Carcass Lipid Research Articles

Protein, lipid and glycogen stores in newly-hatched turkey ( Meleagris gallopavo) poults as affected by post-hatch Stressors and holding time

The effects of post-hatch Stressors (commercial hatchery services which included cloacal inspection to determine sex, snood removal, and beak and toe trimming) and length of holding without feed or water (24 or 48 hr) on carcass and yolk sac contents of moisture, protein, and lipid in turkey poults were studied. In a separate experiment, the effects of the above Stressors and holding (48 hr) on carcass glycogen were measured. Both Stressors and holding reduced carcass weight and absolute moisture content. The per cent carcass moisture declined with holding in stressed but not in non-stressed poults. Stressors lowered the absolute amount of carcass protein but not carcass lipid. Holding lowered absolute amounts of both carcass protein and lipid. Stressors had no effect on absolute amounts of nutrients in yolk. Yolk weight and total protein, lipid, and moisture declined with holding, but the changes were such that percentage moisture was higher at 48 hr. Both glycogen concentration and total glycogen in carcass declined with 48 hr holding, but Stressors were without effect.

Nutritive Value of Four Soybean Products in Diets for Atlantic Salmon (Salmo salar, L.)

Abstract Four processed soybean products were evaluated as protein sources for Atlantic salmon: solvent-extracted soybean meal (SBM44), dehulled and solvent-extracted soybean meal (SBM50), dehulled full-fat soybean meal (FFSBM) and soybean concentrate (SBC). The soybean products replaced high-quality fish meal at levels corresponding to 0, 14, 28, 42 and 56% soybean protein of total protein. Dietary inclusion of SBC, at the expense of fish meal, did not affect weight gain, carcass lipids, fecal excretion of nutrients or fecal dry matter content significantly. The nutritive value of the SBC protein appeared comparable to that of the fish meal. The three other soybean products impaired performance increasingly with increasing levels of inclusion, indicating lower nutritive value than for the fish meal. The favourable results seen with SBC indicated a great potential of soybean to become an important protein source for Atlantic salmon through improved processing.

Rabbit growth, feed efficiency and body composition: Effects of recombinant porcine somatotropin

The effects of recombinant porcine somatotropin (rpST) were studied on rabbits from INRA 1077 strain, between the ages of 70 and 90 days. Ten rabbits received a daily intramuscular rpST injection (100 mg per day per kg of live weight) and were compared with ten control rabbits. Growth rate and feed efficiency were not affected by treatment. Perirenal fat deposits were smaller in rpST-treated than in the control rabbits (2·01 vs 2·72%) as were reference carcass lipid content (9·4 vs 10·8) and energy value (0·84 vs 0·88 MJ /100 g). The ratio between polyunsaturated fatty acids (FA) and saturated and monounsaturated FA was higher (0·32 vs 0·28). Reference carcass protein content was increased (20·5 vs 19·9%), as was the percentage of skin in slaughter weight (14·3 vs 13·4%). Muscular ultimate pH (24 h post mortem) was lower in the semimembranosus accessorius (5·67 vs 5·78) and in the biceps femmoris (5·65 vs 5·74) of treated rabbits. In conclusion, rpST, as a heterologous hormone, develops protein-rich tissues whilst lowering fat content and appears to affect the balance of muscular energy metabolism.

Palmitate esterification and glycerophosphate acyltransferase activity in adipose tissue of growing lambs

The purposes of this study were to determine the effects of BW in growing lambs on rates of palmitate esterification (PE) and activity of glycerophosphate acyltransferase (GPAT) in subcutaneous and intermuscular adipose tissue in vitro and to determine the relationship between these in vitro measurements and carcass lipid accretion. At 37, 49, 60, and 71 kg of live weight, nine, nine, eight, and seven Columbia-Rambouillet-cross ewe lambs, respectively, were slaughtered and adipose tissue was dissected for glycerolipid biosynthesis assays. One-half of each carcass was boned, and carcass soft tissue lipid was measured. In both adipose tissues, PE and GPAT activity were highest at 37 kg (P = .0001); the greatest accumulation of carcass fat occurred between 37 and 49 kg (P = .0001). Differences in PE and GPAT were less well marked between 49-, 60-, and 71-kg lambs, but both were generally decreased with increased BW. Significant R2 from regressions of mass and percentage of carcass fat on either PE, GPAT, or steady-state glycerolipid synthesis (GLS) were from .39 to .44 (PE), .40 to .58 (GPAT), .50 to .75 (GLS), and .60 to .77 (PE, GPAT, and GLS combined). Changes in PE, GPAT, and GLS with BW were consistent with changes in rates of carcass fat accretion, which indicated a close relationship between glycerolipid biosynthesis in vitro and lipid deposition in vivo in growing-finishing lambs.

