Depletion Ration Research Articles

Some Exergetic Measures of a JT8D Turbofan Engine

In this article, some exergetic measures are calculated for a JT8D turbofan engine at takeoff. Selected exergetic measures in this study are as follows: fuel depletion ration, productivity lack ratio, fuel exergy factor, product exergy factor and improvement potential rates. The engine has low-pressure compressor (LPC) stages, high pressure compressor (HPC) stages, a single HP turbine (HPT), and finally three LPT stages. The exergetic assessment of the JT8D turbofan components provided here should be helpful for designing turbofan engines. Results from this study also evaluate effects of the maximum power setting on the exergetic measures of the engine components commonly used in medium range commercial aircrafts. 

Reevaluation of the Minimum Vitamin A Requirement of Holstein Male Calves Based Upon Elevated Cerebrospinal Fluid Pressure

Forty-one male Holstein calves whose average age was 60 days, live weight 74kg and plasma vitamin A concentration 8.4μg/100ml were fed a vitamin A depletion ration plus one of five daily vitamin A acetate intakes equivalent to 4, 12, 16, 64 or 256μg of retinol per kilogram of live weight for 16 weeks. Daily ration consumption averaged 3.0 kg/day, and live weight increased .81kg/day. The incidence of diarrhea, the number of treatments for diarrhea, and the number of calves exhibiting convulsions were greater in the calves fed the lowest vitamin A intake of 4μg. Average plasma vitamin A concentrations increased .8μg/100ml for each 10% increase in vitamin A intake and terminal values increased .9μg/ 100ml. Cisternal cerebrospinal fluid (CSF) pressures were maintained at a geometric mean of 68mm of saline at vitamin A intakes greater than 29μg per kilogram of live weight. For each 10% decrease in vitamin A intake below the 29μg intake, CSF pressure increased by 8.6%.

Content of Sodium and Potassium in Supraspinatus Muscle from Hypovitaminotic A Holstein Calves

Twenty-three six-week-old Holstein male calves were fed a vitamin A depletion ration, at levels anticipated to produce a weekly increase in live weight of 5%, supplemented with one of four vitamin A intakes : 4, 12, 36, or 108μg per kilogram of live weight per day for a 16-week period. Live weight gain was slightly less in those calves fed the 4 and 12μg intakes. Plasma vitamin A concentrations essentially reflected intakes of the vitamin, and cerebrospinal fluid pressure was elevated in the calves fed the 4 and 12μg intakes, with the degree of elevation related inversely to the vitamin intake. Dry matter and sodium contents of the supraspinatus muscle were unaffected by vitamin A intake. Slightly lower ash and potassium concentrations were found in the muscle of those calves fed the 4 and 12μg intakes of the vitamin, but when these constituents were expressed on a dry matter basis, there were no apparent effects due to level of vitamin A intake.

Volume and Osmolality of Urine of Hypovitaminotic A Holstein Heifers

Five heifers, approximately 1 yr of age, were previously fed a vitamin A depletion ration containing 3.4% iodized salt and restricted water intake until cerebrospinal fluid pressure (CSFP) was elevated to an average of 348mm of saline. During a 24-hr period in which no water or feed was allowed, these heifers excreted greater volumes of urine of lower osmolality than did five heifers fed the same ration plus adequate amounts of carotene and having normal CSFP's (Experiment I). The ratio of urine osmolality to serum osmolality was less in the heifers receiving no carotene. Similar results as to trend were obtained for two vitamin A-deflcient heifers of approximately 2 yr of age, when compared with two control heifers fed adequate amounts of carotene, except that the salt content of the ration for the four animals was only 0.7% and water intake was allowed ad libitum (Experiment II). In the deficient heifers on the second experiment, hemodilution, hyponatremia, and possibly hyperkalemia were accompanied by outward signs of edema. The greater urine volume and lower urine-to-serum-osmolality ratio of the deficient animals were attributed to reduced renal-concentrating capacity and impaired water homeostasis.

