Biomedical subjects
Publications and source records attributed to D L Garling.
The antimicrobial activity previously attributed to flavanone Mannich bases was found to be due to their breakdown products, 3-methyleneflavanones. Among the latter compounds, highest potency was observed when the flavanone phenyl ring contained bromine or chlorine substituents. 3-Methylene-2-phenylflavanone (8) was synthesized and shown to be equal to hexachlorophene in tests against representative Gram-positive microorganisms.
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The pH of amino acid test diets has been shown to be of major importance in dietary amino acid studies in the channel catfish (Ictalurus punctatus). Maximum growth rate and feed conversion was observed when the test diet was adjusted to pH 7. Growth studies, utilizing a 24% crude protein diet containing an amino acid pattern similar to whole egg protein, indicate that the lysine requirement for fingerling channel catfish is about 1.23% of the diet (dry weight basis) or 5.1% of the dietary protein. The dietary requirement was confirmed by serum free lysine analysis. A marked increase in serum free lysine occurred at a dietary lysine level of approximately 1.2% of the diet.
Twenty-one semipurified diets were formulated to determine the optimum protein:energy ratio (P/E) for channel catfish fingerlings. Seven crude protein levels and three energy levels at each protein level were utilized. The protein, lipid, and digestible carbohydrate sources were hexane-extracted whole egg powder, salmon-corn oil mixture, and white dextrin, respectively. After an initial 2 week conditioning period, the experimental diets were fed in triplicate to groups of 30 +/- 3 channel catfish fingerlings weighing 205 +/- 10 g and kept in 110 liter flow-through aquaria at 26.7 +/- 1.1 degrees. The diets were fed at a rate equalling 3% of the total wet body weight/day divided into three equal feedings and adjusted weekly for 9 weeks. An approximate fivefold increase in body weight was observed. These data indicate that the concept of P/E ratios must be restricted to diets containing adequate levels of protein and total energy. Based on average daily gain, diets containing energy levels between 275 and 341 kcal/100 g had an optimum P/E ratio of approximately 88 (24-36% crude protein). Diets containing 24% crude protein and 275 kcal/100 g diet appeared to be utilized more efficiently in terms of percent protein deposited than diets containing higher crude protein levels.