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The effects of fasting, sedation, recumbency and general anaesthesia on the radiographic appearance of the thoracic cavity of adult cattle were investigated. Fasting and sedation had little effect on the visible lung field but recumbency and general anaesthesia were followed by a reduction in lung field area. The reduction in area appeared to be greatest in the more dependent parts of the lung and was associated with the development of a persistent radiographic opacity. The changes were similar to those previously observed in horses.

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DL-Ethionine (0.87 g/kg) or saline solution (equivalent volume) was administered IV to 4-month-old calves which had been fasted 60 hours before slaughter. The livers of the ethionine-treated calves were large, had a high lipid content, and were diffusely pale yellow on the cut surface. The livers of the saline-treated group were shrunken. In liver samples from calves of both groups, there was reduced parathion and paraoxon metabolism. In the ethionine-treated group, parathion desulfuration also was reduced. In all cases, the changes were greater in the ethionine-treated animals. Fasting of calves with saline solution or ethionine treatment caused a lowering of the liver biotransformation of parathion and paraoxon.

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Thirty-two pigs were used to compare the oxidation rates of uniformly labeled (U-14C) palmitic (16:0), stearic (18:0), oleic (18:1) and linoleic (18:2) acids in fasting neonatal pigs. The pigs were allowed to nurse the sow for 24 to 48 h following birth. Subsequently, they were removed, an indwelling catheter was surgically placed in the external iliac vein and the pigs were fasted for 12 h to attain a postabsorptive state. The 14C fatty acids were administered as a single infusion (10 microCi) via the catheter, and recovery of the label as expired 14CO2 was determined at 45-min intervals for a 6-h period. Blood samples were taken following the infusion (15, 60, 120, 240, 360 min) to monitor activity maintained within the free fatty acid (FFA) fraction of the plasma pool. The oxidation rate of each fatty acid was corrected for the difference in dose dilution using a uniform factor based on plasma concentration of 18:1. The cumulative 6-h 14CO2 recovery rates (percentage of dose) were 19.1, 6.6, 30.1 and 13.1% for 16:0, 18:0, 18:1 and 18:2, respectively. Oleic acid was oxidized at a more (P less than .05) rapid rate than the other fatty acids. Palmitic acid and 18:2 were oxidized more rapidly than 18:0, although the difference between 18:0 and 18:2 was not significant. Plasma FFA pools differed with respect to the proportion of infused activity remaining at various times after administration. At 60 and 120 min postinfusion, the greatest (P less than .05) proportion of activity was maintained in the 18:1 pool (11.9 and 6.6%, respectively, vs 7.7 and 4.3% for 16:0, 6.9 and 3.9% for 18:2 and 3.6 and 2.2% for 18:0). Palmitic acid and 18:2 had a greater (P less than .05) level of activity in the plasma FFA pool at 60 min than did 18:0. This same pattern was observed through 2 h, but by 240 min postinfusion, the proportion of activity remaining in each of the plasma pools was similar. Rate of oxidation appeared to corrrespond with plasma concentration and proportion of activity remaining in the plasma FFA pool.

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Nineteen Landrace sows mated to Landrace boars were randomly assigned, on d 91 of pregnancy, to three groups: (1) control (six sows)--fed standard 13% protein corn-soybean meal gestation diet at 1.82 kg/d to d 112 of pregnancy; (2) 4-d fast (seven sows)--fed standard gestation diet to d 94 of pregnancy, fasted from d 95 to 98 of pregnancy and then refed a semipurified fat-free diet ad libitum until d 112 of pregnancy, and (3) 8-d fast (six sows)--treated the same as groups 2, except that the fast began on d 91 and extended through d 98 of pregnancy. The fat-free diet consisted of dextrose and soybean meal and was fortified with minerals and vitamins. On d 112 of pregnancy, all fetuses were removed by Caesarean section and determinations were made of fetal body and liver weights, fetal liver and gastrocnemius muscle glycogen concentrations, and maternal uterus and peritoneal adipose tissue glycogen levels. Sows in groups 2 and 3 consumed more (P less than .01) average daily feed during the refeeding period than did the control sows. Fasting and refeeding failed to affect maternal or fetal tissue glycogen concentration, or fetal body or liver weight. Average sow tissue glycogen concentrations were .23 and 3.0 mg/g tissue for peritoneal adipose tissue and uterus, respectively. Average fetal liver and gastrocnemius muscle glycogen concentrations were, 87 and 62 mg/g tissue, respectively. Average fetal body and liver weights were 1,287 and 39.5 g/fetus, respectively. We conclude that fasting followed by refeeding of a fat-free diet to pregnant sows during late gestation does not increase maternal or fetal tissue glycogen content and appears to be of no value in enhancing pig survival in early postnatal life.

