Effect of dietary supplementation with stearic acid on the severity of myocardial lesions

Histological studies were conducted on ventricular myocardium obtained from male rats of the Sprague-Dawley strain after 16 weeks of feeding diets containing 20 per cent (w/w) soybean oil, low erucic acid rapeseed oil or high erucic acid rapeseed oil. Additional groups of rats were fed similar diets supplemented with up to 8 g/kg of tristearin. Increasing dietary intake of stearic acid normalised the plasma ratio of C16:0 to C18:0 for rapeseed oil treatments to ratios analogous to that observed for rats fed soybean oil. Tristearin supplementation did not have a significant effect on myocardial lesion incidence but decreased the severity of lesions observed for rapeseed oil treatments.     

The effects of crude and refined low erucic acid rapeseed oils in diets for broiler chickens

1. The effects of feeding diets containing 15% of low erucic acid Zephyr rapeseed oil (B. napus) and of crude, refined and hydrogenated Span rapeseed oils (B. campestris) on growth and on tissue lipids of female broilers were determined.

2. Feeding refined or hydrogenated Span oil led to smaller body weights than feeding soybean oil, while refined Zephyr oil and crude Span oil supported a growth response similar to soybean oil.

3. The treatments had significant effects on the total lipid contents of heart (P ≤ 0.05) and spleen (P ≤ 0.001) but not liver.

4. There was no indication of lipid accumulation in the tissues of the chickens fed low erucic acid rapeseed oil as compared with those of the birds fed soybean oil.

5. Only small amounts of erucic acid were incorporated into heart, liver or spleen lipids when rapeseed oil was fed.     

The effects of crude and refined low erucic acid rapeseed oils in diets for laying hens

1. The effects of feeding diets containing 15% crude or refined low erucic acid Span rapeseed oils, refined regular rapeseed oil or lard to pullets on productive performance and the lipids of egg yolk were determined.

2. Productive performance was best with the low‐fat control diet, less good with the crude low erucic acid Span oil or lard‐containing diets, intermediate with the diet containing refined Span oil and worst with the diet containing regular rapeseed oil.

3. The various dietary treatments did not affect total lipid content of egg yolk but did affect the fatty acid composition of egg yolk lipids.

4. No substantial amounts of erucic acid were found in the eggs indicating that the hen is able to control the lipid concentration in egg yolk though control of the fatty acid composition of lipids is poorer.     

Pathological changes in chickens, ducks and turkeys fed high levels of rapeseed oil.

Rations containing 25% of either regular rapeseed oil (36% erucic acid), Oro rapeseed oil (1.9% erucic acid), soybean oil or a mixture of lard and corn oil were fed to chickens, ducks and turkeys. The regular rapeseed oil ration caused growth depression, increased feed conversion and anemia in all species. All the ducks and some of the chickens fed the regular rapeseed oil ration died. These dead birds were affected with hydropericardium and ascites. No deaths in the turkeys could be attributed to the regular rapeseed oil ration but some turkeys fed this ration had degenerative foci characterized by infiltrations of histiocytic and giant cells in the myocardium. Severe fatty change in the heart, skeletal muscles, spleen and kidney was found at an early age in all birds fed the regular rapeseed oil ration. Less severe fatty change but no other lesions were found in birds fed the Oro rapeseed oil and soybean oil rations.     

Influence of dietary fat source and copper supplementation on broiler performance, fatty acid profile of meat and depot fat, and on cholesterol content in meat

