calves, CE concentrations in the high-density lipoprotein fractions were distinctly decreased, whereas those in the low-density lipoprotein fractions were practically unaltered. The acute-phase proteins haptoglobin and serum amyloid A were detected in sera from the bacteria- and virus-inoculated calves; however, the two acute-phase proteins were also found in sera from the control calves. These results suggest that decreases in LCAT activity and the CE concentration are involved in the pathogenesis of pneumonia induced by inoculation of calves with Pasteurella haemolytica and bovine herpes virus-1, and also that the change in the LCAT system is more intimately related to the occurrence of calf pneumonia than the induction of acute-phase proteins such as haptoglobin.  相似文献   

3.
The objective of this study was to investigate the effect of transportation and commingling on measures of the acute-phase protein response in newly weaned beef calves. Thirty-two (Exp. 1; average BW = 266 +/- 20.8 kg) and thirty-six (Exp. 2; average BW = 222 +/- 34.6 kg) Brahman-crossbred calves were randomly allotted to one of four treatments (2 x 2 factorial arrangement [transportation x commingling] in a completely randomized design). Body weight and jugular blood were collected at weaning, after shipment, and 1, 3, and 7 d after transport for Exp. 1, and at weaning and 1, 5, 9, 13, 17, and 21 d after transport for Exp. 2. Feed intake within pen was recorded daily for Exp. 2. Plasma fibrinogen, ceruloplasmin, haptoglobin, and cortisol concentrations were determined for all collection times. Additionally, serum amyloid-A and alpha-acid glycoprotein concentrations were determined in Exp. 1 and 2, respectively. In Exp. 2, commingled calves tended (P = 0.13) to have a higher DMI than noncommingled calves (5.3 and 4.8 kg/d, respectively). Transported calves lost more BW than nontransported calves from the time of weaning to d 1 (2.0 and 3.1% more BW loss for Exp. 1 and 2, respectively). With the exception of haptoglobin in Exp. 1, each of the acute-phase proteins measured in these studies increased over each sampling day. In Exp. 1, transported calves had higher (P < 0.05) mean serum amyloid-A concentrations than nontransported calves (48.9 vs. 33.4 microg/mL). There was a significant sampling day x transportation interaction (P < 0.01) for fibrinogen, ceruloplasmin, and haptoglobin in Exp. 1; transported calves had higher concentrations of fibrinogen following transport and on d 2 and 3, and ceruloplasmin on d 3. Haptoglobin concentrations were higher (P = 0.04) in nontransported calves on d 1 and 2 of Exp. 1. In Exp. 2, overall mean haptoglobin concentrations were higher in nontransported vs. transported calves. The results of these studies indicate that stressors associated with transportation affect the acute-phase protein response in newly weaned beef calves. More research is needed to determine whether these proteins might be valuable indicators of stress following the weaning process.  相似文献   

4.
Bovine acute phase proteins (APPs), lipopolysaccharide binding protein (LBP), serum amyloid A (SAA), haptoglobin (Hp) and alpha1-acid glycoprotein (AGP) were evaluated as inflammatory markers during an outbreak of bovine respiratory disease (BRD) caused by bovine respiratory syncytial virus (BRSV). Calves (n = 10) presented mild to moderate signs of respiratory disease. Secondary bacterial infections, Pasteurella multocida and Mycoplasma dispar as major species, were detected in tracheobronchial lavage samples. Concentrations of SAA and LBP increased at week 1 had the highest values at week 3 and decreased at week 4 of outbreak. Some calves had high Hp concentrations at week 3, but AGP concentrations did not rise during respiratory disease. Higher SAA, LBP and Hp concentrations at a later stage of BRD (week 3) were associated with the low BRSV-specific IgG1 production, suggesting that these calves had enhanced inflammatory response to the secondary bacterial infection. In conclusion, APPs (especially SAA and LBP) are sensitive markers of respiratory infection, and they may be useful to explore host response to the respiratory infections in clinical research.  相似文献   

