Significant Reduction In Weight Gain Research Articles

Potentiation of Ionophorous Anticoccidials with Duokvin: Battery Trials against Cryptosporidium baileyi in Chickens

Three battery tests, employing 444 Arbor Acres chickens, were conducted to study the anticryptosporidial efficacy of the polyether ionophorous anticoccidials alone and in combination with a new dihydroquinoline antioxidant, duokvin. The following efficacy percentages for the ionophores at the recommended level were established on the basis of oocyst output: lasalocid 45, monensin 37, semduramicin 29, narasin 23, and maduramicin and salinomycin 21. The efficacy of the ionophores, with the exception of lasalocid, could be increased to 36-88% by combination with duokvin. However, these combinations resulted in a significant weight gain reduction due to toxic interaction. Efficacy showed a strong negative correlation with body weight gain and bursa weight, suggesting an indirect mode of action against the parasite. It has been concluded that neither ionophorous anticoccidials nor their combinations with duokvin can be recommended for chemoprophylaxis against avian cryptosporidiosis.

Effects of dietary calcium and vitamin D 3 on weight gain and mineral composition of the blue tilapia ( Oreochromis aureus) in low-calcium water

Influences of dietary calcium and vitamin D 3 (cholecalciferol) were evaluated with fingerling blue tilapia using a 2×2 factorial design. Four purified diets were formulated to contain 34% crude protein from egg albumin and casein with 3.20 kcal available energy/g. The basal diet (0.2 g Ca/kg) was supplemented with either 0 or 7.5 g Ca/kg (from CaCl 2·2H 2O) and 0 or 2000 IU vitamin D 3/kg. Experimental diets were fed in triplicate to groups of blue tilapia initially averaging 2.30±0.09 g in 38-liter aquaria receiving water with <0.1 mg Ca/l for a period of 24 weeks. Significantly ( P<0.05) greater weight gain and concentrations of ash, calcium, phosphorus and magnesium in bone and scale tissues were observed for fish fed the calcium-supplemented diets compared to those fed diets without supplemental calcium regardless of vitamin D 3 supplementation. Fish fed the diet without supplemental vitamin D 3 but with supplemental calcium had a significant reduction in weight gain at the end of 12 weeks compared to those fed the diet supplemented with both nutrients; this trend continued in subsequent weeks although differences were not significant. Effects of vitamin D 3 on mineralization of hard tissues were negligible at all sampling periods. Dietary supplementation of vitamin D 3 was not required for tilapia to utilize dietary calcium for growth and tissue mineralization. Based on these results, dietary calcium had the most profound effects on growth and mineral composition of blue tilapia reared in low-calcium water and effects of vitamin D 3 were more subtle.

A comparison of single and repeated oral infection of chicks with two avian reoviruses

Groups of specific pathogen-free light hybrid chicks were inoculated with one dose or repeated doses on alternate days of avian reovirus strain R2 isolated from tenosynovitis, or strain 49 82 , isolated from infectious stunting. Strain 49 82 induced significant reductions in weight gain after infection by either method, as did strain R2 after repeated doses. Neither virus induced clinical signs or gross lesions of stunting or tenosynovitis in the five weeks of observation. Both viruses and methods of infection induced similar microscopic changes of reovirus tenosynovitis in the hock joints. Repeated doses caused a more prolonged persistence of virus in the intestine than a single dose. Cloacal swabbing indicated that strain 49 82 was more persistent in the gut after repeated doses than virus R2. For both strains, the persistence of virus in the liver was shortlived and the proportions of birds with virus in the hock joints were similar after both methods of infection. Repeated inoculations did not exacerbate the joint lesions or heighten the neutralising antibody response. However, for certain studies of reovirus infections, repeated inoculations with the virus may give a more accurate simulation of a natural infection.

Maternal and developmental toxicity of manganese in the mouse

Manganese (II) chloride tetrahydrate was investigated in Swiss mice for maternal and developmental toxicity after subcutaneous (s.c.) exposure to doses of 0, 2, 4, 8 and 16 mg/kg per day from gestation day 6 through 15. Females were sacrificed on gestation day 18, and fetuses were examined for external, visceral, and skeletal abnormalities. Maternal toxicity included significant reductions in weight gain and food consumption at 8 and 16 mg/kg/day, as well as several treatment-related deaths in the high dose-group. There were no treatment-related effects on the number of total implants, early resorptions, dead fetuses or sex ratio, whereas a significant increase in the number of late resorptions was found in the 4, 8, and 16 mg/kg/day groups. Fetotoxicity, consisting primarily of reduced fetal body weight and an increased incidence of morphological defects was also observed at 8 and 16 mg/kg/day. There were no differences between control and manganese-treated groups in the incidence of individual or total malformations. The no observable adverse effect level (NOAEL) for maternal toxicity of MnCl 2· 4H 20 in mice was 4 mg/kg/day, while the NOAEL for embryo/fetal toxicity was 2 mg/kg/day.