1. Three hundred and twenty d-old chickens were fed on a wheat/maize-soyabean meal diet supplemented with (i) 50 g/kg lard, (ii) 25 g/kg lard and 25 g/kg rapeseed oil, (iii) 50 g/kg rapeseed oil, and (iv) 50 g/kg rapeseed oil and 200 mg copper per kg as copper sulphate pentahydrate. 2. Final weights at 39 d of age in chickens receiving rapeseed oil were lower by 9% than in those fed on the diet containing only lard (P<0.05). The fatty acids profiles of lipids extracted from the tissues of 10 chickens per group reflected those of the diets. 3. The polyunsaturated fatty acid (PUFA) content of breast muscles and abdominal fat (expressed as a percentage of total fatty acids) was increased and the ratio of n-6:n-3 fatty acids was decreased by the substitution of lard by rapeseed oil (P<0.001). These changes were more pronounced for the adipose tissue than for breast muscles. 4. Copper sulphate supplementation increased the final body weight of chickens by 4.3% (P<0.05), reduced the saturated fatty acid (SFA) proportion (P<0.05) in abdominal fat and increased the PUFA:SFA ratio (P<0.05). The magnitude of improvement, however, was small. 5. The substitution of rapeseed oil for lard decreased the concentration of cholesterol in breast muscles by 13%. Copper supplementation further reduced the cholesterol content by 25%. Both effects were significant (P<0.001).     

Fatty haemorrhagic liver syndrome in laying hens on diets supplemented with rapeseed products.

Livers of laying hens of Hy-Line No 934E on low erucic acid rapeseed meals and rapeseed oil were studied. Gross lesions in the livers of hens on experimental diets were moderate to severe fatty degeneration, focal necrosis and moderate to severe haemorrhage. Histological examination revealed oedematous foci and lysis of hepatocytes along with large amounts of lipid droplets in the necrotic lesions. Necrotic lesions were not always associated with large haemorrhages. Connective tissue infiltration of older degenerative and haemorrhagic lesions was not extensive. Abdominal haemorrhage from livers occurred when extensive necrosis in the form of hepatocyte lysis and some vascular changes were present, suggesting hepatocytic degeneration caused by toxic products or their metabolites present in rapeseed by-products.     

The effect of supplementing sheep with rapeseed and linseed oils on the activity of pancreatic digestive enzymes

The aim of this study was to compare the effect of rapeseed and linseed oils added to the diet on pancreatic enzyme activities in sheep. The experiment was conducted on six adult sheep with a catheter introduced into the common bile–pancreatic duct and a T‐cannula into the duodenum. The animals were divided into three groups, two sheep in each. A twice‐replicated 3 × 3 Latin square was used in the experimental design. The sheep were fed meadow hay and the concentrate alone or the same ration supplemented with rapeseed or linseed oils at a dose of 5% of the basal diet. After adaptation period, a mixture of pancreatic and bile juice was collected for three consecutive days. The secretion of bile–pancreatic juice showed an increasing trend in sheep fed rapeseed and linseed oils (69.5 and 68.5 ml/hr respectively) in comparison with control ones (59.8 ml/hr). Lipase and trypsin activities were significantly increased when sheep were fed diets with rapeseed or linseed oils (175 and 21.6 or 179 and 23.2 U/L respectively) in comparison with those fed control diet (128 and 13.1 U/L respectively). It was concluded that oil as a dietary supplement can mainly modify the secretion of bile–pancreatic juice and enzymatic activity of the pancreas and also might affect animal production.     

富含ω-3多不饱和脂肪酸鸡蛋的研究

10 0只 5 2周龄蛋鸡分为 5组 ,对照组饲喂基础日粮 ,试验组分别饲喂 3%的胡麻油 ,3%的菜籽油 ,3%的大豆油和 3%的花生油 ,研究日粮中添加植物油对鸡蛋中ω 3多不饱和脂肪酸的影响。结果表明 :日粮中添加 3%植物油可明显提高生产性能和增加蛋黄中亚麻酸 (C18:3)的含量(P <0 .0 5 )。 2 0d、30d和 4 0d收集的鸡蛋蛋黄中 ,试验组的亚麻酸含量明显高于对照组 (P <0 .0 5 )。试验 1组增加幅度最高 ,分别比对照组提高 88.9%、95 .2 %、95 .6 % ,鸡蛋蛋黄中亚麻酸的含量 2 0～ 30d呈上升趋势 ,30～ 4 0d呈下降趋势。     