5.
Forty crossbred steers (Brahman x English) were categorized into two groups: 1) early weaned (EW; n = 20); and 2) normal weaned (NW; n = 20). Calves were 89 and 300 d of age at the time of EW and NW, respectively; SEM = 4.4. Early-weaned calves were kept on-site (University of Florida, Ona), provided supplement (1% of BW), and grazed on annual and perennial pastures until NW. At the time of normal weaning, all calves were loaded on a commercial livestock trailer and transported to the North Carolina State University Research Feedlot in Butner (approximately 1,200 km). Upon arrival, calves were stratified by BW and randomly allotted to four pens per weaning age treatment. Individual calf BW and blood samples were collected at the time of normal weaning, on arrival at the feedlot (d 1; 24 h following weaning), and on d 3, 7, 14, 21, and 28 of the receiving period. Individual BW was collected at the start and end of the growing and finishing periods, and feed intake by pen was measured daily. As an estimate of stress during the receiving period, plasma was collected and analyzed for the acute-phase proteins, haptoglobin and ceruloplasmin. Early-weaned calves were lighter (P = 0.03) at normal weaning than NW calves (221 vs. 269 kg; SEM = 10.6). By d 28, EW calves tended (P = 0.12) to be lighter than NW calves (242 vs. 282 kg, respectively). Gain:feed was improved for EW compared with NW calves during both the receiving (G:F = 0.157 vs. 0.081) and growing (0.159 vs. 0.136) periods. There tended (P < 0.10) to be weaning age x day interactions for each acute-phase protein. Ceruloplasmin concentrations increased in NW, but not EW calves, and peaked on d 7 (27.6 and 34.2 mg/100 mL for EW and NW calves, respectively; P < 0.05). Haptoglobin concentrations increased in both groups and were greatest (P < 0.05) in NW calves on d 3 (7.63 vs. 14.86 mg of haptoglobin/hemoglobin complexing/100 mL). No differences in ADG or G:F were detected during the finishing phase; however, overall G:F was improved (P = 0.03) for EW vs. NW calves (0.155 vs. 0.136). Carcass measures, including backfat thickness, USDA yield grade, marbling score, and LM area, did not differ between treatments. These data imply that EW calves, which are maintained onsite before shipping, may be more tolerant to the stressors associated with transportation and feed yard entry. Early weaned calves, managed within the system described in this study, may have improved G:F.  相似文献   

6.
The acute phase response as indicated by serum haptoglobin and total haemolytic complement activity (CH50) was measured in 72 cross-bred steer calves purchased at sales in Ontario. During the 28 day (d) trial, 18 steers were randomly assigned to each of the following groups: 1) control; 2) vaccinated (Infectious Bovine Rhinotracheitis, Parainfluenza-3, Bovine Viral Diarrhea, Bovine Respiratory Synctial Virus vaccine plus Pasteurella haemolytica vaccine); 3) supplemental chelated Cr (0.14 mg/kg); and 4) Cr plus vaccines. Haptoglobin concentrations were low at arrival, increased (P < 0.05) on day 7, and returned to near initial levels (P > 0.05) by day 14. Supplemental Cr reduced (P < 0.05) haptoglobin on day 7 when morbidity was highest. Following antibiotic treatment for respiratory disease haptoglobin was lower (P < 0.05) than during morbidity; however, during morbidity, haptoglobin concentrations were not greater in sick calves (P > 0.05) than in healthy calves. Complement activity was lowest on day 7 (P < 0.05) and peaked on day 14 (P < 0.05). Complement activity tended to be lower on day 7 for vaccine, Cr, and Cr+ vaccine groups; however, the difference from controls was not significant (P > 0.10). Complement activity did not increase on day 14 (P > 0.05) with Cr supplementation as in other treatments. Morbid calves had lower (P < 0.05) CH50 activity than healthy calves on day 14. Following antibiotic treatment, the Cr-supplemented group had higher (P < 0.05) CH50 than during morbidity. In general, chromium supplementation reduced the acute phase response in newly arrived feeder calves.  相似文献   

