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Optimizing growth and body composition while maintaining health, welfare, and meat quality challenges the broiler industry. The objective of this study is to identify molecular pathways in developing adipose and muscle that underlie differential growth rate and body composition in broiler chickens. A conventional (Cobb700) line and a slow-growing (RedBro) line were compared with lines that represent divergent growth and body composition within the context of commercial broiler genetics. Eggs (n = 60) from each line were obtained from commercial hatcheries and incubated until embryonic d 17 (E17), or until hatch and raised to 5 (D 5) or 10 d (D 10) of age. At each age, breast muscle (BM) and subcutaneous (SQ) fat pad (n = 10) were collected, weighed, and snap frozen. Neck and abdominal (ABD) fat pads (n = 10) were collected at D 10 and D 14. Adipocyte size at E17 and D 10 was determined in H&E-stained tissue sections using ImageJ. T-tests were used to compare body and tissue weights and adipocyte size between lines (α = 0.05). RNA (n = 5 tissue -1ּ age-1 / /age) from adipose and breast was isolated for transcriptomic analyses using 3’ RNAseq. Raw reads were mapped to the chicken genome (bGalGal1.mat.broiler.GRCg7b). Differentially expressed genes (DEGs; fdr P-value < 0.1) were identified using the R package DEseq2 R (version 4.3.1). Sets of DEGs were analyzed for functional annotation using Database for Annotation, Visualization, and Integrated Discovery (david.ncifcrf. gov). Body weight was significantly heavier in Cobb vs. Redbro chicks at each age (P < 0.05). The most notable differences in relative tissue weight occurred for adipose (SQ) at E17 and D5, and for BM at D 10. Relative fat pad weight (SQ) was significantly greater in Cobb vs. Redbro at E17 and D5. In the embryo, this difference was associated with larger adipocytes, suggesting increased capacity for energy storage in fast-growing broilers. In contrast, at D5, Cobb exhibited a significant increase in abundance of small adipocytes, indicating a shift towards adipocyte hyperplasia and/or enhanced mobilization of stored energy post-hatch. Differences in adiposity and adipocyte size were associated with 103 and 153 DEGs at E17 and D5, respectively. These gene sets were enriched in various growth-related functions, including tissue morphogenesis, peptide transport, and mitogenesis. Relative breast weight diverged significantly at D 10, with heavier BM in Cobb chicks. The set of 278 DEGs at this age were enriched in multiple GO categories related to lipid metabolism (16% of genes) and protein metabolism. Although relative breast muscle weight did not differ at E17, 362 DEGs were identified at this age, and were enriched in functions related to skeletal muscle development (n = 43) and mitogenesis, among others. In conclusion, these results identify both phenotypic and transcriptomic differences that underlie, and in some cases precede, divergent growth in broiler chickens. Further investigation is required to determine how these differences affect mature body composition. [ABSTRACT FROM AUTHOR]

Increased tissue redox state may result in sub-optimal growth. Our goal was to determine if glutathione (GSH) content and expression of proteins involved with GSH metabolism change in longissimus dorsi (LD), subcutaneous adipose (SA), and liver tissues of growing vs. finishing steer phenotypes. Tissues were taken from 16 Angus steers (BW = 209 ± 29.4 kg) randomly assigned (n = 8) to develop through Growing (final BW = 301 ± 7.06 kg) vs. Finished (final BW = 576 ± 36.9 kg) growth phases, and at slaughter had achieved different rib-eye area (REA) (53.2, 76.8 cm²), marbling scores (296, 668), and 12th rib adipose thickness (0.54, 1.73 cm), respectively (Amino Acids, doi:10.1007/s00726-018-2540-8). GSH content (mg/g wet tissue) was determined by a commercial assay and the relative content of target protein and mRNA in tissue homogenates was determined by Western blot and reverse-transcribed PCR analyses, respectively. The effect of growth phase (Finished vs. Growing) was assessed by ANOVA using the GLM procedure of SAS. The LD of Finished steers had more (P < 0.04) GSH (42%) and GSH synthesizing (GCLC, 61%; GCLM, 21%) and metabolizing (GPX1, 42%; GPX3, 73%; GGT1, 56%) enzymes, and less (P < 0.02) GPX2 (46%), EAAC1 (30%) and glutamine synthetase (GS) (28%), whereas GTRAP3-18 and ARL6IP1 did not differ (P > 0.57). Principal component analysis found that GSH content of LD was associated with REA and marbling score. The SA of Finished steers had less (P < 0.04) GSH (38%), GSH metabolizing (GPX4, 52%; GGT1, 71%) enzyme mRNA, and GTRAP3-18 (123%) and ARL6IP1 (43%), whereas the mRNA content of GSH-synthesizing enzymes and content of EAAC1 and GS did not differ (P > 0.32). The liver of Finished steers had less (P < 0.02) mRNA content of GSH synthesizing (GCLC, 39%; GSS 29%) and metabolizing (GPX1, 30%) enzymes, and more (P < 0.01) GSTM1 metabolizing enzyme (114%). The change in GSH content as steers fattened indicate an increased antioxidant capacity in the LD of Finished steers, and a decreased antioxidant capacity in SA, consistent with changes in enzyme and transporter expression. Changes in liver enzyme and transporter expression were consistent with no change in GSH content. The relationship of EAAC1 regulatory proteins (GTRAP3-18, ARL6IP1) to GSH, EAAC1, and GS content differs and changes as Growing steers develop into Finished phenotypes. These findings provide mechanistic insight into how antioxidant capacity occurs in tissues of economic and metabolic importance as cattle fatten. [ABSTRACT FROM AUTHOR]

