Different Degrees Of Response Research Articles

Fat Absorption from the Small Intestine of Gnotobiotic Chicks1

The small intestine of 3-week-old gnotobiotic chicks was divided into five equal segments for analysis. Since it has been found that most fat absorption occurs in the third and fourth segments, they were selected for study. The major fatty acids in the diet and the feces of chicks were palmitic, stearic, oleic, and linoleic acids. Consequently, these fatty acids were selected for quantitative analyses in the absorption studies. Germ-free chicks were contaminated at 7 days of age with bacteria isolated from the third and fourth intestinal segments, except for the Escherichia coli contaminant, which had been previously isolated from a chicken with air sac disease. There were two different degrees of response by chicks to the bacterial contaminants in this study. For this reason, the chicks were placed retrospectively into two categories according to their response to environmental conditions. The first category (A) contained germ-free chicks and chicks monocontaminated with E. coli, Staphylococcus, or Lactobacillus. The second category (B) was composed of conventional chicks and chicks monocontaminated with Streptococcus faecalis or Clostridium welchii, dicontaminated with S. faecalis and C. welchii, and accidentally polycontaminated with coliforms and anaerobic gram-positive bacilli. Chicks in category A demonstrated increased absorption of palmitic and stearic acids and total fat as compared to category B chicks. Conversely, category B chicks showed slightly increased absorption of oleic and linoleic acids. Thin-layer chromatographic analyses demonstrated that cholesterol esters were affected similarly to fatty acids. The site of absorption of fatty acids, cholesterol esters, and total fat was unchanged, regardless of the environment.

Salt Concentration a Factor in the Availability of Phosphorus from Rock Phosphate as Revealed by the Growth and Composition of Alfalfa

AbstractA study of the availability of phosphorus held in rock phosphate in relation to the soluble salt content of sandclay cultures was made. An effort was made to relate the availability of the phosphorus to the relative bonding energies of Putnam clay for calcium, magnesium, potassium, and hydrogen. Alfalfa was grown as the test crop. The less than 0.2 µ Putnam clay was brought to desired cation saturation by making the system unsaturated by treating the Na suspended clay with hydrogen‐Amberlite (IR‐120), electrodialyzing to reconcentrate, and then adding carbonates or hydroxides of Ca, Mg, and K. Trace elements and nitrogen as ammonium nitrate were added in small amounts. Phosphorus was added as either rock phosphate or phosphoric acid. Calcium, magnesium, potassium, and sodium salts were added. Calcium and magnesium salts were added in series at 0.010, 0.020, 0.041, 0.081, and 0.163 moles per liter and potassium and sodium salts at 0.020, 0.041, 0.081, and 0.163 moles per liter of soil water.The results showed all salts influenced the availability of phosphorus held in rock phosphate. However, calcium salts reduced phosphorus uptake with small reduction in plant yields. Variable effects on plant yields and phosphorus uptake resulted when magnesium salts were used. Potassium salts of different anions produced different degrees of response, with the first increments of the carbonate and sulfate giving a positive yield response while the chloride depressed growth and phosphorus uptake. Sodium sulfate gave a reduction in crop yields and phosphorus uptake indicating an influence of excessive sodium.