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D M Burgess

Publications and source records attributed to D M Burgess.

6 recordsLinked to original sources
PubMed2000

Isolation and identification of ruminal methanogens from grazing cattle.

To obtain information on the diversity of ruminal methanogens in grazing animals, three ruminal methanogens from grazing cattle were characterized and identified. Two of the isolates were rod-shaped, with one staining Gram-positive and being non-motile (BRM9), and the other (BRM16) staining Gram-negative and being motile. These isolates grew only on H(2)/CO(2) and formate, and optimally at 38 degrees C and pH 6.5-7.0. The third isolate (CM1) was non-motile, pseudosarcina-shaped, and grew on H(2)/CO(2), acetate, and methyl-containing compounds, with optimal growth at 40 degrees C and pH 6.5. DNA was prepared from the three isolates, and their 16S rRNA genes were sequenced. Phenotypic data and comparisons of nearly complete 16S rDNA sequences showed that BRM9, BRM16, and CM1 are strains of Methanobacterium formicicum, Methanomicrobium mobile, and Methanosarcina barkeri respectively. To the best of our knowledge, this is the first information on ruminal methanogens in cattle maintained under grazing management.

Animal Husbandry↗
PubMed1999

Hypergastrinaemia, abomasal bacterial population densities and pH in sheep infected with Ostertagia circumcincta.

Serum gastrin and pepsinogen concentrations, food intake, abomasal pH and abomasal aerotolerant and anaerobic bacterial populations were measured in sheep infected with Ostertagia circumcincta to search for links between hypergastrinaemia, food intake and changes in the abomasal environment. Abomasal pH and serum gastrin and pepsinogen concentrations were elevated in each of five sheep infected via abomasal cannulae with 150000 exsheathed larval stage three, followed 11 days later by 100000 sheathed larvae given intraruminally. Unparasitised abomasa contained aerotolerant bacterial population densities of between 10(3) and 10(6) cells ml(-1) and these did not change significantly following parasitism. In contrast, anaerobic bacterial population densities increased markedly by about 10(4)-fold following parasitism. Anaerobic numbers changed rapidly when abomasal pH increased from 2.5 to 3.5. At pH 4 and above, anaerobic bacterial numbers approached levels expected in rumen contents but parameters other than pH did not relate to bacterial numbers. Brief periods when serum gastrin was lower than expected, coinciding with raised abomasal pH, were not explicable by increased bacterial numbers. Food intake, which decreased for a variable period from around Day 5 p.i., correlated poorly with serum gastrin concentration, suggesting hypergastrinaemia is not the sole cause of anorexia in parasitised animals. The survival of substantial numbers of rumen bacteria in the abomasum at only slightly raised pH may significantly lower the bacterial protein available to the sheep.

Abomasum↗
PubMed1994

Drinking during pregnancy decreases word attack and arithmetic scores on standardized tests: adolescent data from a population-based prospective study.

Women (1529) were interviewed in midpregnancy, and a cohort of their children has been examined at various ages. The two standardized tests presented herein are part of a large battery of tests administered when the children were 14 years old. "Word Attack" (n = 462) measures phonological processing on a task involving the reading of pseudowords in nontimed performance. "Arithmetic" (n = 191) measures auditorily processed mental computations in timed performance. Scores on both tests were associated with prenatal alcohol exposure in a dose-dependent fashion. These effects were robust when considered in relation to a wide variety of potentially confounding variables, such as prenatal exposure to tobacco and other drugs, sociodemographic characteristics, and traumatic postnatal events. A variety of alcohol scores were related to these two performance measures, but those involving a massing of drinks on a given occasion had the strongest association. The higher the average number of drinks/occasion, the poorer the offspring performance on tasks thought to underlie numerical problem solving and reading proficiency. Earlier reports of prenatal, alcohol-related neurobehavioral deficits in childhood have now been extended into adolescence.

Adolescent↗