The Relationship Between Various Indices of Carcass Growth and Development and Reproduction in Turkey Hens

Growth and carcass development measures were compared in turkey hens from a line selected for egg production (E line) and a line selected for BW at 16 wk (F line). Hens in both lines reached their maximal BW 4 wk after photostimulation. Maximal BW in F line hens was 20% greater than their respective BW after 89 days of production compared with only a 12% difference in E line hens. In both lines, there was a decline in BW through 49 days of production but no further decreases at 89 days. The same trend was observed for both the absolute or relative weights of the abdominal fat pad. The weight of the oviduct was near maximal size in E line hens near the onset of production, whereas it continued to increase in size in F line hens through 49 days of production. The same was true for liver weight in F line hens, whereas in E line hens liver size continued to increase throughout the experiment. Carcass DM and lipid were higher and carcass protein lower in F line compared with E line hens near the onset of lay.In a second experiment, heavy weight hens were fed the standard Ohio Agricultural Research and Development Center breeder diet or a diet with supplemental fat and increased ME. There were no significant diet effects on BW or egg production, but hens fed the high-fat, high-energy diet did have increased carcass protein (percentage DM; P < .08). Carcass protein was negatively correlated with carcass lipid (−.780; P < .001) and positively correlated with egg production at 84 and 120 days (.351, P < .1).

The effects of porcine somatotropin and dietary lysine on growth performance and carcass characteristics of finishing swine fed to 105 or 127 kilograms.

One hundred twenty barrows (initially 59 kg) were used to determine the effects of dietary lysine and porcine somatotropin (pST) on growth performance and carcass characteristics of finishing pigs fed to heavy market weights (127 kg). Pigs were injected daily with either 4 mg of pST or a placebo and fed diets containing either .8, 1.0, 1.2, or 1.4% lysine in a 2 x 4 factorial arrangement. Performance data were collected and evaluated for the weight ranges: 59 to 105, 105 to 127, and 59 to 127 kg. In addition, daily accretion rates of protein (DPA), lipid (DLA), moisture, and ash were determined by slaughtering six randomly selected pigs at the start of the experiment, then one pig per pen when pigs reached mean weights of 105 and 127 kg. Pigs injected with pST had greater (P < .05) ADG than control pigs at all weight ranges. Increased dietary lysine had no effect (P > .20) on ADG during the entire trial (59 to 127 kg). Although control pigs showed no increase in ADG with increasing lysine, ADG of pST-treated pigs tended to increase. This resulted in a pST x lysine interaction (P < .07) for ADG from 59 to 127 kg. Feed consumption decreased (P < .05) in pigs from 59 to 105 kg and 59 to 127 kg with pST treatment and with increasing dietary lysine. Feed conversion (G/F) was improved (P < .01) by pST administration and a tendency for a pST x lysine interaction (P < .12) was observed. At 105 kg, average backfat thickness, kidney fat, longissimus muscle area, and DPA were unaffected by dietary lysine but were improved by pST treatment (P < .01). At a slaughter weight of 127 kg, average backfat thickness decreased and DPA increased (linear, P < .05) with increasing dietary lysine and pST treatment (P < .01). Longissimus muscle area was increased and DLA was decreased (P < .01) by injections of pST but both were unchanged by dietary lysine. These data indicate that growth performance and carcass characteristics at 105 and 127 kg were improved by daily administration of 4 mg of pST. At both slaughter weights, increasing dietary lysine resulted in increased carcass leanness (increased carcass protein and decreased carcass lipid). Although increasing lysine did not improve overall (59 to 127 kg) ADG and feed efficiency, pST-treated pigs showed a greater response to increasing dietary lysine. The data indicate that pST-treated pigs (4 mg/d) require approximately 28 g/d of lysine.