Developmental Toxicity of Inhaled trans-1,2-Dichloroethylene in the Rat

Developmental Toxicity of Inhaled trans-1,2-Dichloroethylene in the Rat. Hurtt, M. E., Valentine, R., and Alvarez, L. (1993). Fundam. Appl. Toxicol. 20, 225-230.The developmental toxicity of trans-1,2-dichloroethylene (t-DCE), a component of certain Freon cleaning agents, was examined in pregnant rats. t-DCE was administered by inhalation 6 hr daily on Days 7-16 of gestation (the day copulation was confirmed was termed Day 1 of gestation) at exposure levels of 0, 2000, 6000, or 12,000 ppm. The offspring were then examined on Day 22 of gestation. Overt maternal toxicity was expressed as a significant reduction in weight gain at 12,000 ppm and in feed consumption at 6000 and 12,000 ppm. During the exposure period, lacrimation and stained periocular hair, and signs of occular irritation, were observed in all groups. In addition, increased incidences of alopecia, lethargy, and salivation were observed in the high-dose dams. Significant increases in the mean number of resorptions per litter were seen in the litters of dams exposed to 6000 and 12,000 ppm of t-DCE; however, these values are within the range of historical controls and not considered to be treatment related. The mean combined and female fetal weights were significantly reduced in the litters of dams exposed to the highest concentration (l 2,000 ppm) of t-DCE. Marginal effects on feed consumption, unaccompanied by other changes and reflective of the pattern seen at higher doses, were seen at 2000 ppm. Thus, marginal maternal toxicity was seen at 2000 ppm and exposures to 6000 ppm t-DCE or higher caused frank maternal toxicity while the fetus was affected only at 12,000 ppm. Therefore, t-DCE is not considered to be uniquely toxic to the rat conceptus.

Developmental Toxicity of Inhaled trans-1,2-Dichloroethylene in the Rat

The developmental toxicity of trans-1,2-dichloroethylene (t-DCE), a component of certain Freon cleaning agents, was examined in pregnant rats. t-DCE was administered by inhalation 6 hr daily on Days 7–16 of gestation (the day copulation was confirmed was termed Day 1 of gestation) at exposure levels of 0, 2000, 6000, or 12,000 ppm. The offspring were then examined on Day 22 of gestation. Overt maternal toxicity was expressed as a significant reduction in weight gain at 12,000 ppm and in feed consumption at 6000 and 12,000 ppm. During the exposure period, lacrimation and stained periocular hair, and signs of occular irritation, were observed in all groups. In addition, increased incidences of alopecia, lethargy, and salivation were observed in the high-dose dams. Significant increases in the mean number of resorptions per litter were seen in the litters of dams exposed to 6000 and 12,000 ppm of t-DCE; however, these values are within the range of historical controls and not considered to be treatment related. The mean combined and female fetal weights were significantly reduced in the litters of dams exposed to the highest concentration (12,000 ppm) of t-DCE. Marginal effects on feed consumption, unaccompanied by other changes and reflective of the pattern seen at higher doses, were seen at 2000 ppm. Thus, marginal maternal toxicity was seen at 2000 ppm and exposures to 6000 ppm t-DCE or higher caused frank maternal toxicity while the fetus was affected only at 12,000 ppm. Therefore, t-DCE is not considered to be uniquely toxic to the rat conceptus.

Morbidity and the growth of stunted and nonstunted children, and the effect of supplementation

Children aged 9-24 mo were recruited by a survey of poor areas of Kingston, Jamaica. Stunted children were randomly assigned to supplementation or not. Weekly morbidity histories were taken for 2 y. Separate multiple regressions on each symptom for weight or length gain in 2-mo intervals showed significant reductions in weight gain with coughing, apathy, anorexia, diarrhea, and fever, ranging from -2.1 to -16.8 g/d ill. Apathy and diarrhea reduced gains in length (-0.26 and -0.20 mm/d ill). Significant reductions in linear growth with lower respiratory-tract infections (-0.16 mm/d ill) occurred only in nonsupplemented children. Growth over 4-mo intervals was reduced if diarrhea occurred in the first 2 mo of the interval but there were no long-term effects of apathy, fever, or anorexia. Some of the effects of morbidity on growth were therefore transient and morbidity is unlikely to be a major cause of growth retardation in this population.

