George E. Spates

Biological Control of Salmonella typhimurium in Young Chickens

The effect of dietary lactose and anaerobic cultures of cecal microflora of mature chickens on the colonization of young broiler chickens by Salmonella typhimurium was evaluated. Newly hatched chicks were given either no treatment (controls), anaerobic cecal cultures, lactose (2.5%) in the drinking water, or both anaerobic cultures and lactose. Chicks were challenged per os at 3 days of age with either 10(6) or 10(8) S. typhimurium resistant to nalidixic acid and novobiocin. On day 10, the cecal contents of the chicks were examined for S. typhimurium, pH, short-chained volatile fatty acids (VFAs), undissociated VFAs, and lactic acid. Chicks given either lactose alone or cecal anaerobes alone had significantly (P less than 0.05) fewer S. typhimurium recovered from their ceca than the controls. Chicks given the combination of dietary lactose and cecal anaerobes had significantly fewer S. typhimurium recovered from their ceca than the chicks given dietary lactose or cecal anaerobes alone. Chicks given lactose had significant (P less than 0.05) increases in the lactic acid concentration of their cecal contents. Increased lactic acid concentrations were directly correlated to decreased cecal pH values and caused a reduction in the total concentration of VFAs but a significant (P less than 0.05) increase in the undissociated form of some VFAs.

Intracloacal Salmonella typhimurium infection of broiler chickens: reduction of colonization with anaerobic organisms and dietary lactose.

The combined effect of treatments with dietary lactose plus anaerobic organisms on cecal colonization of broiler chicks by Salmonella typhimurium was evaluated. Chickens treated with a combination of anaerobic organisms and 7% dietary lactose were resistant to cecal colonization by S. typhimurium. The number of recoverable S. typhimurium cells per gram of cecal contents taken on days 10 and 15 after infection was significantly reduced. Treatment with anaerobes without the addition of lactose did not effectively control cecal colonization. Intracloacal inoculations with bacterial concentrations that varied by 10,000-fold resulted in roughly similar levels of colonization. The treatments resulted in reduced cecal pH and elevated levels of undissociated volatile fatty acids. Statistically significant correlations (P less than 0.01) were observed between the S. typhimurium concentrations in cecal material and the concentrations of undissociated fatty acids (r = -0.79, and between the bacterial counts and pH (r = 0.72).

In Vitro Inhibition of the Growth of Salmonella typhimurium and Escherichia coli 0157:H7 by Bacteria Isolated from the Cecal Contents of Adult Chickens

A Veillonella species and Enterococcus durans were isolated from the cecal contents of adult broilers. Mixed cultures of Veillonella and E. durans inhibited the growth of Salmonella typhimurium and Escherichia coli 0157:H7 on media containing 2.5% lactose (w/v). The growth of S. typhimurium or E. coli 0157:H7 was not inhibited by mixed cultures containing Veillonella and E. durans on media containing only 0.25% lactose or by pure cultures of Veillonella or E. durans on media containing either 0.25% or 2.5% lactose. The mixed cultures of Veillonella and E. durans produced significantly (P<0.05) more acetic, propionic, and lactic acids in media containing 2.5% lactose than in media containing 0.25% lactose. The inhibition of the enteropathogens was related to the production of lactic acid from lactose by the E. durans and the production of acetic and propionic acids from lactic acid by the Veillonella .

A continuous-flow high-yield process for preparation of lipid-free hemoglobin

Hypotonic hollow-fiber dialysis of bovine red blood cells followed by ultrafiltration through 0.1-micron pore hollow fibers provides a simple method for isolation of lipid-free hemoglobin. Hemoglobin (Hb) isolated by comparative techniques were all contaminated with membrane stroma. HPLC analysis of Hb revealed a protein peak of 99.6% purity and sodium dodecylsulfate-polyacrylamide gel electrophoresis analysis revealed a single band. The process requires hypoosmotic dialysis of bovine RBC to a final 160-180 mosmol/kg osmotic pressure. Additional reduction in osmotic pressure causes irreversible cell lysis which leads to lipid contamination of the Hb. Processing of 1/2 liter of packed red blood cells requires 4-5 h, resulting in an average of 90% hemoglobin recovery.

Glycosidase activity from midgut region of Stomoxys calcitrans (Diptera: Muscidae)☆

Abstract Midgut homogenates from Stomoxys calcitrans (L.) contain at least eight glycosidases. Glycosidase activity was found to change during digestion of the first blood meal. Enzyme activity was found for α-glycosidase, α-mannosidase, α-galactosidase, α- l -arabinosidase, β-galactosidase, β-glucosidase, β-glucuronidase, and N- acetylglucosaminidase . All enzymes had acidic pH optima of 5.0–6.5.

Proteolytic and haemolytic activity in the midgut of the stable fly Stomoxys calcitrans (L.): Partial purification of the haemolysin

Abstract Midgut proteolytic and haemolytic activities were determined in stable flies at various times after the flies were fed. A significant correlation was found between haemolytic activity and midgut protein levels. However, there was no correlation between proteolytic activity and midgut protein levels. Lipid extracts of midgut homogenates had high haemolytic activity. A thin layer chromatographic procedure was devised for isolating and purifying the haemolytic substance, haemolysin, from lipid extracts.

Possible correlations between reproductive performance of Stomoxys calcitrans and lipid content of blood diets

1. 1. Adult stable flies were fed blood meal diets of freeze-dried bovine or porcine blood, or fresh bovine or porcine blood, for ten consecutive generations; the reproductive performance of adults fed freeze-dried or fresh porcine blood was significantly higher (P < 0.05) than that of adults fed freeze-dried or fresh bovine blood. 2. 2. Quantitative analyses of cholesterol, triglycerides, phospholipid phosphorus, phospholipid classes, and fatty acid composition of the diet were made. 3. 3. There was no direct correlation between the percentage distribution of lipid classes and the fecundity of flies. However, the locations of phosphatidyl choline and sphingomyelin within the blood components may be a factor in the diet.

Hemolysin of the stable fly, Stomoxys calcitrans

Abstract 1. 1. A hemolysin found in whole fly homogenates and in midgut homogenates of Stomoxys calcitrans (L.) is heat labile, has a slightly acidic pH optimum, and is non-dialyzable. 2. 2. Hemolytic activity is enhanced by dialysis but not by removal of Ca2+ alone. 3. 3. The hemolytic curves obtained are sigmoidal, which suggests some cooperative acivity. 4. 4. This hemolysin is activated by addition of trypsin to the homogenates.

Studies on the biochemical basis of the nutritional quality of tsetse fly diets

Batches of freeze-dried pig and cow blood, whose nutritional value to G. p. palpalis ranged from low to near optimum, were analysed for amino acid, triglyceride and cholesterol content. The results of the chemical analyses were compared with the nutritional quality parameters observed when each batch of blood was fed to G. p. palpalis in an attempt to establish a chemical basis for the nutritional quality of diets for Glossina. In general, those pig or cow blood diets that had a higher nutritional quality also had a significantly higher amino acid content than the suboptimal diets. There were significant differences between the triglyceride and cholesterol content of pig and cow blood, with pig blood having more triglyceride, but less cholesterol than bovine blood. There was no apparent correlation between the triglyceride and cholesterol content and the nutritional quality of blood.

Ingestion, utilization and excretion of blood meal sterols by the stable fly, Stomoxys calcitrans

Abstract The daily ingestion, utilization, and excretion of the blood-meal lipids by the stable fly were determined for the first gonotrophic cycle. Based on TLC analysis of the excreta, all of the blood lipids were utilized except for sphingomyelin (