Effect of feeding finishing pigs extruded full-fat soybeans on performance and pork quality.

This experiment was designed to test whether changing the type and amount of added dietary fat would affect performance or meat quality. Dietary fat was added as tallow or extruded full-fat soybeans (FFS). Isoenergetic diets containing 10% FFS, 20% FFS, or 4% tallow were fed for 3 or 6 wk before slaughther. A conventional corn-soybean meal diet served as a no-added-fat control. Each of the seven dietary groups contained 20 pigs, equally distributed among four pens, with barrows and gilts segregated. Significance of treatment, sex, and interaction effects were evaluated for 34 meat quality, composition, and sensory evaluation traits. Treatment x sex interactions were not detected (P greater than .05). Treatment main effects were detected for percentage of fat and water in the bacon and for lipid oxidation in bacon and the longissimus muscle. The 6 df for treatment were partitioned into six contrasts to test for the trends within and between diets. A trend toward reduced fat and increased moisture in bacon was detected in the 10% FFS diet over time (P less than .05). In general, lipid oxidation of bacon and longissimus muscle increased with level of FFS in the diet, length of time on the diet, and storage time of the meat. Although statistically significant, the magnitude of these effects was small and did not affect the sensory characteristics of longissimus muscle samples. It was concluded that short-term feeding of FFS before slaughter did not adversely affect animal growth or meat quality.

Characterization of lipid in loin and bacon from finishing pigs fed full-fat soybeans or tallow.

This experiment tested whether the lipid composition of pork could be altered by changes in dietary lipid, that what effects these changes would have on production and meat characteristics. Pigs were fed diets containing 10 or 20%+ extruded full-fat soybeans (FFS) or 4% tallow for a 3- or 6-wk finishing period, with a corn-soybean meal diet fed as a control. Seventy barrows and 70 gilts were allotted into seven treatment groups with four pens per group. Analysis was on 28 experimental units, which were composite samples from pens. The significance of treatment, sex, and treatment x sex interaction F-statistics was evaluated on chloroform-methanol extractable total lipid, triacylglycerol, phospholipids, cholesterol, individually fatty acids (FA), and the major classes of FA obtained from longissimus muscle and bacon. Treatment effects (P less than .05) were detected for cholesterol content of longissimus and for total lipid and phospholipid content of bacon. Treatment effects (P less than .01) were detected for monoenoic, dienoic, and polyenoic (P) FA in both tissues, and for saturated (S) FA in bacon (P less than .05). Treatment effects (P less than .001) were detected in both tissues for the P:S ratio. The P:S ratio increased 54% for longissimus and 100% for bacon in the pigs fed FFS for 6 wk compared with pigs consuming a corn-soybean meal diet.

Metabolic conversion of six steroid hormones by human plasma high-density lipoprotein.

Sixteen different steroid hormones were individually tested in equilibrium dialysis against plasma high-density, low-density and very-low-density lipoproteins (HDL, LDL, VLDL) under physiological conditions. Six steroid hormones (androstenediol (AEDOL), estradiol (E2), dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT), pregnenolone (P5), and progesterone (P4)) demonstrated metabolic interaction with HDL, particularly HDL3. In four cases (AEDOL-HDL, E2-HDL, DHEA-HDL and P5-HDL) the interaction products were more lipophilic, while in the other two cases (DHT-HDL, P4-HDL) they were hydrophilic compared to the original steroid hormone substrates. The lipophilic products appeared to be long-chain fatty acid steroid hormone esters at the C-3 position of the steroid hormone. This was confirmed, in preparative incubations, for the two strongest steroid hormone reactants (DHEA and P5) by gas chromatography-mass spectroscopy (GC-MS). Naturally occurring DHEA and P5 esters were identified in normal fresh human plasma by GC-MS, and their fatty acid compositions were similar to that of native HDL3 cholesterol esters. It was deduced that lecithin-cholesterol acyl transferase enzyme was responsible for the lipophilic type conversion activity with P5 greater than DHEA greater than AEDOL greater than E2. For DHT and P4, which exhibit a fundamentally different (hydrophilic) type of metabolic conversion, a totally different form of HDL-associated metabolic activity is indicated. These newly discovered steroid hormone-lipoprotein interactions may be important for steroid hormone processing in plasma and/or steroid hormone delivery to cells.