7.
Using purified bovine haptoglobin (Hp) and specific antisera, a single radial immunodiffusion (SRID) assay method has been developed to measure the serum Hp level in cattle. Bovine Hp is a highly polymerized protein showing heterogeneous molecular forms in serum. After treatment with cysteine or glutathione, Hp was partially reduced to a homogeneous form, suitable for SRID assay. This method gives values comparable to those obtained by hemoglobin-binding capacity assay, and has the advantage of being simple and convenient. Although serum Hp was not detectable in healthy cattle, it was found more than 50-fold after invasive surgery, indicating that Hp is a characteristic acute-phase protein in cattle.  相似文献   

8.
The effects of feeding different types of fiber to weanling pigs on growth performance, intestinal and liver cytokine expression, circulating acute-phase proteins, and IGF-I were evaluated. Intestinal tissue abundance of DNA, protein, and phosphorylated S6 kinase were also determined. Pigs (n = 120; initially 5.2 kg and 24 d of age) were randomly assigned to diets containing 1 of 4 fiber sources: 1) control diets containing no added fiber source, 2) diets containing 7.5% distillers dried grains with solubles (DDGS), 3) diets containing 7.5% soybean hulls, or 4) diets containing 7.5% citrus pulp. The experimental diets were fed for 4 wk in 2 phases (phase 1, wk 1 and 2; phase 2, wk 3 and 4). Intestinal tissue samples, liver samples, and blood samples were collected from a subset (n = 24; 6 pigs/treatment) of the pigs on d 7, and blood samples were collected from another subset (n = 24; 6 pigs/ treatment) of pigs on d 28 of the experiment. Dietary treatment had no effect on ADG, ADFI, or G:F throughout the experiment. Likewise, pig BW variability (CV), plasma IGF-I, or the plasma concentration of the acute-phase proteins, alpha(1)-acid glycoprotein, C-reactive protein, and haptoglobin, were not affected by dietary treatment. Real-time RT-PCR analysis revealed that on d 7, pigs fed DDGS had a greater (P < 0.05) relative abundance of the mRNA encoding IL-6, IL-1beta, and IL-10 in ileum tissue than pigs fed all other diets. Diets containing DDGS had no effect on the relative abundance of tumor necrosis factor alpha or interferon-gamma mRNA in ileum tissue on d 7. The d-7 mRNA expression of cytokines was not altered in jejunum, colon, or liver tissue by dietary treatment. Intestinal tissue protein content or jejunum and ileum DNA concentrations were not affected by diet. Western blot analysis found no effect of dietary treatment on the activation of S6 kinase in jejunum, ileum, or colon tissue on d 7. These results indicate that feeding 7.5% of a fiber source as DDGS, soybean hulls, or citrus pulp does not affect growth performance or circulating markers of inflammation in weanling pigs and that feeding DDGS increases the expression of both proinflammatory and antiinflammatory cytokines in intestinal tissue.  相似文献   

9.
The study aimed to establish an experimental model to investigate the pathogenesis of lung infection by Pasteurella multocida, an important cause of bovine respiratory disease. An experimental model is required to assist the development of an effective vaccine. Sixteen 8-week-old calves were challenged intratracheally with 10(9) or 10(10) colony forming units of P. multocida in either 60 or 300 ml saline in a 2 x 2 factorial experiment. All animals became dull within 2-6h post-infection (p.i.) and two calves were killed humanely because of suspected endotoxic shock. Remaining animals showed increased respiratory rates by 15-20 h p.i. and, at 23 h p.i., calves given the high dose, high volume challenge showed higher (P < 0.05) rectal temperatures. From 24 to 36 h p.i., clinical signs decreased in a majority of animals. Plasma haptoglobin concentrations increased (P < 0.05) in calves given the high volume challenge irrespective of the number of bacteria. At post-mortem examination (4d p.i.), lung lesions, mainly in the apical lobes, were found in all calves. Histopathological examination showed areas of purulent pneumonia with a tendency to abscessation and inflamed interlobular septa characterised by accumulation of neutrophils and oedema. The clinical and pathological responses described were typical of bovine pneumonic pasteurellosis.  相似文献   