Effect of extrusion on efficiency of utilization of maize starch by rainbow trout ( Oncorhynchus mykiss)

When rainbow trout diets contained about 290 g maize starch per kg dry matter, extrusion prior to mixing caused significant reductions in weight gain but greater reductions in feed consumption, thus resulting in significant improvements of feed conversion ratio and efficiency of utilization of dietary gross energy. Differences due to genotype (Normal vs. Wax) and form of stacch (whole grain vs. isolated starch) were significant in untreated material but disappeared after extrusion (trial 1). Extrusion of maize to three different degrees improved digestibilities of energy and starch, the respective results being higher for restricted feeding than for feeding to satiation (trial 2). With increasing degree of extrusion, not only starch degradability by amyloglucosidase but also performance of trout was improved when diets were fed either restricted or to satiation (trial 3).

TOXICITY OF RAPAMYCIN—A COMPARATIVE AND COMBINATION STUDY WITH CYCLOSPORINE AT IMMUNOTHERAPEUTIC DOSAGE IN THE RAT

Sprague-Dawley rats were treated for 14 days with rapamycin (RAP; 1.5 mg/kg/day i.p.), cyclosporine (15 mg/kg/day by gavage), both drugs in combination, or appropriate drug vehicles. Hematological parameters and biochemical indices of renal and hepatic function were determined throughout the experimental period, at the end of which the rats were killed and tissues examined histologically. There was a significant reduction in weight gain in RAP- but not CsA-treated animals, while rats given both drugs showed a reduction in body weight over the 14-day experimental period. There were no significant alterations in absolute or differential white blood cell counts or in T or B cell numbers, except in the drug combination group, in which an absolute lymphopenia was detected on day 14. Small but significant increases in urinary flow rate (UFR) were found with either drug alone, and there was a marked (4-fold) increase in UFR in response to drug combination. Both RAP and CsA caused a small elevation in serum creatinine concentrations, but only with CsA was there a significant elevation in urinary enzyme activity and reduction in 51Cr. EDTA clearance. The drug combination exacerbated renal impairment, the extent of which was greater than the additive effect of either drug alone. Hyperbilirubinemia of similar magnitude was observed in rats receiving either CsA alone or in combination with RAP. In contrast to its effect on renal function, however, the CsA+RAP combination was without additional effect on liver function compared with the minor changes seen with either drug alone. Plasma and urinary glucose levels were elevated in all drug treatment groups and especially in animals given both drugs. RAP administration did not significantly affect whole-blood CsA concentrations, although the possibility of a pharmacokinetic interaction cannot be totally excluded. Histological studies revealed striking thymic medullary atrophy in all drug-treated animals. In addition, all rats given RAP showed focal myocardial necrosis of overall mild-moderate severity. Kidneys of RAP-treated rats appeared normal, whereas mild, focal, acute tubular necrosis was evident in all CsA-treated animals. Pancreases of all drug-treated animals were normal.

Effects of altered dietary iron intake in Mycobacterium paratuberculosis-infected dairy cattle: sequential observations on growth, iron and copper metabolism and development of paratuberculosis

Twenty calves were orally inoculated with Mycobacterium paratuberculosis at six weeks old. At six months old, 10 of these, plus four uninfected controls were maintained on limited dietary copper and supplemented iron intake for a further 27 months. During this time all these animals, together with a further four untreated controls, were bred before being killed and examined for evidence of paratuberculosis. Despite significant reduction in weight gain, attributable to both iron supplementation and infection, no significant difference was found in the numbers of iron-supplemented and unsupplemented animals that developed clinical signs nor in the extent and severity of intestinal lesions between groups. Accumulation of iron in paratuberculosis lesions was not affected by iron supplementation but was positively correlated with the frequency of shedding of M paratuberculosis in faeces (P less than 0.05). Dietary iron supplementation alone resulted in serum hyperferraemia, hepatic siderosis and slight hypocuprosis, whereas, in infected animals, this resulted in marked hypocuprosis and anaemia within groups (P less than 0.05). Infection alone resulted in serum hypoferraemia and intestinal and hepatic siderosis which was positively correlated with the severity of infection within groups (P less than 0.05). Susceptibility to paratuberculosis may result from failure ultimately to limit monokine-mediated iron sequestration in intestinal tissue.