The objective was to investigate the of effect chemical composition of dietary fat on transcription of genes involved in lipid metabolism in adipose tissue and the liver via transcriptional profiling in growing pigs. A total of 48 Genetiporc 6.0 × Genetiporc F25 (PIC, Inc., Hendersonville, TN) barrows (initial BW of 44.1 ± 1.2 kg) were randomly allotted to 1 of 6 dietary treatments. Each experimental diet included 95% of a corn-soybean meal basal diet and 5% cornstarch (control; CNTR), animal-vegetable blend (AV), coconut oil (COCO), corn oil (COIL), fish oil (FO), or tallow (TAL). Pigs were sacrificed on d 10 (final BW of 51.2 ± 1.7 kg) to collect tissues. Expression normalization across samples was performed by calculating a delta cycle threshold (ΔCt) value using RPL32. Delta delta cycle threshold (ΔΔCt) values were expressed relative to the CNTR treatment. In adipose tissue, adding dietary fat, regardless of the source, decreased the mRNA abundance of FASN compared with the CNTR (P = 0.014). Pigs fed a COIL-based diet tended to have greater adipose tissue expression of FASN (P = 0.071) than pigs fed the other dietary fat sources tested. Abundance of PRKAG-1 mRNA was greater in adipose tissue of barrows a fed COIL-based diet than barrows fed CNTR or FO-based diets (P = 0.047). In the liver, adding dietary fat, regardless of source, increased the mRNA abundance of ACACA, ATGL, INSR, PPAR-α, PRKAG-1, and SCD (P ≤ 0.020) and tended to increase the abundance of HSL (P = 0.071) and SREBP-1 (P = 0.086) compared with the CNTR. Pigs fed a TAL-based diet had greater hepatic transcription of HSL than pigs fed CNTR-, COCO-, or FO-based diets (P = 0.013). Hepatic transcription of FASN tended to be greater in pigs fed COCO than in pigs fed other dietary fat sources (P = 0.074). Dietary omega-3 fatty acid content tended to negatively correlate with mRNA abundance of PRKAG-1 (P = 0.065) in adipose tissue and ATGL (P = 0.063) in the liver. Dietary fat SFA content was negatively correlated with PPAR-α in the liver (P ≤ 0.039). Dietary fat MUFA content tended to be positively correlated with ACACA, PPAR-α, and PRKAG-1 mRNA abundance in the liver (P ≤ 0.100). To conclude, the intake of omega-3 fatty acids suppressed the mRNA abundance of genes involved in lipolysis in both adipose tissue and the liver. Dietary SFA are greater inhibitors of lipogenesis in adipose tissue than omega-6 fatty acids. Intake of medium-chain fatty acids alters hepatic lipid metabolism differently than intake of longchain fatty acids. [ABSTRACT FROM AUTHOR]

