Further studies on short-term adaptations in the expression of lipogenic genes in broilers.

This experiment was conducted to determine possible relationships between certain indices of lipid metabolism and specific gene expression in chickens fed graded levels of dietary crude protein. Male, broiler chickens (Gallus gallus) growing from 7 to 28days of age were fed diets containing 12 or 30% protein ad libitum. Both groups were then switched to the diets containing the opposite level of protein. Birds were sampled at 0, 6, 9, 12, 18 and 24h following the switch in protein levels. Measurements taken included in vitro lipogenesis (IVL), malic enzyme (ME), aspartate aminotransferase (AAT) and isocitrate dehydrogenase (NADP) (ICD) activities. In addition, ME, AAT, ICD, fatty acid synthase (FAS), and acetyl coenzyme carboxylase (ACC) gene expression rates were determined. IVL and ME activities were inversely related to dietary protein levels (12 to 30%) and to acute changes from 12 to 30%. In contrast, expression of ME, FAS and ACC genes was decreased by feeding a 30% protein diet (acute or chronic feeding). Results of the present study demonstrate a continued role for protein in the regulation of broiler metabolism. It should be pointed out; however, that metabolic regulation at the gene level only occurs when feeding very high or very low levels of dietary protein.

The role of feeding regimens in regulating metabolism of sexually mature broiler breeders.

A trial was conducted to determine the effects of different rearing feed regimens on plasma hormone and metabolite levels and hepatic lipid metabolism and gene expression on sexually mature broiler breeders. Cobb 500 birds were divided into 2 groups at 4 wk and fed either an everyday (ED) or skip-a-day (SKP) regimen. At 24 wk of age, all birds were switched over to an ED regimen. At 26.4 wk, breeder hens were randomly selected and killed at intervals after feeding. Livers were sampled from 4 hens at 4-h intervals for 24 h for a total of 28 samples per treatment. Blood was sampled from 4 hens per sampling time; sampling times were 0, 30, and 60 min and 2 and 4 h after feeding and then every 4 h up to 24 h for a total of 36 samples per treatment. Main feeding regimen, time, and interaction effects were analyzed. Significant interaction effects were found between time and feeding regimen for acetyl-coenzyme A carboxylase and malic enzyme mRNA expression. The peak for acetyl-coenzyme A carboxylase expression was higher in ED-reared birds, whereas the peak for malic enzyme expression was higher in SKP-reared birds. Overall, plasma levels of insulin-like growth factor-II were higher in SKP-reared birds. Overall, plasma corticosterone levels were also higher in SKP-reared birds and significant interaction effects between time and feeding regimen were seen. The expression of apolipoprotein A1 was significantly higher in ED-reared birds: significant interaction effects were also noted. Other researchers also found some of the differences observed in the present study in 16-wk-old pullets. In summary, different feeding regimens alter metabolic responses, some of which carry over into sexual maturity.

IGF-I mediated inhibition of leptin receptor expression in porcine hepatocytes.

A study was conducted to elucidate hormonal control of leptin receptor gene expression in primary cultures of porcine hepatocytes. Hepatocytes were isolated from swine and seeded into T-25 flasks. Cultures were established in medium containing fetal bovine serum for one day and switched to serum-free medium (William's E medium and 1 ng/mL insulin) for the remainder of the 3d culture period. For the final 24 h, medium was supplemented with porcine growth hormone (GH, 100 or 500 ng/mL), insulin-like growth factor 1 (IGF-1, 50 to 250 ng/mL) or triiodothyronine (T3, 100 ng/mL). RNA was extracted and relative quantitative RT-PCR was performed with primers for long form leptin receptor. Receptor expression was calculated relative to 18S rRNA. Insulin had no effect (P>0.05), while T3 increased leptin receptor mRNA abundance (P<0.05). Treatment with GH or IGF-I reduced leptin receptor expression (P<0.05). Phosphorylation of ERK1/2 in response to acute leptin treatment was inhibited by previous exposure to GH or IGF-I. Hepatocytes secreted IGF-I under basal conditions and this was enhanced by GH addition. These data suggest porcine hepatocytes may be less sensitive to leptin stimulation due to the actions of endogenous IGF-I on leptin receptor expression.

Effects of short term triiodothyronine administration to broiler chickens fed methimazole.