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Both intravenous single injections of 6-tritium labeled glucose and primed continuous infusions of uniformly labeled carbon-14 glucose were applied to four nonpregnant Saanen goats. Four sequential treatments were high milk production, low milk production, "dry" with no milk production, and fasting during the dry period. The diet was 25% chopped alfalfa hay and 75% grain, and by design feed intake decreased sequentially (1.85, 1.49, .80) and 0 kg/day) with the progression from high production to fasting. Glucose irreversible loss averages from single injections of tritium labeled glucose were 199, 169, 96, and 58 mg/min for respective treatments; similar averages from continuous infusions of carbon labeled glucose for the first three treatments were 164, 132, and 76 mg/min, or about 20% less. Other blood glucose kinetic parameters were estimated after single injections, and averages declined from 5.9 to 4.5 g for pool size, 315 to 134 mg/min for total entry rate, and 115 to 76 mg/min for recycling as goats went from high production to fasting. Transfer of blood glucose to milk constituents was determined by continuous infusion. Transfer quotients for lactose were 73% for high production and 67% for low production; for casein they were 1.8 and 1.9%. The percentage of glucose irreversible loss accounted for in lactose was 31% for high production and 17% for low production whereas less than .2% was in casein.

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Phosphorus nutrition and fasting are dependent factors which markedly influence the tolerance of young chickens to high temperature. A study was conducted to further characterize the nature of this interaction. Male chicks fed low phosphorus diets and fasted 24 hr exhibited significantly shorter survival time after exposure to acute heat when compared to fasted chicks previously fed adequate dietary phosphorus. When chicks were fasted for 48 hr, the effect of previous diet was considerably more pronounced. These results showed that the effect of low phosphorus nutrition was potentiated by fasting 48 hr which in itself improved survival time over that of chicks fasted 24 hr. The apparent metabolic responses of chicks to heat as indicated by changes in plasma glucose and total ketones were not related to the observed dietary effects. Plasma phosphate (Pi) and calcium (Ca) decreased significantly during heat exposure. The Ca/pi molar ratio was increased significantly at heat induced exhaustion, indicating a relatively greater heat induced change in Pi. From the initiation of heat exposure to heat exhaustion, the percent change in Pi, but not Ca, was similar in all groups despite marked differences in the time within which this occurred. We concluded that the effect of low phosphorus nutrition on heat tolerance of young chickens persists after a 48-hr fast. In addition, the effects of previous diet were somewhat more pronounced in 48-hr fasted chicks when compared to those fasted 24 hr.

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The effects of serotonin [5-hydroxytryptamine (5-HT)] on food intake and water consumption were investigated in young broiler chicks. Artificial cerebrospinal fluid containing either 0, 33, 67, or 100 microgram of 5-HT/10 microliter was injected into the lateral ventricle of either 24-hr fasted or fully fed chicks maintained in a thermoneutral environment with continuous lighting. Neither cannulation per se nor injection of 10 microliter of artificial cerebrospinal fluid had an effect on food intake or water consumption. Furthermore, food intake was not affected by 5-HT in fasted chicks. In fully fed chicks, however, food intake was significantly decreased by 67 and 100 microgram of 5-HT. Water consumption was affected by 5-HT injection in fully fed chicks. Results with fasted chicks remain equivocal. Data suggest that 5-HT may be involved in the neurohumoral control of food intake.

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An experiment involving 35 White Leghorn hens was conducted to study the influence of graded levels of supplemental yellow grease on rate of food passage (transit time). Seven experimental diets (0, 5, 10, 15, 20, 25, and 30% supplemental fat) were formulated. Transit time was determined by utilizing either Cr2O3 or 144Ce as indicators. First appearance of the markers in the excreta and percentages of the markers ingested that were recovered in excreta 10 hr after feeding were criteria used to determine transit time. There was a significant (P less than .01) linear effect of fat on transit time of Cr2O3 whereby the time required for the marker to appear in the excreta increased with increments of supplemental fat. Average first appearance time of Cr2O3 was 193, 219, 214, 227, 251, 250, and 270 min for the diets containing 0, 5, 10, 15, 20, 25, and 30% supplemental fat, respectively. Transit time of 144Ce also was increased slightly (P less than .10) by fat supplementation. Transit time, measured as percentage of marker recovered in excreta 10 hr after feeding, was faster for the control than for the fat-supplemented diets, although the linear effects of fat were not statistically significant (P greater than .10). The results show that supplemental fat increased transit time of ingesta in chickens. This observation may be helpful in understanding the nature of the extrametabolic effect of fat in poultry diets. By increasing transit time, supplemental fats may improve digestibility of other dietary constituents and thereby increase the utilization of dietary energy.

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The oral acute toxicity of 3 beta-adrenoceptor stimulants, 2 beta-adrenoceptor blockers, and 2 anti-gastric ulcer drugs was studied in 8-week old, SD-JCL rats and ICR-JCL mice, fasted overnight for 17-20 hours. The results were compared with those from rats and mice allowed to feed normally. The order of the fed:fasted ratio of LD50 values in rats was pirenzepin less than propantheline less than pindolol less than salbutamol less than orciprenaline less than fenoterol less than bunitrolol, and was in the range 1.3-4.7. The increased toxicity in fasted animals was considered to be related to acceleration in gastric emptying and intestinal absorption, but not to a general change in the condition of the test system or a decrease in the detoxification ability of the liver because after intraperitoneal administration acute toxicity was similar in fed and fasted rats.