Evaluation of beef tallow as a natural source of conjugated linoleic acid

Cis‐9, trans‐11 conjugated linoleic acid (9c, 11t CLA) is a potential anticarcinogen that is found in higher concentrations in beef lipids. However, the effect of CLA on lipid peroxidation, which is closely related to carcinogenesis, is controversial. In this study, we determined the levels of 9c, 11t CLA contents and thiobarbituric acid reactive substances (TBARS) in the tissues of rats fed beef lipid. Sprague‐Dawley rats (male, 8 weeks old) were fed experimental diets containing 20% lyophilized beef, and 12% beef tallow or vegetable oils, for 56 days. With the exception of the brain, the tissues from the rats fed the experimental diets accumulated 9c, 11t CLA, depending on the levels of CLA in the diets. The beef tallow group showed significantly higher 9c, 11t CLA contents in all tissues examined than the other diet groups. The intake of beef lipid did not affect the TBARS levels in the rat tissues. The hepatic lipid content from the beef tallow group was lower than that from the group fed vegetable oils. These results suggest that beef is a good source of 9c, 11t CLA, and that the intake of an appropriate level of beef lipid is not hazardous to health.     

Elevated bile acids in the plasma of laying hens fed rapeseed meal

A simple procedure was developed for the estimation of bile acid taurine conjugates in fowl plasma. Laying hens fed a diet containing rapeseed meal (RSM) (400 g kg-1) for 12 weeks had higher bile acid levels (154 mumol litre-1) than hens fed a control soyabean diet (116 mumol litre-1) (P less than 0.01). The incidence of liver haemorrhages was higher (34.8 per cent) in RSM-fed hens than in controls (21 per cent), but the severity of the lesions did not correlate with the bile acid concentration in affected birds. Histological examination of sections from livers of RSM-fed birds did not reveal significant hepatocyte degeneration outside the immediate vicinity of the haemorrhage. Canalicular bile plugs were never seen. The incidence of liver haemorrhages (13 per cent) and plasma bile acids (85 mumol litre-1) were lower in hens fed a diet containing beta-aminopropionitrile (0.5 g kg-1), a known lathyrogen. Acute treatment of hens with the hepatotoxin alpha-naphthyl isothiocyanate over four days induced necrosis of hepatocytes and resulted in elevated bile acid concentrations (262 mumol litre-1) compared with controls (73 mumol litre-1) given arachis oil. It was concluded that laying hens fed high levels of RSM develop cholestasis but the toxic principle is not known.     

Fatty acid profiles and sensory and carcass traits of tissues from steers and swine fed an elevated monounsaturated fat diet

Twelve Angus X Hereford steers were assigned to either a control high-energy diet or a test diet consisting of 20% rapeseed at the expense of 20% corn. Twelve pigs were allotted to a control diet and two test diets containing either 10 or 20% canola oil (CO). Both CO and oil in the rapeseed contained 60 to 64% oleic acid. Cattle fed rapeseed exhibited little effect from the diet due to apparent indigestibility of the rapeseed. Total saturated fatty acids decreased from 40% in adipose tissue of the control pigs to 15% in the 20% CO-fed pigs. The ratio of monounsaturated to saturated fatty acids (M/S) increased from 1.19 in adipose tissue from control pigs to 3.63 with the addition of 20% CO to the diet. In muscle, the M/S ratio increased from 1.21 in control pigs to 2.46 in the 20% CO treatment group. The percentage of the saturated fatty acids in muscle decreased from 42% in the control to 23% in the 20% CO treatment. Significant increases in "oiliness" and decreases in fat firmness were observed when increasing levels of canola oil were fed. Sensory traits, cooking loss and shear-force values of pork chops were similar among treatment groups. In conclusion, monounsaturated fatty acid content can be elevated substantially in pork without adversely influencing the quality of the meat, thus producing a product perceived to be more healthful by the consumer.     