Body composition of two commercial broiler strains subjected to early feed restriction or feeding with dried chick excreta

Mini Bro and Red Bro broiler chickens were used to study the effects of feed restriction or feeding with dried chick excreta (DX) on carcass composition (CC), plasma very low density lipoproteins (VLDL), and triglycerides (Tg) concentrations. Feed treatments were: (1) controls fed ad libitum, (AL); (2) 50% feed restriction of AL-controls for 2 weeks starting at 1 week of age, (FR); (3) identical to AL controls except that dried chick excreta replaced 20% of the finishing diet during Weeks 5 and 6 of age (DX). At 4 weeks of age, carcass lipid was significantly ( P < 0.01) increased compared with the AL controls. The carcass composition, at 4 and 7 weeks of age, was not affected by sex or strain. At 7 weeks of age, males contained significantly more ( P < 0.01) protein and moisture and numerically less fat than females. Treatment had no significant effect on VLDL whereas Tg concentrations were significantly ( P < 0.05) affected by treatment. However, no significant sex and strain effects were observed on plasma VLDL or Tg concentrations. Carcass composition was not affected by treatment. Phenotypic correlations between body weight (BW) and carcass weight (CW), in both strains were highly significant ( P < 0.01) and all exceeded 0.8. Neither plasma Tg or VLDL concentrations showed any consistent correlations with BW. Correlations between AFW and plasma VLDL or Tg concentrations were inconsistent. It is concluded that DX can be added to finisher diets without adverse effects on carcass composition. Evidence that plasma VLDL or Tg concentrations are a good measure of fatness is lacking.

The Influence of Differences in Dietary Amino Acids During the Early Growing Period on Growth and Development of Nicholas and British United Turkey Toms

From 0 to 4, 4 to 8, and 8 to 12 wk of age, Nicholas (NIC) and British United Turkeys (BUT) toms were fed one of two series of experimental diets. All toms were fed the same diet, appropriately adjusted for age period, from 12 to 16 and 16 to 24 wk. The first series was formulated to 1984 NRC specifications whereas the second series contained higher concentrations of lysine and total sulfur amino acids (NRC+). The NIC toms were heavier (P ≤ .05) at 4, 8, 12, and 16 wk, but there were no strain differences at 20 wk. The NRC+ diets significantly increased BW in both strains at 12 wk, but there were no diet effects at 16 or 20 wk. At 12 wk, BUT toms had significantly more carcass protein and less carcass lipid compared with NIC toms, but there were no significant dietary effects on these variables. In both strains, the NRC+ diets significantly increased the relative weight of the eviscerated carcass and both the absolute and relative weights of the Pectoralis major muscles at 12 wk. At 20 wk, absolute and relative weight of the Pectoralis minor muscles was significantly heavier in BUT toms and in toms fed the NRC+ diets. The tibia and femur were longer in BUT toms compared with NIC toms.From 1 to 24 wk, weekly BW from 50 toms per strain and treatment combination were used to calculate growth curve parameters according to the Gompertz equation. The slope of the growth curve was significantly less in BUT toms, but the BW and age at the point of inflection were increased compared with NIC toms. There were no significant diet effects on any growth curve parameters.

Coincidence of genetic loci for plasma cholesterol levels and obesity in a multifactorial mouse model.

We have examined backcross progeny derived from a cross of Mus spretus with C57BL/6J, that range from 1 to 50% carcass lipid (n = 215), and from 22 to 130 mg/dl plasma total cholesterol (n = 238). Statistical analysis revealed that distal mouse chromosome 7 exhibits significant linkage both to plasma total cholesterol (likelihood of the odds [LOD] 5.8) and to carcass lipid (LOD 3.8). A locus on chromosome 6 also shows significant linkage to plasma total cholesterol (LOD 5.6), but no linkage to carcass lipid. Neither chromosomal region contains any previously mapped genes likely to influence lipoprotein metabolism, indicating that novel genetic factors contributing to plasma lipoprotein levels have been identified.