10.
The study objective was to determine health and performance of ranch calves from different preconditioning strategies during a 42-d receiving period when commingled with calves of unknown health histories from multiple sources. Steer calves from a single source ranch (RANCH) were weaned and immediately shipped to a feedlot (WEAN, initial BW = 247 +/- 29 kg); weaned on the ranch for 45 d before shipping, but did not receive any vaccinations (WEAN45, initial BW = 231 +/- 26 kg); or weaned, vaccinated with modified live viral vaccine, and held on the ranch for 45 d before shipping (WEANVAC45, initial BW = 274 +/- 21 kg). Multiple-source steers were purchased through auction markets (MARKET, initial BW = 238 +/- 13 kg), and upon receiving, a portion of ranch-origin steers from each weaning group was commingled with a portion of MARKET cattle (COMM). The experimental design was completely randomized with a 2 x 3 +1 factorial arrangement of treatments. Factors were RANCH vs. COMM and weaning management (WEAN vs. WEAN45 vs. WEANVAC45) as the factors; MARKET cattle served as the control. Calves of WEAN, WEAN45, and MARKET were vaccinated on arrival at the feedlot. Ranch-origin calves tended (P = 0.06) to have greater ADG than COMM or MARKET calves, although ADG was not affected (P = 0.46) by weaning management. Across the 42-d receiving period, DMI was not affected (P = 0.85) by cattle origin. However, MARKET, WEAN45, and WEANVAC45 calves consumed more (P < 0.001) DM than WEAN calves. Gain efficiency was not affected (P > or = 0.11) by treatment. Ranch-origin calves were less (P < 0.001) likely to be treated for bovine respiratory disease than MARKET calves; COMM calves were intermediate. Calves that were retained on the ranch after weaning (WEAN45 and WEANVAC45) were also less likely to be treated (P = 0.001) than MARKET or WEAN calves. As expected, differences in morbidity related to differences in health costs. Calves of WEAN45 and WEANVAC45 had less (P < 0.001) health costs than MARKET and WEAN calves. On arrival, serum haptoglobin concentrations were greater (P < 0.001) in MARKET and WEAN compared with WEAN45 and WEANVAC45 calves. Calves from a single source that are retained on the ranch for 45 d after weaning exhibit less morbidity and less health costs during the receiving period at the feedyard than when cattle are commingled or trucked to the feedyard immediately after weaning.  相似文献   

11.
Acute phase proteins (APPs) such as serum amyloid A (SAA), haptoglobin (Hp), and plasma fibrinogen (Fb) are diagnostic and prognostic biomarkers. This study determined the pattern of SAA in traumatic reticuloperitonitis (TRP) in cows, and compared the findings with Hp, and plasma Fb concentrations in the differential diagnosis of TRP using receiver operating characteristic (ROC) analysis. Blood samples were collected from 89 cows: 53 cases of TRP, 16 animals with other internal disorders and 20 healthy controls.SAA and Hp had a similar pattern and magnitude of changes in TRP. Using the ROC method, the optimal cut-off for the diagnosis of TRP was 68 μg/mL for SAA and 0.74 g/L for Hp, with 100% sensitivity and 86.1% specificity; either of these parameters may therefore be used as a sensitive and relatively specific tool for the differential diagnosis of TRP in cattle. The diagnostic accuracy of plasma Fb was significantly lower than either SAA or Hp (P < 0.01). The combined use of these APPs (whilst aware of their conditional interdependence) may not provide any additional diagnostic information than can be obtained using either SAA or Hp alone.  相似文献   