The purposes of these experiments were to determine possible relationships among certain indices of lipid metabolism and specific gene expression in chickens (Gallus gallus) fed methimazole (MMI) and the subsequent effects of providing supplemental T3 to relieve the effects of MMI. Male, broiler chickens growing from 14 to 28 days of age were fed diets containing 18% crude protein and either 0 or 1 g MMI/kg of diet. At 28 days, birds received 18% crude protein diets containing either 0 or 1 mg triiodothyronine (T3)/kg. Birds were sampled at 0, 1, 2 & 4 days post relief from MMI or at 0, 3, 6, 9, 24 & 48 h. Measurements taken in the first experiment included in vitro lipogenesis (IVL), malic enzyme (ME), isocitrate dehydrogenase (ICDNADP), aspartate aminotransferase (AST) enzyme activities and the expression of the genes for ME, fatty acid synthase (FAS) and acetyl coenzyme carboxylase (ACC), ICD and AST. The same enzyme activities and gene expressions were assayed over the intervals mentioned above. In vitro lipogenesis was eliminated due to constraints imposed by sampling times. Gene expression was estimated with real time RT-PCR assays. Dietary MMI decreased IVL and ME at 28 days of age. T3 supplementation for 1 day restored both IVL and ME. Continuing T3 replenishment decreased IVL without affecting ME activity. Although MMI decreased ME gene expression, there was only a transitory relationship between enzyme activity and gene expression when apparent thyroid function was restored with exogenous T3. Metabolic changes in response to feeding T3 occurred within a short period, suggesting that changes in intermediary metabolism preceded morphological changes. Furthermore, the thyroid state of the animal will determine responses to exogenous T3.

Expression and activity of the 5'-adenosine monophosphate-activated protein kinase pathway in selected tissues during chicken embryonic development.

The 5'-adenosine monophosphate-activated protein kinase (AMPK) is a highly conserved serine-threonine protein kinase and a key part of a kinase-signaling cascade that senses cellular energy status (adenosine monophosphate:adenosine triphosphate ratio) and acts to maintain energy homeostasis by coordinately regulating energy-consuming and energy-generating metabolic pathways. The objective of this study was to investigate aspects of the AMPK pathway in the liver, brain, breast muscle, and heart from d 12 of incubation through hatch in chickens. We first determined mRNA and protein expression profiles for a major upstream AMPK kinase, LKB1, which is known to activate (phosphorylate) AMPK in response to increases in the adenosine monophosphate:adenosine triphosphate ratio. Expression of LKB1 protein was greatest in the brain, which demonstrated tissue-specific patterns for phosphorylation. Next, AMPK subunit mRNA and protein expression profiles were determined. Significant changes in AMPK subunit mRNA expression occurred in all tissues from d 12 of incubation to hatch. Differences in the levels of active (phosphorylated) AMPK as well as alpha and beta subunit proteins were observed in all 4 tissues during embryonic development. Finally, we determined the protein level and phosphorylation status of an important downstream target for AMPK, acetyl-coenzyme A carboxylase. The expression of acetyl-co-enzyme A carboxylase and phosphorylated acetyl-coenzyme A was greater in the brain than the liver, but was undetectable by Western blotting in the breast muscle and heart throughout the period of study. Together, our results are the first to demonstrate the expression and activity of the AMPK pathway in key tissues during the transition from embryonic to posthatch development in chickens.

Uncoupling protein expression in skeletal muscle and adipose tissue in response to in vivo porcine somatotropin treatment.

These experiments examined the potential roles of somatropin (pST) and IGF-I in the regulation of uncoupling protein (UCP)2 and UCP3 and their regulatory proteins peroxisome proliferator activated receptor (PPAR) alpha, gamma and delta using in vivo pST treatment of swine and in vitro supplementation of pST or IGF-I to adipose slices. Six, 90kg barrows were treated with recombinant pST (10mg) for 2 week while another six pigs were injected with buffer. Total RNA from outer subcutaneous adipose (OSQ) and middle subcutaneous adipose (MSQ) tissues, leaf fat, liver and longissimus (LM) was amplified by reverse transcription-PCR with quantification of transcripts by capillary electrophoresis with laser-induced fluorescence detection. UCP2 mRNA abundance increased in liver (P<0.001) and all three adipose tissues by pST treatment (P<0.05). Administration of pST increased UCP3 mRNA abundance by 42% in LM (P<0.01). PPARalpha mRNA abundance increased with pST treatment by 29% in liver (P<0.05), while decreasing 25% in LM (P<0.05). PPARgamma mRNA abundance decreased 32% (P<0.01) while PPARdelta increased 48% in LM (P<0.01) with pST administration. In vitro, pST reduced UCP2 mRNA abundance in OSQ and MSQ tissue slices (P<0.05). UCP3 mRNA abundance decreased in OSQ (P<0.05) but increased in MSQ (P<0.05) with pST. In contrast, IGF-I increased UCP2 and UCP3 mRNA abundance in both MSQ and OSQ slices (P<0.05). These experiments suggest pST, IGF-I and metabolic adaptations to pST contribute to regulating UCP2 and UCP3.

