Brief Summary of Minutes of Annual Meeting

Accomplishments: The research objectives for NCCC097, October 2004 to September 2009, are: (see http://nimss.umd.edu/homepages/outline.cfm?trackID=3848) 1. Share and critique new techniques, experimental designs, and new unpublished data regarding adipocyte biology. 2. Through the interactive process at the meeting and afterward, elicit input to improve experimental design and to develop mutual interests toward joint projects. 3. Study biological regulation of catabolic (fatty acid mobilization and oxidation) and anabolic (fatty acid synthesis, elongation and desaturation, and triacylglycerol synthesis) lipid metabolism in domestic species at the molecular, cellular, tissue, and organismal level 4. Study cellular and molecular controls of adipocyte hyperplasia, differentiation and growth in domestic species. 5. Study nutrient determinants of excess fat deposition (diet composition, and amount and source of dietary fat, calories, and protein). 6. Study mechanisms associated with genetic variation in excess fat deposition and the post-genomic variation of individual phenotypes (determinants of cellularity, receptor populations, alternative metabolic signalling pathways, alternative gene expression and promoter function) 7. Establish approaches to maintain or enhance intramuscular fat concentration, but at the same time maintain or decrease subcutaneous and intermuscular fat. Intramuscular fat (marbling) is an important contributor to the organoleptic properties of meat, but the molecular and cellular mechanisms that retard intramuscular fat deposition until late in development are not understood. 8. Investigate the interplay between adipose tissue, liver, gut, and skeletal muscle lipid metabolism. The growth of adipose tissue is regulated, not only within the adipocyte, but also by the the interorgan interchange of metabolites, various lipoproteins, and numerous hormones and signalling molecules. 9. Investigate the role of endocrine factors produced by the adipocyte in co-ordinate regulation of feed intake, reproductive competency, energy expenditure, and immune function. 10. Study mechanisms for intervention strategies to decrease excess fat deposition (exercise, caloric restriction, pharmacotherapy, selective control of gene expression through transcription factors and modulation of promoter function). Given these objectives, NCCC097 scientists conducted the following work over the past year. The Experiment Station, followed by the objective number(s) met by the work, are provided for each entry. Growth, Development & Functional Aspects of Adipose Tissue 1. Experiment Station: Washington State University; Project objectives: 4, 6. Bovine adipocytes and have been isolated, purified and initially studied in vitro to determine the phenomenon of mature fat cells returning to a proliferative-competent state (dedifferentiation). Present research has stalled, while determination of a specific mechanism (other than employment of metabolic markers) that might be used to discern cellular switching events in the dedifferentiation of mature adipocytes is investigated. Further, single cell cytomic, proteomic and genomic analysis is being studied, which will be needed in order to evaluate single mature cells. This research has application to both the animal industry (altering carcass composition), as well as with human health (obesity and diabetes). 2. Experiment Station: University of Georgia and USDA/ARS, Richard B. Russell Agriculture Research Center, Athens, Georgia; Project objectives: 1, 5, 9, 10. Ovariectomized (OVX) prepuberal gilts averaging 164 d of age and 79 ± 4 kg BW were fed either 3 kg of feed (control fed [CF]; n = 6) or feed restricted (RST; 33% of CF diet; n = 6) for 8 d. On d 8, blood samples were collected every 15 min for 8 h for LH and leptin assay. Real-time PCR was performed on total RNA extracted from MSQ fat collected on d 9. Total RNA was also extracted from three additional adipose tissue depots and subjected to microarray analysis for feed restriction effect. A compromise of an ANOVA normalization based method and a LOWESS normalization-based method were used analysis of microarray data. Following normalization the adjusted data is analyzed, for each gene separately, via a mixed linear model with the biological replication as a random effect. CF