Nonspecific and metabolic interactions between steroid hormones and human plasma lipoproteins.

Previous observations demonstrated that steroid hormones associate with plasma lipoproteins. The objective of this study was to estimate the relative importance of lipoproteins as steroid hormone binding agents in comparison to sex hormone binding globulin, corticosteroid binding globulin, and albumin in both normal and hyperlipidemic human plasma. The 16 steroid hormones and related metabolites included in the study were: androstanediol, androstenediol, androstenedione, androsterone, corticosterone, cortisol, dehydroepiandrosterone, deoxycorticosterone, dihydrotestosterone, estradiol, estriol, estrone, 17 alpha-hydroxyprogesterone, pregnenolone, progesterone, and testosterone. The binding activity of these 16 steroid hormones with purified high density lipoprotein (HDL), low density lipoprotein and very low density lipoprotein were separately evaluated by equilibrium dialysis incubations to yield 48 steroid hormone-lipoprotein combinations for further study. In incubations with HDL, six steroid hormones (androstenediol, dehydroepiandrosterone, dihydrotestosterone, estradiol, pregnenolone, and progesterone) were identified as non-equilibrium, apparently due to metabolic conversion of the steroid hormones. The metabolic activity for the three delta 5-3 beta hydroxy steroids and estradiol appears to be fatty acid esterification by lecithin:cholesterol acyltransferase. The computer program TRANSPORT, which was used to evaluate only the nonspecific steroid hormone-lipoprotein association levels in a 16 x 6 matrix at simultaneous equilibrium, indicated that lipoprotein-bound steroid hormones ranged from 1% for cortisol to 56% for pregnenolone in normal human blood. Simulated projections of the increase in nonspecific steroid hormone association with lipoproteins during hyperlipidemia are also presented. These results demonstrate how lipoproteins are likely to be important in the transport and metabolism of steroid hormones in human plasma.

Esterification of dehydroepiandrosterone by human plasma HDL.

Evidence for metabolic esterification of dehydroepiandrosterone (DHEA) in human blood plasma, identification of the active lipoprotein (LP) subclass involved, namely HDL3, as well as positive identification of the long-chain fatty acid esters of DHEA formed as incubation products is presented. The esterification reaction of DHEA and subsequent transfer and transport of DHEA esters in human plasma appears to proceed in a manner similar to that of cholesterol. The experiments presented serve as a model predicting similar metabolic transformations during HDL3 interactions with other steroid hormones that have the delta 5-3 beta-hydroxy steroid ring structure and exhibit nonequilibrium associations with HDL. These observations imply that significant quantities of DHEA, particularly in the conjugated ester form, can enter cells via the membrane receptor-mediated pathways of LP internalization.

Characterization of steroid hormone association with human plasma lipoproteins.

Partition coefficient analysis, equilibrium dialysis, and computer simulation were used to evaluate associations of twelve steroid hormones (androstanediol, androstenediol, androstenedione, androsterone, dehydroepiandrosterone, dihydrotestosterone, estradiol, estriol, estrone, hydroxyprogesterone, progesterone, and testosterone) with human plasma high density lipoproteins (HDL), low density lipoproteins (LDL), and very low density lipoproteins (VLDL). It was determined that partitioning of steroid hormones (SH) between the aqueous medium and the surfaces of lipoproteins (LP) was the initial (first order) SH-LP interaction. For some SH, especially dehydroepiandrosterone, significant second order interactions, which may involve chemical conversions, were detected. The first order binding values of the twelve SH with three LP were combined with the corresponding binding values of SH with sex hormone-binding globulin, corticosteroid-binding globulin, and albumin in a 6 X 12 matrix. The computer program TRANSPORT was used to analyze the matrix and determine the distribution of each SH among six different binding agents in the "normal" male. It was concluded that LP are important vehicles for SH conveyance in plasma and may also be important for SH entry into cells.