Isotopic dietary analysis of a Neanderthal and associated fauna from the site of Jonzac (Charente-Maritime), France.

We report here on the isotopic analysis (carbon and nitrogen) of collagen extracted from a Neanderthal tooth and animal bone from the late Mousterian site of Jonzac (Charente-Maritime, France). This study was undertaken to test whether the isotopic evidence indicates that animal protein was the main source of dietary protein for this relatively late Neanderthal, as suggested by previous studies. This was of particular interest here because this is the first isotopic study of a relatively late Neanderthal associated with Mousterian of Acheulian Tradition (MTA, dating to approximately 55,000 to 40,000 BP) technology. We found that the Jonzac Neanderthal had isotopic values consistent with a diet in which the main protein sources were large herbivores, particularly bovids and horses. We also found evidence of different dietary niches between the Neanderthal and a hyena at the site, with the hyena consuming mainly reindeer.

Finishing steers with diets based on corn, high-tannin sorghum or a mix of both: Color and lipid oxidation in beef.

We tested the hypothesis that feeding high-tannin sorghum (HTS) to steers would produce beef more resistant to oxidative deterioration. We observed lower thiobarbituric acid-reactive substances (TBARS) in Gluteus medius of steers fed HTS before it was displayed (P=0.028), which could be explained by a reduced response to stress in these animals. While steers finished with corn and corn+HTS had elevated plasma cortisol at the end of the feeding period (P=0.047 and 0.093, respectively), animals fed HTS and corn+vitamin E did not. However, feeding HTS increased the rate of discoloration and TBARS accumulation after aerobic display of Longissimus lumborum and Gluteus medius. Diet did not affect the activity of oxidation-related enzymes and fatty acid composition of muscle. The accelerated rate of lipid oxidation during display of beef could be partially explained by a numerically lower concentration of tocopherols in the tissue.

Growth performance and muscle oxidation in rats fed increasing amounts of high-tannin sorghum.

Oxidative processes deteriorate the quality of meat products. High tannin sorghums (HTS) contain flavonoid oligomers known as proanthocyanidins or condensed tannins. These compounds act as anti-oxidants in vitro, but their effectiveness in vivo remains unclear. We tested the hypothesis that moderate amounts of dietary HTS could reduce markers of oxidation on muscle of rats without having detrimental effects in growth. We used 2 groups of 38 male Sprague Dawley rats at 5 and 13 wk of age each. Each age group was fed 4 diets in a completely randomized design. The younger group was fed the experimental diets for 10 wk (10W); whereas the older group was fed for 2 wk (2W). The diets were modified from the NIH-07 diet and contained HTS and corn at ratios of 0:50 (S0, control), 20:30 (S20), 35:15 (S35), and 50:0 (S50) as a percentage of the diet. Growth and the efficiency of gain were assessed periodically measuring BW, ADFI, ADG, and G:F. Oxidation in muscle was measured in fresh tissue and after 6 d of aerobic-refrigerated storage. Muscles evaluated were LM and soleus (SM). Fresh liver was also evaluated. Thiobarbituric acid-reactive substances (TBARS) and carbonyl content were used as markers of lipid and protein oxidation, respectively. No differences in BW, ADFI, ADG, and G:F were observed in 2W rats. Greater (P < 0.05) ADFI and ADG were observed in 10W-S35 group between d 1 and 7 and greater BW (P = 0.049) was observed in group 10W-S35 at d 70 compared with 10W-S0. No differences were observed between S0 and any HTS diet in G:F in 10W and 2W rats. No differences in TBARS or carbonyls were observed in liver. No differences in TBARS were observed in fresh and aged LM and SM. When LM samples were aged for 6 d, decreased carbonyl contents (P < 0.01) were observed in 10W-S35 and 10W-S50 diets compared with 10W-S0. Reductions in carbonyls were also observed in aged SM between 2W-S50 and 2W-S0 (P = 0.013). We concluded that inclusion of 35% HTS in the diet increased intake and growth rate of young, fast-growing rats without changing the efficiency of gain. Feeding HTS reduced markers of protein oxidation in rat muscle after 6 d of refrigerated storage. If similar results are observed in animals such as swine or cattle, the use of HTS as animal feed should be reassessed.