Effects of essential oils from fennel (Foeniculi aetheroleum) and caraway (Carvi aetheroleum) in pigs

The ban of antibiotics as a feed additive requires alternatives to stabilize the health and performance particularly of the young animals. Essential oils obtained from fennel seed (Foeniculi aetheroleum) and caraway seed (Carvi aetheroleum) were tested in diets for weaned piglets in comparison with either a diet without feed additive or with a combination of formic acid and copper (positive control). Four groups of sixteen piglets (live weight 7 kg, age 26 days) received diets without (1) or with supplements of 7.5 g formic acid + 160 mg Cu/kg (2), 100 mg fennel oil/kg (3) or 100 mg caraway oil/kg (4) during 3 weeks after weaning. In the subsequent 4 weeks, all piglets were fed a diet without these additions. Fennel oil contained almost 2/3 anethol, approximately 1/5 fenchon and the remaining part consisting of alpha + beta-pinen, limonen (p-mentha-1,8-dien) and estragol. In the caraway oil, half of the contents was represented by limonen and the other half by carvon. There were no piglet losses and only few cases of diarrhoea. The combination of formic acid and copper increased feed consumption by 27% and daily weight gain by 25%. There were no differences in the performance between the group fed fennel oil and the control without additives. Piglets fed caraway oil tended to consume less feed and to gain approximately 10% less. In feed choice experiments, pigs consumed the same two diets from two troughs with 50% of total feed amount, as expected. The diets containing fennel or caraway oils were consumed at less than 50%. If the diet contained 100 mg fennel oil/kg, the decrease of percentual feed intake was significant. The results of the feeding experiment and of the feed choice experiment question the classification of fennel and caraway oils as flavour additives or as 'appetite promoters' in diets for weaned piglets.     

Dietary structured lipids for post-weaning piglets: fat digestibility, nitrogen retention and fatty acid profiles of tissues

In four groups of post-weaning piglets the effects of triacylglycerol structure and fatty acid profiles of four dietary fats on apparent faecal nutrient digestibility, nitrogen retention and fatty acid profiles of platelet and erythrocyte membranes, liver, adipose tissue and skeletal muscle were examined. Dietary fats included as 10% (w/w) of the diets were two structured fats of rapeseed oil interesterified with tridecanoin (R1) or coconut oil (R2), respectively, one mixture of rapeseed oil and coconut oil (R3) and rapeseed oil as control (R4). Faeces and urine from piglets weaned at 28 days of age were collected quantitatively during three periods each of 5 days, in which the piglets were kept in metabolism cages for measurement of apparent faecal nutrient and energy digestibility and nitrogen retention. Apparent faecal fat digestibilities were significantly improved in groups fed interesterified fats or the physical mixtures (R1, R2 and R3) compared with rapeseed oil (R4). Apparent faecal nitrogen digestibility and retention were similar in all four groups in the three periods, but increased with time. Apparent faecal fat digestibilities were significantly improved from the first to the third week in the groups R1 and R2. Fatty acid profiles in platelet and erythrocyte membranes and in tissues reflected the fatty acid profile of the dietary fat, except for medium-chain fatty acids, which were only found in low proportions, indicating that 10:0 was mainly used as an energy source.     

Growth and carcass composition of broilers fed sunflower oil and olive oil

Sunflower and olive oils were fed at the same dietary inclusion levels to male broilers as a means of varying the dietary linoleic acid concentration while maintaining similar concentrations of total fat and total unsaturated fatty acids. The type of oil and the dietary supplementation level influenced growth rate, food utilisation and carcass composition. Birds grew faster and utilised food more efficiently when fed the sunflower oil and had higher concentrations of body fat. Increasing the level of supplementation with either oil decreased body fat content. The different responses to the two oils were not related to differences in dietary amino acid balance, ME: protein ratios or rates of food passage through the digestive tract.     