Lipid oxidation in plasma and tissues from estrogenized chicken hens.

Four groups of 5-month-old chicken hens were given estradiol treatments and/or 5% dietary oil supplement for 14 days, after which blood plasma, liver, heart, and skeletal muscle were analyzed for lipid oxidation by TBA assay for malonaldehyde. Plasma from estradiol-treated birds had 8-fold higher levels of malonaldehyde compared to untreated birds. The bulk of this effect was due to a 5-fold increase in plasma lipid, but this lipid also contained a 70% higher concentration of malonaldehyde. Estradiol treatments produced significantly increased TBA numbers in liver, heart, and skeletal muscle. Corn oil supplementation significantly increased the malonaldehyde concentration in fat extracted from liver and heart, but not from plasma or skeletal muscle. It was concluded that estradiol treatment, in addition to generally increasing the deposition of fat in plasma and organs, also enhanced the concentration of malonaldehyde equivalents in plasma and organ fat.

Butylated hydroxytoluene addition improves the thiobarbituric acid assay for malonaldehyde from chicken plasma fat.

Samples of plasma lipid were tested for autoxidation during the heating step of the thiobarbituric acid (TBA) assay for malonaldehyde. Butylated hydroxytoluene (BHT) was used to quench sample autoxidation during the assay, and 25 ppm BHT was found effective in eliminating autoxidation in fresh plasma fat. At this concentration, BHT does not interfere with the reaction of malonaldehyde with TBA. Depending on fat concentration, absorbance at 532 nm was 2-5 times higher when samples were assayed without BHT compared to identical samples with 25 ppm BHT addition. It is concluded that BHT addition to the TBA assay before the heating step improves the reliability of the assay by eliminating autoxidation which may generate the majority of oxidative products measured in TBA assays lacking antioxidant protection.

Relationship of plasma estradiol and progesterone levels to egg productivity in domestic chicken hens.

Female chickens from eight different genetic stocks, ranging from 13 to 21 months of age, and exhibiting various levels of egg production were studied. Plasma samples were collected between 1700 and 2200 hr to determine basal circulating levels of progesterone (P4) and 17 beta-estradiol (E2) by radioimmunoassay. Linear regression analysis was used to describe the relation between mean hormone levels (E2, P4, and E2/P4) and mean egg production from these groups, and correlation coefficients were used to evaluate the general usefulness of these hormone parameters for estimating egg production within a group or flock of hens. Of the three hormone parameters evaluated, basal circulating E2/P4 was found to be the best estimator of egg productivity.

Comparative plasma lipid response of pullets and laying hens to estradiol and progesterone.

The effects of estradiol and progesterone treatment on plasma hormone and lipid concentrations were measured in laying hens and sexually immature pullets. Pullets and hens were divided into three groups and injected with estradiol (1 mg/kg bw), progesterone (4 mg/kg bw), or vehicle (propylene glycol) once each day for 14 days. Blood samples were collected before treatment and 24 hr after the 7th and 14th treatments. Plasma progesterone (P), estradiol (E2), triglycerides (TG), cholesterol (C), and phospholipids (PL) were measured. E2 treatments elevated hen plasma TG 7.2X, PL 5.1X, and C 7.2X; and pullet plasma TG 6.8X, PL 3.7X, and C 2.5X. However, because hen plasma was initially mildly hyperlipidemic, the E2-treated hens developed severe hyperlipidemia, but egg production was unaffected. Progesterone treatments of pullets had little or no effect on plasma lipids, but progesterone treatment of hens significantly reduced initial plasma TG and PL and also reduced egg production. No substantial differences were found in circulating E2 or P in hormone-treated hens and pullets, which indicated no extreme differences in plasma hormone clearance rates. These results indicate that long-term rather than short-term hepatic priming may account for observed differences in layer and pullet response to estradiol treatment.

Plasma sex hormone and lipid patterns in normal and restricted-ovulator chicken hens.

