Arthur H. Smith

Acetate as a precursor of amino acids of casein in the intact dairy cow.

Five lactating dairy cows were injected intravenously with acetate-I-14C or acetate-2-14C. Eight amino acids, recovered from casein collected at 3, 10, 22, and 34 hours after acetate-14C injection, were assayed for carbon-14. Carbon from acetate was transferred most efficiently to glutamic and aspartic acids and in lesser amounts to alanine, serine, glycine, proline, and arginine. Lysine did not contain significant amounts of 14C. The labeling of amino acids from acetate-14C differed markedly from that previously observed for glucose-14C. Carbon from uniformly labeled glucose was transferred most efficiently to alanine and serine and in smaller amounts to glutamic and aspartic acids, glycine, proline, and arginine. The specific activities of alanine, serine, and lactose were quite similar after acetate-14C injection suggesting a close relationship between the precursors of the three carbon amino acids and lactose. The distribution of 14C among the amino acids formed by the intact cow was consistent with results that would be expected if the TCA cycle and the glycolytic pathway were the pathway for transfer of carbon from acetate to amino acids of casein.

Weight Growth of Colony-Reared Chimpanzees

Body weight data, collected routinely from the US Air Force chimpanzee colony at Holloman AFB, was used for a longitudinal analysis of growth. Data were fitted to a model based on human growth patterns, which is described and compared to other treatments applied to growth data. Results are compared to other observations of chimpanzee and of human growth.

The effect of chronic erythrocytic polycythemia and high altitude upon plasma and blood volumes.

Conclusion Chronic erythrocytic polycythemias were produced in adult female domestic fowl (chicken): (a) hormonally (by androgen injection) at sea level, or (b) by protracted high-altitude (12,500 ft) exposure. Plasma volumes were determined directly by injected 131I human serum albumin dilution methods. Total body erythrocyte and blood volumes were calculated from plasma volumes and adjusted peripheral hematocrits. Androgen treatment or high-altitude exposure similarly increased the hematocrits approximately 45% and the body erythrocytic volumes approximately 65%. These two procedures, however, affected the plasma volumes differently. No change in plasma volume was found at high altitude; however, there was a significant (17%) reduction in plasma volume in the androgen-treated birds as compared with either the sea-level controls or the high-altitude birds. It appears, therefore, that the vascular system of the body accounts for an increase in erythrocytic mass by either (a) a reduction in plasma volume or (b) no change in plasma volume, in which case differential changes occur in total blood volumes.

Tissue metabolism in growing birds.

Conclusions 1. Tissue respiration studies show that oxygen consumption rate of mature chicken liver slices fits body weight-tissue metabolic rate relationship derived by Kleiber (5) for mature mammals. The oxygen consumption rate of mature chicken kidney slices, however, is much lower than that of mature mammals(7). 2. The relationship between tissue and whole animal metabolic rate in growing chickens is different for the kidney and liver. The Qo2 of kidney tissue (homogenate or slice) is essentially the same for all age groups of birds tested. The Qo2 of liver tissue in vitro is the same for very young and mature birds, but is significantly higher in one-month-old birds. This same sequence has been noted by Kleiber(2) in the whole animal metabolic rate (per unit weight) of growing birds.

Secretion in cow's milk of intravenously injected radioactive phosphorus P32.

Summary Intravenous injection of 15 and 30 millicuries of P32 respectively into 2 lactating cows produced a maximum relative activity per liter of milk of 1.2% of the injected dose at about 5 hours after injection. The relative activity per liter milk is plotted against time after injection and regression equations are presented for interpolating the data. A week after injection, the milk still contains slightly over 0.1% of the injected p32 per liter. Casein with a radioactivity of 2 microcuries per gram was prepared out of milk collected during 3 days after injection of 40 millicuries of P32. A histogram shows the relative rate of P32 secretion in milk. In a week, the 2 cows secreted in their milk 20 and 23% respectively of the injected P32.

Mobility of skeletal phosphorus in a mature dairy cow as determined with radioactive phosphorus.

Summary 1. Radioactive P32 was injected intravenously to measure the “labile” phosphorus pool in the skeleton of a mature, lac-tating dairy cow. This pool contains about 15% of the total skeletal phosphorus which was 15 times as large as the total circulating phosphorus pool in the plasma. 2. Autoradiograms and radioassays indicated that this labile pool extended throughout the skeleton but its distribution was determined by the type of bone involved. Cortical bone contains only one-third as much phosphorus in the labile state as does trabecular bone. 3. About 12% of the injected phosphorus-32 was present in the skeleton at the time of slaughter of the animal, 3 days after the injection.

Lactation activity, chemical composition, and in vitro metabolism of rat mammary tissue.

Summary Mammary tissue of rats at the end of pregnancy and at the height of lactation was analyzed for dry matter and nitrogen content, and the metabolic rate of this tissue was measured in vitro. Lactation increased the water content of the mammary tissue and the protein content of the mammary dry matter. Lactation did not affect the metabolic rate per unit of fresh tissue in vitro; it increased the metabolic rate per unit of dry matter and decreased the metabolic rate per unit of nitrogen in the tissue. Observations were also made on rats that suckled only 1-3 instead of 6 young; and measurements were taken on rats with 6 young at earlier stages of lactation before full milk production was reached. These indicate a positive correlation between the intensity of lactation and the magnitude of the effect that lactation has on the composition and metabolic rate of mammary tissue.

Organ and Body Mass Changes in Restrained and Fasted Domestic Fowl

Summary Organ and body mass changes in restrained adult, male domestic fowl were compared with tissue from control and fasted animals. Body mass loss rate in the restrained animals was 63.5% (p < .001) greater than in the fasted group, yet the two groups recovered at the same rate. Compared with controls and fasted animals, restrained fowl exhibited an increase in size of heart, lungs, kidneys, liver, and adrenals but a greater loss of spleen, superficial pectoral muscle, small intestine, and pancreas masses. Relative water content of organs generally increased in restrained and decreased in fasted animals. The data suggest that restraint—although accompanied by inanition—affects organ and body mass in the domestic fowl in a different way than does fasting.

Independent Influence of Chronic Hypoxia and Sexual Development Upon Circulating Erythrocyte Concentration in Male Chickens.

Summary In cockerels raised at high altitude and sea level, and with the sexual development of some repressed by stilbestrol treatment, it is possible to differentiate the erythropoietic effect of androgens and chronic hypoxia. The actions of these factors appear to be independent of each other, a particular level of androgen (indicated by gonad size) producing equal increments in the hematocrit, in either the presence or absence of hypoxia.

Effect of artificial changes in egg composition on hatchability and chick growth.

Summary and Conclusions Artificial decrease in albumen quality and quantity caused by local X-irradiation of the oviduct reduces the hatchability of eggs. The distribution of embryo mortality is different from that encountered in normal eggs: very early mortality is markedly increased. Chicks from such eggs have a lower hatch weight; however, no effect on subsequent chick growth was observed.