Effect of dietary protein quality and fatty acid composition on plasma lipoprotein concentrations and hepatic triglyceride fatty acid synthesis in obese cats undergoing rapid weight loss

OBJECTIVE: To determine effects of dietary lipid and protein on plasma lipoprotein and free fatty acid concentrations and hepatic fatty acid synthesis during weight gain and rapid weight loss in cats. ANIMALS: 24 ovariohysterectomized cats. PROCEDURE: Cats were fed a high energy diet until they gained 30% of their ideal body weight and then randomly assigned to receive 1 of 4 weight reduction diets (6 cats/diet) at 25% of maintenance energy requirements. Diets contained a low or high quality protein source and a lipid source deficient or sufficient in long chain essential fatty acids. Plasma samples and liver biopsy specimens were obtained before and after weight gain and during and after weight loss for determination of free fatty acid, triglyceride, and lipoprotein concentrations. Synthesis of these substances was measured by use of isotope enrichment. RESULTS: Plasma total cholesterol concentration and concentration of lipoprotein fractions increased after weight gain, compared with baseline values. Weight loss resulted in a significant decrease in concentrations of all lipoprotein fractions except high density lipoprotein. High density lipoprotein concentration was significantly greater in cats fed diets containing an oil blend, compared with cats fed diets containing corn oil. Fatty acid synthesis after weight loss was below the detection limit of the measurement technique. CONCLUSIONS AND CLINICAL RELEVANCE: In cats undergoing rapid weight loss there is neither increased triglyceride synthesis nor decreased transport of very low density lipoproteins from the liver, suggesting that their involvement in the development of hepatic lipidosis may be minimal.     

Influence of maternal dietary fat upon rat pups.

Mother rats were fed purified rations containing different fats during gestation and lactation and at 1 day after parturition. Litter sizes were reduced to 2 male and 2 female pups. The behavior and the brain chemical composition of these selected pups were compared with similarly selected pups from dams fed a commercial ration. All offspring were fed a commercial ration after weaning. Pups from dams fed 20% safflower oil were similar to controls. Feeding 20% cocoa butter to dams resulted in pups with reduced exploratory activity and with a rapid learning performance in a T-maze, employing the aversive stimulation of an electrical shock. Feeding dams a fat-free ration produced pups which had reduced rates of growth, small brains at 2 months of age, and low brain concentrations of cholesterol, DNA, and RNA.     

High mortality with severe dystrophic cardiac calcinosis in C3H/OUJ mice fed high fat purified diets

Severe degenerative myocardial disease occurred in female C3H/OUJ mice fed purified diets for 36 weeks; the diet contained 5% or 20% fat as non-hydrogenated soybean oil. Deaths of lactating females of this group (17/35 high fat diet and 7/35 low fat diet animals) were due to sudden cardiovascular collapse. Cardiomegaly with marked atrial and ventricular myocardial mineralization was seen at necropsy. Histologically, the random, myopathic foci were characterized by severe myocardial degeneration, mineralization, and fibrosis. Mural thrombosis, pulmonary arteriosclerosis, and mild myocardial inflammatory cell infiltrates were also present. Pathological changes were similar to those of dystrophic cardiac calcinosis, an incidental necropsy finding in certain mouse strains.     

Biochemical and histological effects of feeding thermally oxidized rapeseed oil and lard to rats.

Four groups of weanling rats were fed semisynthetic diets containing 15 percent by weight of dietary fats for 28 days. Two groups received thermally oxidized low-erucic acid rapeseed oil (OLE) or lard (OLA) and the other two groups received the respective fresh fats (FLE, FLA) as controls. Average daily feed consumption and feed efficiency were not affected by either OLE or OLA, however final body weights were depressed by the OLA in the diet. The relative heart weights and heart total lipids were significantly increased in both the OLE and OLA groups. A majority of the animals in both the OLE and OLA groups exhibited various gross symptoms attributable to heated fat toxicity such as seborrhea, diarrhea and polyuria. Excessive hair loss was noted in all the animals fed the heated fats. Tissue fatty acid changes due to OLA were confined largely to the polar liver lipids, whereas OLE produced dramatic changes in both the neutral heart lipids as well as in the neutral and polar liver lipids. Histological evaluation of the hearts, livers and kidneys indicated that OLA was very injurious to the kidneys, whereas OLE caused greater damage to both the hearts and livers.     

