Effect Of Dietary Fat Level Research Articles

Effect of dietary cholesterol and fat levels on lipid peroxidation and the activities of antioxidant enzymes in rats.

The aim of this study was to investigate the effect of dietary fat levels, with or without cholesterol, on lipid peroxidation and the activities of antioxidant enzymes in rats. Thirty-two Wistar rats aged 4 weeks were divided into 4 groups and fed high (20%; HF) or low (5%; LF) fat, with or without 1% cholesterol, for 6 weeks. Cholesterol feeding resulted in significantly higher concentrations of serum cholesterol, but lowered serum triacylglycerol levels. Cholesterol feeding also led to markedly decreased levels of hepatic thiobarbituric acid reactive substances (TBARS) and lower activities of hepatic superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase, and glucose-6-phosphate dehydrogenase (G6PDH) when compared with cholesterol-free counterparts in both HF and LF diets. On the other hand, rats fed high-fat diets showed increased serum and liver TBARS, but decreased hepatic GSH-Px, SOD, and G6PDH activities. Hepatic catalase activity was lower in rats fed cholesterol-containing diets, but higher in rats fed high-fat diets, and interaction existed between cholesterol and fat feeding. These results suggested that dietary cholesterol might delay lipid peroxidation and decrease the activities of the hepatic antioxidant enzymes. The degree of lipid peroxidation was also influenced by dietary fat levels.

Effects of dietary fat levels on growth, feed efficiency and biochemical compositions of Eurasian perch Perca fluviatilis

A feeding experiment was conducted for 10 weeks with Eurasian perchPerca fluviatilis juveniles (33.1–35.9ginitial body weight) using three dietary fat levels (11.7, 15 and 19.3%). Theresults showed that increasing dietary fat content increased growth, feedefficiency and protein utilization of perch (P < 0.05) but did not affectmortality. Lipid analysis showed that the composition of some perch tissueswerealso significantly affected by increasing dietary fat content, with an increaseof lipid deposition in the viscera (from 64.9% in fish fed 11.7 % fat to 78.8%in fish fed 19.3% fat) and liver (from 12.4 to 23.8%) (P < 0.05), while themuscle composition was not affected by the dietary treament. Highdocosahexaenoic acid (22:6n-3, DHA) and high docosahexaenoicacid/eicosapentoenoic acid (20:5n-3, EPA) ratios were found in the liver andmuscle lipids as compared to the dietary fatty acid compositions, suggestingthat Eurasian perch might possess a high capability of converting the longchainhighly unsaturated fatty acids, especially DHA from its dietary precursors.

Dietary lipid level, hepatic lipogenesis and flesh quality in turbot ( Psetta maxima)

A study was undertaken with marketable size turbot to evaluate the effects of dietary fat levels on chemical composition, lipogenesis and flesh quality. Four experimental diets containing graded levels of fish oil in order to obtain 10%, 15%, 20% and 25% of crude fat were fed to triplicate groups of turbot (initial body weight of 660 g) for 12 weeks in full strength seawater at temperature of 17°C. Nutrient digestibility was not influenced by dietary fat levels. The best growth performance was observed in fish fed 10% and 15% dietary fat. High dietary lipid levels led to higher fat deposition in whole fish, although lipid level in muscle remained low (1.1% in dorsal muscle and 1.7% in ventral muscle irrespective of diet). Significant subcutaneous fat accumulation was detected in turbot. No protein sparing effect by lipid was observed in turbot fed high dietary fat. Hepatic lipogenic enzymes (glucose-6-phosphate dehydrogenase, G6PD; malic enzyme, ME and acetyl CoA carboxylase) did not show any clear change in activity in response to dietary fat content. With regards to quality parameters, there were no differences in gutted and fillet yields among treatments. Sensory analyses of dorsal fillets indicated only a difference in exudation (corresponding to loss of water) and whiteness within treatments in accordance with instrumental colour analyses and on ventral fillets, only a difference of sweet flavour was observed. No differences in hardness were detected by either instrumental texture analysis or sensory analysis. In conclusion, although high dietary lipid levels affected growth and whole body composition of turbot adversely they induced very few alterations in flesh quality.