Skeletal muscle and adipose tissues play important roles in maintaining whole-body Glu and N homeostasis by the uptake of Glu and release of Gln. To test the hypothesis that expression of highaffinity Glu transporters (GLAST1, EAAT4, EAAC1, GLT-1) and glutamine synthetase (GS) would increase in longissimus dorsi and adipose tissue of newborn Angus steers randomly assigned (n = 6) to develop through suckling (S; 32 d) and/or weanling (W; 184 d), backgrounding (B; 248 d), and finishing (F; 423 d) production stages. Carcass quality was determined at slaughter to verify shifts in adipose and lean deposition with development. Expression of mRNA (RT-PCR/Southern) and relative protein abundance (Western analysis) were determined in tissue homogenates isolated from longissimus dorsi, and kidney and subcutaneous adipose. The effect of production stage or tissue type on carcass and protein abundance was assessed by 1-way ANOVA using the GLM procedure of SAS, and Fisher's protected LSD procedure was used to separate data means. Neither GLAST1 nor EAAT4 mRNA or protein was detected. EAAC1, GLT-1, and GS mRNA were identified in all tissues, but GLT-1 and GS protein were not detected in kidney or subcutaneous adipose, and GS protein was not detected in longissimus dorsi. The EAAC1 content of subcutaneous (P = 0.06) and kidney (P = 0.02) adipose was 2 times greater in B and F than W steers, whereas GS was 5 times greater (P < 0.07) in B than F steers (B = W > F). For longissimus dorsi, EAAC1 (P < 0.01) and GLT-1 (P < 0.04) content decreased with development (S > W > B = F, S = W > B = F, respectively). Within F steers, EAAC1 and GLT-1 mRNA was expressed by subcutaneous, kidney, omental, mesenchymal, and intramuscular adipose tissues, whereas GS mRNA was expressed by all except for intramuscular. Only EAAC1 protein was detected in any adipose tissue, with EAAC1 content being 104% and 112% greater (P < 0.01) in intramuscular than in kidney or subcutaneous adipose, respectively, and not differing (P > 0.45) from omental or mesenchymal adipose. These data demonstrate (1) longissimus dorsi and adipose tissues of steers developing through typical production stages have different capacities for Glu uptake and Gln synthesis, (2) the importance of EAAC1 and GS in adipose metabolism, and (3) the differential metabolic fate of Glu by adipose tissues as steers developed, as evidenced by the marked decrease of GS content in subcutaneous and kidney adipose of F steers. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the impact of stocker production systems differing in growth rate on rumen fermentation characteristics and utilization of substrates for fatty acid synthesis in intramuscular (IM), subcutaneous (SC), and perirenal (PR) adipose tissues. Angus steers were assigned to 4 stocker cattle production systems in 2 consecutive years: 1) 1.0 kg/d of 40% CP cottonseed meal-based supplement while grazing dormant native range (CON), 2) ground corn/soybean meal-based supplement while grazing dormant native range fed at 1% of BW (CORN), 3) grazing wheat pasture at a high stocking rate to achieve a low rate of BW gain (LGWP), and 4) grazing wheat pasture at a low stocking rate for a high rate of BW gain (HGWP). Eight ruminally cannulated steers were used to determine rumen fermentation characteristics. Steers were harvested during the stocker phase at similar age (different carcass weight) in Exp. 1 (3 steers/treatment) or at similar carcass weight in Exp. 2 (4 steers/treatment). Adipose tissues were analyzed for mRNA expression of genes involved in glucose (solute carrier family 2, member 4 [GLUT4], glucose-6-phosphate dehydrogenase [G6PDH], phosphofructokinase, muscle [PFKM], and pyruvate kinase 2, muscle [PK2]), lactate (lactate dehydrogenase B [LDHB]), and acetate (acetyl-CoA synthetase, cytosol [ACSS2]) utilization for fatty acid synthesis. The acetate:propionate ratio was least (P < 0.05) for HGWP steers, intermediate for CORN and LGWP steers, and greatest for CON steers. At similar age, LGWP and HGWP steers tended (F-test; P < 0.15) to have greater (P < 0.10) G6PDH and ACSS2 mRNA expression than CON and CORN steers in SC and PR but not IM adipose tissue. Expression of PFKM and PK2 mRNA tended (F-test; P < 0.15) to be greater (P < 0.10) in HGWP than CON and LGWP steers in IM but not SC or PR adipose tissue. At similar HCW, expression of GLUT4 and G6PDH mRNA were greater (P < 0.10) in SC adipose tissue of LGWP and HGWP steers compared with CON and CORN steers but not in IM and PR adipose tissue. Expression of LDHB mRNA was lesser (P < 0.10) in SC adipose tissue but greater (P < 0.10) in PR adipose tissue of LGWP and HGWP steers compared with CON and CORN steers. These results indicate a shift toward glucose utilization in SC adipose tissue but a shift towards lactate utilization in PR adipose tissue. These results suggest that diet and changes in VFA profile can influence substrates utilized for fatty acid synthesis, but diet has a greater effect in SC than IM adipose tissue. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the impact of stocker production systems differing in growth rate on differential adipogenic and lipogenic gene expression of intramuscular (IM), subcutaneous (SC), and perirenal (PR) adipose tissues. Angus steers were assigned to 4 stocker cattle production systems in 2 consecutive years: 1) cottonseed meal-based supplement while grazing dormant native range (CON), 2) ground corn/soybean meal-based supplement while grazing dormant native range (CORN), 3) grazing wheat pasture at a high stocking rate for a low rate of BW gain (LGWP), and 4) grazing wheat pasture at a low stocking rate for a high rate of BW gain (HGWP). Steers were harvested during the stocker phase at similar age (different carcass weight) in Exp. 1 (3 steers/treatment) or at similar carcass weight in Exp. 2 (4 steers/treatment). Adipose tissues were analyzed for mRNA expression of adipogenic [peroxisome proliferator activated receptor y [PPARy], sterol regulatory element binding factor 1 [SREBF1], CAATT/enhancer binding protein ß, and delta-like homolog 1) and lipogenic (glycerol-3-phos-phate dehydrogenase [GPDH], fatty acid synthase [.FASN], and diacylglycerol acyltransferase 2 [DGAT2]) genes. Multivariate analysis was used to evaluate the expression of adipogenic or lipogenic genes collectively. There was not a treatment x adipose tissue interaction (F-test, P > 0.15) when steers were harvested at similar age, but a treatment x adipose tissue interaction (F-test, P < 0.05) was evident when steers were harvested at similar carcass weight. At similar carcass weight, treatment had no effect (P > 0.10) on the canonical varíate of adipogenic or lipogenic mRNA expression in IM adipose tissue, but faster rates of gain of LGWP and HGWP steers increased (P < 0.10) the canonical variate of adipogenic and lipogenic mRNA expression in SC and PR adipose tissue compared with CON and CORN steers. Strong positive correlations (P < 0.05) of PPARy, SREBF1, GPDH, FASN, and DGAT2 mRNA expression with the canonical variate indicate that these genes strongly influenced differences between treatments and adipose tissues. These results suggest that contrary to our hypothesis rate of gain has little influence on differentiation and lipid synthesis of IM adipose tissue at similar carcass weight but faster rates of gain increase differentiation and lipid synthesis of SC and PR adipose tissue even at similar carcass weight. [ABSTRACT FROM AUTHOR]

