ALBERT

Description: SummaryDry-matter intake (D.M.I.) from Panicum maximum(guinea grass) was studied in digestibility trials with Holstein and water buffalo bulls and in a feeding trial with lactating cows.Differences in voluntary D.M.I. per unit body weight0·73 between the Holsteins and water buffaloes were not significant. Average D.M.I. for all bulls in all main trials was 2·16 kg per 100 kg B.W. Average D.M.I. by the lactating cows was 2·08 kg per 100 kg B.W., for all practical purposes the same as for the bulls.D.M.I. was not related to stage of maturity or season of harvest of the guinea grass. Intakes of digestible protein, T.D.N., and digestible energy in different seasons and at different growth stages were related to the percentage of those nutrients in the grass.Correlation coefficients were 0·68 between D.M.I. and B.W.0·73, 0·59 between D.M.I. and T.D.N. content, and 0·58 between D.M.I. and crude protein content, D.M.I. was not closely related to dry-matter content (r = 0·30) or crude fibre content (r= 0–01) of the guinea grass.

Description: Fifteen digestibility trials were conducted in the wet, early dry, and late dry seasons in the Philippines. Panicum maximum (guinea grass) was fed at growth stages of 1–4 months to Bos taurus (Holstein), Bos indicus (Red Sindhi), and Bos bubalis (water buffalo) bulls.Significant differences were shown between digestibility coefficients from water buffaloes and those from Holstein cattle, the former having a 5–7 % advantage in most cases. Ratios of volatile fatty acids in rumen fluid from the two species were not different. Separate tables of digestible protein, TDN and digestible energy values for guinea grass were computed for cattle and water buffaloes.

Description: SUMMARYGestating female pigs received either a low or a high intake per day of diets containing either a low or high protein concentration. A change in the composition of both diets occurred after 2 years, when the protein quality of the high protein diet was improved and the energy content of both diets was increased. Vitamin A determinations were carried out on 245 piglet livers and 32 pairs of kidneys and lungs at birth from 47 sows. The livers, kidneys and lungs of 16 sows were also analysed for vitamin A after approximately 4 years on experiment. Vitamin A was detected at birth with antimony trichloride in the liver of the piglet, but not in the kidney or lung. The sow's kidney was found to contain only small amounts and lung tissue only traces.A dietary vitamin A level of 4800 i.u./kg during the breeding life of healthy sows, or 8600 i.u./day during gestation, was adequate from the point of view of both a constant storage in piglet livers at birth over eight to ten parities and a relatively high concentration remaining in sow livers after that period. This conclusion is in line with recommendations of the Agricultural Research Council (1966).As a consequence of differences in both the condition of the sows and in their responses in the two periods, the results for each period are presented separately. In the first 2-year period, when the sows received a relatively low intake of dietary protein during gestation (between 248 and 317 g protein/sow/day), and a low energy intake; that is, when protein was used for energy production, the liver vitamin A storage of the piglet at birth was increased by raising either the daily protein intake during gestation to 352 g, or the food intake from 1·8 to 2·3 kg/sow/day. Liver vitamin A and N concentrations were negatively correlated with liver weight, but increasing dietary protein concentration raised liver weight and its vitamin A content. Liver vitamin A per piglet was not affected by litter size.A conclusion may not be drawn concerning the contribution of dietary energy to the differences in response between periods, because in addition to dietary changes other differences occurred between periods. Nevertheless, in the second 2-year period, when energy intake during gestation was adequate for normal growth and development, a difference of 150 g in protein intake/sow/day (363 g against 208 g) had no effect on liver weight or its vitamin A content. Furthermore, there was no significant treatment effect on total protein or albumin concentrations in the serum of the sow.