Amount of Dietary Fat and Type of Soluble Fiber Independently Modulate Postabsorptive Conversion of β-Carotene to Vitamin A in Mongolian Gerbils

Current dietary guidelines recommend a decrease in fat intake and an increase in fiber consumption. Decreased bioavailability (BV) of carotenoids is thought to be associated with both of these recommendations. A 2 x 4 factorial design was used to test the effects of dietary fat level at 10 or 30% of total energy and fiber type using no fiber, silica, citrus pectin or oat gum (7 g/100 g) on beta-carotene (betaC) BV in 4- to 5-wk-old Mongolian gerbils. We assessed BV as both accumulation of betaC and bioconversion of betaC to vitamin A (VA) in tissues. A VA- and betaC-deficient diet was fed for 1 wk followed by one of eight isocaloric, semipurified diets supplemented with carrot powder [ approximately 1 microgram betaC, 0.5 microgram alpha-carotene (alphaC)/kJ diet] for 2 wk (n = 12/group). Increasing dietary fat resulted in higher VA (P: = 0.074) and lower betaC (P: = 0.0001) stores in the liver, suggesting that consumption of high fat diets enhances conversion of betaC to VA. The effect of soluble fiber on hepatic VA storage was dependent on fiber type. Consumption of citrus pectin resulted in lower hepatic VA stores and higher hepatic betaC stores compared with all other groups, suggesting less conversion of betaC to VA. In contrast, consumption of oat gum resulted in hepatic VA and betaC stores that were higher (P = 0.012) and lower (P = 0.022), respectively, than those of citrus pectin-fed gerbils. The level of dietary fat consumed with soluble fiber had no interactive effects on hepatic VA, betaC or alphaC stores. Results demonstrate that betaC BV is independently affected by dietary fat level and type of soluble fiber, and suggest that these dietary components modulate postabsorptive conversion of betaC to VA. This study confirms the negative effects of citrus pectin on betaC BV, and suggests that oat gum does not adversely affect betaC BV.

Influence of dietary fat level and increased adiposity on growth and fat deposition in rainbow trout, Oncorhynchus mykiss (Walbaum)

Rainbow trout, Oncorhynchus mykiss (Walbaum), (initial weight ∼ 90 g) were fed diets differing in fat content (27.5% versus 12.6%) to examine the effects of dietary fat level on growth and fat deposition. During phase 1, which was run for 11 weeks, the fish were fed either a high- (27.5%) or low-fat (12.6%) diet. The fish were held at 14.5 °C under a 24 h:0 h light:dark photoperiod and were fed for 4 h each day during this phase. Subsequently, in phase 2, both diets were presented simultaneously, and the influence of adiposity on growth and fat deposition was examined in a growth trial which lasted for 8 months. There were no significant differences in body weights at the end of phase 1 (360.7 ± 7.7 g versus 348.2 ± 18.7 g for the fish on the high- and low-fat diets, respectively), but body composition was influenced by the fat content of the diet. The trout fed the high-fat diet had higher viscerosomatic indices (VSI: 11.7 ± 2.0% versus 9.1 ± 0.7%) and higher visceral fat contents (per cent fat: 38.0 ± 6.7% versus 23.3 ± 3.7%) than trout fed the low-fat diet. The percentage fat contents of the carcass (per cent fat: 12.4 ± 1.0% versus 9.3 ± 0.7%) and whole body (per cent fat: 15.4 ± 1.6% versus 10.5 ± 0.7%) were higher amongst the trout fed the high-fat diet, and these fish had a higher energy gain than those fish fed the low-fat diet. Differences in adiposity between the trout fed the high- and low-fat diets did not result in any differences in weight gain when the fish were provided with both diets simultaneously. During phase 2, the fish that had previously been fed the low-fat diet deposited more fat than those fed the high-fat diet during phase 1. The latter maintained whole body fat concentrations at ± 15% (phase 1: 15.4 ± 1.6%; phase 2: 15.2 ± 1.2%), whereas the fish that had been fed the low-fat diet increased their body fat concentration during phase 2 (phase 1: 10.5 ± 0.7%; phase 2: 14.7 ± 1.3%). Thus, there were no significant differences between groups in either body weight or proximate composition by the end of the experiment.