Fibroblast growth factor 21 (FGF21) is a multifaceted metabolic regulator which has sev-eral potential applications in the treatment of metabolic disease. When administered in vivo, FGF21 exhibits a plethora of actions, modulating metabolic homeostasis in a diverse manner. However, the mechanism and site of action underlying these effects were, until recently, entirely uncertain. Using mouse models lacking either FGF receptor isoform 1 (FGFR1) or ßKlotho (KLB), a transmembrane co-factor critical for FGF21 action, our group and others sought to determine the tissue on which FGF21 acts and the receptor complex responsible for mediating its in vivo efficacy. Importantly, when KLB was ablated from all tissues mice were completely refrac-tory to FGF21 action. Therefore, to determine the precise tissue of action we utilized mice with tissue specific deletion of FGFR1 in either adipose tissue or neurons, respectively. Surprisingly, in animals with neuronal FGFR1 loss there was no change in the metabolic activity of FGF21, suggesting a lack of central FGF21 action in the pharmacologic setting. In contrast, we found dramatic attenuation of metabolic efficacy in mice with adipose-specific FGFR1 ablation following either acute or chronic dosing with recombinant FGF21. Furthermore, several recent studies have suggested that the metabolic effects of FGF21 may occur via modulation of adipokines such as adiponectin and leptin. Importantly, the action of FGF21 via adipose tissue results in alterations in both secretion as well as systemic sensitivity to these factors. Therefore, while FGF21 itself does not seem to directly act on the CNS, leptin and other endocrine mediators may serve as intermediary facilitators of FGF21's secondary central effects downstream of an initial and direct engagement of FGF21 receptor complex in adipose tissue. Further stud-ies are required to delineate the precise mechanistic basis underlying the interplay between peripheral and central FGF21 modes of action in both the physiological and pharmacological settings. [ABSTRACT FROM AUTHOR]

Tendon injuries affect all levels of ath-letic horses and represent a significant loss to the equine industry. Accumulation of microdamage within the tendon architecture leads to formation of core lesions. Traditional approaches to tendon repair are based on an initial period of rest to limit the inflammatory process followed by a controlled reloading program designed to promote the maturation and linear arrangement of scar tissue within the lesion. However, these treatment protocols are inefficient, resulting in prolonged recov-ery periods and frequent recurrence. Current alterna-tive therapies include the use of bone marrow-derived mesenchymal stem cells (BMSC) and a population of nucleated cells from adipose containing adipose-de-rived mesenchymal stem cells (AdMSC). Umbilical cord blood-derived stem cells (UCB) have recently re-ceived attention for their increased plasticity in vitro and potential as a therapeutic aid. Both BMSC and Ad-MSC require expansion in culture before implantation to obtain a pure stem cell population, limiting the time frame for implantation. Collected at parturition, UCB can be cryopreserved for future use. Furthermore, the low immunogenicity of the UCB population allows for allogeneic implantation. Current research indicates that BMSC, AdMSC, and UCB can differentiate into teno-cyte-like cells in vitro, increasing expression of scler-axis, tenascin c, and extracellular matrix proteins. When implanted, BMSC and AdMSC engraft into the tendon and improve tendon architecture. However, treatment with these stem cells does not decrease recovery period. Furthermore, the resulting regeneration is not optimal, as the resulting tissue is still inferior to native tendon. Umbilical cord blood-derived stem cells may provide an alternate source of stem cells that promote improved regeneration of tendon tissue. A more naive cell popula-tion, these cells may have a greater rate of engrafitment as well as an increased ability to secrete bioactive fac-tors and recruit additional reparative cells. Further work should clarify the role of distinct stem cell sources in the regenerating tendon and the need for a naive or differen-tiated cell type for implantation. [ABSTRACT FROM AUTHOR]

Two feedlot studies were conducted to investigate the timing and duration of supplemental vitamin A withdrawal from feedlot cattle (Bos taurus) diets to reduce intramuscular adipose tissue vitamin A concentration and improve carcass quality. In Exp. 1, Angus crossbred steers (n = 84, BW = 211 ±4 kg) were allotted to 4 treatments: no supplemental vitamin A for 227 d, no supplemental vitamin A for 112 d followed by 115 d of supplemental vitamin A, supplemental vitamin A for 112 d followed by no supplemental vitamin A for 115 d, or supplemental vitamin A for 227 d. In Exp. 2, Angus crossbred steers (n = 80, BW = 210 ± 5 kg) were allotted to 4 treatments: early weaning with or without supplemental vitamin A, and traditional weaning with or without supplemental vitamin A. In both experiments, serum vitamin A concentrations were greatest (P < 0.05) 56 d after cattle were weaned and placed in the feedlot, regardless of feedlot dietary vitamin A concentration. Hepatic vitamin A stores were dramatically decreased (P < 0.05) in the first 56 d and remained depressed as long as steers were not supplemented with vitamin A. At the end of the finishing period, vitamin A concentrations were less in intramuscular than subcutaneous adipose tissue. Growth was not affected by finishing cattle without supplemental dietary vitamin A (P > 0.10). Dietary vitamin A supplementation did not affect USDA yield grades. However, in Exp. 2, cattle without supplemental vitamin A had greater (P < 0.001) ether extractable lipid in the LM. Ether extractable lipid in the LM or marbling scores were enhanced when intramuscular adipose tissue vitamin A concentration was reduced in response to feeding diets without supplemental vitamin A. [ABSTRACT FROM AUTHOR]