An examination of the role of feeding regimens in regulating metabolism during the broiler breeder grower period. 1. Hepatic lipid metabolism.

A trial was conducted to determine the effects of feeding regimens on hepatic lipid metabolism in 16-wk-old broiler breeder pullets. A flock of 350 Cobb 500 breeder pullets was divided into 2 at 4 wk of age and fed either every day (ED) or skip-a-day (SKIP) from 4 to 16 wk of age. Total feed intake did not differ between the 2 groups. At 112 d, 52 randomly selected ED-fed pullets, and 76 SKIP-fed pullets were individually caged and fed a 74-g (ED) or 148-g (SKIP) meal. Four pullets from each group were killed at intervals after feeding and livers were collected, weighed, and snap-frozen for determination of lipogenic gene expression. Total RNA was isolated from livers using Trizol reagent and then quantitatively measured by noting the optical density 260:280 ratio and qualitatively measured by gel electrophoresis. The expression of certain regulatory genes in metabolism [acetyl coenzyme A carboxylase; fatty acid synthase; malic enzyme (MAE); isocitrate dehydrogenase (ICDH); and aspartate aminotransferase (AAT)] were determined by real-time reverse-transcription PCR. Remaining liver portions were analyzed for enzyme activity of MAE, ICDH, and AAT as well as glycogen and lipid contents. Liver weight was higher in SKIP than in ED birds. Feeding caused dramatic increases in liver weight, glycogen, and lipids of SKIP birds. Expression of acetyl coenzyme A carboxylase, FAS, and MAE genes were increased in SKIP birds 12 and 24 h after feeding, with the increases in MAE expression from 0 to 24 h after feeding being of the greatest magnitude. In contrast, SKIP decreased ICDH and AAT gene expression, which parallels findings noted in fasting-refeeding experiments conducted with much younger birds. Skip-a-day feeding resulted in far greater changes in gene expression compared with ED, which was indicative of the inconsistent supply of nutrients in such regimens. Enzyme activity of MAE, ICDH, and AAT was reflective of noted changes in gene expression. In summary, the feeding regimen greatly affected hepatic gene expression in breeder pullets.

Mechanisms regulating feed intake, energy expenditure, and body weight in poultry.

To achieve energy balance and maintain a constant BW, changes in feed intake and energy expenditure must be coordinated and tightly regulated. This may not hold true for some poultry species intensively selected for such economically important traits as growth and meat production. For example, the modern commercial broiler breeder does not adequately control voluntary feed intake to meet its energy requirements and maintain energy balance. As a consequence, feeding must be limited in these birds to avoid overconsumption and excessive fattening during production. It is important to determine a genetic basis to help explain this situation and to offer potential strategies for producing more efficient poultry. This review summarizes what is currently known about the control of feed intake and energy expenditure at the gene level in birds. Highly integrated regulatory systems have been identified that link the control of feeding with the sensing of energy status. How such systems function in poultry is currently being explored. One example recently identified in chickens is the adenosine monophosphate-activated protein kinase pathway that links energy sensing with modulation of metabolic activity to maintain energy homeostasis at the cellular level. In the hypothalamus, this same pathway may also play an important role in regulating feed intake and energy expenditure commensurate with perceived whole body energy needs. Genes encoding key regulatory factors such as hormones, neuropeptides, receptors, enzymes, and transcription factors produce the molecular components that make up intricate and interconnected neural, endocrine, and metabolic pathway networks linking peripheral tissues with the central nervous system. Moreover, coordinate expression of specific gene groups can establish functional pathways that respond to and are regulated by such factors as hormones, nutrients, and metabolites. Thus, with a better understanding of the genetic and molecular basis for regulating feed intake and energy expenditure in birds important progress can be made in developing, evaluating, and managing more efficient commercial poultry lines.