Long-term effects of dietary fat level and feeding rate on growth, feed utilization and carcass quality of Atlantic salmon

Two extruded diets designed to have fat levels of 220 g kg−1 (F22) and 300 g kg−1 (F30) were fed to Atlantic salmon Salmo salar L. in two different experiments during the sea rearing period (from 0.2–0.3 kg to 3–4 kg). Each diet was fed restricted and isoenergetically at two feeding rates to fish in triplicate groups. In one of the experiments, a supplementary group of fish was fed to satiation with the F30 diet. All fish were slaughtered and evaluated for quality according to a commercial standard. No difference in growth was observed between fish fed the two diets at similar feeding rates and the growth was proportional to the amount of dietary energy offered. Feed conversion ratios decreased according to higher energy content in the F30 diet, and the nitrogen and phosphorus retention increased significantly. Fish fed the F30 diet revealed a higher incidence of sexual maturity. Fat content in cutlets and dressed carcasses were significantly affected by feeding rate but not by dietary fat level. Fish fed the F30 diet had more visceral fat and, consequently, lower dress-out percentage. Mortality, liver size and liver colour were not significantly affected by dietary fat level. These experiments showed that even large differences in dietary fat level employed for the entire sea rearing period of Atlantic salmon, did not, or only marginally affected the cutlet and dressed carcass fat content. The high fat diet improved the feed utilization, thus decreasing the discharge to the environments. Furthermore, it resulted in greater growth at ad libitum feeding.

Effect of dietary fat level on lipoprotein composition in different breeds of pigs

Blood cholesterol concentration is associated positively with the incidence of atherosclerosis. Dietary, genetic and environmental factors may play an important role in the development of high serum cholesterol level (Grundy, 1986), specially the quality and quantity of dietary fat. Human and porcine lipoprotein metabolism is very similar, then pig has been established as a suitable animal in which determine relationship between nutrition and atherogenesis (Pond, 1986).The aim of this study was to determine the effect of an experimental diet supplemented with an 8% of added fat (27.67% saturated, 34.90% monounsaturated and 37.43% of polyunsaturated fatty acids) on lipoprotein composition in four different breeds of pigs.

Effect of dietary fat level on lipoprotein composition in different breeds of pigs

Blood cholesterol concentration is associated positively with the incidence of atherosclerosis. Dietary, genetic and environmental factors may play an important role in the development of high serum cholesterol level (Grundy, 1986), specially the quality and quantity of dietary fat. Human and porcine lipoprotein metabolism is very similar, then pig has been established as a suitable animal in which determine relationship between nutrition and atherogenesis (Pond, 1986).The aim of this study was to determine the effect of an experimental diet supplemented with an 8% of added fat (27.67% saturated, 34.90% monounsaturated and 37.43% of polyunsaturated fatty acids) on lipoprotein composition in four different breeds of pigs.

Protein Kinase C Is Activated and Diacylglycerol Is Elevated in Epidermal Cells from Sencar Mice Fed High Fat Diets

Studies reported here determined the effect of dietary fat level on membrane phospholipid composition, phosphoinositide labeling, 1,2-sn-diacylglycerol and protein kinase C activity in epidermal cells from female Sencar mice. Animals were fed either high fat (24.6 g/100 g diet) or control (5 g/100 g diet) diets at constant energy intake for 6 to 7 wk or 15 to 22 wk, and epidermal cells were isolated. The level of phosphatidylinositol was significantly lower in the animals fed the control diet than in the animals fed the high fat diet (0.6 vs. 1.2 nmol/106 cells). The fatty acid composition of the phospholipids showed significantly lower arachidonic acid level in phosphatidylinositol when the animals were fed the high fat diet. Protein kinase C activity in the solubilized particulate and soluble fraction of the cells was 131 ± 18% and 62 ± 14% greater, respectively, in animals fed the high fat diet compared with animals fed control diet. The level of 1,2-sn-diacylglycerol was significantly higher in animals fed the high fat diet (mean nmol/mg lipid ± SEM: control, 4.5 ± 0.5; high fat, 7.0 ± 0.5). Incorporation of [3H]inositol into inositol lipid was not altered by diet. Because protein kinase C and 1,2-sn-diacylglycerol have been implicated in tumor promotion, the increase in protein kinase C activity and the elevation of 1,2-sn-diacylglycerol in cells from animals fed the high fat diet may be important in the high cancer rate observed with these diets.