gilts gained more BW (8.2 vs. -2.5 kg; SE = 0.6 kg; P < 0.001) and BF (2 vs. -3 mm; SE = 1mm; P < 0.02) than RST gilts. RST failed to affect indices of leptin or LH secretion except for LH pulse amplitude which was greater (P < 0.01) than CF gilts. RST failed to affect MSQ expression of leptin, long form leptin receptor (Ob-rb), AFABP (adipocyte fatty acid binding protein), C/EBP± or PPAR³2 transcripts compared to CF gilts. In the microarray study, the number of genes significantly (P = 0.001) affected by RST study was depot dependent. Regardless of level of significance, stearoyl-CoA_desaturase, PPAR³, LPL, and malate dehydrogenase decreased the most with feed restriction while AFABP, C/EBP±, and glycerol-3-phosphate dehydrogenase changed very little. 3. Experiment Station: USDA/ARS Western Human Nutrition Research Center and University of California, Davis, Davis, California; Project objectives: 1, 6, 10. Initial characterization of tumor suppressor candidate 5 (Tusc5) was introduced at last years NCCC097 meeting, and has been extended to further described at the 2007 meeting. First, based on the presence of an IFN-stimulated growth regulator domain present in Tusc5, plus its induction by PPARg agonism and stimulation toward the end of the adipogenic differentiation cascade, it is hypothesized that the function of this protein is to promote fat cell growth arrest in the fully-differentiated phenotype. Thus, levels should be reduced in obese white adipose tissue, a site which may display elevated adipocyte turnover and growth, at least during the phase in which adiposity gain is most robust. Working with collaborators from France and the U.S., we have confirmed that Tusc5 mRNA expression is in fact significantly reduced in the WAT of obese Pima Indians and a French cohort of obese women, albeit modestly. Second, we originally observed two transmembrane domains in Tusc5, and tested whether the protein is on the cell surface of adipocytes. Preliminary results, however, point to an intracellular localization, likely with Golgi or ER. Third, the unique co-expression of Tusc5 in adipocytes and peripheral nerves has been confirmed by ISH, and we have identified other genes with similar expression. In another line of research, we are attempting to identify markers of fatty acid combustion in muscle, in order to use said markers in prognostic and diagnostic tests to evaluate an individuals propensity toward poor fat utilization in this tissuethe latter is a hallmark of insulin resistance and predicts development of type 2 diabetes. We are working with our colleagues in the metabolomics arena and with Dr. Mary-Ellen Harper of the University of Ottawa, and others, to use broad metabolite analysis toward this end. Our preliminary data indicate that in the course of fatty acid b-oxidation, many metabolites from previously-unappreciated pathways and pathways related to glucose and amino acid metabolism are affected. Current studies are focused on further confirming these results and ultimately we wish to test candidate molecules using plasma from people of differing insulin sensitivity and in response to nutritional and physical activity interventions. 4. Experiment Station: The University of Wyoming; Project objectives: 1, 3, 5, 8. Using quantitative (real-time) PCR and Western blot analysis, mRNA transcript abundance of three enzymes and two protein transcription factors involved in lipogenesis in subcutaneous (s.c.) adipose tissue during lactation in the beef cow were evaluated. The overall project objective was to employ strategic nutritional inputs (fatty acid supplements) to affect mammary gland lipogenesis such that adipose tissue accretion could occur rapidly enough for the lactating beef cow to attain an 80-day post partum interval for successful rebreeding. We hypothesized that BCS at parturition and postpartum dietary fat supplementation will alter protein transcription factors and mRNA abundance of adipose tissue lipogenic and lipolytic enzymes during lactation in beef cows. Our objective was to determine abundance of mRNA for acetyl-CoA carboxylase (ACC), hormone-sensitive lipase (HSL), and lipoprotein lipase (LPL), and protein transcription factor (STAT-5 and PPAR-g) levels in adipose tissue of 3-yr old Angus × Gelbvieh beef cows nutritionally managed to achieve a BCS of 4 ± 0.07 (BW = 479 ± 