Description: SUMMARYAn experiment, involving 68 female pigs, was undertaken to measure the effects of two diets differing in protein content, and of two patterns of feeding. The animals were housed in an enclosed building. The experiment extended through several parities; culled sows were replaced by gilts during the experiment, the whole course of which lasted 5 years.The diets were given at the rate of 1–8 or 2–3 kg per day throughout gestation, but the rate was reversed during the 5-week lactation so that, for litters of eight to nine pigs sows in each treatment group received the same quantity of food per parity. As a result of unsatisfactory performance, dietary composition was changed after 2 years so that for the last 3 years the digestible energy contents were higher.Treatments significantly influenced gestation live-weight gain, lactation weight loss and gestation backfat gain. The lower rate of gestation feeding was associated with low or negative gestation weight increases after the third to fourth litters, and a greater apparent rate of decline with increasing age in birth and 3-week weight per piglet. The high gestation, low lactation, rates of feeding led to slightly greater litter size and lower weaning weights per pig. A daily intake of 208 g crude protein and 8'3 g lysine appeared to meet the sow's requirements throughout gestation.In the pregnant sow feeding area, winter air temperatures were on average 16 °C below those in the summer, but were rarely below freezing point. Winter backfat gain was lower than, and gestation gain only half that in the summer. Litter size was also greater following summer pregnancies and 3-week weight per pig was greater following winter pregnancies. Independent of litter size, birth and 3-week weight per pig were positively correlated with gestation gain within treatment and season. The apparent positive correlation of litter size at 3 weeks with gestation backfat and weight gain was not found at birth. Litter size at birth was negatively correlated with gestation gain within season. The percentage of fertile matingswas less for matings between 1 September and 31 January. This coincided approximately with the reduced litter size (alive) which occurred following winter gestations.Lactation weight loss and 3-week weight per pig declined with increasing age of sow and the degree of weight loss was unrelated to subsequent litter size.The apparent effect of seasons and treatments on litter size at birth appeared not to be an obvious function of changes in live weight, which were also marked between seasons and treatments, but level of food intake in early gestation may have affected litter size independently. It was concluded that birth weight especially in the older sows, was associated with the rate of food intake in gestation, and possibly also in lactation, and with gestation empty weight gain.

Description: The U.S. Geological Survey, at the Denver Federal Center, Lakewood, Colorado assays C14 concentration of water samples using liquid scintillation techniques. The laboratory synthesizes benzene from precipitated barium carbonate using techniques described by Noakes, Kim, and Akers (1967). Three ml of the synthesized benzene is pipetted into a tared, low potassium-40 glass vial. The sample is weighed and 1ml of a scintillation solution is added to the vial. The scintillation solution used is a mixture of 10g PPO and 0.025g dimethyl-POPOP scintillators in 250ml toluene. Calculations of dates are made with the radiocarbon half-life of 5568 years; plus or minus numbers quoted herein are the standard error for the counting of radioactive disintegrations.

Description: The radiocarbon dating laboratory at the USDA Sedimentation Laboratory was established to supplement current watershed geomorphologic investigations. The principal objective of the program is to provide information on valley aggradation rates and sequences.

Description: In this paper, we study the propagation of a shock wave in water, produced by the expansion of a spherical piston with a finite initial radius. The piston path in the x, t plane is a hyperbola. We have considered the following two cases: (i) the piston accelerates from a zero initial velocity and attains a finite velocity asymptotically as t tends to infinity, and (ii) the piston decelerates, starting from a finite initial velocity. Since an analytic approach to this problem is extremely difficult, we have employed the artificial viscosity method of von Neumann & Richtmyer after examining its applicability in water. For the accelerating piston case, we have studied the effect of different initial radii of the piston, different initial curvatures of the piston path in the x, t plane and the different asymptotic speeds of the piston. The decelerating case exhibits the interesting phenomenon of the formation of a cavity in water when the deceleration of the piston is sufficiently high. We have also studied the motion of the cavity boundary up to 550 cycles.

Description: A theoretical analysis has been made of turbulent viscous interaction on iso-thermal surfaces at hypersonic speeds. The important parameters governing the effects of incidence and displacement have been obtained under both strong and weak interaction conditions for flat-plate flows. A more general expression relating boundary-layer growth to the external pressure field and effective body shape has been obtained. The method is applied to the wedge compression corner problem and the results compared with some experimental data. © 1974, Cambridge University Press. All rights reserved.

Description: We observed a gradual change in the structure of a shock wave passing through a long tube of bubbly liquid, which we attribute to the motion of the bubbles relative to the liquid. We show that the effect of the motion on the structure of a shock wave is like that of thermal relaxation on gasdynamic shock waves: the pertinent relaxation time is the time viscous forces in the fluid take to alter the velocity of a bubble to that of the fluid. Our theory predicts certain changes in the speed of the shock wave and in its structure. We could not verify the prediction as to wave speed: in dilute mixtures it is too small to be measured. But we report experiments on the structure of the wave, which support our theoretical conclusion that the observed changes are due to the relative motion. © 1974, Cambridge University Press. All rights reserved.