Effects of exposure of lactating female rats to polychlorinated biphenyls (Pcbs) on testis weight, sperm production and sertoli cell numbers in the adult male offspring

To investigate the effects of intermittent and continuous exposure of lactating rats to Aroclor 1242 (a PCB congener), testis weight, daily sperm production (DSP) and Sertoli cell number per testis were examined in the adult male offspring. Thyroxine (T4) was also measured because of the well-documented effects of polychlorinated biphenyls (PCBs) on this hormone. In experiment 1.3 groups of lactating female rats received daily subcutaneous injections of low (0.8 mg) or high (1.6 mg) doses of Aroclor 1242 in 0.1 ml corn oil from parturition to weaning of pups at 21 days. In experiment II, 3 groups of lactating rats received 2 subcutaneous injections per week of 0.8 or 1.6 mg Aroclor 1242, as in experiment 1. In both experiments, control rats received vehicle alone. Serum T4 was measured at 21 and 90 days of age, and testis weight, DSP and Sertoli cell numbers were examined at 90 days. In experiment I (continuous exposure), both the low (0.8 mg) and high (1.6 mg) doses suppressed T4 concentrations at 21 days of age. Testis weight was increased by 14.8% (LD) and 16.5% (HD) compared with controls. DSP was increased by 20.4% in the low dose and 25% in the high dose animals compared with controls. The number of Sertoli cells per testis was increased by 32.6 and 39.4% in low and high dose animals, respectively. A similar study in which the lactating females were only dosed twice per week (experiment 11) did not show any differences in these parameters. These results indicate that continuous exposure of lactating female rats to PCBs increases testis weight, sperm production and Sertoli cell numbers in the adult male offspring.     

Mead acid supplementation does not rescue rats from cataract and retinal degeneration induced by N-methyl-N-nitrosourea

Fatty acids and their derivatives play a role in the response to ocular disease. Our current study investigated the effects of dietary mead acid (MA, 5,8,11-eicosatrienoic acid) supplementation on N-methyl-N-nitrosourea (MNU)-induced cataract and retinal degeneration in Sprague-Dawley rats. Experiment 1 was designed to inhibit cataract formation, with the dams fed a 2.4% MA or basal (<0.01% MA) diet during lactational periods. On postnatal day 7, male pups received a single intraperitoneal (ip) injection of 50 mg/kg MNU or vehicle. Lens opacity and morphology were examined 7 and 14 days after the MNU injection. Experiment 2 was designed to inhibit retinal degeneration and was performed with female postweaning rats. In this experiment, dams were fed the 2.4% MA or basal diet during the lactational periods. Thereafter, the female pups were continuously fed the same diets during their postweaning periods. On postnatal day 21 (at weaning), pups received a single ip injection of 50 mg/kg MNU. Retinal morphology was examined 7 days after the MNU injection. In experiment 3, six-week-old female rats were fed the 2.4% MA or basal diet starting at one week before the MNU injection and were then continuously fed the same diets until sacrifice. Rats at 7 weeks of age were given a single ip injection of 40 mg/kg MNU, and the retina was then examined morphologically one week after the MNU injection. In experiment 1, mature cataract was found in all of the MNU-treated groups, with or without MA supplementation. In experiments 2 and 3, atrophy of both the peripheral and central outer retina occurred in all rats exposed to MNU, with or without MA supplementation, respectively. The severities of the cataracts and retinal atrophy in the rats were similar regardless of MA supplementation. Dietary mead acid, which is used as a substitute in essential fatty acid deficiency in the body, does not modify MNU-induced cataract and retinal degeneration in rat models.