36 kg; n = 18) or 6 ± 0.07 (BW = 579 ±53 kg; n = 18) at parturition. Beginning 3 d postpartum, cows within each BCS were assigned to isonitrogenous and isocaloric diets of hay plus low-fat control (CON) supplement, or supplements (5% of DMI as fat) with either cracked high-linoleate (LIN) or cracked high-oleate (OLE) safflower seeds until d 60 of lactation. At d 30 and 60 of lactation, s.c. adipose tissue biopsies were collected for RNA extraction, quantitative RT-PCR determination of transcript abundance, and Western blot analysis for STAT-5 and PPAR- ³. Adipose tissue of BCS 4 cows had less mRNA for LPL (P = 0.001) and HSL (P = 0.09) compared with BCS 6 cows. Abundance of LPL mRNA was lower (P = 0.002) at d 30 postpartum compared with d 60; whereas, HSL mRNA was greater at d 30 (P = 0.001). Cow BCS did not affect (P = 0.35) ACC mRNA; however, it tended to be higher (P = 0.13) at d 60 compared to d 30 of lactation. Abundance of PPAR- ³ tended (P = 0.13) to be lower in adipose tissue of BCS 4 cows compared with BCS 6 cows. Both STAT-5 (P = 0.0001) and PPAR- ³ (P = 0.05) were greater at d 30 compared to d 60 postpartum. We conclude that abundance of adipose tissue mRNA for LPL and HSL are influenced by cow BCS, and changes in mRNA abundance during lactation indicates a shift in nutrient partitioning away from the mammary gland to s.c. adipose tissue. Furthermore, STAT-5 and PPAR-g likely play a role in the transcription regulation of LPL and HSL in adipose tissue during lactation in beef cows. 5. Experiment Station: University of New Hampshire; Project objectives; 1, 8, 9. The possible causal link between obesity and atopic airway disease was investigated. Allergy and asthma are type 2 acquired immune disorders that develop because of activation of CD4 T helper lymphocytes by antigen presenting cells, such as macrophages. Atopy, (a biochemical precondition of airway allergy development, marked by an elevation in circulatory IgE antibodies, to common aeroallergens) was greater among young healthy adult obese (n = 21) than non-obese (n = 22) women (p <0.01). Plasma leptin, estradiol and insulin resistance also were found to be higher among obese than non-obese women (p <0.05). Using multivariate logistic regression analysis with fat mass leptin, estradiol and insulin resistance as independent factors, only percentage fat mass was significant and positively correlated with atopy among the women. The healthy women were studied further, along with 18, obese and non-obese women with asthma of similar age, to identify a possible mechanism(s) that could explain the link between fat mass and atopy. Atopy and total circulatory levels of specific IgE antibodies were greater among obese and asthmatic women in comparison to respective controls (p < 0.05). Plasma adiponectin was lower between asthmatic and non-asthmatic women; and was lower between obese and non-obese women, but only when specific IgE antibodies was treated as a covariate. Dietary analysis of the women using a food frequency questionnaire, indicated that intake of arachidonate (AA), primarily from animal protein sources, was greater among asthmatic (p <0.01) and obese (p <0.1) than their respective controls. Using multivariate regression analysis with dietary AA, plasma adiponectin, and percent fat mass as independent factors, fat mass and AA were positive predictors of total specific IgE antibodies (p <.05). Arachidonate is precursor of the eicosanoid metabolite, prostaglandin E2 (PGE2). PGE2 is produced by macrophages and has been shown, in vitro, to modify CD4 T helper cells to produce cytokines that signal type 2 acquired immunity. Weight gain therefore could promote recruitment of macrophages, that can be modified in phenotype by the n-6 fatty acid, arachidonate to produce eicosanoids that favor development of a type 2 immune response. Miniature swine are currently being used to investigate this question. 