Utilization of Carotene from Corn Silages by Steers

Silages were made from well-eared, well-matured corn which had received a normal rate of fertilization and from corn which had received an additional 200 lb. of nitrogen per acre. Neither silage contained significant amounts of nitrates. However, the high nitrogen-fertilized silage contained less beta carotene. Hereford steer calves grazing green pasture had high initial blood plasma carotenoids but low levels of vitamin A. After being fed a carotene-deficient ration consisting of white corn, molasses dried beet pulp and soybean meal for 61 days, plasma carotenoid levels declined markedly but vitamin A values increased to normal. The carotene-deficient ration at different levels of intake resulted in varying rates of gain but did not influence the rate of vitamin A depletion. Fifty-six steers which had been fed the depletion ration for 137 days were fed silage rations for 126 days. Blood plasma carotenoid and vitamin A levels quickly returned to normal after the silage rations were fed, and supplemental vitamin A had no measureable effect. Forty-two non-depleted steers were fed silage rations for 182 days, followed by a full feed of ground ear corn for 56 days. Feeding 20,000 I.U. of vitamin A per head daily brought about no improvement in performance or carcass value. However, plasma vitamin A values of nonsupplemented steers declined when the ear-corn ration which contained suboptimum amounts of carotene was fed. Growing-fattening steers were able to meet their daily vitamin A requirements from the carotene supplied by the corn silages. There were no apparent differences in feeding value of silages from corn which had received normal or excessive amounts of nitrogen fertilization.

Some Biochemical Constituents in Urine of Vitamin A-Deficient Holstein Calves

Summary To study possible effects of hypovitaminosis-A on urine composition, 30 male Holstein calves, average age 53 days and live weight 158lb, and partially depleted of their vitamin A reserves, were fed a vitamin A depletion ration supplemented with artificially dehydrated alfalfa leaf meal to provide a deficient or adequate carotene intake, 15 or 150 μ g per pound of live weight daily. Cerebrospinal fluid pressures were higher in the deficient group accompanied by lower vitamin A concentrations in the plasma and liver. Specific gravity, osmolality, and total solids of urine were significantly lower in the calves receiving a 15 μ g intake. Concentrations and total daily outputs of urea nitrogen and creatinine were slightly less in the urine of the deficient calves. To further study urine composition, repeat collections were made with five pairs of calves. In the deficient calves, average osmolality was again less, as well as concentrations and total daily outputs of sodium and chloride. Potassium was unaffected, but concentrations and total daily outputs of phosphorus were greater. The latter element was the only criterion which was significantly different. Kidney calcium concentrations were slightly higher.

Effect of Level of Ration Intake and Duration of Vitamin A Deficiency Upon Some Biochemical Constituents in Serum, Cerebrospinal Fluid, and Aqueous Humor of Holstein Calves Fed Fixed Carotene Intakes

Summary Forty-eight male Holstein calves, averaging 79±6 days of age and 7.2±1.8 β of vitamin A per 100ml of plasma, were fed one of two intakes of a vitamin A depletion ration, 100%, estimated to provide an anticipated weekly gain of approximately 10lb, or 60%, which was six-tenths of the ration allowance of the 100% intake group, for one of two durations, 12-wk or 24-wk, and one of six carotene intakes from artificially dehydrated alfalfa, 10-, 20-, 30-, 40-, 50-, or 60-β per pound of live weight per day. Marked differences between the 60% and 100% intake groups were observed in daily rate of live weight gain, 1.36 vs. 2.08lb, in heart rate, 74 vs. 88 beats per minute, in the QT electrocardiographic interval, 0.364 vs. 0.314sec, and in the systolic index, 0.400 vs. 0.378. These differences in the calves fed the 60% level of ration intake were accompanied by higher concentrations of plasma and liver vitamin A, by slightly lower cerebrospinal fluid pressures, and by an alteration in the protein distribution of serum and cerebrospinal fluid. The latter changes were primarily attributable to decreases in the beta-globulin fraction. Also, slightly lower concentrations of chloride in serum and of sodium and potassium in cerebrospinal fluid occurred in the 60% level of ration intake calves. To maintain equivalent cerebrospinal fluid pressures, calves fed the 60% level of ration intake required 0.74 as much carotene as calves fed the 100% level of ration intake, and to maintain equivalent liver vitamin A stores per unit of live weight, 0.86 as much carotene. Duration of deficiency, either 12-wk or 24-wk, had an inappreciable effect on most of the criteria studied. There was some indication of greater cerebrospinal fluid pressures in the calves fed the three lowest carotene intakes for the 24-wk duration than in comparable calves of the 12-wk grouping, as well as higher serum magnesium and cerebrospinal fluid sodium concentrations. Calves fed the three lowest carotene intakes, deficient as evidenced by elevated cerebrospinal fluid pressures, exhibited greater protein concentrations in serum and cerebrospinal fluid (also slightly greater in aqueous humor but not statistically significant) than did calves fed the highest three carotene intakes, adequate as evidenced by no elevation in cerebrospinal fluid pressures. These increased total protein concentrations were attributable, primarily, to increases in the beta-globulin fraction and to a lesser degree in the gamma-globulin fraction.