The relationships of circulating estradiol, estrone, and progesterone levels to plasma lipid levels and ovulatory frequency were studies in sexually mature hens. New Hampshire X Columbian (NH X C) cross-bred hens, which have a relatively low frequency of ovulation, were compared with pure-bred White Leghorn (WLH) hens with a high frequency of ovulation. A mutant strain of WLH hen, exhibiting the phenotypic characteristic of restricted ovulation (RO) was also tested. It was fund that NH X C hens had a basal circulating estrogen: progesterone ratio 2.7 X greater than WLH hens. Furthermore, WLH-RO hens exhibited 3 X HIGHER BASAL PLASMA ESTROGEN AND 4 X lower progesterone than normal WLH hens, resulting in an estrogen:progesterone ratio which was l2.6X higher. In additional, WLH-RO hens did not exhibit any diurnal variation in circulating progesterone levels, and had smaller primary sex organs and also intermittent hyperlipidemia. It is concluded that the basal circulating estrogen:progesterone ratio in sexually mature hens is a good indicator of ovulatory frequency, and that the magnitude of the ratio is determined primarily by the progesterone component.

The role of 25-hydroxy-vitamin D3 in the induction of atherosclerosis in swine and rabbit by hypervitaminosis D.

Fibromuscular intimal thickening was seen in the ascending and thoracic aorta of the swine fed 62,500 IU of vitamin D3/kg of diet for three months duration; and after 3 months of vitamin D3 withdrawal, atherosclerotic lesions were found. In rabbits, pronounced aortic smooth muscle cell necrosis developed with the forced feeding of 10,000 IU vitamin D3 dissolved in corn oil/kg body weight/day for 14 days. Serum analyses indicated that blood calcium did not differ from that of animals fed corn oil alone, but that the level of serum 25-hydroxy-vitamin D3 measured by HPLC was 30 times that in the control animals. These data suggest that choleclaciferol (the oxidized sterol with vitamin D3 activity) has a very destructive influence on the integrity of arterial wall, and that smooth muscle cell necrosis could be caused by enhanced membrane permeability to Ca2+ following 25-hydroxy-vitamin D3 incorporation into smooth muscle cell membranes.

Influence of dietary sex hormones on chick lipid metabolism.

The major ovarian hormones (estradiol and progesterone), the major testicular hormone (testosterone), and the major precursor to steroid hormones (cholesterol) were fed ad libitum in various combinations for either 2 weeks or 2 months (56 days) to 5-day-old female chicks; the effects of these treatments on liver lipids and plasma lipoproteins were measured. After two weeks, chicks fed basal diet supplemented with 0.05% estradiol had significant increases in plasma total cholesterol, triglycerides, and phospholipids (P less than .01). The combined supplementation of 0.05% estradiol plus 1% cholesterol produced an additive increase in plasma total cholesterol resulting in levels higher than obtained by either treatment alone (P less than .01). The addition of 0.2% progesterone to the 1% cholesterol diet inhibited the accumulation of plasma cholesterol (P less than .05), liver cholesterol (P less than .01), and liver triglycerides (P less than .01), which were found in comparable animals fed only 1% cholesterol. Likewise, the addition of 0.2% progesterone to diet containing 0.05% estradiol inhibited (P less than .01) accumulations in all of the plasma lipid classes which were found in comparable birds fed only 0.05% estradiol. After 2 months feeding, 0.1% testosterone had no effect on plasma or liver lipids. The combination of 0.05% estradiol plus 0.1% testosterone for 2 months was not very effective in reducing the hyperlipidemia caused by estradiol alone, but this treatment did result in a peculiar dwarf chicken. The results demonstrate strong steroid sex hormone interactions which produce major changes in chick plasma and liver lipid metabolism.

Excess dietary lysine induces hypercholesterolemia in chickens.

Lysine and arginine supplements were fed to 5-day-old chicks to test whether they would develop hypercholesterolemia in response to excess lysine in a fashion similar to mammals. Chicks developed hypercholesterolemia with a 4-5% lysine but not with arginine supplementation. These results indicate the lysine induced hypercholesterolemia is not due to anaplerotic interactions of arginine and lysine with the urea cycle.

