Ruminal microbial development in conventionally or early-weaned calves   总被引：8，自引：0，他引：8  

K L Anderson  T G Nagaraja  J L Morrill  T B Avery  S J Galitzer  J E Boyer 《Journal of animal science》1987,64(4):1215-1226

Eight bull calves (four Holsteins and four Ayrshire calves with mean birth weight of 38.8 kg) were ruminally cannulated at 3 d of age and allocated to one of two weaning programs. All calves were fed colostrum for 3 d after birth and milk until weaning. Calves in the conventional-weaning program were fed a starter diet from 3 d of age and weaned at 6 wk of age. In the early-weaning program, calves were fed a highly palatable pre-starter diet from 3 d of age until they consumed 227 g/d, and then fed a mixture of pre-starter (227 g) and starter diet ad libitum. Calves in this group were weaned at 4 wk of age. Ruminal samples were collected at 3 and 7 d, then weekly thereafter through 8 wk and at 10 and 12 wk of age to assess microbial activity. Calves in the early-weaned group had a higher concentration of total ruminal volatile fatty acids at an earlier age than the calves in the conventional-weaning program. This was accompanied by a trend toward higher lactate concentrations and lower ruminal pH in the early-weaned group during their first 4 wk of age. Lactate and ammonia concentrations decreased with calf age. The total anaerobic bacterial counts increased slightly with calf age, whereas Streptococcus bovis and facultative bacterial populations decreased with calf age. Amylolytic, proteolytic, lactobacilli, lactate-utilizers, cellulolytic and methanogenic bacterial populations increased progressively in both groups. Cellulolytic and methanogenic bacteria were present in both groups at 3 d of age. No protozoa were detected in calves of either group. In general, the most significant changes in bacterial populations and metabolic activity in both groups occurred between 4 and 6 wk of age. Although calves in both groups had similar patterns of bacterial development, calves in the early-weaning program tended to have high ruminal microbial activity at an earlier age than the conventionally weaned calves.  相似文献   

Steam-rolled wheat diets for finishing cattle: effects of dietary roughage and feed intake on finishing steer performance and ruminal metabolism   总被引：2，自引：0，他引：2  

K K Kreikemeier  D L Harmon  R T Brandt  T G Nagaraja  R C Cochran 《Journal of animal science》1990,68(7):2130-2141

Two experiments were conducted to determine the influence of dietary roughage concentration and feed intake on finishing steer performance and ruminal metabolism. In Exp. 1, 126 steers (334 kg) were used in a completely randomized design and fed (120 d) diets of steam-rolled wheat without roughage or containing 5, 10 or 15% roughage (50% alfalfa hay:50% corn silage). Steers fed 5 or 10% roughage gained faster (quadratic, P less than .05) and were more efficient (quadratic, P less than .05) than steers fed 15% or no roughage. In Exp. 2, six ruminally cannulated steers (447 kg) were used in a 6 x 6 latin square design and fed (twice daily) diets of steam-rolled wheat without roughage or containing 5 or 15% alfalfa hay at twice or three times NE required for maintenance. Increasing dietary roughage increased (linear, P less than .01) ruminal liquid passage 38%, indigestible ADF passage 63%, Yb-labeled wheat passage 75% and fiber fill 31%. The rate of in situ starch digestion tended to increase (linear, P = .16), and ruminal VFA concentration was 40 mM higher (P less than .01) at 4 h after feeding with increased roughage. Increased feed intake increased (P less than .05) ruminal starch fill, fiber fill, liquid fill and liquid passage 23%, Yb-labeled wheat passage 50% and Dry-labeled hay passage 20%. It reduced protozoa five- to sixfold (P less than .01) but doubled total bacterial counts (P less than .01). Ruminal NH3N was lower (P less than .01) and total VFA concentration was 50 mM higher (P less than .01) at 4 h after feeding. The acetate:propionate ratio was reduced from 2.3 to 1.3 (P less than .01) with increased intake. Adding roughage to a steam-rolled wheat diet increased passage and tended to increase rate of starch digestion; increased feed intake with its associated effects on ruminal fill and passage dramatically shifted the microbial population and fermentation end products.  相似文献   

Chemical characteristics of rumen bacterial endotoxin     

T G Nagaraja  E E Bartley  L R Fina  H D Anthony  B E Brent  D A Sapienza 《Journal of animal science》1979,48(5):1250-1256

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Modification of Klein's wet ashing procedure for determination of mercury     

S Vibhakar  K V Nagaraja  O Kapur 《Journal of the Association of Official Analytical Chemists》1983,66(2):317-318

An investigation of the use of HCl in Klein's method (25.108-25.115) to prevent loss of mercury during wet digestion resulted in consistently good recoveries from jowar and fish samples. Recoveries for the modified method ranged from 90.9 to 97.0% compared with 14.4 to 35.5% for the original method.  相似文献   

Rapid detection of avian pneumovirus in tissue culture by microindirect immunofluorescence test.     