Effects of triiodothyronine administration on dietary [ 14C]triolein partitioning between deposition in adipose tissue and oxidation to [ 14C]CO 2 in ad libitum-fed or food-restricted rats

Refeeding a chow meal containing [1- 14C]triolein to food-restricted rats results in increased accumulation of [ 14C]lipid in carcass and epididymal adipose tissue and lower oxidation to [ 14C]CO 2 compared to ad libitum-fed rats (Biochem. J. 285, 773–778, 1992). In the present experiments the effects of treatment with triiodothyronine (T 3) for three days on lipid accumulation in refed food-restricted rats has been examined. T 3 decreased accumulation of [ 14C]lipid in carcass and epididymal adipose tissue (32 and 77%, respectively) of food-restricted rats on refeeding the chow-[1- 14C]triolein meal. This decreased accumulation of [ 14C]lipid was accompanied by increased [ 14C]CO 2 production (77%) and decreased heparin-elutable lipoprotein lipase activity in the epididymal fat pad (90%) and subcutaneous adipose tissue (80%). Accumulation of [ 14C]lipid in the latter did not decrease significantly. In contrast, T 3 treatment of ad libitum-fed rats increased [ 14C]lipid deposition in carcass (44%) and in subcutaneous adipose tissue (240%) on refeeding, when compared to untreated ad libitum rats. Lipoprotein lipase activity in the two adipose tissue depots of the refed ad libitum + T 3 rats, however, decreased. Thus, the effects of T 3 on [ 14C]lipid deposition are adipose-tissue-depot-specific and depend on the previous dietary intake (over 14 days) of the rat. T 3-treatment increased the lipoprotein lipase activity released from perfused hearts to a similar extent in both food-restricted and ad libitum-fed rats compared to the corresponding untreated groups. The rates of lipogenesis in-vivo in liver, epididymal and subcutaneous adipose tissue of food-restricted rats refed chow were not altered by T 3. It is concluded that the increased deposition of dietary lipid in the food-restricted rat can be partially reversed by treatment with T 3, suggesting that the low-T 3 state associated with this condition may be in part responsible.

Performance of juvenile Oreochromis niloticus (L.) reared on diets containing cowpea, Vigna catiang, and black gram, Phaseolus mungo, seeds

Sixteen isocaloric diets containing one of three protein levels (20, 25 and 30%) were prepared by partially or totally replacing fish meal with seeds of the legume Vigna catiang (cowpea) and Phaseolus mungo (black gram). Oreochromis niloticus fingerlings (mean weight of 2.60±0.52 g) were fed the test diets twice daily to satiation over a 70-day period. Poor growth rates were noted when fish meal was completely replaced by each of the plant protein sources. Weight gain generally declined as the dietary level of legume seeds increased. Poor feed conversion was observed for fish fed diets with higher plant materials at 20% dietary protein. PER tended to increase with decreasing dietary protein level. Carcass lipid of fish fed 20% protein diets was increased significantly except for one group. It was noted that each of the tested legume seeds could replace about 33% of the fish meal in the test diets without any adverse effect on growth rate.

Relationship of body composition of mature ewes with condition score and body weight

Fourteen mature, ovariectomized, western-range ewes with an initial mean BW of 72 +/- 4.5 kg and mean condition score (CS) of 7.5 +/- .3 were used to evaluate the relationship between CS and body composition. Diets of chopped straw and alfalfa hay were formulated to provide either maintenance energy or less than maintenance energy (100 or 60% of ME) to induce changes in BW and CS. After 180 d, ewes were weighted, scored for body condition, and slaughtered. All carcass components, viscera, and organs were analyzed for lipid, DM, and ash, and protein was determined by difference. Body weight and CS values were related by regression analysis to percentage of composition and weights of carcass components, carcass, and empty body. Body weight and CS were highly correlated (r = .89) and analysis indicated that each increase in CS resulted in an increase of 5.1 kg of BW. Condition score accounted for more variation of percentage of lipid in the empty body (R2 = .95) and carcass (R2 = .90) than did BW (R2 = .84 and .80, respectively). In contrast, BW accounted for more of the variation in carcass weight (R2 = .97) and empty BW (R2 = .99). Inclusion of both BW and CS in regression models did not increase the variation accounted for with the single best predictor. With mature western-range ewes in this study, CS was highly related to carcass lipids and could be used to describe energy reserves available to ewes.