Effect of Duration of Deficient Carotene Intake upon Subsequent Utilization of Carotene from Alfalfa by Holstein Calves

Summary Thirty-two Holstein male calves, approximately 63 days of age, were fed a vitamin A depletion ration at an intake to provide an anticipated seven-day increase in live weight of 10lb. until partially depleted of their vitamin A stores. When the average plasma vitamin A concentration was 8.0±1.8 γ per 100ml., each calf was then fed in addition to the vitamin A depletion ration, one of two initial period carotene intakes per pound of live weight per day, 12- or 48-γ, for one of two durations, 4- or 16-wk. Each calf was then changed to one of two final period carotene intakes, 60- or 240-γ. Durations for the final periods were either 24 wk. for the calves fed the initial period carotene intake for 4 wk., or 12 wk. for the calves fed the initial period carotene intake for 16 wk. During the terminal seven-day period of the initial 16-wk. carotene intake period, only those calves fed the 12-γ carotene intake had cerebrospinal fluid pressures above 120mm. of saline. During the terminal seven-day period of the 12-wk. final carotene intake period, those calves fed the 12-γ initial period carotene intake and the 60-γ final period carotene intake had pressures greater than 120mm. but of smaller magnitude than observed during the initial carotene intake period. Based upon blood plasma and liver vitamin A concentrations, determined on samples obtained terminally during the final carotene intake period, calves fed the 12-γ initial carotene period intake for 16 wk. utilized the 60- and 240-γ carotene intakes 0.6 to 0.8 as effectively as calves fed 48-γ carotene intake initially. While the differences between the 12- and 48-γ carotene for the 4-wk. duration were slight, across both the 4- and 16-wk. durations, calves fed the 12-γ intake utilized carotene between 0.7 and 0.9 as efficiently as calves fed the 48-γ intake.

Some Biochemical Constituents in Serum, Cerebrospinal Fluid, and Aqueous Humor of Vitamin A Deficient Holstein Calves

Summary Sixteen male Holstein calves previously raised to 63 days of age on a limited whole milk, limited starter, and ad libitum chopped alfalfa hay ration were fed a vitamin A depletion ration until their plasma vitamin A averaged 8.3 ± 2.2 γ per 100 ml. Each calf was then fed for a 16-wk. period one of four carotene intakes, 16 or 24 γ per pound of live weight per day, to provide marked increases in cerebrospinal fluid pressure, 32 γ, to provide slight elevation in pressure, or 40 γ, to provide no elevation. Terminal cerebrospinal fluid pressure decreased with increasing intakes of carotene, apparent intraocular (scleral) pressure exhibited no consistent change, and plasma and liver concentrations of carotenoids and vitamin A increased. Of the biochemical constituents studied, no trends with carotene intake were observed for serum, and only potassium of cerebrospinal fluid decreased slightly; whereas, for aqueous humor, sodium was higher in the calves fed the 16-, 24-, and 32-γ carotene intakes, potassium increased with an increase in carotene intake, chloride decreased, and osmotic pressure was greater in calves fed the 16-, 24-, and 32-γ carotene intakes than in those fed the 40-γ intake. These results do not directly explain the increased cerebrospinal fluid pressure or change in aqueous humor composition occurring in vitamin A deficiency. However, the data pertaining to cerebrospinal fluid suggest either an overproduction or underabsorption of fluid (without change in the concentration of the constituents in serum or cerebrospinal fluid), resulting in greater volume within the restricted subarachnoid space and ventricles of the central nervous system.