Developmental toxicity of subcutaneously administered meso-2,3-dimercaptosuccinic acid in mice

meso-2,3-Dimercaptosuccinic acid (DMSA) is a watersoluble effective antidote for the treatment of heavy-metal intoxications. Information concerning the developmental toxicity of DMSA, however, has not been available. In order to determine the potential developmental toxicity of DMSA, pregnant Swiss mice were given 0,410, 820, or 1640 mg DMSA/kg/day subcutaneously on Days 6–15 of gestation. Maternal effects included a significant reduction in weight gain during the exposure and postexposure periods at 1640 mg/kg/day. Food consumption was similar to controls at all doses levels except for the high dose group in the post-treatment period. Results of hematological and serum biochemical analyses in the DMSA-treated groups were comparable to those of the controls. However, in light of the pronounced effects on maternal weight gain the dose of 1640 mg/kg/day would be maternally toxic. Significant increases in the number of resorptions and the incidence of stunting were found, along with a significant decrease in the number of live fetuses per litter, when the 1640 mg/kg/day group was compared with the controls. Significant reductions in fetal body weight and fetal body length means were also found when the 820 and 1640 mg/kg/day groups were compared with the controls. Consequently, these results indicate that DMSA would be embryotoxic to mice at 1640 mg/kg/day and fetotoxic at 820 mg/kg/day. In contrast, very slight fetotoxicity was observed at 410 mg/kg/day. Gross external, internal soft tissue, and skeletal examinations of the fetuses revealed that DMSA was teratogenic in the mouse when given subcutaneously at 820 and 1640 mg/kg/day. Thus, the no teratogenic observed effect level for DMSA under these test conditions was 410 mg/kg/day for Swiss mice. This is approximately one-twentieth of the acute LD50.

Insecticide Toxicity to the Soybean Looper and the Velvetbean Caterpillar (Lepidoptera: Noctuidae) as Influenced by Feeding on Resistant Soybean (PI 227687) Leaves and Coumestrol

Permethrin, fenvalerate, acephate, methyl parathion, and methomyl were tested on larvae of the velvetbean caterpillar, Anticarsia gemmatalis (Hubner), and the soybean looper, Pseudoplusia includens (Walker), fed on a susceptible (‘Bragg’) or a resistant (PI 227687) soybean cultivar. At LD50, susceptibility of A. gemmatalis larvae to fenvalerate and acephate was significantly enhanced by feeding on the resistant cultivar (1.5 and 1.6 times, respectively). P. includens reared on resistant leaves were also significantly more susceptible to acephate (2 times) than when they were reared on susceptible leaves. The toxicity of the other insecticides examined for each insect was not affected. Incorporation of coumestrol, an isoflavonoid associated with PI 227687 resistance, into a modified artificial diet resulted in significant reductions in weight gain for P. includens larvae. Feeding on a diet amended with coumestrol significantly enhanced the toxicity of fenvalerate (1.5 times) while reducing toxicity of methomyl (2 times) to larvae of P. includens .

Developmental toxicity of cobalt in the rat.

To determine the potential developmental toxicity of cobalt, pregnant Sprague-Dawley rats were given by gavage a daily dose of 0, 25, 50; and 100 mg/kg cobalt(II) chloride on d 6-15 of gestation. Females were sacrificed on d 20. Maternal effects included significant reductions in weight gain and food consumption, particularly at 100 mk/kg.d. Hematocrit, hemoglobin concentration, mean corpuscular volume, mean corpuscular hemoglobin, and reticulocytes were increased significantly in the 100-mg/kg.d group. No treatment-related changes were recorded in the number of corpora lutea, total implants, resorptions, the number of live and dead fetuses, fetal size parameters, or fetal sex distribution data. Increased incidence of stunted fetuses per litter was the only adverse finding at 50 and 100 mg/kg.d group. However, this increase was not statistically significant. Examination of fetuses for gross external abnormalities, skeletal malformations, or ossification variations revealed that cobalt did not produce teratogenicity or significant fetotoxicity in the rat at doses as high as 100 mg/kg.d.