Effect of dietary fat level on weight gain, digestibility, and fillet composition of Atlantic halibut

Two experiments were carried out to obtain information on the effect of dietary fat levels on juvenile (6–12 g) and larger (0.6–1.5 kg) Atlantic halibut ( Hippoglossus hippoglossus). The juvenile halibut were fed dry diets containing 12% fat and 54% protein and 21% fat and 49% protein, respectively. The larger fish were fed moist diets formulated to be isonitrogenous (19–21% protein on a wet-weight basis), to contain equal amounts of carbohydrate (9–10%) and increasing amounts of fat (8, 12, 16 or 20%, respectively). Dietary fat level did not result in significant differences in weight gain for any of the two size classes of halibut. No significant effects of the various diets were seen for feed efficiency, chemical composition of fillets and livers or digestibility of dietary dry matter, fat and protein for the larger fish. Large individual variation was observed in all recorded data.

Apparent digestibility of canthaxanthin in rainbow trout: effect of dietary fat level, antibiotics and number of pyloric caeca

Apparent digestibility coefficients (ADC) of lipid and canthaxanthin were studied in twelve rainbow trout families with 45 to 89 pyloric caeca, fed four experimental diets containing the same level (130 mg/kg) of synthetic canthaxanthin. Diets differed in lipid content (lipid-poor, 4%; lipid-rich, 15%) and by antibiotic supplementation (a combination of Flumequine 0.8 g/kg and Gentamycin 3.45 g/kg). The test families and their number of pyloric caeca did not induce any significant variation in the lipid or canthaxanthin ADC. Lipid ADC was significantly higher for the lipid-rich, antibiotic-supplemented diet (94.4%) than for the other diets (from 89.6% to 91.4%). Canthaxanthin ADC was significantly higher for the lipid-rich diets (64.3% without antibiotics, 54.1% with antibiotics) than for the lipid-poor diets (35.8% without antibiotics, 38.7% with antibiotics).

Effect of dietary fat level on feed intake, growth, plasma metabolites and hormones of calves fed dry or liquid diets

To study the role of fat in adaptation to ruminating function and growth, 24 male Holstein calves were assigned at 3 d of age to conventional or veal feeding regimes. At 6 weeks of age, conventionally-fed calves were weaned to dry diets containing 3 or 10% fat, whereas veal calves were maintained on liquid diets with 10 or 18% fat. There was a significant interaction of fat level and feeding system on average daily gain (ADG); higher dietary fat content lowered ADG of ruminating calves and increased ADG of liquid-fed calves. Calves fed the higher fat dry diet adapted slowly to weaning with frequent bloating; dry matter (DM) intake and ADG were lower at 42–48 d, and total days to 160 kg was greater, but did not increase total DM intake to 160 kg compared to calves fed the lower fat dry diet. Calves fed low fat liquid diets required more days to reach 160 kg than did those fed high fat liquid diets, resulting in higher total DM (but not energy) intake. Overall ADG of calves fed either low fat diet were not different; this was caused by higher gain after 84 d by calves fed the solid diet. Calves fed liquid diets had decreased hematocrit ( P < 0.0002) and increased plasma content of glucose and insulin ( P < 0.0001), cholesterol ( P < 0.025), and T 3 and T 4 ( P < 0.072), as compared to calves fed dry diets. High fat diets increased cholesterol ( P < 0.0046), and total ( P < 0.0027) and neutral ( P < 0.0047) lipid in plasma, as compared to low fat. High fat increased hematocrit in liquid-fed calves (feeding × fat, P < 0.082). All plasma measures were strongly influenced by age; however, no measures explained different abilities of ruminating and liquid-fed calves to utilize high fat diets. Ability of liquid-fed calves to utilize high fat diets may be related to high insulin associated with high lactose intake and plasma glucose concentration.