Sensitivity of Blood Plasma and Liver Vitamin A Concentrations and Vitamin A Depletion Time to Carotene and/or Vitamin A Intake

Summary Blood plasma vitamin A concentrations and liver vitamin A concentrations obtained at slaughter, upon the completion of a carotene and/or vitamin A supplement feeding period and vitamin A depletion time (the weeks required for the blood plasma vitamin A level to decrease to 4.0 γ/100ml., when only a vitamin A depletion ration was fed upon completion of the supplement feeding), were obtained from five experiments. In four of these, Holstein calves previously partially depleted of their vitamin A stores were fed carotene intakes ranging from 12 γ to 540 γ per lb. live weight per day and/or vitamin A intakes ranging from 2.0 γ to 62.5 γ for periods of either 12 or 16 wk. In the fifth experiment, Hereford steers previously grazing native grass pasture were fed intakes of vitamin A from 5.8 to 116.0 γ for a period of 40 wk. The following results were obtained: (1)Average coefficients of variation across all experiments were 19.4% for plasma vitamin A, 9.2% for log (liver vitamin A), and 18.6% for vitamin A depletion time. Thus, log (liver vitamin A) exhibited a smaller experimental error as a percentage of its mean than either plasma vitamin A or vitamin A depletion time. (2)Average sensitivities of these criteria to carotene or vitamin A intake, which was defined as the ratio of the linear slope of the response criteria on intake to the standard deviation of the criterion, Mandel and Stiehler (10), was 4.6 for plasma vitamin A on log (intake), 7.8 for log (liver vitamin A) on log (intake), and 0.1 for vitamin A depletion time on actual intake. Calculation of the sensitivity of vitamin A depletion time in terms of log (intake) gave a range of sensitivities between 0.3 and 23.9, which increased with the intake level. Depletion time was calculated to become more sensitive than plasma vitamin A at carotene intakes of greater than 110 γ and vitamin A intakes of greater than 18 γ, and more sensitive than log (liver vitamin A) at carotene intakes of greater than 126 γ and at vitamin A intakes of greater than 22 γ.

Effect of Some Antioxidants on the Utilization of Carotene by Holstein Calves

Summary The effect of three antioxidants, N,N′-diphenyl-para-phenylenediamine (DPPD), 6-ethoxy-2,2-4-trimethyl-1,2-dihydroquinoline (Santoquin), and 2,5-ditertiarybutylhydroquinone (DTBH), on the utilization of carotene from alfalfa was studied with 32 male Holstein calves. These calves were raised to 63 days of age on a standard limited whole milk, limited starter, and free-choice alfalfa hay regime. On the 64th day of age each calf was fed an intake of a vitamin A depletion ration to provide an anticipated rate of gain in live weight of 10 lb. per 7-day period. When the blood plasma vitamin A level for each calf had decreased to or less than 10.0 γ/100 ml., each calf was then fed either 60 or 540 γ carotene from artificially dehydrated alfalfa per pound live weight per day without or with the addition of one of the three antioxidants at 0.01% of the ration for 12 consecutive 7-day intervals. Upon completion of this period, the comparison period, the carotene was removed from the rations of all calves and the antioxidants from the rations of half the calves previously receiving them. This regime, the final depletion period, was maintained until each calf's blood plasma vitamin A concentration decreased to less than 4.0 γ per 100 ml. for two consecutive 7-day intervals, at which time the calf was slaughtered. The following results were found: 1. Calves fed antioxidants during the comparison period, when carotene from alfalfa was included in the ration, had higher concentrations of carotenoids in the plasma than did the control calves. 2. Calves fed antioxidants during only the comparison period and calves fed antioxidants during both the comparison and final depletion periods had longer vitamin A depletion times than the control calves. This finding indicated greater vitamin A storage at the end of the carotene feeding period and thus greater utilization of carotene. 3. Based on the inappreciable differences of the responses between calves fed antioxidants during only the comparison period and those fed antioxidants during both the comparison and final depletion periods, it was suggested that the main site of activity of the antioxidants with respect to their effect on utilization of carotene was the gut. 4. Upon the completion of the final depletion period, liver lipids and liver total tocopherol concentrations were slightly greater in the calves fed antioxidants. 5. At the end of the final depletion period calves fed DPPD had significantly lower spinal fluid pressures than the controls or those fed Santoquin or DTBH.