6. Experiment Station: Michigan State University; Project objectives: 1, 3, 7, 9. Signaling mechanisms that explain the lower adipogenic capacity of bovine intramuscular (IM) preadipocytes when compared to subcutaneous (SC) preadipocytes were examined. We hypothesized that the lower adipogenesis of IM preadipocytes was caused by decreased glucocorticoid receptor expression (GR), sensitivity to glucocorticoids, peroxisome proliferator-activated receptor³2 (PPAR³2) expression, and(or) PPAR³2 ligand synthesis. Stromal-vascular cells, containing preadipocytes, were isolated from IM and SC adipose tissue of 3 Angus-cross steers. Immunoblot analysis detected GR immunoreactive bands of ~97, ~62, and ~48 kDa, which were equally expressed in IM and SC cells (P > 0.50). Intramuscular preadipocytes were less adipogenic than SC preadipocytes as determined by glycerol-3-phosphate dehydrogenase (GPDH) activity and oil red O staining (P < 0.05). Dexamethasone (DEX), a synthetic glucocorticoid, increased GPDH activity similarly in preadipocytes from both depots (P < 0.05). Immunoblot analysis revealed a PPAR³2 immunoreactive band of ~53 kDa, which was expressed equally in IM and SC cells (P = 0.39). Conversely, IM cells secreted more derivatives of the presumptive PPAR ligand prostacyclin (PGI2) than SC cells (P = 0.046). Because exposure of SC preadipocytes to an inhibitor of PGI2 synthesis had no effect on adipogenesis (P = 0.99), and exogenous cPGI2 (PGI2 analog) tended to enhance adipogenesis (P = 0.06), the greater secretion of PGI2 derivatives by IM preadipocytes does not explain their lower adipogenesis. Exposing IM and SC preadipocytes to the cyclooxygenase (COX) inhibitor/ PPAR³2 ligand, ibuprofen (IBU) for 48 h or 12 d resulted in a treatment by depot interaction (P = 0.002). Ibuprofen exposure for 48 h enhanced DEX stimulation of GPDH activity only in IM cells (P = 0.009). Exposure to 100 ¼M and 500 ¼M IBU for 12 d enhanced DEX induction of differentiation in IM preadipocytes, whereas only 100 ¼M IBU enhanced DEX induction of differentiation in SC preadipocytes (P d 0.05). In the absence of DEX, exposure to IBU for 12 d maximally increased GPDH activity in IM preadipocytes by 12-fold, but only increased GPDH activity by 1.5-fold relative to control in SC preadipocytes (P < 0.001). Contrary to IBU, 500 ¼M aspirin (a COX inhibitor) did not affect GPDH activity either alone (P > .37), or combined with DEX (P > 0.60) in either cell population. Because IBU diminished adipogenic differences between IM and SC preadipocytes, it is suggested that these adipogenic differences may be partially related to differences in the endogenous activation of PPAR³2. The use of selective PPAR³2 agonists or antagonists offers potential to selectively alter adipogenesis in economically-important bovine adipose tissue depots. 7. Experiment Station: Iowa State University; Project objectives: 1, 3, 6. The objective of this study was to identify single nucleotide polymorphisms (SNPs) in bovine fatty acid synthase (FAS) gene and to test the association of SNPs with beef fatty acid composition. Sequencing of the four exons of the thioesterase (TE) domain of FAS from Angus bulls identified three novel SNPs, A17924G, C18663T, and C18727T. Polymorphism A17924G was predicted to result in an amino acid change from threonine (genotype AA) to alanine (genotype GG). A PCR-RFLP assay was developed to genotype 331 Angus bulls for the A17924G SNP in which three genotype classes were detected, AA (n =121), AG (n = 168), and GG (n = 42). The genotypes were significantly associated with fatty acid composition of longissimus dorsi (LD) muscle of purebred Angus bulls. Cattle with the GG genotype had a lower atherogenic index (AI), less percentages of myristic acid (14:0) and total saturated fatty acid (SFA), and greater contents of oleic acid (18:1) and total monounsaturated fatty acids (MUFA) in the triacylglycerol (TAG) fraction of LD muscle than did the beef cattle with genotypes AA (P < 0.05). The differences of individual fatty acid percentage in total lipid of LD muscle were similar as those in TAG fraction. In conclusion, this SNP may be used as a DNA marker to select breeding stock to improve the healthfulness of fatty acids in beef. 8. Experiment Station: Auburn University; Project objectives: 1, 2, 3, 6, 8, 10. Animal work was initiated to assess aspects of lipogenesis, mitochondrial function and biogenesis, fatty acid oxidation (beta oxidation and peroxisomal oxidation) and the role of uncoupling proteins at the ribonomics level in back-fat and loin muscle from genetically diverse cattle with an emphasis on residual feed efficiency. To this end qRT-PCR real time methodology is being developed appropriate for transcription profiling bovine tissues. 