Faris F Jirjis  Sally L Noll  David A Halvorson  Kakambi V Nagaraja  Evelyn L Townsend  Sagar M Goyal  Daniel P Shaw 《Journal of veterinary diagnostic investigation》2002,14(2):172-175

An indirect immunofluorescence (IFA) test with a 96-well, flat-bottomed microplate was developed to detect avian pneumovirus (APV) antigen in Vero cell cultures. Samples of nasal turbinates and swabs from infraorbital sinuses and trachea were collected from 4-week-old poults experimentally inoculated with APV. The APV titers by tissue culture IFA staining were compared with that of visual reading of cytopathic effect (CPE). The ability of IFA staining to detect APV antigen correlated well with visualizing CPE. The use of IFA staining of Vero cell cultures allowed detection of APV in substantially less time than the use of visualizing CPE. In addition, the use of IFA allowed specific identification of the virus in cell culture.  相似文献   

Cell-mediated immunity against turkey coronaviral enteritis (bluecomb)     

K V Nagaraja  B S Pomeroy 《American journal of veterinary research》1980,41(6):915-917

Studies on cell-mediated immune response in turkeys infected with turkey coronavirus (TCV) were made. A whole blood culture technique was developed for quantitatively evaluating in vitro lymphocyte reactivity to mitogens concanavalin A, phytohemagglutinin-P, and TCV antigen. The degree of blastogenesis was quantitated by the measurement of the uptake of the [125I]deoxyuridine in the presence of fluorodeoxyuridine. The stimulation indices were consistently higher in the infected birds compared with those in the noninfected controls, and they were statistically significant (P < 0.05). The detection of TCV specific responses indicated that cell-mediated immunity may be important in determining the immunity against turkey coronaviral enteritis. The whole blood lymphocyte transformation assay was emphasized as a convenient and useful in vitro indicator of cell-mediated immunity in TCV infection.  相似文献   

Dry-rolled or steam-flaked grain-based diets and fecal shedding of Escherichia coli O157 in feedlot cattle     

Fox JT  Depenbusch BE  Drouillard JS  Nagaraja TG 《Journal of animal science》2007,85(5):1207-1212

Hindgut is a major colonization site for Escherichia coli O157 in cattle. In this study, diets were formulated to effect changes in hindgut fermentation to test our hypothesis that changes in the hindgut ecosystem could have an impact on fecal shedding of E. coli O157. Feedlot heifers (n = 347) were prescreened for the prevalence of E. coli O157 by fecal and rectoanal mucosal swab cultures. A subset of 40 heifers identified as being positive for fecal shedding of E. coli O157 was selected, housed in individual pens, and randomly allocated to 4 dietary treatments. Treatments were arranged as a 2 x 2 factorial, with factor 1 consisting of grain type (sorghum or wheat) and factor 2 being method of grain processing (steam-flaking or dry-rolling). Four transition diets, each fed for 4 d, were used to adapt the animals to final diets that contained 93% concentrate and 7% roughage. The grain fraction consisted of dry-rolled sorghum, steam-flaked sorghum, a mixture of dry-rolled wheat and steam-flaked corn, or a mixture of steam-flaked wheat and steam-flaked corn. Wheat diets contained 52% wheat and 31% steam-flaked corn (DM basis). Fecal and rectoanal mucosal swab samples were obtained 3 times a week to isolate (enrichment, immunomagenetic separation, and plating on selective medium) and identify (sorbitol negative, indole production, and agglutination test) E. coli O157. The data were analyzed as repeated measures of binomial response (positive or negative) on each sampling day. Method of processing (dry-rolled vs. steam-flaked), sampling day, and the grain type x day interaction were significant (P < 0.05), but not the method of processing x grain type interaction. The average prevalence of E. coli O157 from d 9 was greater (P < 0.001) in cattle fed steam-flaked grains (65%) compared with those fed dry-rolled grains (30%). Average prevalence in cattle fed sorghum (51%) or wheat (43%) were similar (P > 0.10) on most sampling days. Results from this study indicate that feeding dry-rolled grains compared with steam-flaked grains reduced fecal shedding of E. coli O157. Possibly, dry-rolling allowed more substrate to reach the hindgut where it was fermented, thus making the hindgut inhospitable to the survival of E. coli O157. Dietary intervention to influence hindgut fermentation offers a simple and practical mitigation strategy to reduce the prevalence of E. coli O157 in feedlot cattle.  相似文献   