Effects of Dietary Fat Level and Lysine:Energy Ratio on Energy Utilization and Tissue Synthesis by Broiler Chicks

An experiment was designed to estimate the effect of dietary fat (20 or 80 g/kg) on the responses of broiler chicks to changes in the ratios of bioavailable lysine (LB) to true metabolizable energy corrected to zero nitrogen balance (TMEn) in their diets. A comparative slaughter experiment used an initial slaughter group of 44 10-day-old male chicks; an additional 120 chicks from the same population were used in the 14-day experiment. Dietary treatments comprised two basal diets differing in fat content and formulated to have similar nutrient:TMEn ratios. Each basal diet was supplemented with four levels of lysine to provide four LB:TMEn ratios calculated, and subsequently found, to be the same in each basal diet series. Each of the eight diets was diluted with five levels of cellulose to ensure a range of intakes under ad libitum feeding. Three individually housed chicks were assigned to each of the 40 diets. Carcasses were assayed for water, nitrogen, lipids, ash, and gross energy; changes in these variables during the experiment were the response criteria.The fat content of the diet had no effect (P>.05) on the chick responses to LB:TMEn ratios. At a fixed energy intake the body weight gain, retained water, retained energy as protein and retained ash increased with the LB:TMEn ratio, with no conclusive evidence of a maximum response having been reached for any variable at an LB:TMEn ratio of .83 g/MJ. Retained energy was independent (P>.05) of the LB:TMEn ratio but the energy retained as neutral lipids tended to decrease as the ratio increased. The data support the view that the lysine requirement of the broiler chick varies according to the response criterion used in its assessment.

Effect of Dietary Fat Level on Dose Response Relationships During Aflatoxicosis in Young Chickens

The effect of aflatoxin in poultry is greater on birds fed a low fat diet, but it is not known whether this effect is associated with a lower apparent minimum effective dose (MED), altered slope of the response curve, or both. Aflatoxin at 16 dosages ranging from 0 to 3.797 μg/g of feed was fed to six groups of 15 young chickens per treatment ingesting a 2 or 4% fat diet for 3 wk. The weights of the body, liver, bursa of Fabricius, and spleen and the total lipid content of the liver were measured. Mathematical models were fitted to the data and dose-response curves were predicted as continuous functions of aflatoxin concentration. Quadratic polynomials fit body weight and spleen weight whereas plateau-linear models fit liver weight and liver lipid content in both 2 and 4% fat diets. The weight of the bursa of Fabricius was fit equally well by quadratic and linear plateau models. Dietary fat had negligible effects on the apparent MED (μg of aflatoxin per gram of feed) for body, liver and spleen weights, which were calculated from the modeling approach to be 1.37 and 1.41, 1.68 and 1.69, and 1.49 and 1.46 on 2 and 4% fat diets, respectively. The apparent MED for liver lipid content was appreciably lower for birds fed the 2% fat diet than those fed the 4% fat diet (.88 and 1.62, respectively). Similarly, the apparent MED for the bursa was 1.48 and 1.74 for birds fed the 2 and 4% fat diets, respectively. The lower MED for these two variables on the lower fat diet were accompanied by a lesser slope of the linear response, which could result in either an enhanced or ameliorated effect of aflatoxin, depending on its dose. The response curves for liver lipids and bursa which were upward and downward turning curves, respectively, were essentially mirror images of each other, implying that both variables may be responding to a specific metabolite of aflatoxin. These observations, which add a biological factor to the documented statistical factors controlling the apparent MED of aflatoxin, illustrate some of the difficulties in estimating an MED suitable for practical poultry operations.