12.
This experiment evaluated the impacts of administering a bovine appeasing substance (BAS) to beef calves at weaning on their performance, physiological responses, and behavior during a 42-d preconditioning program. Eighty calves (40 heifers and 40 steers; 90% British × 10% Nellore) were weaned at 233 ± 2 d of age (day 0); ranked by sex, weaning age, and body weight (BW); and assigned to receive BAS (IRSEA Group, Quartier Salignan, France; n = 40) or placebo (diethylene glycol monoethyl ether; CON; n = 40). Treatments (5 mL) were topically applied to the nuchal skin area of each animal following dam separation. Within treatment, calves were allocated to one of eight drylot pens (four pens per treatment; pen being the experimental unit) and received a free-choice total mixed ration (TMR) from day 0 to 42, intake of which was assessed daily. Live behavior observations were conducted on days 1, 2, 4, 8, 16, and 32. Temperament was assessed and blood samples were collected via jugular venipuncture on days −21, 0, 3, 7, 14, 28, and 42. Hair samples were collected from the tail switch on days 0, 14, 28, and 42. Calves were vaccinated against bovine respiratory disease viruses on days −21 and 0. Average daily gain from day 0 to 42 did not differ between treatments (P = 0.57) but was greater (P = 0.05) in BAS vs. CON calves from day 0 to 28. Intake of TMR was greater (P = 0.05) during the first week for BAS vs. CON calves (treatment × week; P = 0.08). The mean proportion of calves feeding simultaneously and performance of social and play behaviors were greater (P ≤ 0.05) for BAS vs. CON calves. Escape attempts were greater (P < 0.01) for BAS vs. CON calves on day 1 (treatment × day; P = 0.03). Exit velocity was greater (P = 0.04) for CON vs. BAS calves on day 14 and tended (P = 0.10) to be greater for CON vs. BAS calves on day 7 (treatment × day; P = 0.03). Mean plasma concentrations of haptoglobin were greater (P = 0.02) in CON vs. BAS calves. Hair cortisol concentrations were greater (P = 0.05) in CON vs. BAS calves on day 14 (treatment × day; P = 0.03). Mean serum concentrations of antibodies against bovine viral diarrhea virus were greater (P = 0.02) in BAS vs. CON calves. Collectively, BAS administration to beef calves at weaning alleviated stress-induced physiological reactions, improved temperament evaluated via chute exit velocity, enhanced humoral immunity acquired from vaccination, and appeared to have accelerated adaptation to novel management scheme and environment.  相似文献   

13.
We have previously reported that supplementation with Saccharomyces cerevisiae fermentation products (SCFP) ameliorates clinical signs and lung pathology following experimental bovine respiratory syncytial virus (BRSV) infection in preweaned dairy calves. The objectives of this study were to determine the effect of SCFP supplementation on the metabolic and endocrine responses, and disease outcome of a viral–bacterial coinfection in preweaned calves. Twenty-seven, 1- to 2-d-old Holstein-Angus cross calves were enrolled in the study; one SCFP calf was removed from the trial during the pre-challenge phase due to complications from nephritis. Calves were assigned to two treatment groups: control or SCFP-treated, base milk replacer with 1 g/d SCFP (Smartcare, soluble formula) and calf starter top dressed with 5 g/d SCFP (NutriTek, insoluble formula). Calves were infected with BRSV on day 21, followed 6 d later by intratracheal inoculation with Pasteurella multocida (PM). Calves were euthanized on day 10 post-viral infection. Calves receiving SCFP had reduced thoracic ultrasonography scores on day 7 post-viral infection (P = 0.03) and a tendency toward reduced scores on day 10 post-viral infection (P = 0.09). Calves receiving SCFP also had less severe lung pathology scores at necropsy (P = 0.06). No differences between treatments were observed in lung viral loads (P = 0.48) or bacterial lung recovery (P = 0.34); however, there was a distinction in the lung location for PM recovery, with PM isolated more frequently from the cranial lobes in SCFP-treated calves, but more frequently from the caudal lobes of control calves. Calves treated with SCFP tended (P = 0.07) to have higher serum IL-6 concentrations following the coinfection. Calves treated with SCFP had lower concentrations of serum nonesterified fatty acids and beta-hydroxybutyric acid compared with controls following experimental challenge (P = 0.03 and P = 0.08, respectively), suggesting metabolic changes favoring growth and development. There were no differences between groups in gene expression of insulin receptor, insulin-like growth factor 1 (IGF-1), IGF-1 receptor (IGF-1R), growth hormone receptor, or haptoglobin in the liver. Results from this study suggest that supplementing with SCFP may moderate the impact of a respiratory viral–bacterial coinfection on preweaned calves through metabolic and immune modifications.  相似文献   