Chronic dieldrin exposure increases hepatic disposition and biliary excretion of [ 14C]dieldrin in rainbow trout

Previous work demonstrated that exposure of laboratory animals including fish to certain organochlorine (OC) insecticides altered the tissue distribution of a subsequent tracer dose of the same [14C]OC. In the present study, 10- to 20-g rainbow trout were exposed to 15 ppm dieldrin in the diet. Fish were subsequently challenged at 2-week intervals with an intraperitoneal injection of 0.1 mg/kg [14C]dieldrin and viscera (liver, bile, mesenteric fat, kidney, and intestine) analyzed for radioactivity, 24 hr later. After 10 and 12 weeks of dieldrin pretreatment, [14C]dieldrin was significantly elevated relative to controls in liver (200%), bile (500%), and fat (500 and 1200% for 10 and 12 weeks, respectively) of pretreated fish. Other tissues were unchanged. Chloroform/methanol extractions revealed a time-dependent increase in label disposition to carcass lipid in controls but not in pretreated fish. Altered disposition could not be explained by changes in total body lipid or induction of total cytochrome P-450 or ethoxyresorufin-O-deethylase, pentoxyresorufin-O-deethylase, glutathione S-transferase, or UDP glucuronosyltransferase activities. In vivo assessment of [14C]dieldrin metabolism revealed no increase in hepatic and only a slight (22%) increase in biliary polar:nonpolar concentration ratio after 9 weeks 20 ppm dieldrin pretreatment. Results suggest that constitutive changes in liver integral to dieldrin sequestration, transport, or excretion may be an adaptive response of trout to chronic OC exposure.

Detection of [U‐13C]eicosapentaenoic acid in rat liver lipids using13C nuclear magnetic resonance spectroscopy

Fatty acid carbons are well-resolved in 13C nuclear magnetic resonance (NMR) spectra of lipid extracts, but application of this methodology to the metabolism of 13C-labelled fatty acids has not yet been reported. In the present study, 13C NMR was used to monitor the presence of 98% [U-13C]eicosapentaenoic acid (EPA) in liver and carcass lipids 24 h after it had been injected into the stomach of a rat. Natural abundance 13C NMR spectra of liver total fatty acid extracts were obtained from four control rats for comparison. At 24 h post-injection, quantitative high resolution 13C NMR showed 13C enrichment in liver fatty acid extracts was present mainly at olefinic and at the n-1 to n-4 carbons, but 13C signal intensities for C-1 to C-4 of [U-13C]EPA were markedly reduced or absent. Small 13C resonances, possibly indicative of some 13C incorporation into docosahexaenoic acid and saturated or monounsaturated fatty acids, were present in spectra of liver fatty acids. Liver and carcass fatty acid composition was similar in both the controls and the EPA-injected rat, suggesting little accumulation of the injected [U-13C]EPA after 24 h. We conclude that the carbon-specific data provided by 13C NMR of lipid extracts may be useful in monitoring the fate of individual carbons during tracer studies using 13C-labelled fatty acids.

Effects of exogenous insulin or vanadate on disposal of dietary triacylglycerols between mammary gland and adipose tissue in the lactating rat: insulin resistance in white adipose tissue.

The effects of exogenous insulin or vanadate (an insulin mimetic) on the disposal of dietary [14C]lipid between oxidation to 14CO2, deposition in adipose tissue or uptake by mammary gland and transfer to suckling pups were studied in virgin and lactating rats. After an oral load of [1-14C]triolein, virgin rats treated with a supraphysiological dose of insulin over 24 h showed a decrease (58%) in 14CO2 production and increased accumulation of [14C]lipid in carcass and white adipose tissue. There was a 2.5-fold increase in lipoprotein lipase activity in the latter. Chronic vanadate administration (12 days) had no effect on these parameters. In lactating rats, the stimulation of the deposition of [14C]lipid in adipose tissue by exogenous insulin was about 10% of that in virgin rats. In prolactin-deficient lactating rats there was no stimulation of [14C]lipid deposition in adipose tissue by insulin. However, both insulin and vanadate treatment increased the accumulation of [14C]lipid in mammary gland to the values seen in the mammary glands plus pups of normal lactating rats. Lipoprotein lipase activity in the gland was also restored to normal values. It is concluded that in lactation there is resistance to insulin stimulation of dietary lipid deposition in adipose tissue, and that this is not due to circulating prolactin. In addition, exogenous insulin plays a role in the regulation of lipoprotein lipase and hence of dietary lipid uptake into lactating mammary gland.