Administration of adrenocorticotropic hormone during chicken embryonic development prematurely induces pituitary growth hormone cells.

Treatment of fetal rats and embryonic chickens with exogenous glucocorticoids induces premature GH cell differentiation. However, it is unknown whether the developing adrenal gland is capable of mounting this response autonomously. The present study determined whether stimulation of the adrenal gland in developing chicken embryos through administration of ACTH could induce a premature increase in GH cells. We found that plasma corticosterone and ACTH levels increased between embryonic day (e) 11 and e17, consistent with GH cell (somatotroph) ontogeny. Injection of ACTH into eggs on e9, e10, or e11 increased somatotrophs on e14. In contrast, thyroid-stimulating hormone, CRH, alpha-MSH, GHRH, and TRH were ineffective. Culture of e11 pituitary cells with ACTH failed to induce somatotrophs, suggesting an indirect action of ACTH on GH cells in vivo. Intravenous administration of ACTH dramatically increased plasma levels of corticosterone within 1 h and increased the percentage of pituitary somatotrophs within 24 h. Although ACTH administration increased the relative abundance of pituitary GH cells, there was no effect on plasma levels of GH, IGF-I, or IGF-II, or in hepatic expression of IGF-I or IGF-II mRNA. We conclude that ACTH administration can increase the population of GH cells in the embryonic pituitary. However, this treatment alone does not lead to downstream activation of hepatic IGF production. These findings indicate that the embryonic adrenal gland, and ultimately anterior pituitary corticotrophs, may function to regulate pituitary GH cell differentiation during embryonic development.

Responses of chickens subjected to thyroid hormone depletion-repletion.

The purpose of this experiment was to determine the relationship between lipid metabolism and the expression of specific genes in chickens fed methimazole to produce hypothyroidism. Male, broiler chickens growing from 14 to 28 days of age were fed diets containing 18% crude protein and either 0 or 1 g methimazole per kg of diet. At 28 days, these two groups were further subdivided into groups receiving 18% crude protein diets containing either 0 or 1 mg triiodothyronine (T(3)) per kg. Birds were sampled at intervals from 0 to 120 h. Measurements taken included in vitro lipogenesis (IVL), malic enzyme (ME), isocitrate dehydrogenase (ICD-NADP), aspartate aminotransferase (AAT) activities and the expression of the genes for ME, fatty acid synthase (FAS), NADP-ICD, AAT and acetyl coenzyme carboxylase (ACC). Gene expression was estimated with real time RT-PCR assays. Expression rates were noted as C(t)'s. Dietary methimazole decreased IVL and ME at 28 days of age. T(3) and supplementation for 1 day restored both IVL and ME. Paradoxically, continuing T(3) replenishment for a longer period decreased IVL without affecting ME activity. Although methimazole decreased ME gene expression, there was only a transitory relationship between enzyme activity and gene expression when plasma T(3) was replenished with exogenous T(3). These data explain the apparent dichotomies in lipid metabolism elicited by changes in the thyroid state of animals. Most metabolic changes in response to feeding T(3) occurred within a short period of time, suggesting that changes in intermediary metabolism preceded morphological changes. Furthermore, the thyroid state of the animal will determine responses to exogenous T(3).

Beta-adrenergic regulation of uncoupling protein expression in swine.

This study examined the beta-adrenergic regulation of uncoupling protein (UCP) 2 and UCP3 gene expression in porcine tissues. In vitro experiments examined changes in UCP2 and UCP3 gene expression in middle (MSQ) and outer (OSQ) subcutaneous adipose tissues from crossbred neutered male pigs. Incubation of tissue slices (24 h) with 0 to 1000 nM isoproterenol increased UCP2 and UCP3 mRNA abundance in MSQ and OSQ, relative to 18S rRNA (P<0.05). For the in vivo experiment, nine randomly selected pigs (80 kg) were presented with a diet supplemented with 10.0 ppm ractopamine for 2 weeks. Another eight pigs were maintained on a control diet. Dietary ractopamine did not affect adipose UCP2 or UCP3 gene expression (P>0.05). However, UCP2 mRNA abundance was depressed in semitendinosus white (STW, P<0.05) and semitendinosus red (STR, P<0.001) by ractopamine feeding. Also, ractopamine decreased UCP3 mRNA abundance by 28% in STW (P<0.05). The in vitro data suggest that beta-adrenergic agonists directly affect adipose tissue UCP expression, although these adipose effects can be masked by the in vivo physiology. The in vivo data indicate that beta-adrenergic agonists may function in regulating UCP2 and UCP3 expression in selected muscles.