14.
We compared the field efficacy of a new antibiotic, florfenicol, with tilmicosin in the treatment of naturally occurring undifferentiated bovine respiratory disease. Beef calves with rectal temperatures greater than 40.5 degrees C and signs compatible with undifferentiated bovine respiratory disease were entered into the trial. Calves were randomly assigned to receive either florfenicol (20 mg/kg bodyweight intramuscularly; 2 injections 48 h apart) or tilmicosin (10 mg/kg bodyweight subcutaneously; 1 injection). Clinical measures of efficacy included mortality, rectal temperature, illness index score, assessment of treatment success or failure, and the number of relapses or reinfections. Performance was assessed based on weight gains from day 0 to day 90. Two hundred and twenty calves entered the trial; 112 received florfenicol and 108 received tilmicosin. Seventeen deaths occurred between day 0 and day 90, but only 10 during the 28-day trial period. Seven calves receiving tilmicosin died, compared with 3 receiving florfenicol (P = 0.20). Of the 220 initial treatments, 45 (20%) were categorized as treatment failures; 27 in the tilmicosin group and 18 in the florfenicol group (P = 0.10). The number of calves experiencing a 2nd relapse was significantly different, with 17 of 30 (57%) calves on tilmicosin compared with 7 of 26 (27%) calves on florfenicol relapsing at least twice (P = 0.02). Average daily gains over 90 days were 1.55 kg/day for florfenicol-treated calves and 1.51 kg/day for tilmicosin-treated calves. No significant adverse reactions were noticed with either drug. Results indicate that florfenicol and tilmicosin are comparable in the treatment of undifferentiated bovine respiratory disease in western Canada.  相似文献   

15.
Thirty-three colostrum-deprived Holstein bull calves (initial BW of 131 ± 4 kg) were used to determine the effect of timing of anthelmintic administration relative to vaccination on antibody titer response to vaccine component antigens. When calves were at least 3 mo of age, they were sorted randomly into individual pens and assigned to 1 of 3 treatment groups, treatments consisted of 1) dewormed 2 wk before vaccination (DPV), 2) dewormed at the time of vaccination (DV), or 3) control, vaccinated but not dewormed (CONT). All calves were inoculated with infective larvae of brown stomach worms (Ostertagia ostertagi) and intestinal worms (Cooperia spp.) on d 1, 7, 10, 14, and 18 for a total dose of 235,710 infective larvae per calf. Calves (DPV and DV) were dewormed on d 21 or 35 with a 10% fenbendazole suspension at 5 mg/kg of BW. On d 35, all calves were vaccinated with a modified-live virus respiratory vaccine containing IBRV (infectious bovine rhinotracheitis virus), BVDV-1 (bovine viral diarrhea virus genotype 1), BVDV-2 (BVDV genotype 2), PI-3 (parainfluenza-3), and BRSV (bovine respiratory syncytial virus). During the 103-d experiment, weekly fecal egg counts, blood, and rectal temperatures were collected and health status was recorded daily. Blood samples were obtained weekly to determine serum neutralizing (SN) antibody titers to IBRV, BVDV-1, BVDV-2, and PI-3 and cytokine levels for IL-4, IL-6, TNF-α (tumor necrosis factor-α), and IFN-γ (interferon-gamma). There was a tendency (P < 0.09) for CONT calves to have greater IL-4 concentrations. By design, control calves had greater (P < 0.01) fecal egg counts during the experiment. All calves developed antibody titers to IBRV, BVDV-1, BVDV-2, and PI-3 by d 15 postvaccination. On d 88, all calves were challenged with IBRV and blood samples were obtained on d 88, 89, 90, 93, 95, 98, 99, and 103. All calves had increased rectal temperatures during the final 7 d of the IBRV challenge. However, the CONT group had greater (P < 0.01) rectal temperatures on each sampling day except d 90 compared with the DPV and DV treatments. Therefore, deworming before or at vaccination reduced parasite burden and decreased rectal temperature increase after an IBRV challenge. Deworming strategy had no effect on antibody response to vaccination or IBRV challenge.  相似文献   