Relative Value of Carotene from Alfalfa and Vitamin A from a Dry Carrier Fed at Medium to High Levels to Holstein Calves

Summary Forty-eight 63-day-old male Holstein calves, previously fed limited whole milk to 35 days of age and up to 3.0 lb. of starter and ad libitum chopped alfalfa hay, were fed an intake of a vitamin A depletion ration to give an anticipated 10 lb. increase in live weight per 7-day period. When the blood plasma vitamin A level for each calf decreased to 10.0 γ/100 ml. or less, each calf was fed in addition to the depletion ration one of three levels of carotene, 60, 180, and 540 γ from alfalfa, or one of three levels of vitamin A, 5.5, 10.8, and 21.0 γ from a dry carrier, daily per pound of live weight for 12 successive 7-day age periods. Upon the completion of the supplement feeding period half of the calves were slaughtered. The remaining calves were then maintained on only the depletion ration until the blood plasma vitamin A level decreased to less than 4 γ/100 ml. for two consecutive 7-day periods for the purpose of observing vitamin A depletion time. The following results were obtained: 1. Plasma carotenoids and vitamin A concentrations increased at diminishing rates with an increase in the carotene intake from artificially dehydrated alfalfa. Liver carotenoids and vitamin A concentrations as well as vitamin A depletion time increased proportionally with increased carotene intake. 2. When the calves received vitamin A intake from a dry carrier, inappreciable differences were observed for plasma and liver carotenoid concentrations. Plasma vitamin A increased at diminishing rates and liver vitamin A and vitamin A depletion time at constant rates with increased vitamin A intake. 3. From the relationships of plasma and liver vitamin A concentrations and vitamin A depletion time with carotene or vitamin A intake, it was found that on a weight basis carotene fed at the 60 γ intake level was equivalent to approximately 1/5 to 1/7th as much as vitamin A (alcohol); at the 180 γ intake level, 1/10th to 1/13th; and at the 540 γ intake level, 1/20th to 1/24th.

Relationship between Plasma Vitamin A and Liver Vitamin A in Calves Fed a Vitamin A Depletion Ration and Calves Fed Minimum Levels of Vitamin A or Carotene

Summary Data on blood plasma vitamin A and liver vitamin A concentrations from 58 Guernsey and Holstein calves fed a vitamin A depletion ration and whose average age and body weight was 128±19 days and 263±72lb., respectively, and from 39 Holstein calves fed minimum levels of vitamin A or carotene and whose average age and body weight were, respectively, 200±9 days and 436±48lb. were explored as to possible relationship. When plasma vitamin A and liver vitamin A were expressed as logarithms, a positive linear relationship was found between these two variables. In calves fed the vitamin A depletion ration, the blood plasma vitamin A level was found to be less at a given concentration of vitamin A in the liver than in the calves fed minimum levels of vitamin A or carotene. Positive linear relationships of log liver vitamin A concentration on log plasma vitamin A concentration were derived for purposes of estimating liver stores of vitamin A in calves fed the vitamin A depletion ration and in calves fed minimum levels of vitamin A or carotene. These had applicable limits for prediction of approximately 3.6 and 25.8γ of vitamin A per 100ml. of blood plasma.

Effect of Two Levels of Intake of a Vitamin a Depletion Ration on Some Blood Constituents and Deficiency Criteria in the Dairy Calf

Summary Ten pairs of 36-day-old calves were fed a vitamin A depletion ration at two levels of intake, low and high, until the blood plasma vitamin A values decreased to less than 4.0 γ % for two consecutive 7-day periods. This resulted in a 7-day increase in body weight of 7.1±1.5 and 11.0±0.4lb. for the low and high levels of intake, respectively. Over-all, plasma carotenoids and vitamin A were found to decrease while whole blood and plasma ascorbic acid exhibited no change. None of these constituents were affected by the level of intake of the depletion ration. Hemoglobin was observed to decrease in the calves on the low level of intake of the depletion ration but no change was found for the calves on the high level. Heart rates of animals on the high level of intake averaged 20 beats per minute higher than those on the low level of intake, whereas rectal temperatures and terminal spinal fluid pressures were unaffected. Among the histological changes, only the frequency of occurrence of squamous metaplasia in the interlobular ducts of the parotid gland was significantly greater in the high level group.