Effects of temperature and stabilizer on the viability of a live attenuated avian metapneumovirus vaccine     

Ramakrishnan MA  Velayudhan BT  Anantharaman S  Noll SL  Halvorson DA  Nagaraja KV  Goyal SM 《Avian diseases》2007,51(4):979-981

A commercial live attenuated, freeze-dried avian metapneumovirus vaccine, Pneumomune, was assessed for its viability at three different temperatures (5.6 C, 21 C, and 37 C). No significant reduction in virus titer was observed when the vaccine was stored at 5.6 C for a period of 24 hr. However, reductions in virus titer of 1 log10 and 2 log10 were observed after 24 hr at 21 C and 37 C, respectively. Batch-to-batch variation in virus reduction was also observed. The addition of a dye or a vaccine stabilizer to the vaccine preparation did not have any deleterious effect on the survival of vaccine virus.  相似文献   

Oxygenic Photoautotrophic Growth Without Photosystem I     

JW Lee  CV Tevault  TG Owens  E Greenbaum 《Science (New York, N.Y.)》1996,273(5273):364-367

Contrary to the prediction of the Z-scheme model of photosynthesis, experiments demonstrated that mutants of Chlamydomonas containing photosystem II (PSII) but lacking photosystem I (PSI) can grow photoautotrophically with O2 evolution, using atmospheric CO2 as the sole carbon source. Autotrophic photosynthesis by PSI-deficient mutants was stable both under anaerobic conditions and in air (21 percent O2) at an actinic intensity of 200 microeinsteins per square meter per second. This PSII photosynthesis, which was sufficient to support cell development and mobility, may also occur in wild-type green algae and higher plants. The mutants can survive under 2000 microeinsteins per square meter per second with air, although they have less resistance to photoinhibition.  相似文献   

Effects of level and source of carbohydrate and level of degradable intake protein on intake and digestion of low-quality tallgrass-prairie hay by beef steers.     

J S Heldt  R C Cochran  C P Mathis  B C Woods  K C Olson  E C Titgemeyer  T G Nagaraja  E S Vanzant  D E Johnson 《Journal of animal science》1999,77(10):2846-2854

Ruminally fistulated steers (n = 13; 263 kg) were used in an incomplete Latin square with 13 treatments and four periods to evaluate the effects of level and source of supplemental carbohydrate (CHO) and level of degradable intake protein (DIP) on the utilization of low-quality, tallgrass-prairie hay. Steers were given ad libitum access to forage (5.7% CP, 2.6% DIP, and 74.9% NDF). The supplementation treatments were fashioned as a 2x3x2 factorial arrangement plus a negative control (NC; no supplement). The factors included two DIP levels (.031 and .122% BW) and three CHO sources (starch, glucose, and fiber) fed at two levels (.15 and .30% BW) within each level of DIP supplementation. The effect of supplementation on forage OM intake (FOMI) was dependent (P<.01) on level and source of CHO and level of DIP fed. When DIP was low, forage, total, and digestible OM intakes were generally greater for the starch treatment than for the nonstarch treatments. However, when the DIP level was high, intakes were greater for the nonstarch (i.e., fiber and glucose) treatments. Generally, FOMI decreased (P<.01) when more supplemental CHO was provided. Supplementation typically increased fiber digestion, but the response was dependent (P<.01) on level and source of CHO and level of DIP. Generally, supplements with low levels of CHO improved NDF digestion (NDFD). However, supplements with the high level of CHO decreased NDFD, except for fiber at the high level of DIP. Organic matter digestion was increased by supplementation, but the impact of increasing CHO was dependent (P<.01) on source of CHO and level of DIP. Supplementation treatments had significant impact on ruminal pH, NH3 N, and the total concentration of organic acids as well as their relative proportions. In conclusion, supplemental DIP enhanced the use of low-quality forage; however, the impact of supplemental CHO on low-quality forage use was dependent on source and level of CHO offered, as well as the level of DIP provided.  相似文献