The long-term effect of feeding the catecholamine analog ractopamine (RAG; ractopamine hydrochloride, Elanco Animal Health, Indianapolis, IN) on the expression of genes involved in energy and lipid metabolism in subcutaneous adipose tissue was studied. Large White pigs (84 kg) were fed corn- and soy- bean meal-based diets supplemented with 0, 20, or 60 mg/kg of RAG for 14, 28, or 42 d. Expression (mRNA abundance) in adipose tissue of sterol regulatory binding protein-1 (SREBP-1), PPARα, PPAR-γ2, fatty acid synthase (FAS), glucose transporter 4 (GLUT4), and stearoyl-CoA desaturase was determined by Northern blotting. Feed intakes did not differ, and RAG (20 and 60 mg/kg) improved BW gain at d 14, 28, and 42 (P < 0.05) and increased loin eye area (measured on d 42 only; P < 0.05). Expression of SREBP-1 and PPARγ2 declined (P < 0.05) with RAG by d 28 and 42, whereas expression of PPARα was increased (P < 0.05) on d 14, 28, and 42. After 14 d, expression of FAS and GLUT4 was decreased (P < 0.05) with 60 mg/kg of RAC, whereas both RAC concentrations attenuated FAS expression on d 28 and 42. Overall, adipose tissue stearoyl-CoA desaturase expression was not affected by RAC but showed somewhat less expression (P < 0.15) on d 28 at 60 mg/kg of RAC. Although prolonged chronic RAG feeding most likely downregulates adipose tissue membrane β-adrenergic receptors, mRNA abundances of anabolic lipid metabolism transcription factors, glucose transporters, and enzymes (SREB:P-1 PPARγ2, FAS, GLUT4) were still attenuated up to d 42. Conversely, a transcription factor related to oxidative metabolism expression (PPARα) was enhanced. We conclude that even after 42 ci, RAC still decreased expression of lipogenic genes in adipose tissue by yet undefined cyclic adenosine monophosphate-directed mechanisms, but in contemporary lean pigs, this effect is likely of limited practical significance. [ABSTRACT FROM AUTHOR]

Genetic regulation of the site of fat deposition is not well defined. The objective of this study was to investigate adipogenic differentiation state-specific gene expression in feedlot cattle (>75% Angus; <25% Simmental parentage) of varying adipose accretion patterns. Four groups of 4 steers were selected via ultrasound for the following adipose tissue characteristics: low subcutaneous-low intramuscular (LSQ-LIM), low subcutaneous-high intramuscular (LSQ-HIM), high subcutaneous-low intramuscular (HSQ-LIM), and high subcutaneous-high intramuscular (HSQ-HJM). Adipose tissue from the subcutaneous (SQ) and intramuscular (TM) depots was collected at slaughter. The relative expression of adipogenic genes was evaluated using quantitative PCR. Data were analyzed using the mixed model of SAS, and gene expression data were analyzed using covariate analysis with ribosomal proteip L19 as the covariate. No interactions (P> 0.10) were observed between IM and SQ adipose tissue depots for any of the variables measured. Therefore, only the main effects of high and low accretion within a depot and the effects of depot are reported. Steers with LIM had smaller mean diameter IM adipocytes (P < 0.001) than HIM steers. Steers with HSQ had larger mean diameter SQ adipocytes (P < 0.001) than LSQ. However, there were no differences (P> 0.10) in any of the genes measured due to high or low adipose accretion. Preadipogenic delta-like kinasel mRNA was greater in the IM than the SQ adipose tissue; conversely, differentiating and adipogenic genes, lipoprotein lipase, PPAR-'y, fatty acid synthetase, and fatty acid binding protein 4 were greater (P < 0.001) in the SQ than the IM depot. Intramuscular adipocytes were smaller than SQ adipocytes and had greater expression of the preadipogenic gene, indicating that more hyperplasia was occurring. Meanwhile, SQ adipose tissue contained much larger (P < 0.001) adipocytes that had a greater expression (P < 0.001) of differentiating and adipogenic genes than did the IM adipose tissue, indicating more cells were undergoing differentiation and hypertrophy. Adipogenic differentiation state-specific gene expression was not different in cattle with various phenotypes, but adipogenesis in the SQ and IM adipose tissues seems to occur independently. [ABSTRACT FROM AUTHOR]

