Evaluation of methanol-grown bacteria and hydrocarbon-grown yeast as sources of protein for poultry: trials with laying birds.

1. Two 90-d trials were carried out with laying hens at peak production, for the evaluation of two single-cell protein (SCP) sources in practical-type layer diets of relatively low protein content. The SCP tested were: Pruteen, produced from methanol-utilising bacteria, and a Lavera-type yeast which utilises the normal paraffins of heavy gas oil. 2. In one trial the inclusion of 50 g yeast/kg diet had little effect on performance. Pruteen at the same concentration decreased production rate and egg size due to a significant reduction in food consumption (5%), but did not affect food utilisation. 3. In another trial diets containing 60 and 100 g Pruteen/kg had similar, non-significant depressive effects on production rate (about 8%), without affecting food intake, egg size or body weight. 4. The relatively low arginine concentration in Pruteen necessitated increasing the dietary protein content in order to meet the calculated requirements. 5. A 17-carbon fatty acid was introduced at low concentration into the diet by the inclusion of 100 g Pruteen/kg; only traces of it could be detected in the yolk lipids of eggs laid by hens fed on this diet.

Regulation of de novo purine synthesis in chick liver slices. Role of phosphoribosylpyrophosphate availability and of salvage purine nucleotide synthesis.

The differences between the uricotelic chick and the ureotelic rat, in the regulation of purine synthesis de novo, were studied in intact liver tissue. Chick liver, in comparison with rat liver, was found to contain a high activity of purine synthesis de novo, a high content and availability of 5-phosphoribosyl 1-pyrophosphate (PP-rib-P), comparable activity of PP-rib-P synthetase, and low activity of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and of adenine phosphoribosyltransferase (APRT). The results suggest that the intensive activity of the pathway of purine synthesis de novo in the chick liver is mediated by the high PP-rib-P concentration, which may be due at least in part to the relative partial deficiency of HGPRT.

Utilization of choline from crude soybean lecithin by chicks. 1. Growth and prevention of perosis.

Data obtained with growing chicks fed a semi-purified diet indicate that choline from crude soybean lecithin is as well utilized as synthetic choline chloride, on the basis of growth, relative liver weight and prevention of perosis. Extrapolation of the results on growth and perosis prevention, obtained between 1 and 3 weeks of age, to performance on practical-type diets yields choline requirements for broiler-type chicks ranging from 800 to 1000 mg./kg. diet (as choline chloride). The requirement seems to decrease with age.

The effect of ribose 5-phosphate and 5-phosphoribosyl-1-pyrophosphate availability on de novo synthesis of purine nucleotides in rat liver slices.

The effect of increasing cellular ribose 5-phosphate (ribose-5-P) availability by methylene blue-induced acceleration of the oxidative pentose phosphate pathway on the rate of 5-phosphoribosyl-1-pyrophosphate (P-ribose-PP) generation, was studied in slices of rat liver at varying Pi concentration. It was found that at Pi concentration prevailing in the tissue of extracellular physiological Pi concentration, ribose-5-P availability is saturating for P-ribose-PP generation, as gauged by the rate of adenine incorporation into tissue nucleotides. The effect of altering P-ribose-PP availability on the rate of de novo purine production gauged by the rate of formate incorporation into purines, was also studied. It was found that the physiological P-ribose-PP concentration in rat liver tissue is limiting for purine synthesis de novo. Depletion of cellular P-ribose-PP, achieved by increase of P-ribose-PP consumption, decelerated purine synthesis, while increase of P-ribose-PP availability, achieved by activation of P-ribose-PP synthetase occurring at elevated Pi concentration, resulted in acceleration of purine synthesis.

The replacement of some of the soybean meal by the first limiting amino acids in practical broiler diets. I. The value of special supplementation of chick diets with methionine and lysine.

1. Three trials were carried out in order to determine the amount by which dietary protein concentration can be reduced while maintaining the dietary concentrations of the first two limiting amino acids, methionine and lysine. 2. In all trials growth rate and food utilisation declined as the protein concentration of a well-balanced standard chick diet was lowered by replacing soybean meal with sorghum grain (milo), but this trend could be partly or completely prevented when methionine or methionine and lysine levels were restored. 3. Addition of 0-06 to 0-07% methionine, above that considered to be normal, is sufficient to replace approximately 0.9% soybean protein. 4. In diets containing approximately 3 percentage units less soybean protein than required, a supplementation of about 0.15% each of methionine and lysine can replace nearly 2-0% soybean protein, but cannot bring about chick performance equal to that obtained on the control ration, indicating an insufficiency of a third, or third and fourth, limiting amino acid in such low-protein diets.

The replacement of some of the soybean meal by the first limiting amino acids in practical broiler diets. 2. Special additions of methionine and lysine as partial substitutes for protein in finisher diets.

1. Four trials were conducted to determine to what extent dietary protein concentration could be lowered while maintaining the concentrations of methionine and lysine, the first two limiting amino acids. 2. When the protein concentrations of well-balanced standard finisher diets were lowered by replacing soybean meal with sorghum grain (milo), there were progressive decreases in growth rate and increases in food consumption in spite of the substitution raising the energy content of the diets. 3. Maintaining methionine and lysine concentrations partly or completely reversed these trends. 4. Adding 0-12% methionine (above that generally considered to be the normal level in finisher diets) plus 0-20% lysine replace about 3 to 4 percentage units of soybean protein. 5. The recommended level of lysine supplementation may be exaggerated, since preliminary data indicate satisfactory results with a special supplementation of 0-10% each of methionine and lysine.