Effect of Dietary Fat and Protein Levels on Monensin Toxicity in Broiler Chicks

The effects of dietary fat level, fat source, and protein level on the growth response of broiler chicks were evaluated in two experiments with a factorial design. A higher level of soybean oil (SO) (3.5 vs. .5%) in diets containing either 18.2 or 20.4% protein significantly (P<.05) counteracted the depressing effect of monensin on feed intake and weight gain in male chicks in the first experiment. Dietary protein level did not significantly (P>.05) affect the response to monensin, nor did monensin affect feed to gain ratio. The higher SO level of 3.5% in diets containing 18.2% protein reduced, at times significantly (P<.05), the depressing effect of monensin on feed and water intake, water to feed ratio, weight gain, and the retention of dry matter and nitrogen in female chicks in the second experiment. A similar higher level of tallow resulted in less pronounced effects on most of the parameters. Monensin supplementation did not affect dietary metabolizable energy content, but significantly (P<.01) increased feed to gain ratio and the percent of fecal dry matter. It was concluded that the toxicity of monensin to chicks might be alleviated by increasing dietary unsaturated fat and protein levels.

Hepatic Mitochondrial and Peroxisomal Oxidative Capacity in Riboflavin Deficiency: Effect of Age, Dietary Fat and Starvation in Rats

The effects of riboflavin deficiency on mitochondrial and peroxisomal substrate oxidation were examined in young (treatment begun at weaning) and adult Sprague-Dawley rats that were fed diets low and high in fat. State 3 respiration rates (ADP-stimulated) were used as an estimate of mitochondrial oxidation rates. The oxidation of palmitoyl-CoA and palmitoylcarnitine, and to a lesser extent, glutamate, pyruvate and succinate, by hepatic mitochondria isolated from the young rats was depressed with riboflavin deficiency. There was no effect of dietary fat level on mitochondrial substrate oxidation. Carnitine palmitoyltransferase-A (CPT-A) Vmax was increased with riboflavin deficiency and with increasing dietary fat. Cyanide-insensitive palmitoyl-CoA oxidation was used to estimate peroxisomal palmitate oxidation. Expressed as total hepatic capacity, peroxisomal palmitate oxidation was depressed with riboflavin deficiency. This effect was the result of the reduced feed intake rather than riboflavin deficiency per se. Increasing dietary fat resulted in increased peroxisomal palmitate oxidation. Starvation of young rats did not change mitochondrial oxidation rates, although riboflavin-deficient starved rats exhibited increased rates of palmitoyl-CoA oxidation as well as increased CPT-A Vmax. In adult rats, after 5 wk of deficiency, only palmitoyl-CoA and palmitoylcarnitine oxidation rates were depressed. Dietary fat level did not interact with riboflavin deficiency. However, CPT-A Vmax was increased with riboflavin deficiency and with increased dietary fat level. Further, depressed hepatic fatty acid oxidation can occur in adult rats as a sequel to the feeding of riboflavin-deficient diets.

Effect of dietary fat levels on the susceptibility of colonic cells to nuclear-damaging agents.

The effect of two levels and types of dietary fats on the susceptibility of colonic cells to the nuclear-damaging effect of 1,2-dimethylhydrazine dihydrochloride (DMH), 2-amino-3,4-dimethylimidazo(4,5-f)quinoline (MeIQ), and gamma-radiation was investigated. Corn oil and beef tallow were added to the semisynthetic diet at 5% and 20% levels (weight/weight). A diet-related effect was not evident until after two weeks of feeding. Animals (C57BL/6J female mice) that were given the 20% corn oil or beef tallow diets had significantly (p less than 0.05) more nuclear aberrations in their colons 24 hours following treatment with DMH (5 mg or 10 mg/kg body wt or MeIQ (100 mg/kg body weight) than did those given low-fat diets (5% corn oil or beef tallow). The nuclear-damaging effect of gamma radiation was unaffected by dietary treatments. A high-fat diet had the most pronounced effect on DMH-treated animals, and maximum nuclear aberrations were observed 24 hours following the treatment. Thus, we concluded that increased levels of dietary fats elevate the toxicity of DMH and MeIQ to colonic epithelial cells.