16.
Castration in weaned calves is stressful and affects profitability by reducing ADG and increasing susceptibility to disease. This study evaluated the effect of meloxicam, a nonsteroidal anti-inflammatory drug (NSAID), on performance and health of calves received as steers compared with bull calves surgically castrated on arrival at the feedlot. British × Continental bulls (n = 145) and steers (n = 113; BW = 193 to 285 kg) were transported for 12 h in 3 truckloads (d 0), weighed, and randomly assigned to receive either lactose placebo (CONT; 1 mg/kg) or meloxicam (MEL; 1 mg/kg) suspended in water and administered per os, 24 h before castration. On d 1, bulls were surgically castrated (CAST) and steers were processed without castration (STR). Combinations of CONT/MEL and CAST/STR were allocated to 24 pens (6 pens per treatment) of 8 to 14 calves each. Pen was the experimental unit. Plasma meloxicam concentrations at the time of castration (d 1) were determined by HPLC-mass spectroscopy. Pen-level ADG, DMI, and G:F were estimated using BW obtained on d 0, 14, and 28 and weigh-back of feed. Individual animals were classified as sick based on a depression score of ≥2 on a 5-point scale and a rectal temperature of ≥39.8°C. On d 0, 1, and 14, calf chute temperament was evaluated using a 4-point scale. Data were analyzed using generalized linear mixed models and survival curve analyses. Castration reduced pen ADG (P < 0.001) and G:F (P < 0.001) from d 1 to 14, yet no effects (P > 0.45) were apparent by d 28. For all treatment groups, DMI increased with days on feed (P < 0.0001) but was less in CAST compared with STR calves (P < 0.016) throughout the study. From d 15 to 28, ADG increased (P = 0.0011) in CAST but not STR calves, and G:F decreased (P = 0.0004) in STR but not CAST calves. In CAST calves only, MEL treatment reduced the pen-level first pull rate (P = 0.04) and reduced bovine respiratory disease morbidity rate (P = 0.03). The frequency of chute escape behavior was greater on arrival and at castration in CAST vs. STR calves (P < 0.01) but not significantly different at d 14 (P = 0.22). Mean MEL concentrations at castration were no different between treated STR and CAST calves (P = 0.70). Meloxicam administration before castration in postweaning calves reduced the incidence of respiratory disease at the feedlot. These findings have implications for developing NSAID protocols for use in calves at castration with respect to addressing animal health and welfare concerns.  相似文献   

17.
Efficacy and field safety of tulathromycin administered as a single-dose treatment to crossbreed beef calves with undifferentiated bovine respiratory disease (BRD) were evaluated in a multicenter field study conducted at four US feedlots. Two hundred castrated male calves were enrolled at each study site. The treatment groups were physiologic saline (n = 160) given SC at 0.02 ml/kg, tulathromycin (n = 320) given SC at 2.5 mg/kg, and tilmicosin (n = 320) given SC at 10 mg/kg. Nasopharyngeal swabs for bacterial culture were obtained before treatment. The cure rate for calves treated with tulathromycin (78%) and tilmicosin (65%) was significantly (P < or = .0001) higher than that of calves treated with saline (23.8%). The cure rate of calves treated with tulathromycin (78.4%) was significantly (P = .0007) higher than that of calves treated with tilmicosin (64.9%). No adverse events related to tulathromycin were reported. Under the conditions of this study, tulathromycin administered as a single-dose treatment was efficacious in the treatment of undifferentiated BRD.  相似文献   