Chronic low-dose infusions of dexamethasone in rats

Glucocorticoid-induced hypertension in rats has been studied using long-term, low-dose dexamethasone treatment. Dose-related increases in systolic blood pressure were achieved, without loss in body weight, with subcutaneous continuous infusions of 1, 2 and 5 micrograms dexamethasone per day, respectively, for 4 weeks. Rats treated with 10 micrograms dexamethasone per day lost weight at a rate of 10 g per week. Lower doses caused a significant reduction in weight gain compared with controls. Renin, aldosterone, plasma sodium and potassium concentrations were unaffected by dexamethasone treatment. Plasma atrial natriuretic peptide (ANP) concentrations were decreased by 40-50% by dexamethasone. These decreases were negatively correlated with increases in systolic blood pressure and haematocrit. Glucocorticoid-induced decreases in ANP contrast with ANP increases in response to mineralocorticoid treatment in rats with deoxycorticosterone-induced hypertension. Plasma concentrations of the endogenous glucocorticoid, corticosterone, were suppressed to the same very low levels by 5 and 10 micrograms dexamethasone per day; 1 and 2 micrograms doses were less effective. Unlike mineralocorticoid-induced hypertension, the pressor effects of dexamethasone were ameliorated but not abolished by dietary sodium restriction and were unaffected by sodium loading. Two micrograms of dexamethasone reduced plasma ANP in rats on either high- or low-sodium diets by 29 and 34%, respectively. We conclude that low-dose infusions (less than 5 micrograms/day) of dexamethasone are suitable for studying glucocorticoid-induced hypertension without the complications of weight loss that have been reported by others or of the mineralocorticoid-like side effects which endogenous glucocorticoids may exhibit.

Subchronic toxicity of tetramethylsuccinonitrile

The acute rat oral LD50 for tetramethylsuccinonitrile (TMSN) is 38.9 ± 7.4 mg/kg. A series of three 90-day subchronic toxicity studies were conducted with Sprague-Dawley-derived albino rats. In each study, rats were administered corn oil solutions of TMSN by intubation. In the first study, groups of 15 male and 15 female rats were given 0, 1, 3, or 10 mg/kg TMSN. Significant reductions in weight gain were observed at 10 and 3 mg/kg/day. Survival, demeanor, food consumption, hematology, and urinalysis were not affected. Except for a reduction in fasting blood glucose in the 10 mg/kg test group, no effects were observed in clinical pathology parameters. Absolute and relative liver weights were increased at 10 mg/kg (both sexes) and 3 mg/kg (males). Both absolute and relative kidney weights were increased and treatment-related morphological lesions, characterized as tubular nephrosis, were observed in all test groups of males, but not in females. Other TMSN-related microscopic observations were limited to liver changes in both sexes at 10 mg/kg. Two subsequent 90-day studies, each conducted with 15 male rats per group, used levels of 0, 0.001, 0.01, 0.1, 0.3, or 1.0 mg/kg/day TMSN. Renal weight increases were observed at 1.0 mg/kg TMSN. Microscopic renal lesions similar to those seen in the first study were observed down to 0.1 mg/kg TMSN. A no-effect level was established at 0.01 mg/kg TMSN. No treatment-related microscopic lesions of the kidney were observed in groups of male rats given 3.0 mg/kg TMSN by gavage for 90 days and then removed from treatment for 14 days. Thus, tubular nephrosis produced by subchronic expsure to TMSN is reversible in the male rat. Groups of 15 male rats also were exposed to 1, 5, or 10 ppm TMSN in drinking water for 90 days. No adverse effects on in vivo parameters or clinical pathology were observed. Increases in kidney weights were seen at 10 and 5 ppm TMSN. Histopathologic changes characteristic of tubular nephrosis were noted in rats from all treatment groups. Dogs administered capsules containing TMSN for 90 days at levels equivalent to 0.3, 1.0 and 3.0 mg/kg/day exhibited slight suppressions of body weight gain at the two higher dosage levels and a small increase in blood thiocyanate at 3 mg/kg. No other functional or morphological changes related to treatment were observed in any organs evaluated, including liver and kidney.

Growth hormone inhibition causes increased selenium levels in Duchenne muscular dystrophy: a possible new approach to therapy.

Nine children with Duchenne muscular dystrophy were given Sanorex (mazindol), a growth hormone inhibitor, daily for 6 months. There was no significant change in their muscle function, but there was...