Thiazolidinediones (TZD) are insulin sensitizing agents currently used for the treatment of type 2 diabetes and are widely used as adipogenic agents because they are ligands of peroxisome proliferator-activated receptor gamma (PPARγ), a key adipogenic transcription factor. In vivo and in vitro studies of TZD as potential modifiers of intramuscular or marbling adipogenesis are reviewed. Thiazolidinedione-induced adipogenesis has been reported in numerous cell culture systems, including rodent, human, bovine, and porcine adipose tissue stromal-vascular (S-V) cell cultures. Studies of porcine S-V cell cultures derived from semitendinosus muscle show that TZD can potentially modify intramuscular or marbling adipogenesis. Preadipocyte recruitment was TZD-dependent in muscle S-V cultures but TZD-independent in adipose S-V cultures. There appear to be differences between adipocytes in muscle and subcutaneous adipose tissue, reminiscent of differences observed in adipocytes from different adipose tissue depots. Troglitazone, a TZD, induces marbling adipogenesis without inhibiting myogenesis when cells are grown on laminin precoated culture dishes. Additionally, troglitazone treatment does not increase lipid content in porcine adipose tissue or muscle S-V cell cultures. Thiazolidinedione treatment increases lipid content of muscle in rodents and humans; however, rosiglitazone treatment for 49 d in pigs did not influence muscle lipid content and meat quality, but several significant changes in muscle fatty acid composition were observed. Although timing of treatment with TZD needs to be optimized, evidence suggests these compounds may enhance marbling deposition in swine. [ABSTRACT FROM AUTHOR]

Thiazolidinediones (TZD) are insulin sensitizing agents currently used for the treatment of type 2 diabetes and are widely used as adipogenic agents because they are ligands of peroxisome proliferator-activated receptor gamma (PPARγ), a key adipogenic transcription factor. In vivo and in vitro studies of TZD as potential modifiers of intramuscular or marbling adipogenesis are reviewed. Thiazolidinedione-induced adipogenesis has been reported in numerous cell culture systems, including rodent, human, bovine, and porcine adipose tissue stromal-vascular (S-V) cell cultures. Studies of porcine S-V cell cultures derived from semitendinosus muscle show that TZD can potentially modify intramuscular or marbling adipogenesis. Preadipocyte recruitment was TZD-dependent in muscle S-V cultures but TZD-independent in adipose S-V cultures. There appear to be differences between adipocytes in muscle and subcutaneous adipose tissue, reminiscent of differences observed in adipocytes from different adipose tissue depots. Troglitazone, a TZD, induces marbling adipogenesis without inhibiting myogenesis when cells are grown on laminin precoated culture dishes. Additionally, troglitazone treatment does not increase lipid content in porcine adipose tissue or muscle S-V cell cultures. Thiazolidinedione treatment increases lipid content of muscle in rodents and humans; however, rosiglitazone treatment for 49 d in pigs did not influence muscle lipid content and meat quality, but several significant changes in muscle fatty acid composition were observed. Although timing of treatment with TZD needs to be optimized, evidence suggests these compounds may enhance marbling deposition in swine. [ABSTRACT FROM AUTHOR]

To determine the response to alteration in site and form of carbohydrate delivery to the digestive tract, in vitro rates of lipogenesis and lipolysis in mesenteric (MESA), omental (OMA), and subcutaneous (SQA) adipose depots were compared. Forty crossbred beef steers (243 ± 2 kg of BW) were fed 161 (LI) or 214 (HI) kcal of ME/(kg of BW0.75·d) or they were fed LI and infused for 35 d into the rumen (R) or abomasum (A) with starch hydrolysate (SH) or into the abomasum with glucose (G). Jugular blood samples were collected, steers were slaughtered, and adipose depots were sampled and prepared for assessment of lipogenesis and lipolysis in vitro. Blood concentrations of glucagon were increased (P = 0.04) in HI-H2O compared with LI-H2O steers, whereas A-SH tended to increase (P = 0.08) circulating IGF-I relative to R-SH, and A-G tended to have elevated (P = 0.09) T3 compared with A-SH. Lipolysis, as assessed by NEFA release, was unaffected by treatment. Glycerol release by the MESA and SQA was in- creased or tended to be increased (P ≤ 0.08) in HI-H2O compared with LI-H2O steers. In A-G compared with A-SR steers, glycerol release from OMA increased (P = 0.008) and from SQA tended to be increased (P = 0.08). Acetate incorporation into total neutral lipids (TNL) increased or tended to increase with ME intake and SH infusion (P ≤ 0.09) across all depots. Rates of acetate incorporation into fatty acids (FA) also increased or tended to be increased (P ≤ 0.1) by SH infusion across all depots, but only that of SQA was increased with ME intake (HI-H2O vs. LI-H2O; P = 0.02). Rates of acetate incorporation into FA and TNL in MESA were increased (P ≤ 0.03) by A-SH compared with R-SH, but site of SH infusion did not affect the rates in SQA or OMA. Glucose incorporation into TNL for MESA and SQA increased or tended to be increased (P ≤ 0.1) by dietary and infused energy, whereas for OMA they tended to be increased (P = 0.1) only by SH infusion. In contrast, glucose incorporation into FA was unaffected by energy supply but tended to be increased (P = 0.07) by SH in MESA and tended to be greater (P = 0.08) for A-G than A-SH in OMA. The general across-depot pattern of acetate incorporation rate into FA and TNL was SQA > OMA > MESA, whereas, for glucose incorporation, rates across depots were equivalent. These data provide evidence that the postruminal supply of energy, specifically carbohydrate, stimulates lipogenesis from acetate and glucose and is more pronounced in abdominal depots relative to the subcutaneous depot. [ABSTRACT FROM AUTHOR]