9. Experiment Station: The Ohio State University; Project objectives: 3, 4, 6, 10. The nine currently identified cytoplasmic fatty acid binding proteins (FABPC) belong to the superfamily of lipid binding proteins. FABPC all possess similar protein structures but show tissue specific expression. This tissue specific expression pattern suggests unique or specialized functions for the various FABPC. Recently, animal genetic studies suggested H-FABP is a candidate gene responsible for intramuscular fat accumulation in pigs. We investigated the expression of H-FABP during pig adipocyte development. In addition, maturity of intramuscular and subcutaneous adipose tissue was studied by examining the expression of H-FABP, as well as, other adipose marker genes in both tissues. These studies suggest that H-FABP may play a role in adipose tissue development and function in the pig. 10. Experiment Station: University of Illinois; Project objectives: 1,2,6,7. Chronic Wasting Disease (CWD) is the only prion disease extant in free-ranging animals and is transmissible to livestock by experimental inoculation. A frequent symptom of prion disease in several species is loss of weight with either normal or reduces intake reflecting neural damage to body weight or feeding centers. To look for genetic resistance, nucleic acid sequences of the prion gene (Prnp) were examined and genotypes compiled for 182 white-tailed deer in northern Illinois, 62 of which were positive for CWD. Nine nucleotide polymorphisms, seven silent and two coding, were found in the sampled population. Five polymorphic loci demonstrated significantly different distributions of alleles between infected and non-infected individuals. Nucleotide base changes 60C/T, 285C/A, 286G/A, and 555C/T were observed with higher than expected frequencies in CWD negative animals suggesting disease resistant patterns, while 153C/T was observed more than was expected in positive animals, alluding to susceptibility. Both coding polymorphisms, Q/H95 and G/S96, have been previously described in white-tailed deer populations sampled in CO and WI. Despite similarities in observed genotypes, frequency distributions of coding polymorphisms in WI and IL deer populations were significantly different from each other, a surprising result considering the sampled areas are less than 150 km apart. The number of polymorphisms per animals, silent or expressed was highly correlated to disease status, with negative animals having more base changes than positive animals. An additive association of silent polymorphism number with disease resistance has not been previously reported in prion diseases. Most beef marketed in the US is aged to improve tenderness and consumer acceptability. Because of the inconsistencies in tenderness changes during aging, we attempted to look at the relationship between aging and initial tenderness irrespective of animal age, genetics or nutritional status. Cattle were selected to represent a full range of quality grades from Utility to Prime. Steaks from these cattle were aged in vacuum bags for 0 to14 days and tenderness assessed. Shear values decreased with aging time across most grade categories, however, improvement was not uniform. Shear values overlapped a great deal across all USDA grades so to gain a better understanding of changes with aging, steaks were grouped based on initial shear value differences of 1 kg. Shear value of the toughest steaks decreased the most during aging (-36%), while steaks with the lowest shear values actually toughened as shears increased (16%). The same pattern emerged when steaks were grouped by initial tenderness. These results suggest that initially tough steaks will benefit from aging while the quality of very tender steaks may decline with aging. Dietary Constituents Regulating Lipid Deposition or Lipid Composition: 1. Experiment Station: The Ohio State University; Project objectives: 8, 9, 10. Over-consumption of nutrients relative to energy expenditure is a main cause of weight gain, leading to obesity. The brain has important glucose-sensing neurons that detect fluctuation of blood glucose levels at fasting and feeding stages and responds by alteration in synthesis and secretion of neuropeptides to regulate food intake. The role of glucose transporter 2 (GLUT2), a possible glucose sensor in the brain in regulation of food intake in neuronal cell line, was investigated. Overexpression of GLUT2 gene increased ATP/AMP ratios, which inactivates AMP activated protein kinase, leading to suppression of the hunger signal in the neuronal cells. This finding on the function of GLUT2 in regulation of food intake will not only help us better understand the mechanism of glucosensing, but allow us to develop strategies targeting GLUT2 for regulation of food intake in obese subjects. 