18.
Five studies were conducted to evaluate the effects of lipid source on performance and health of stressed feeder cattle. A total of 332 heifers (195 +/- 2.37 kg initial BW) in trial 1 and 336 heifers (206 +/- 1.70 kg initial BW) in trial 2 were fed diets containing ground flaxseed (FLAX), rolled full-fat soybeans (SOY), or tallow (TAL) at 13, 20, or 4%, respectively (DM basis). All diets were formulated to be isonitrogenous and isocaloric. The ADG and G:F for the first 7 d and for the entire feeding period were greater (P < 0.05) for TAL and FLAX than for SOY. Percentage of animals treated and retreated for bovine respiratory disease did not differ among dietary treatments. The FLAX treatment increased (P < 0.05) total n-3 PUFA concentrations in the plasma, whereas SOY increased (P < 0.05) plasma concentrations of total n-6 PUFA. In trial 3, 18 steers were individually fed diets containing TAL and 18 steers were fed a diet containing SOY (20% of DM). In trials 4 and 5, 18 steers were individually fed diets containing TAL and 18 steers were fed diets containing FLAX (12.9% of DM). On d 14 and 17 of study 3, 4, and 5, 16 steers from each dietary treatment were injected i.v. with Escherichia coli O55:B5 lipopolysaccharide (LPS), and 2 steers from each diet were injected with saline. Rectal temperatures after LPS challenge were lower (P < 0.05) for SOY and FLAX than for TAL, and plasma TNF was greater (P < 0.05) for SOY than for TAL. Serum haptoglobin and blood fibrinogen increased and white blood cell count decreased in response to LPS, but none of these variables was affected by treatment. Although this research failed to measure an effect of lipid source on feedlot morbidity or mortality, these studies indicate that altering the source and type of dietary fatty acids may modify the immune response in stressed feeder cattle and that performance may be hindered by feeding full-fat soybeans to receiving cattle.  相似文献   

19.
Four studies conducted at feedlots in Greeley and Wellington, Colorado; Nebraska; and Texas compared the efficacy of tulathromycin to florfenicol or tilmicosin for the treatment of cattle with undifferentiated bovine respiratory disease (BRD) and subsequent feedlot performance and carcass characteristics. In each study, 100 calves with BRD were treated with tulathromycin given SC at 2.5 mg/kg body weight. At the Greeley, CO, and Nebraska study locations, 100 calves were treated with florfenicol given SC at 40 mg/kg body weight, and at the Wellington, CO, and Texas study locations, tilmicosin was given SC at 10 mg/kg body weight. Cure rate, a derived variable that included assessments of mortality, rectal temperature, and attitude and respiratory scores from day 3 to day 28 and day 3 through harvest, was the primary assessment of BRD efficacy. Cure rates of calves treated with tulathromycin were significantly (P < or = .009) higher than those calves treated with florfenicol. At Wellington, CO, the cure rate of calves treated with tulathromycin was significantly higher (P < or = .018) compared with tilmicosin-treated calves. The differences in cure rates between tulathromycin and tilmicosin treatment groups in the Texas study were not significantly different (P > .05). Tulathromycin was more efficacious in the treatment of undifferentiated BRD compared with florfenicol and, in one study, compared with tilmicosin.  相似文献   

20.
Two identical viruses designated 371 and 375 were recovered from nasal secretions of 2 of 7 calves in a beef cow-calf herd in which calves (45 to 105 days of age) had signs of acute respiratory tract disease. The cytopathic, morphologic and physico-chemical characteristics of the isolates were those of bovine respiratory syncytial virus. Although a humoral antibody response to bovine respiratory syncytial virus was not observed, it was concluded that this virus probably had a part in the respiratory tract disease in these calves.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号