The effect of intrauterine esophageal ligation on growth of fetal rabbits

Babies with pure esophageal or duodenal atresia weight less than normal babies at birth. Whether this is due to the obstruction to fetal swallowing or some other cause is not known. To determine how intrauterine interruption of swallowing affects fetal growth, we developed a model of esophageal atresia in the fetal rabbit. Twenty-five time-mated rabbits at 24 days gestation were anesthetized with halothane and ketamine. The uterus was exposed through a midline abdominal incision. The head and neck of the fetus in the distal end of one horn were isolated through a 2-cm hysterotomy. Biparietal diameter (BPD) was measured and the esophagus was isolated and ligated through a midline cervical incision. The fetus in the distal end of the opposite horn underwent sham operation. Four days later, cesarean section was done. The newborn rabbits were weighed, and crown/rump length and BPD were measured. Ligation of the esophagus was confirmed by re-exploration of the neck. Three does died under anesthesia and two aborted. From the remaining 20, 156 fetuses were recovered, of which 135 were alive. One set of operated fetuses was dead, leaving 19 pairs for analysis. There was a statistically significant reduction in weight gain (31.7 +/- 1.3 g to 29.1 +/- 0.9 g, P less than 0.05) following interruption of the esophagus but linear growth was unchanged. Obstruction to normal fetal swallowing may account for the low birth weight with normal head circumference reported in babies with esophageal and duodenal atresia.

Dietary copper enhances the hepatotoxicity of senecio jacobaea in rats

To determine the effects of dietary copper on the toxicity of Senecio jacobaea (tansy ragwort), a plant that contains the hepatotoxic pyrrolizidine alkaloids (PAs), young male rats were fed diets containing 0 or 5% dried tansy ragwort tops and 0 or 5% μg/g copper (as copper sulfate) for 5 weeks. Hepatotoxicity was measured by the activities of plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). Comsumption of diets containing 5% tansy ragwort alone produced a significant reduction in weight gain accompanied by a 122% increase in plasma AST activity, a 106% increase in ALP activity, and a 152% increase in ALT activity, compared to pair-fed controls. When copper was added to the tansy ragwort diet, the activities of both plasma AST and ALT were increased by more than 350%. Plasma ALP activity was also further enhanced by dietary copper in the tansy ragwort-fed animals but to a lower extent. Supplementary copper alone or a reduction in food intake had no significant effect on any of the enzyme activities. The results suggest that copper potentiates the hepatotoxic effects of tansy ragwort in rats.

Dietary Phosphorus Levels during Growth of Brown Egg Type Replacement Pullets

Caged Sex-Sal (DeKalb Warren) replacement pullets were fed diets containing .30%, .35%, or .41% available phosphorus from 0 to 20 weeks of age; in a second study pullets were fed the above levels plus a level of .25% available phosphorus from 2 to 20 weeks of age. Some of the pullets were fed diets restricted by 11 to 16% from 8 weeks of age. Reducing the dietary phosphorus did not harm weight gain, feed intake, feed conversion efficiency, bone ash or total calcium and inorganic phosphorus levels in plasma. There was a very small but significant reduction in weight gain and feed intake when .30% or .35% available phosphorus was fed from 0 to 4 weeks of age, but this difference disappeared at the later ages. With the nonstimulatory lighting schedule used, plasma phosphorus decreased markedly in the latter phase of the studies at all levels of dietary phosphorus and thus represented a nondietary age effect. These results show that dietary available phosphorus for caged, brown egg type pullets on full or restricted feeding programs can be decreased to a level as low as .25% from 2 to 20 weeks, and .30% from hatching to 20 weeks without adverse effect.

Heated oils - chemistry and nutritional aspects.

Used frying oil can be separated by means of column chromatography on silica gel into an unpolar fraction, which contains predominantly the unaltered triglycerides, and a polar fraction consisting of all oxidation and decomposition products formed during the heating process. The size of the polar fraction indicates the degree of fat deterioration. A similar procedure was applied to obtain fractions from a heated oil to be used in long-term feeding experiments. Several tons of a sunflower oil which had been used in the industrial production of fish fingers were separated into a polar fraction (1) and an unpolar fraction (2). The sunflower oil had not been overheated and was taken at the moment when the production would have been stopped, according to factory practice, and the oil discarded. Fractions 1 (group U) and fraction 2 (group P) as well as the original unheated sunflower oil (group F) and the heated sunflower oil (group H) were fed to rats over 18 months at a level of 20% in the diet. Fraction 1 caused a highly significant reduction in weight gain of the animals as compared with unheated sunflower oil but had only an insignificant detrimental effect upon the many biochemical, histological and clinical parameters. The order of the weight gain caused by the four samples was: U < H < P < F. The changes of other parameters as well as the implications of these long-term feeding studies will be discussed in detail.