Expression of lipogenic enzymes in chickens.

Hubbard x Hubbard chickens (Gallus gallus) growing from 7 to 28 days of age were fed 12 or 30% protein diets and then switched to the diets containing the opposite level of protein. Birds were killed on days 28, 29, 30 and 31. Measurements taken included in vitro lipogenesis (IVL), malic enzyme (ME), isocitrate dehydrogenase (ICD) and aspartate aminotransferase (AAT) activities and the expression of the genes for ME, fatty acid synthase (FAS) and acetyl coenzyme carboxylase (ACC). Gene expression was determined with a combined RT-PCR using SYBR green as a fluorescent probe monitored in a real time mode. IVL and ME activity were inversely related to dietary protein levels (12 to 30%) and to acute changes in either level. In contrast, both ICD and AAT activities were increased by any increase in dietary protein. Lipogenic gene expression was inversely related to protein level, whether fed on an acute or chronic basis. It appears that real time RT-PCR is an acceptable method of estimating gene expression in birds. In addition, further work will focus on primer sizes that might further optimize RT-PCR as an instrument for studying the regulation of avian lipid metabolism. Results of the present study demonstrate a continued role for protein in the regulation of broiler metabolism. However, it should be pointed out that metabolic regulation at the gene level only occurs when feeding very high levels of dietary protein.

Investigation of the insulin-like growth factor system in the avian epiphyseal growth plate.

Components of the insulin-like growth factor (IGF) system were investigated in chondrocytes isolated from the avian growth plate. The genes for IGF-I, IGF-II, type 1 IGF receptor (IGF-R), IGF binding protein-2 (IGFBP-2), IGFBP-3, IGFBP-5 and IGFBP-7 were found to be expressed in both proliferative and hypertrophic chondrocytes. The expression of IGF-II in proliferative chondrocytes was extremely high relative to IGF-I. Although IGF-I expression was significantly increased in hypertrophic chondrocytes, the level was still low relative to IGF-II. In cell culture, IGF-I stimulated proteoglycan synthesis and increased the expression of Indian hedgehog (Ihh) and type X collagen, markers of chondrocyte differentiation. IGF-II was found to be equally efficacious in stimulating proteoglycan biosynthesis. These observations suggest that IGF-II may play a significant role in avian growth plate physiology, which is consistent with several reports on mammalian endochondral bone growth.

The effect of blood removal on oxidation and shelf life of broiler breast meat.

Blood components, especially hemoglobin, are powerful promoters of lipid oxidation and may decrease the shelf life of meat products. Therefore, this study examined different slaughter techniques to determine their effects on pH (24 h), color (L*a*b* values at 24 h), lipid oxidation, residual hemoglobin concentration (24 h), and sensory evaluation (d 1 and 4 postmortem; PM) in broiler breast fillets. The treatments included 1) CO(2) slaughter and not bled, 2) no stunning and bled, 3) electrical stunning (ES) and bled, 4) CO(2) stunning and bled, and 5) ES and decapitation. The birds were conventionally processed, and analyses were performed at 24 h PM except residual hemoglobin for which the samples were frozen (-80 degrees C) until analyses ( < 2 mo). There were no significant differences in pH or b* values at 24 h PM among any of the treatments. L* values were significantly higher, indicating lighter fillets in the ES and decapitated birds compared with the darker fillets from the CO(2) stunned and bled birds. The CO(2) slaughter and not bled birds had significantly higher a* values, indicating more red color, when compared with the ES and bled and decapitated birds. There were no significant differences in the residual hemoglobin contents in the broiler breast muscle when comparing all of the treatments except CO(2) slaughter and not bled, which was significantly (around 15%) greater. Overall TBA-reactive substances (TBARS; raw, cooked at 24 h, and cooked at 72 h PM) indicated that ES and bled birds had the lowest TBARS when compared with the remaining treatments. Consumer panels detected increased aroma (chicken meaty and warmed-over aromas) and flavor (chicken meaty and warmed-over flavors) in not bled samples at 24 h PM. By 72 h PM, however, there were no significant differences in aroma or flavor. Therefore, different slaughter and bleeding method may affect color and sensory properties of the broiler breast fillets, and the ES and decapitation method had the most favorable results for sensory quality.