Effects of dietary fat level and aflatoxin B 1 treatment on rat hepatic lipid composition

Sprague-Dawley rats were given either ten daily doses of aflatoxin B 1 (AFB 1) or the solvent tricaprylin intragastrically over a 2-wk period and were fed diets containing either 1.6 or 20% corn oil throughout the study. Hepatic lipid composition was analysed in groups of five rats both 3 and 13 wk after the start of treatment, in order to determine short-term and longer-term alterations. Total lipid and cholesterols (total, free and esterified) increased on the high-fat diet at wk 3. At wk 13 only total and esterified cholesterol were increased by 20% corn oil. AFB 1 treatment resulted in large intra-group variations in total lipid and cholesterol at wk 3, but these were no longer apparent by wk 13. AFB 1 produced various alterations in the fatty acid composition of hepatic phosphatidylcholine (PC) and phosphatidylethanolamine (PE), apparent at wk 3 but not at wk 13. The unsaturation index decreased but no changes were seen in the saturated fatty acids. Only in animals fed 20% corn oil did AFB 1 result in significant changes in 18:2, 20:3 and 22:6 fatty acids, while 20:4 and 22:5 tended to decrease and 18:1 to increase in response to AFB 1 treatment with both diets in both phospholipids. The high-corn oil diet was found to increase 18:2, 22:6, and total unsaturation in PC and PE, while the ratio of 20:4 to 18:2 tended to decrease in these phospholipids, γ-Glutamyltranspeptidase, an indicator of liver damage, was significantly increased in AFB 1-treated animals, with the greatest increase over controls in those fed the high-fat diet.

Effects of Dietary Fat Level on Laying Hens Fed Various Concentrations of Calcium

The effects of supplementing laying hen diets with 0, 5, or 10% fat in the presence of 3.0, 3.6, or 4.2% dietary calcium was investigated using laying hens over a 7-week period.There was no significant effect of the fat or calcium treatments on laying hen performance as judged by feed intake, weight gain, egg production, egg weight, and egg shell deformation. Although there was an increase in fat retention with an increase in dietary fat level (P<.01), a larger proportion (P<.05) of unabsorbed fat was present as soap in the excreta of birds on these diets relative to those fed the control diet. There was evidence to indicate that most of the soap observed in the excreta of laying hens was formed in postabsorptive areas of the gut, thereby explaining why the detrimental effects of soap formation were not seen in the laying hen. Increasing the dietary calcium level reduced both percentage calcium (P<.01) and magnesium (P<.05) retention. There were no significant effects of the treatments on nitrogen and phosphorus retention. There were also no significant effects of the treatments on shell ash, shell calcium, magnesium, and phosphorus content. Increasing the dietary calcium level increased bone ash (P<.05) while reducing bone magnesium content (P<.05). There were no significant effects of the fat and calcium treatments on bone calcium and phosphorus content.

Effect of Dietary Fat Level and Polyunsaturated Fatty Acid Content on the Phospholipid Composition of Rat Cardiac Mitochondrial Membranes and Mitochondrial ATPase Activity

Weanling rats were fed either high fat diets containing 40% of calories as fat or low fat diets containing 15% of calories as fat for 14 days. All diets were formulated to contain equivalent essential nutrients per calorie content for the nonfat components. For both dietary fat levels, the polyunsaturated to saturated fatty acid (P/S) ratio was adjusted by substitution of beef tallow for soybean oil to provide a dietary P/S ratio of 2.0 or 0.25. After feeding, hearts were removed from six replicate groups of animals per diet treatment, and mitochondria were isolated. Phospholipids were extracted from the mitochondrial membranes, and cardiolipin, phosphatidyl-choline and phosphatidylethanolamine content were quantitatively analyzed using an iatroscanner. In addition, fatty acyl tail composition of each purified phospholipid was determined. Mitochondrial ATPase was also assessed by a ATP-32Pi exchange assay. Feeding high fat diets increased phosphatidylcholine content of the mitochondrial membrane. High fat diets resulted in a relative increase in mitochondrial cardiolipin content that was apparently unaffected by the P/S ratio of the diet fed. Both the fat level in the diet and the P/S content altered ATPase activity. This study indicates that for an animal model, diets analogous in fatty acid content and composition to those potentially consumed by humans can result in alterations in membrane structural constituents of cardiac mitochondria and have the potential to alter lipid-dependent functions of integral membrane proteins.