Influence of nitrogen on cellulolysis rate and saprophytic survival in soil of some cereal foot-rot fungi     

S.D. Garrett 《Soil biology & biochemistry》1976,8(3):229-234

Records of longevity of saprophytic survival in standard segments of colonized wheat straw buried in soil have been analysed for five species of cereal foot-rot fungi: Gaeumannomyces graminis var. tritici, Fusarium roseum f. sp. cerealis, Cercosporella herpotrichoides, Curvularia ramosa and Cochliobolus sativus. Also included in this survey has been Phialophora radicicola var. tgraminicola, which is a harmless, non-pathogenic parasite of grass and cereal roots. Longevity of survival has been expressed as the median period (S50), i.e. weeks the fungus survives in 50% of the straws sampled. S50 values for four of these fungi vary widely with the N status of the soil: ample soluble N promotes longevity of G. graminis and F. roseum but shortens survival of P. radicicola and C. sativus. The survival of C. herpotrichoides and C. ramosa is unaffected by N supply. These different responses can be explained through the operation of two mechanisms (1) cellulolysis of the wheat straw tissue (ca. 40% cellulose) by the primary fungal colonizer (2) liability of the fungus to be prematurely displaced from its straw substrate by the intense microbial competition developing in soils of high N status and fertility. C. herpotrichoides falls outside the scope of this analysis, because its cellulolytic ability is poor and it seems to survive in the straw tissue mainly as resting mycelium.Cellulolytic ability as a determinant of saprophytic survival has been expressed by the cellulolysis adequacy index (CAI), which is the ratio of cellulolysis rate to linear growth rate (as a parameter of general metabolic rate) for each fungal species. Studies on growth of three species in axenic culture on filter-paper cellulose with mineral nutrients have shown that as CAI value increases, so the need for N for prolonged survival of the fungal colony decreases; this is because a high CAI value reduces the minimum rate of hyphal growth and consequent extension of cellulolysis that is necessary for maintenance of the fungal colony. This relationship between CAI and S50 values appears to apply not only to survival in axenic cultures but also to survival in soils of low N status, in which microbial competition is limited by a critical shortage of this nutrient. In soils of high N status, on the other hand, longevity of survival seems to be determined chiefly by the degree of success in saprophytic competition for survival with other micro-organisms.  相似文献   

Characterisation of Pasteurella multocida isolated from fowl cholera outbreaks on turkey farms     

PJ BLACKALL  JL PAHOFF  D MARKS†  N FEGAN  CJ MORROW‡ 《Australian veterinary journal》1995,72(4):135-138

SUMMARY: Biochemical profiles, restriction endonuclease analysis (REA) and ribotyping were used to investigate Pasteurella multocida isolates from outbreaks of fowl cholera on 7 turkey farms in New South Wales. While only a single isolate was available from 5 of the farms, multiple isolates, 4 and 12 respectively, were available from the other 2 farms. The available field evidence suggested that 8 outbreaks had occurred with one farm suffering 2 outbreaks. The isolates obtained were all confirmed as Pasteurella multocida . Biochemical profiles allocated the isolates to 4 groups, 3 being variants of P multocida subsp multocida and the fourth being P multocida subsp septica . REA performed with Hpall established 7 groups. Ribotyping using the Hpall digests probed with the 16S rRNA operon of Haemophilus paragallinarum recognised the same 7 groups as REA. Unlike the biochemical profiles, both REA and ribotyping provided a fine subdivision that identified outbreaks as either related or unrelated. The REA and ribotyping patterns as well as biochemical profiles were stable for all isolates from the outbreaks in which multiple isolates were obtained from either the same bird or from different birds. REA and ribotyping were found to be superior to biotyping methods for the investigation of fowl cholera outbreaks.  相似文献   

Estimates of subprimal yields from beef carcasses as affected by USDA grades, subcutaneous fat trim level, and carcass sex class and type.     

D B Griffin  J W Savell  J B Morgan  R P Garrett  H R Cross 《Journal of animal science》1992,70(8):2411-2430

One hundred beef carcasses were selected to represent the mix of cattle slaughtered across the United States. Selection criteria included breed type (60% British/continental European, 20% Bos indicus, and 20% dairy carcasses), sex class (beef and Bos indicus: 67% steers, 33% heifers; dairy: 100% steers), USDA quality grade (4% Prime, 53% Choice, and 43% Select), USDA yield grade (10% YG 1, 43% YG 2, 40% YG 3, and 7% YG 4), and carcass weight (steers: 272.2 to 385.6 kg, heifers: 226.8 to 340.2 kg). One side of each carcass was fabricated into boneless subprimals and minor cuts following Institutional Meat Purchase Specifications. After fabrication, subprimals were trimmed progressively of fat in .64-cm increments beginning with a maximum of 2.54 cm and ending with .64 cm. Linear regression models were developed for each individual cut, including fabrication byproduct items (bone, fat trim) to estimate the percentage yield of those cuts reported by USDA Market News. Strip loin, top sirloin butt, and gooseneck rounds from heifers tended to have a higher percentage yield at the same USDA yield grade than the same cuts from steers, possibly resulting from increased fat deposition on heifers. Percentage of fat trimmed from dairy steers was 2 to 3% lower than that from other sex-class/carcass types; however, due to increased percentage of bone and less muscle, dairy steers were lower-yielding. Fat trimmed from carcasses ranged from 7.9 to 15.6% as the maximum trim level decreased from 2.54 to .64 cm.  相似文献   