Conclusion: genetic diversity and science communication - some issues of 'translation' and language.

This commentary concerns some key themes from the symposium. While molecular genetics may provide new opportunities to articulate biological concepts of race, the ideological baggage associated with the term suggests that it is best dropped from discussions. In screening programmes and genetic practice, ethnic identity is likely to be an uncertain surrogate to identify individuals with particular genetic variants. Precise language and explanation will aid communication about genetic matters. Talking of genes for particular traits or diseases is unhelpful. School teaching of classic Mendelian genetics is ineffective and should be replaced with some teaching of elementary developmental biology based on matters of everyday salience and interest. Social science literature is replete with unfounded claims of geneticization.

Molecular cloning, genomic organization, and expression of three chicken 5'-AMP-activated protein kinase gamma subunit genes.

The 5'-AMP-activated protein kinase (AMPK) plays a key role in regulating cellular energy homeostasis. The AMPK is a heterotrimeric enzyme complex that consists of 1 catalytic (alpha) and 2 regulatory (beta and gamma) subunits. Mutations of the gamma subunit genes are known to affect AMPK functioning. In this study, we characterized the genomic organization and expression of 3 chicken AMPK gamma subunit genes (cPRKAG). Alternative splicing of the second exon of the cPRKAG1 gene resulted in 2 transcript variants that code for predicted proteins of 298 and 276 amino acids. Use of an alternate promoter and alternative splicing of the cPRKAG2 gene resulted in 4 transcript variants that code for predicted proteins of 567, 452, 328, and 158 amino acids. Alternative splicing of exon 3 of the cPRKAG3 gene resulted in the production of "long" and "short" transcript variants that code for predicted proteins of 382 and 378 amino acids, respectively. We found evidence for differential expression of individual gamma subunit gene transcript variants and, in some cases, tissue-specific expression was observed. The cPRKAG subunit genes displayed similar structural features and high sequence homology compared with corresponding mammalian gamma subunit gene homologues.

The relationship of body composition, feed intake, and metabolic hormones for broiler breeder females.

Three hundred twenty Cobb 500 broiler breeder pullets at 21 wk of age were selected from a flock fed according to Cobb Breeder Management Guide specifications. One hundred sixty pullets at 21 wk of age were switched to ad libitum feeding, and the remaining 160 pullets continued to be control-fed. The pullets were photostimulated at 22 wk and maintained until 36.5 wk. Plasma samples were obtained, BW was determined, and hens were killed for determination of body composition at the following periods: 24 h prior to photostimulation, 2.5 wk after photostimulation, 24 h after first egg, and 36.5 wk following peak egg production. Compared with ad libitum-fed breeders, the restricted breeders had a higher percentage carcass protein and lower percentage carcass fat at all sampling periods. Total egg numbers were greater, and abnormal eggs were less for the restricted pullets compared with the ad libitum-fed pullets at 36.5 wk. Carcass percentage fat of ad libitum-fed pullets was positively related to plasma glucagon, insulin-like growth factor-II (IGF-II), and 17beta-estradiol but negatively related to plasma insulin, insulin/glucagon M ratio, insulin-like growth factor-I (IGF-I), thyroxine (T4), and triiodothyronine (T3). Carcass percentage fat of feed-restricted pullets was negatively related to IGF-I, IGF-II, and T4. The T4 was the most important hormone for predicting the percentage carcass fat in ad libitum-fed pullets, and IGF-I was the most important hormone for predicting the percentage carcass fat in feed-restricted pullets. The percentage carcass protein for ad libitum-fed breeders was positively correlated to IGF-I, T4, T3, insulin/glucagon M ratio, and insulin. Carcass percentage protein for feed-restricted breeders was positively correlated to IGF-I, IGF-II, T4, and glucagon. Stepwise regressions for predicting percentage carcass protein for breeders fed by both systems shows that T3 and IGF-I concentrations were the most important for ad libitum-fed breeders, whereas IGF-II and T4 were best for feed-restricted breeders. The hormone status of breeders may be a key indicator to help predict the body composition and thus support management decisions for maintaining optimum production.