Dietary Addition of Cellular Metabolic Intermediates and Carcass Fat Deposition in Broilers

Ninety-six 1-day-old male broilers were fed a diet containing 0, 2, 4, 6, 8, or 10% of a 1:1 mixture of pyruvic acid (PY) and dihydroxyacetone (DH) for ad libitum consumption for 42 days. Feed intake, body weight gain, and feed efficiency decreased linearly (P < .001) with increasing levels of PY and DH. There were no significant differences among treatments for abdominal fat percentage. Carcass chemical analysis revealed small but significant (P < .05) differences among dietary treatments for protein and fat percentages. In a second experiment, 1921-day-old male broilers were fed diets containing 5% of PY, lactic acid (LA), citric acid (CI), DH, or glycerol (GY) or mixtures (1:1) of DH or GY in combination with each organic acid. Bird performance was impaired (P < .05) by PY or CI but not by DH or GY. Lactic acid reduced (P < .05) feed intake by 9% without affecting weight gain. Lactic acid plus DH, CI plus DH, and CI plus GY mixtures decreased (P < .05) bird performance but other combinations had no effect. Pyruvic acid or CI decreased abdominal fat and carcass lipid percentages. Dihydroxyacetone increased (P < .05) carcass lipid percentage and GY increased (P < .05) abdominal fat percentage. Lactic acid plus DH increased (P < .05) carcass lipid percentage. Only PY and CI decreased carcass fat deposition, but they also impaired broiler performance.

Fall molt and lipid storage in raccoons (Procyon lotor)

Energy storage was examined in relation to the timing of the fall molt in racoons (Procyon lotor) in southwestern Ontario, Canada. Total carcass lipids, corrected for body size, increased curvilinearly over time for juveniles and adults. As well, there were changes in the proportions of the three fall molt categories over time, but these changes were not the same for all four age–sex classes. We suggest that various behavioral and physiological factors are responsible for the differences observed in lipid accumulation and molting over time. Finally, the fall molt had no effect on lipid accumulation by juveniles or adults. For juveniles, lipid stores appeared to have some effect on the start of the fall molt. We suggest that this is due to the need for juveniles to attain a certain level of growth and lipid storage before the fall molt can begin. We conclude that the fall molt and lipid accumulation are occurring simultaneously and that the fall molt is not stressful in adult raccoons. There may be some consequences of growth on the timing of the cycle in juvenile raccoons.

Relationship between ham composition and carcass composition in finishing swine (1993)

The relationship between ham and carcass composition of 120 barrows with an average initial weight of 130 lb was used to develop prediction equations to determine carcass composition based on ham composition. Eighty pigs were slaughtered to determine total body and ham composition. The first half were slaughtered at 230 lb and the second half at 280 lb. Longissimus muscle area, backfat thickness, whole ham weight, and trimmed ham weight of each pig were recorded 24 h following slaughter. The right ham and the right side of each carcass were ground and analyzed for protein, lipid, moisture, and ash contents. A correlation analysis was conducted at each slaughter weight to determine the relationship between total carcass and ham composition. Based on the results of the correlation analysis, we determined that it would be beneficial to run a regression analysis to develop prediction equations for carcass protein, lipid, and moisture contents. The ash content of the carcass did not appear to be highly correlated to any of the variables tested and, thus, a prediction equation for total body ash was not formulated. Using a stepwise regression analysis, the following equations and correlation coefficients were developed to determine total carcass composition at a slaughter weight of 230 lb: 1) carcass moisture = .4019 + .3911 (ham moisture) - .5301 (ham lipid) (R2 = .73); 2) carcass lipid = .3325 - .3787 (ham moisture) + .7334 (ham lipid) (R2 = .75); and 3) carcass protein = .1985 + .6757 (ham protein) + .0914 (longissimus muscle area) (R2 = .49). For pigs fed to the heavier slaughter weight of 280 lb, the prediction equations were: 1) carcass moisture = 1.2852 - 1.0558 (ham lipid) - 5.5573 (ham ash) - .0165 (whole ham weight) (R2 = .54); 2) carcass lipid = -.1650 + 1.0089 (ham lipid) + .0085 (whole ham weight) (R2 = .74); and 3) carcass protein = .4528 + 2.6234 (ham moisture) - 1.8241 (ham lipid) - 10.4795 (ham ash) + .4690 (ham protein) (R2 = .86). These results indicate that ham composition can be used to predict total carcass composition.; Swine Day, Manhattan, KS, November 18,1993