2. Experiment Station: The Ohio State University; Project objectives: 5. Most people on a Western diet consume much lower levels of n-3 FA than the recommended daily amounts and much higher levels of n-6 FA than is ideal for good health. Few of these people routinely eat the fish that are good sources of 20:5n-3 and 22:6n-3. Further, there is increasing concern about contaminants such as mercury and dioxins that may limit the healthiness of high fish intake. On average, Americans eat four times as much beef as fish, and studies have shown that cattle consuming forages or feeds containing n-3 FA can produce meat with higher levels of n-3 FA and lower levels of n-6 FA. We examined the ability of n-3 FA in flaxseed-supplemented rations to increase the n-3 FA content of bovine muscle. A significant increase in n-3 FA levels in bovine muscle from cattle fed rations supplemented with flaxseed and increased expression of genes that regulate lipid metabolism was observed. 3. Experiment Station: University of New Hampshire; Project objectives: 1, 2. The goal of this discovery-based project is to expand knowledge about the levels of polybrominated diphenyl ethers (PBDEs) in breast milk of lactating women from the Seacoast region of New Hampshire and to examine potential relationships between breast milk PBDE levels and maternal characteristics, their living environment and dietary intake. Women, ages 22 to 40 who were in the early stages of lactation (less than two weeks) or in the last trimester of pregnancy and planned to breastfeed for at least the first three months postpartum, were eligible for the study. Participants were asked for a maximum of nine breast milk samples during the first three months of breastfeeding. Each participant provided up to three samples at the end of their first, second and third month of breastfeeding for evaluation of day-to-day and month-to-month variation in PBDE levels. Participants were asked to complete four questionnaires during their 3-month commitment in the study, which provided maternal, diet and environment information. A total of forty women completed the study from November 2005 to October 2006 with an average age of 31 years. There was limited diversity among participants; 39 out of 40 participants were Caucasian, and 80% of participants had completed a 4-year college degree or higher. To date, 20 out of 40 breast milk samples have undergone PBDE analysis for eight major congeners. Participant means over the three month collection period was 7.69 to 139.78 ng/g lipid. Data from the first five participants revealed that variation from day to day was minimal with the exception of one outlier during month 2, day 2, so it was decided to only collect one sample per month from each participant. To date, month-to-month variation indicates a downward trend with monthly means at 41.52 ng/g lipid for month one, 38.26 ng/g lipid for month two and 36.40 ng/g lipid for month three. The next steps in the project include awaiting the remainder of the PBDE data, which will allow for an examination of potential relationships between PBDE levels and maternal characteristics, living environment and dietary intake. 4. a. Experiment Station: University of Georgia; Project objectives: 1, 5, 8. Effects of dietary fish oil in gestation or lactation on performance of progeny were investigated. Fish oil was fed as a protected product (Fertilium) in the first experiment beginning at D 60 of gestation through weaning. The study was conducted as a 2 x 2 design with fish oil fed in gestation, lactation or both. Milk was collected at days 1, 7, and 21. Pig performance was monitored through market weight. Selected pigs were challenged with LPS at 14 days of age. The effect of maternal diet on cytokine and cortisol response to an LPS challenge was determined. The addition of the product to the maternal diet resulted a lower n-6/3 ratio (Control 18-20, fish oil 10-12). There