Incidence of Unilateral Fertilizations after Low Dose Deep Intrauterine Insemination in Spontaneously Ovulating Sows under Field Conditions     

EA Martinez  JM Vazquez  I Parrilla  C Cuello  MA Gil  H Rodriguez-Martinez  J Roca  JL Vazquez 《Reproduction in domestic animals》2006,41(1):41-47

A new procedure for non-surgical deep intrauterine insemination (DUI) in unrestrained sows hormonally induced to ovulate, has been reported. In comparison with standard artificial insemination (AI), with this procedure, the sperm numbers inseminated can be reduced 20-fold without reducing the reproductive performance of these hormonally treated sows. The present study evaluated, using two experiments, the reproductive performance applying 20-fold different sperm numbers per AI dose using DUI or standard AI in spontaneously ovulating sows, under field conditions. In experiment 1, AI was applied to crossbred sows at 12, 24 and 36 h after onset of spontaneous oestrus using one of the following two regimes: (i) DUI (treatment) with 0.15 x 10(9) fresh boar spermatozoa in 5 ml of Beltsville thawing solution (BTS) extender (n = 95), and (ii) standard cervical AI (control) with 2.85 x 10(9) fresh spermatozoa in 95 ml of BTS extender (n = 95). The farrowing rates of the two groups of sows were statistically similar (NS). However, a decrease (p < 0.002) in litter size and the total number of pigs born alive was observed in sows inseminated with the DUI procedure. In experiment 2, 42 post-weaned oestrus sows were inseminated following the same design described for experiment 1 during spontaneous oestrus. On day 6 after onset of oestrus, the proximal segment of the uterine horns of the sows were flushed under surgery to retrieve eventual embryos and evaluate the success of fertilization per cornua (e.g. occurrence of effective uni- vs bilateral sperm transport rendering uni- or bilateral, complete or partial fertilization). Retrieved embryos were assessed for cleavage and number of accessory spermatozoa. Although identical overall pregnancy rates were achieved in both insemination groups, the percentage of sows with partial bilateral fertilization and unilateral fertilization was markedly higher (p < 0.05) in the DUI group (35%) compared with the control (standard AI) group (5%), with a consequent lower (p < 0.001) percentage of viable early embryos after DUI. The number of accessory spermatozoa in the zona pellucida of the embryos was highly variable, but higher (p < 0.001) in control animals than in DUI-AI. No accessory spermatozoa were found in oocytes retrieved from sows depicting unilateral fertilization. In conclusion, DUI in spontaneously ovulating sows with 0.15 x 10(9) spermatozoa renders similar farrowing rates but a lower litter size compared with use of standard AI with a 20-fold higher sperm dose. The lower litter size ought to be related to a decreased distribution of spermatozoa after DUI leading to a higher incidence of partial bilateral and unilateral fertilization.  相似文献   

Use of furosemide to obtain bovine urine samples for leptospiral isolation     

R M Nervig  L A Garrett 《American journal of veterinary research》1979,40(8):1197-1200

The use of the diuretic furosemide made it possible to obtain samples of urine from cattle for leptospiral isolations. The drug was injected IV at a dose level of 0.8 mg/kg for heifers and 0.5 mg/kg for calves. The average time to first voiding in heifers was 19 minutes. The average time from the first to the second voiding was 17 minutes. The average time to the first voiding in four calves was 12 minutes; the average time from the first to the second voiding was 10 minutes. A decrease in urinary osmolarity provoked by furosemide created a more favorable condition for the survival of leptospires. Leptospires were isolated in 24 (72.7%) of 33 weekly cultural attempts with the aid of furosemide in three experimentally infected adult cattle. Serovar hardjo was isolated in 16 (57.1%) of 28 weekly cultural attempts with aid of the diuretic in four experimentally infected calves. The recovery frequency was 28.5% from the first voiding and 50% from the second. Leptospires were not isolated from urine obtained from the calves by manual stimulation. Untoward side effects that might have been attributable to furosemide were not observed. Furosemide appears to be well suited to obtain urine samples from cattle for leptospiral isolation.  相似文献   

A description of the dynamics of fetal growth in sheep.     

L J Koong  W N Garrett  P V Rattray 《Journal of animal science》1975,41(4):1065-1068

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Energy value of barley fractions     

H F Hintz  R C Hansen  W N Garrett 《Journal of animal science》1969,28(3):397-400

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Steam pressure processing and pelleting of barley for growing-finishing swine     

H F Hintz  W N Garrett 《Journal of animal science》1967,26(4):746-748

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On Un-American Science Reporting     

Garrett HE 《Science (New York, N.Y.)》1960,132(3428):685-687

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Bacteriologic and histologic features in mice after intranasal inoculation of Brucella melitensis   总被引：1，自引：0，他引：1  

Mense MG  Van De Verg LL  Bhattacharjee AK  Garrett JL  Hart JA  Lindler LE  Hadfield TL  Hoover DL 《American journal of veterinary research》2001,62(3):398-405

OBJECTIVE: To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice. ANIMALS: Female Balb/c mice, 6 to 8 weeks old. PROCEDURE: Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy. RESULTS: Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 10(3), 10(4), and 10(5) CFU. Recovery of brucellae from the lungs was possible early in infection with 10(1), 10(3), and 10(5) CFU, but only the group inoculated with 10(5) CFU consistently yielded quantifiable bacteria. At a dose of 10 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 10(3) CFU. At an inoculum of 10(5) CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis. CONCLUSION AND CLINICAL RELEVANCE: Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice.  相似文献