Degenerative changes in endothelial and smooth muscle cells from aging swine ductus arteriosus and venosus.

Degenerative changes in endothelial and smooth muscle cells from fetal, 2-month-, and 6-month-old swine ductus vasculature were observed. In fetal ductus, a discontinuous internal elastic lamina and increased extracellular mucopolysaccharide deposition were initially noted. At 2 months of age, there was widespread fibromuscular intimal thickening, the appearance of modified smooth muscle cells, increased medial fibrosis, and the occurrence of cell debris and nuclear pyknosis. Early modification of smooth muscle cells was marked by increased occurrence of lysosomes, widely dilated rough endoplasmic reticulum, and Golgi bodies. Abundant aggregates of Weibel-Palade bodies occurred in early endothelial cell degeneration. At 6 months of age, after complete anatomical closure, there was abundant lipid vacuole production by degenerated medial smooth muscle cells. This study demonstrates that at various stages of occlusion, endothelial and smooth muscle cells from ductus vasculature exhibit morphological changes which are qualitatively similar to atherosclerosis.

Morphological evidence of endogenous lipid production in swine ductus vasculature.

Specimens of ductus arteriosus and venosus from 2-month-old and 6-month-old swine were examined by electron microscope. The purpose of the study was to observe the effects of vessel closure and hypoxia on medial vascular smooth muscle cells. At 6 months of age, smooth muscle cells from the medial layer of ductus arteriosus showed signs of considerable cellular degeneration and contained lipid vacuoles which were often surrounded by granular endoplasmic reticulum. Specimens from the portal side of ductus venosus showed initial stages of smooth muscle cell degeneration and lipid vacuolization, while samples from the hepatic side of ductus venosus were nearly normal. This study contains the first reported morphological evidence of organelles in vascular smooth muscle cells which are responsible for endogenous lipid droplet production.

Plasma lipoprotein patterns in patients hospitalized for coronary artery bypass surgery.

Preoperative plasma samples from coronary artery bypass surgery patients were analyzed for relative levels of high-density lipoproteins (HDL) and low-density lipoproteins (LDL) in order to assess the HDL:LDL ratio as an indicator of risk for coronary heart disease. Fasting blood samples were drawn from bypass patients prior to surgery, and bypass patient mean plasma lipid data were compared with values from three other groups: randomly selected, newly admitted hospitalized patients; acutely ill student outpatients; and healthy hospital employees. Sudan Black B prestained plasma samples were electrophoresed on polyacrylamide gels, and HDL:LDL ratios were determined by densitometric gel scan and automatic peak integration. Of the four study groups, the bypass patient group had the lowest mean HDL:LDL ratio; the low ratios were due particularly to reduced levels of HDL2. Chemical analyses indicated that the bypass patient group also had lower mean HDL-cholesterol and higher mean total cholesterol and triglyceride levels than the other groups. When group age and sex differences were taken into account, the bypass group, especially males, also had low ratios. The results also strongly indicated that stresses involved with illness and hospitalization unrelated to clinical coronary heart disease (CHD) can adversely affect lipoprotein patterns.

Morphometrical analysis of the aging process in human arteries and aorta.

Ultrastructural and morphometrical studies were conducted on vascular tissue from 205 human Japanese specimens ranging in age from 15 weeks' gestation to 90 years. Comparison of aorta size with overall body length by allometry revealed that the aging aorta has growth and involution stages comparable to other organs, and that progressive increase in aortic diameter was the major involutional change. The cellular and extracellular components of the medial sections of thoracic and abdominal aorta, renal artery, and superior mesenteric artery were quantitated from electron micrographs and compared at different ages. It was found that the renal artery rapidly accumulated extracellular material with increasing age; in the aortic tissue, however, the peak occurrence of extracellular material occurred at pubescence. Ultrastructural studies revealed a general tendency of aging medial smooth muscle cells to transform from a smooth, rounded morphology to become irregularly shaped.