Forty crossbred beef steers (243 ± 2 kg of BW) with ruminal and abomasal infusion catheters were used to test 2 hypotheses: 1) visceral mass is responsive to energy input and site of carbohydrate (CHO) infusion and 2) rate and site of adipose accretion are dependent on site of CHO infusion and complexity. Treatments included a pelleted, forage-based, basal diet fed at 161 (LI) or 214 (HI) kcal of ME/(kg of BW0.75·d), LI plus ruminal (R-SH) or abomasal (A-SH) infusion of a partial starch hydrolysate (SH), and LI plus abomasal infusion of glucose (A-G). The basal diet was fed in 12 equal portions daily at 2-h intervals, with starch and glucose infused over a 22-h period at rates of 12.6 and 14.4 g/(kg of BW0.75·d). Alter 35 d of infusion, steers were slaughtered; and visceral organ and adipose mass, subcutaneous adipose thickness over the 5th and 12th rib, and LM intramuscular fat concentration were determined. Total intake energy (IE) increased (P = 0.0001) with ME intake. Dietary IE was similar between LI and CHO treatments, but total IE increased (P < 0.001) with CHO infusion. Greater dietary ME intake and CHO infusion increased or tended (P ≤ 0.09) to increase final BW and HCW. As a percentage of empty BW, total stomach complex, rumen, omasum, liver, pancreas, and kidney weights were greater (P ≤ 0.05) for HI vs. LI. Stomach complex, rumen, pancreas, and kidney weights as a percentage of empty BW were greater (P ≤ 0.05) for R-SH vs. A-SH. Compared with A- SH, A-G increased (P ≤ 0.02) total and mucosal weights from the 10-cm sections of the ileum. Increases in rumen mass were associated with no change or an in- crease in rumen total and mucosal DNA concentrations. Greater dietary ME tended (P = 0.06) to increase subcutaneous fat thickness at the 5th rib but did not affect alimentary adipose accretion on an empty BW basis. Omental and total alimentary adipose weights were increased (P ≤ 0.04) by A-G compared with A-SR. Although SR infusion did not alter adiposity, there was a consistent numerical pattern in total alimentary and subcutaneous fat depots with CHO infusion (A-G > A-SR > R-SH). Our findings demonstrate that increasing ruminal CHO supply results in a disproportionate increase in rumen mass, whereas increasing small intestinal CHO supply does not alter gastrointestinal organ mass. Small intestinal energy in the form of glucose resulted in greater adipose accretion, particularly the omental depot. [ABSTRACT FROM AUTHOR]

Presents abstracts of studies about the growth and development of the study of animal science. "Body Protein Deposition Response Following Sudden Changes in Ideal Protein Intake Differs Between Pig Types," by H.R. Mart&icute;nez and C.F.M. de Lange; "Human Somatotropin Is More Efficacious Than Porcine Somatotropin in Growing Pigs," by F.R. Dunshea; "Concentrations of Insulin-Like Growth Factors I and II in Embryonic Fluids of Chickens, Ducks and Turkeys," by D.M. Karcher, J.P. McMurtry and T.J. Applegate.

Presents abstracts of several studies on animal growth and development. "Effect of Gender and Feeding Program on Productive Performance and Carcass Quality of Heavy Pigs," by J. Peinado et al; "Effect of Protein From Placental Bovine Tissue on Puberty and Growth Mice," by F. A. Nunez, J. A. Garcia-Macias, J. A. Lopez and F. G. Rios; "Regulation of Leptin and Leptin Receptor Expression in Porcine Subcutaneous Adipose Tissue," by T. G. Ramsay and M. P. Richards.

The current study was performed to examine the response of the leptin gene to hormonal stimuli in porcine adipose tissue from finishing pigs. Yorkshire gilts (approximately 150 kg BW) were used in this study. Tissue from four to six pigs was used per experiment. Dorsal subcutaneous adipose tissue samples were acquired, and adipose tissue explants (approximately 100 mg) were prepared using sterile technique. Tissue slices were transferred to 12-well tissue culture plates containing I mL of Media 199 with 25 mM HEPES, 0.5% BSA, pH 7.4, and various hormone supplements. Triplicate tissue slices were incubated with either basal medium or hormone-supplemented media in a tissue culture incubator at 37°C with 95% air:5% CO2. Hormones included insulin (100 nM), dexamethasone (1 µM), porcine GH, 100 ng/mL), triiodothyronine (T3, 10 nM), porcine leptin (100 ng/mL), or IGFI (250 ng/mL). Following incubation for 24 h, tissue samples from the incubations were blotted and transferred to microfuge tubes, frozen in liquid N, and stored at -80°C before analysis for gene mRNA abundance by reverse-transcription PCR and subsequent quantification of transcripts by capillary electrophoresis with laser-induced fluorescence detection. Media from the incubations were collected in microfuge vials and stored at -20°C before analysis for leptin content by RIA. Insulin was required to maintain tissue and mRNA integrity; therefore, insulin was included in all incubations. The combination of insulin and dexamethasone stimulated leptin secretion into the medium by 60% (P < 0.05; n = 6). Porcine GH inhibited insulin induced leptin secretion by 25% (P < 0.05; n = 6). Dexamethasone in combination with insulin produced a 22% increase in leptin mRNA abundance relative to insulin (P < 0.05; n = 4), and T3 stimulated a 28% increase in insulin-induced leptin mRNA abundance (P < 0.05; n = 4). Leptin receptor mRNA abundance was decreased by 25% with the combination of insulin and dexamethasone, relative to insulin-treated adipose tissue slices (P < 0.05; n = 4). Porcine GH decreased leptin receptor mRNA abundance by 17% (P < 0.05; n = 6). These data suggest that leptin secretion is a regulated phenomenon and that posttranslational processing may be significant. Alternatively, transport and exocytosis of leptin containing vesicles in the pig adipocyte may be quite complicated, which could account for the differences in observed mRNA abundance and protein secretion. [ABSTRACT FROM AUTHOR]