Blood Levels of Ascorbic Acid and Vitamin A during Vitamin A Depletion and Effect of Administration of Ascorbic Acid during Terminal Vitamin A Depletion in the Dairy Cow

Summary Eighteen calves, nine Guernseys and nine Holsteins, 105 days of age and previously raised on a limited-whole milk and dry-calf starter system, were fed a vitamin a depletion ration in amounts adjusted at 7 day intervals for liveweight. During initial vitamin A depletion, from 105 days of age until each calf's blood plasma level of vitamin A decreased to less than 4.0γ percent, there was no significant decrease either in whole blood or plasma ascorbic acid levels. In contrast, both plasma carotene and vitamin A decreased in a relatively uniform manner. During terminal vitamin A depletion, after blood plasma levels of vitamin A of less than 4.0γ were reached, there was a decrease in consumption of the feed allowed, accompanied by decreases in blood levels of ascorbic acid as well as initial appearance of clinical symptoms of vitamin A deficiency. In addition, spinal fluid pressures of greater than 200mm. H 2 0 were observed. Subsequent administration of ascorbic acid subcutaneously for a 14-day period did not alleviate the anorexia, the clinical symptoms of terminal vitamin A de-pletion or the increased spinal fluid pressure. In contrast, administration of vitamin A orally resulted in complete consumption of the feed allowed, significant decreases in spinal fluid pressure and disappearance or alleviation of clinical symptoms. Upon slaughter, all calves given ascorbic acid had squamous metaplasia in the parotid gland ducts, whereas of those calves given Vitamin A, one showed squamous metaplasia, two had no lesions and three had transitional type epithelium.

Effect of Vitamin A Depletion on Liveweight, Plasma and Liver Levels of Vitamin A and Microanatomy in Young Dairy Calves

Summary The effect of a vitamin A-depletion ration on liveweight, carotene and vitamin A levels in the blood and liver, clinical appearance and microscopic anatomy was studied in 21 young calves beginning at 106 days of age. All calves were fed a vitamin A-depletion ration of 2.67 lb. per 100 lb. of liveweight, with six of the calves receiving in addition a daily equivalent of 107,143 USP units of vitamin A. Observations on the daily feed intakes, clinical appearance, weekly liveweight, plasma carotene and vitamin A were made and tissue samples for histological study and liver samples for carotene and vitamin A analyses were obtained at slaughter. The experimental period was terminated for those calves fed only the depletion ration when the blood plasma level was less than 4 γ per cent for 2 consecutive wk., and for those calves fed the supplemental vitamin A at average ages comparable to those fed only the depletion ration. Until the blood plasma level decreased to 4 γ per cent, all calves readily consumed the vitamin A-depletion ration. At this level of plasma vitamin A, seven of the calves fed only the depletion ration began refusing some feed. Liveweight was not affected and both the gain in liveweight and rate of gain were not significantly different between groups of calves. Blood plasma carotene decreased in all calves with successive weeks on experiment and was characterized by a relatively rapid decrease early in the experimental period with a marked decline in rate of decrease occurring during the middle and end of the experimental period. In contrast, plasma vitamin A values decreased in a uniform manner regardless of the level and, therefore, indicated a possible means of measuring vitamin A stores by prediction, using this relatively uniform rate of decrease as a standard. The liver stores of vitamin A were considered depleted in those calves receiving only the vitamin A depletion ration. Spinal fluid pressures at the termination of the experimental period were elevated in the calves receiving only the depletion ration, while those receiving the supplemental vitamin A remained essentially the same as at the start of the experiment. Exophthalmos was observed in six calves, muscular in coordination in five, diarrhea in four and convulsions in one, all symptoms occurring toward the termination of the experiment for the individual calves. Squamous metaplasia of the interlobular and main ducts of the parotid gland was observed in eight of nine depleted calves and in none of the six controls.