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Intramuscular injection of staphylococcal enterotoxin B (SEB) at a dosage level of 50 microgram/kg of body weight caused death in Dutch rabbits. Lethality was not modified markedly by morphine pretreatment or by hyperthermia, thyrotoxicosis, propylthiouracil feeding, thyroparathyroidectomy, water deprivation, or fasting. The administration of acetylsalicylic acid to the SEB-inoculated rabbit also failed to protect the rabbits from the effect of SEB. Seemingly, the SEB molecular destruction was not markedly modified by alteration of cellular metabolism, and lethal effects of SEB remained unchanged in the morphine- or acetylsalicylic acid-treated rabbits. When SEB was given to six rabbits 3 days after total-body X-irradiation, fever persisted and three rabbits survived. An identical dose of SEB to nonirradiated rabbits produced fever initially, followed by hypothermia and death of all six rabbits.

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Biliary excretion of bilirubin, including the conjugate composition, was studied during feeding and during a 2.5-day fast of three pony mares with chronic external biliary (T-tube) fistulas. Fasting bilirubin excretion (1.96 +/- 0.74 microgram/min/kg of body weight), after establishing a new steady state, was not different from excretion during feeding (1.99 +/- 0.45 microgram/min/kg). Hyperbilirubinemia of fasting resulted from a reduced removal of plasma bilirubin rather than from an increased input of bilirubin into the plasma. Relative plasma excretion of the individual conjugate fractions of biliary bilirubin was not changed by fasting.

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Three trials, each with 100 bullocks previously grazing improved pasture, compared bruising in cattle fasted for 0, 24 and 48 hours prior to transport for slaughter. Overall the weight of bruised trim from unfasted bullocks (0.48 kg) was significantly less (P less than 0.01) than from bullocks fasted for 24 h (0.99 kg) or 48 h (1.03 kg). length of fast overall had no significant effect. This pattern was not consistent within trials.

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Blood samples taken from five great horned owls (Bubo virginianus), eight red-tailed hawks (Buteo jamaicensis), four marsh hawks (Circus cyaneus), two prairie falcons (Falco mexicanus), five golden eagles (Aquila chrysaetos), and five white leghorn chickens (Gallus domesticus) that had been fasted for 24 h were used to determine plasma levels of glucose by the glucose oxidase method. The mean plasma glucose levels were: great horned owls 374.6 mg/100 ml, red-tailed hawks 346.5 mg/00 ml, marsh hawks 369.3 mg/100 ml, prairie falcons 414.5 mg/100 ml, golden eagles 368.4 mg/100 ml, and white Leghorn chickens 218.2 mg/100 ml. The plasma glucose levels obtained for the raptorial birds in this study were considerably higher than those found for the chickens. These values are discussed in relation to the carnivorous food habits of raptors.

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The effect of feeding on plasma-uric acid concentrations of the snake was studied. The values were monitored in 2 gopher snakes and 2 black rat snakes which were fed mice. Plasma uric acid values in snakes increased after eating and gradually returned to base line with the digestion of the mice. Uric acid concentrations were greater in snakes eating 2 mice than in those eating only 1 mouse. The base-line plasma uric acid concentration in snakes was approximately 2 to 5 mg/dl. Plasma uric acid concentrations may be useful in making a diagnosis of gout. Presence of gout is usually indicated by increased uric acid concentrations; however, interpretation of these concentrations should be based on information about the feeding schedule.

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The willow grouse (Lagopus lagopus) are arctic gallinaceous birds with small fat stores and large muscles. In winter, these birds may starve for periods of several days. It was important to know which energy reserves were utlized during periods of starvation. Body composition of female willow grouse and Bantam hens was studied before and after fasting. Grouse have much larger breast muscles than do Bantams, but reproductive organs are larger in hens. The relative amounts of adipose tissue are about equal in grouse and Bantams. When the birds had lost about 20% of their initial body weight due to fasting, Bantams had lost as much weight from their reproductive organs as from the adipose tissue, with little loss from the muscles. Grouse lost more weight from the pectoralis muscles alone than from the adipose tissue. Since the major component of muscle is protein, the grouse obtain a larger proportion of acloric needs during fasting from protein than do the Bantams. Grouse breast muscles are dark red, and the pectoralis consists homogeneously of type IIa (oxidative-glycolytic) fibres, assessed by ATPase and by Sudan Black staining. The supracoracoideus muscle has type II fibres, not resolvable in subtypes. The leg muscle biceps femoris contains the three fibre types I, IIa, and IIb. During fasting, the weight loss of the pectoralis muscle may be accounted for by all fibres losing some material.

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