was no effect of dietary fish oil on growth performance or ultrasound carcass composition. Despite the low inclusion rate(less than 0.5% EPA and DHA) in the diet, milk fatty acid profile was altered in sows fed fish oil. Pigs from sows fed fish oil had an attenuated cortisol and TNF-± response to LPS challenge. b. Experiment Station: University of Georgia; Project objectives: 1, 2. In the second experiment, sows were fed diets containing 2 % soy oil or 2% fish oil during lactation. Data was collected as in the previous study and is being analyzed. A third study was conducted to determine the effect of maternal fish oil consumption on the fatty acid profile of pigs at birth and day 14. Sows were fed 0.5% fish or soy oil beginning at either day 60 or farrowing. Pigs were obtained at birth and day 14. Fatty acid profile of brain, adipose tissue, muscle, liver, lung, heart and kidney will be determined. c. Experiment Station: University of Georgia; Project objectives: 1, 2. This study was conducted as a 2 x 2 factorial with main effects of consuming an omega-3 supplemented diet during growing and/or finishing. Pigs (n=80, barrows and gilts) weighing approximately 25-30 kg were allotted by gender and weight to either Control or Fish Oil diet treatments. The Grower diets were corn-SBM based diets calculated to contain approximately 18% CP, 1% Lysine, and 3327 kcal/kg ME . At d 35 of the study half of the pens in each diet treatment were maintained on the same diet and half switched to the other diet (Control or Fish Oil) for finishing. The Finisher diets will also be corn-SBM based diets calculated to contain approximately 17% CP, 0.9% Lysine, and 3340 kcal/kg ME. At d 70 of the study all pens were switched to a common finisher diet calculated to contain approximately 16% CP, 0.8% Lysine, and 3345 kcal/kg ME. The study ended at d 98. Pig weight and feed intake per pen was recorded weekly. Ultrasound images of the 10th rib loin area was recorded at d 70 (when switched to common diet) and at the end of the study (d 98) in order to evaluate growth parameters and days to finish. Representative pigs were processed at week 5 and 10 to determine th immediate effects of diet on fatty acid profile. One male and one female from each pen was slaughtered at the end of the study period to obtain tissue samples and carcass data for the purpose of determining tissue fatty acid composition and any possible effects on the meat of long term fish oil supplementation in the diet. d. Experiment Station: University of Georgia; Project objectives: 1,2. In previous studies we have shown that composition of gain (protein and lipid accretion rates) influence energy and protein intake. In somatotropin treated pigs, lipid accretion is reduced and protein accretion is stimulated. Pigs allowed to self-select between high and low crude protein diets alter their intake patterns to match the changes in composition of gain. They consume less of the low CP diet in response to reduced caloric needs and tend to increase consumption of the high CP diet in response to the greater rates of lean growth. Similarly, pigs with less backfat select a higher percent protein diet than pigs with greater backfat. The objective of this experiment is to determine the influence of Paylean on diet selection. Paylean increases loin area and reduces fat thickness and would be expected to have effects on selection that are similar to somatotropin. Growing barrows will be allowed to establish a selection pattern and then have Paylean treatment imposed. Twenty barrows with an initial weight of 80 kg were fed the UGA grower diet for 7 days to acclimate to the pens. On day 7 pigs were allowed to select from the high and low protein diets (without Paylean). Each pen had 2 feeders and the position of the high and low CP diets in the pen was changed daily. On day 21, half of the pigs received high and low protein diets supplemented with Paylean (20 ppm) and remained on these diets for an additional 2 weeks. Feed intake will be determined daily. Pigs will be weighed and ultrasounded at weekly intervals. During the pre-treatment period pigs self-selected 18-20% crude protein diets. During the treatment period, there was no difference in total intake between the groups. However, pigs supplemented with Paylean selected a higher percent protein than the control group.