Chronic Dieldrin Exposure Increases Hepatic Disposition and Biliary Excretion of [14C]Dieldrin in Rainbow Trout

Previous work demonstrated that exposure of laboratory animals including fish to certain organochlorine (OC) insecticides altered the tissue distribution of a subsequent tracer dose of the same [14C]OC. In the present study, 10- to 20-g rainbow trout were exposed to 15 ppm dieldrin in the diet. Fish were subsequently challenged at 2-week intervals with an intraperitoneal injection of 0.1 mg/kg [14C]dieldrin and viscera (liver, bile, mesenteric fat, kidney, and intestine) analyzed for radioactivity 24 hr later. After 10 and 12 weeks of dieldrin pretreatment, [14C]-dieldrin was significantly elevated relative to controls in liver (200%), bile (500%), and fat (500 and 1200% for 10 and 12 weeks, respectively) of pretreated fish. Other tissues were unchanged. Chloroform/methanol extractions revealed a time-dependent increase in label disposition to carcass lipid in controls but not in pretreated fish. Altered disposition could not be explained by changes in total body lipid or induction of total cytochrome P-450 or ethoxyresorufin-0-deethylase, pentoxyreso-rufin-O-deethylase, glutathione S-transferase, or UDP glucuronosyltransferase activities. In vivo assessment of [14C]dieldrin metabolism revealed no increase in hepatic and only a slight (22%) increase in biliary polannonpolar concentration ratio after 9 weeks 20 ppm dieldrin pretreatment. Results suggest that constitutive changes in liver integral to dieldrin sequestration, transport, or excretion may be an adaptive response of trout to chronic OC exposure.

Reversal of high-fat diet-induced obesity in female rats.

The purpose of the present study was to test whether the degree of obesity or the duration of the obese state affects the reversibility of diet-induced obesity. This was accomplished by initially feeding adult female Wistar rats either a low-fat diet (Chow) or one of two high-fat diets (HFDs; 30 and 60% of total calories as dietary fat; 30% HFD and 60% HFD, respectively). Fifty-four days, reversal 1 (R1), or ninety-seven days, reversal 2 (R2), later the HFDs were substituted with the low-fat control diet in subgroups of rats. Animals from all groups were sampled at three intervals: the start of R1 (R1 start), and the completion of R1 (R1 end) and R2 (R2 end). At the end of each interval the 60% HFD-fed group had increased body weight, carcass lipid content, and retroperitoneal and parametrial white adipose tissue (RWAT and PWAT) pad weight, fat cell diameter, and fat cell volume, but not fat cell number (FCN), compared with the other groups. The 60% HFD-fed rats also exhibited a marked and persistent hyperphagia that continued even as most of the indexes of obesity approached their maximal values (R1 end). The 60% HFD group had a transient increase in RWAT and PWAT lipoprotein lipase activity that followed the development of most obesity indicators. A clear intermediate level of obesity did not develop in the 30% HFD-fed group. Instead, these animals had nonsignificant increases in these measures of adiposity, making it impossible to test whether the severity of the obesity affected its reversibility in age-matched groups.(ABSTRACT TRUNCATED AT 250 WORDS)