Complex interplay between intrinsic and extrinsic drivers of long-term survival trends in southern elephant seals     

Siobhan C de Little  Corey JA Bradshaw  Clive R McMahon  Mark A Hindell 《BMC ecology》2007,7(1):3

Background  

Determining the relative contribution of intrinsic and extrinsic factors to fluctuations in population size, trends and demographic composition is analytically complex. It is often only possible to examine the combined effects of these factors through measurements made over long periods, spanning an array of population densities or levels of food availability. Using age-structured mark-recapture models and datasets spanning five decades (1950–1999), and two periods of differing relative population density, we estimated age-specific probabilities of survival and examined the combined effects of population density and environmental conditions on juvenile survival of southern elephant seals at Macquarie Island.  相似文献   

Hepatozoon spp Infections in the United States     

Kelly E. Allen  Eileen M. JohnsonSusan E. Little  DVM  PhD 《Veterinary Clinics of North America: Small Animal Practice》2011,41(6):1221-1238

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TETRAPLOIDY IN ANTIRRHINUM MAJUS INDUCED BY SANGUINARINE HYDROCHLORIDE     

Little TM 《Science (New York, N.Y.)》1942,96(2486):188-189

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Comparison of spermatozoal movement and semen characteristics with fertility in stallions: 64 cases (1987-1988).     

D J Jasko  T V Little  D H Lein  R H Foote 《Journal of the American Veterinary Medical Association》1992,200(7):979-985

Information pertaining to evaluation of single ejaculates of semen and records for 2 consecutive breeding seasons were obtained. In all, data for 99 individual breeding seasons (n = 43 Standardbreds and 56 Thoroughbreds) were evaluated. Included in each semen evaluation was examination of semen characteristics and computer-aided analysis of spermatozoal movement characteristics. On the basis of the analysis of breeding records for 4,175 mares (7,017 estrous cycles), a per-estrous cycle fertility rate was calculated from data for 96 of the breeding seasons. Stallions with lower fertility than the mean overall season fertility had significantly (P less than 0.01) lower mean values for subjective appraisal of the percentage of motile and progressively motile spermatozoa and for percentage of morphologically normal spermatozoa. Lower mean values were obtained for computer-aided movement analysis of the percentage of motile and progressively motile spermatozoa, and for mean velocity of motile spermatozoa. Semen characteristics, including spermatozoal movement characteristics, and fertility were significantly (P less than 0.05) correlated for Thoroughbred and Standardbred stallions when analyzed individually and when data for both breeds were combined. Characteristics most highly correlated (P less than 0.01) with fertility data for both breeds combined were: subjective appraisal of the percentage of motile (r = 0.40) and progressively motile (r = 0.46) spermatozoa; percentage of morphologically normal spermatozoa (r = 0.36); and computer-aided analysis of percentage of motile spermatozoa (r = 0.34). However, on the basis of evaluation of a single ejaculate for each stallion, the variation in these characteristics only accounted for approximately 20% of the observed variation in fertility rate.  相似文献   

Differentiation of reference strains of leptospires of the Pomona serogroup by cross-agglutination absorption and restriction endonuclease analysis   总被引：2，自引：0，他引：2  

S C Hathaway  R B Marshall  T W Little  S A Headlam  P J Winter 《Research in veterinary science》1985,39(2):145-150

The serological classification of all reference strains that have been described as representing separate serovars of Leptospira interrogans within the Pomona serogroup was investigated using cross-agglutination absorption and bacterial restriction endonuclease analysis (BRENDA). Comparative cross-agglutination absorption studies indicated that cornelli CB, monjakov Monjakov and kennewicki LT1026 were homologous with pomona Pomona, and dania K1 and tsaratsova B81/7 were homologous with mozdok 5621. BRENDA confirmed these results, except that pomona Pomona and monjakov Monjakov showed a difference in the high molecular weight region. It is proposed that four serovars be currently recognised within the Pomona serogroup: pomona, mozdok, proechimys and tropica. The relative merits of the use of cross-agglutination absorption and BRENDA with respect to identification of Pomona serogroup isolates are discussed.  相似文献   

Correction     

CRAWFORD WH  FRETZ PB  BAILEY JV 《Veterinary surgery : VS》1985,14(1):20-20

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Responses to supplementation in White Fulani cattle under agro-pastoral management in northern Nigeria. 1. Phosphorus     

D. A. Campbell  O. A. Ikuegbu  E. Owen  D. A. Little 《Tropical animal health and production》1996,28(1):183-190

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Haemophilus somnus: investigations of its potential role in bovine mastitis   总被引：4，自引：0，他引：4  

M J Hazlett  P B Little  D A Barnum  M G Maxie  K E Leslie  R B Miller 《American journal of veterinary research》1985,46(11):2229-2234

Mammary glands of 6 lactating Holstein cows were inoculated with Haemophilus somnus strain 43826. Three cows developed chronic mastitis and shed bacteria for up to 1 year. Three cows developed acute gangrenous mastitis, with evidence of bacteremia and endotoxemia. Cows with gangrenous mastitis had lower somatic cell counts early after inoculation in affected quarter secretions compared with those in cows that developed chronic mastitis. Cows with gangrenous mastitis developed hypocalcemia, hypoalbuminemia, azotemia, hyperbilirubinemia, mildly increased serum aspartate aminotransferase and creatine kinase activity, and a marked neutropenia with a degenerative left shift. Histopathologic examination of gangrenous quarters revealed edema, necrosis, and vascular thrombosis with few inflammatory cells. A limited survey failed to recover H somnus from dairy cows with clinical mastitis or from mammary secretions from 41 beef cattle at an abattoir.  相似文献   

Failure of a selective medium to isolate Haemophilus somnus strains   总被引：1，自引：0，他引：1  

JM KWIECIEN  PB LITTLE 《Australian veterinary journal》1989,66(5):159-160

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Problems associated with the serological diagnosis of Leptospira interrogans serovar hardjo infection in bovine populations   总被引：1，自引：0，他引：1  

S C Hathaway  T W Little  D G Pritchard 《The Veterinary record》1986,119(4):84-86

Data combining sequential bacteriology and serology from a longitudinal study of a dairy herd were used to demonstrate the limitations of serology as a diagnostic method in cross-sectional sampling of bovine populations. Whole-herd point serological prevalences showed considerable variation over a two-year sampling period (38.8 to 76.2 per cent), and this was mainly due to varying age-specific prevalence. Owing to the rapid decline in titres and the varying persistence of infection, point serological prevalences failed to approximate to cumulative infection rates (either past or present) at different times of the year. A higher estimate of the number of susceptible animals in the herd than is the case results in inaccurate information on true incidence rates and can confuse assessments of the susceptibility of different age groups, especially if only small numbers are sampled. A sampling exercise demonstrated that a 10-cow sample usually provided little useful information other than establishing the presence or absence of hardjo in the herd. Increasing the sample size markedly improved epidemiological information, investigations of clinical disease, assessments of vaccination needs and public health tracebacks. Preferably 10 sera from each of the yearling, first calver, second calver and older age groups should be tested. Serology was an inadequate indicator of infection in individual animals. Group geometric mean titres taken from a mean serological response curve were shown to have limited application in the interpretation of field data, unless infection had occurred in the previous two months.  相似文献