Excess fat deposition is costly to the producer in terms of input and final product; it also usually does not occur equally across all adipose depots. Further examination is necessary to determine a correlation between varying gene expression and fatty acid composition in different tissue depots, and further, across different breeds. Texel-Suffolk (n = 5) and Suffolk-Suffolk (n = 4) lambs were finished to 203 d of age and used to compare both mRNA and microRNA (miR) gene expression changes between breed and among tissue depots. Seven different depots were harvested and snap-frozen from all nine lambs. The liver, longissimus muscle of the rib, kidney fat, mesenteric fat, omental fat, subcutaneous fat, and intermuscular fat were all harvested. Texel-sired lambs had greater (P < 0.05) flank streaking, quality grade, and weight of fat depots compared to Suffolk. Texelcross lambs had higher (P < 0.05) oleic-to-stearic fatty acid ratio than Suffolk lambs in this study, displaying a breed difference concerning this desaturation ratio. Tissue and breed interactions were observed for oleicto-stearic and palmitoleic-to-palmitic ratio differences (P < 0.05) depending on tissue type. Tissue and breed interactions were trending in various tissues concerning the expression of the gene, stearoyl-CoA desaturase-1(SCD-1). SCD-1 seemed to be upregulated (P < 0.10) in a multitude of tissues while others do not appear to be differentially expressed, dependent upon breed. Data showed an association between SCD-1 and mi-199a-3p among different tissue variations. This may suggest that adipose tissue is more complex than what is currently known. Lipogenic gene expression differed between tissue and adipose depots, and could potentially broaden targets that could aid in maximizing animal efficiency. [ABSTRACT FROM AUTHOR]

Tissues and organs are actively developing during the fetal stage, which is sensitive to nutritional alteration and exerts long-term impacts on offspring performance. Both muscle and adipose tissue are derived from the dermomyotome during the early embryonic stage, and their common origins provide an opportunity to promote myogenic instead of adipogenic differentiation, which enhances the lean/fat ratio of offspring. In previous studies with sheep and cattle, we found that maternal nutrient deficiency reduces fetal myogenesis and the lean/fat ratio of offspring. Stress is common in animals during pregnancy, and we examined the impacts of maternal stress induced by dexamethasone on fetal muscle and adipose development. We found that maternal stress impairs fetal muscle and brown adipose tissue (BAT) development. Mechanistically, we found that maternal stress suppresses mitochondrial biogenesis during fetal muscle and BAT development by elevating DNA methylation in the promoter of peroxisome proliferator-activated receptor-gamma coactivator a (PGC-1a), which persists in offspring muscle and BAT, generating lasting effects on the functions of muscle and adipose tissue. In short, available data clearly show that maternal nutrition and other physiological factors have profound impacts on fetal development, which programs offspring performance. Understanding related mechanisms are important for effective and precise management of animals during gestation in order to enhance production efficiency of offspring. [ABSTRACT FROM AUTHOR]

The article looks at a study regarding fatty acid profiles, lipogenesis, and lipolysis in lipid depots in finishing pigs treated with recombinant porcine somatotropin. It mentions need to determine the effects of recombinant porcine somatotropin and dietary CP concentration on carcass and noncarcass tissues. It also mentions long bones were affected by dietary protein concentration or administration of rpST.

The article offers information on the regulation of fatty acid synthase (FAS) gene expression approach for reducing fat accumulation. Topics discussed include information on the transcriptional inhibitors of FAS; discussions on the rate of FAS gene transcription dictates the level of FAS Messenger RNA; and the information on the factors that affect gene transcription and mRNA stability.

The utility and attractiveness of adipose tissue within meat products vary based on species, cut, and consumer preference. In beef, producers are rewarded for producing carcasses with greater visual marbling at the 12th and 13th rib juncture, while pork producers are either not rewarded or penalized for producing carcasses with too much adipose tissue. Some consumers prefer to purchase leaner meat cuts, while other consumers pay premiums to consume products with elevated fat content. While no clear consumer adipose tissue preference standard exists, advances in beef and swine nutrition have enabled producers to target markets that enable them to maximize profits. One niche market that has increased in popularity over the last decade is manipulating the fatty acid profile, specifically increasing omega-3 fatty acid content, of beef and pork products to increase their appeal in a healthy diet. While much research has documented the ability of preharvest diet to alter the fatty acid profile of beef and pork, the same studies have indicated both the color and palatability of these products were negatively affected if preharvest diets were not managed properly. The following review discusses the biology of adipose tissue and lipid accumulation, altering the omega-3 fatty acid profile of beef and pork, negative fresh meat color and palatability associated with these studies, and strategies to mitigate the negative effects of increased omega-3 fatty acid content. [ABSTRACT FROM AUTHOR]