Wet Feeding Promotes Growth without Affecting Hypothalamic Peptide Gene Expression in Growing Broiler Chicks

From the perspective of animal welfare, freedom from hunger and thirst is an undeniable requirement for the poultry industry. Regulatory mechanisms underlying drinking behavior have not yet been identified in chickens; however, the regulation of osmolality and water intake appears to be closely related. This study clarified whether wet feeding affects appetite, osmolality, and stress-related gene expression in the hypothalami of chicks. In Experiment 1, the effects of different wet feed percentages on the growth of broiler chicks were examined. Wet feeds were prepared by mixing either 0.25 g (20% wet feed), 0.667 g (40% wet feed), or 1.5 g (60% wet feed) of distilled water per g of commercial feed. Then, the wet feeds were offered to 4-day-old broiler chicks until 42 d of age. Forty percent wet feed significantly increased body, breast, and leg weights. In Experiment 2, 7-day-old broiler chicks were given either commercial starter feed or 40% wet feed until 21 d of age. Again, weights of the body, breasts, and legs were significantly increased by wet feeding. The total amount of water loss in the individual waterers was significantly decreased by wet feeding. No significant changes were observed in mRNA levels of the genes encoding appetite-regulatory peptides (neuropeptide Y and α melanocyte-stimulating hormone), osmoregulatory peptides (vasotocin and mesotocin), or stress-related peptides (corticotrophin-releasing factor) in the chicken hypothalamus. Overall, 40% wet feed improved growth without inducing thirst or hunger in broiler chicks. These findings suggest that wet feeding contributes to both meat yield and animal welfare during broiler production.

Low temperature inhibits food intake via TRPA1 channel activation in Nile tilapia (Oreochromis niloticus)

Low temperatures significantly influence feeding behavior in ectothermic vertebrates, but the underlying mechanisms remain elusive. This study investigated the role of transient receptor potential ankyrin 1 (TRPA1) channels in mediating the appetite-suppressing effects of low temperature in Nile tilapia. TRPA1 was found to be highly expressed in the hypothalamus and co-localized with neuropeptide Y (NPY) neurons. Exposure to low temperatures reduced feeding frequency and increased TRPA1 expression. In vitro experiments demonstrated that low temperature and TRPA1 agonists induced calcium influx, which was blocked by a TRPA1 inhibitor. TRPA1 expression exhibited post-prandial increases and was downregulated by fasting. TRPA1 activation dose-dependently inhibited food intake, while its inhibition restored feeding suppressed by low temperature. TRPA1 activation downregulated orexigenic factors and upregulated anorexigenic factors through Ca2+/calmodulin-dependent pathways. These findings suggest that TRPA1 plays a crucial role in sensing low temperatures and regulating feeding behavior in tilapia.

A bird's-eye overview of molecular mechanisms regulating feed intake in chickens-with mammalian comparisons

In recent decades, a lot of research has been conducted to explore poultry feeding behavior. However, up to now, the processes behind poultry feeding behavior remain poorly understood. The review generalizes modern expertise about the hormonal regulation of feeding behavior in chickens, focusing on signaling pathways mediated by insulin, leptin, and ghrelin and regulatory pathways with a cross-reference to mammals. This overview also summarizes state-of-the-art research devoted to hypothalamic neuropeptides that control feed intake and are prime candidates for predictors of feeding efficiency. Comparative analysis of the signaling pathways that mediate the feed intake regulation allowed us to conclude that there are major differences in the processes by which hormones influence specific neuropeptides and their contrasting roles in feed intake control between two vertebrate clades.

Recent Research on Mechanisms of Feeding Regulation in Chicks

Food intake affects poultry productivity. A complete understanding of these regulatory mechanisms provides new strategies to improve productivity. Food intake is regulated by complex mechanisms involving many factors, including the central nervous system, gastrointestinal tract, hormones, and nutrients. Although several studies have been conducted to elucidate regulatory mechanisms in chickens, the mechanisms remain unclear. To update the current knowledge on feeding regulation in chickens, this review focuses on recent findings that have not been summarized in previous reviews, including spexins, adipokines, neurosecretory proteins GL and GM, and central intracellular signaling factors.

The effects of feed restriction, time of day and time since feeding on behavioral and physiological indicators of hunger in broiler breeder hens

Broiler breeder chickens are commercially feed restricted to slow their growth and improve their health and production, however, there is research demonstrating that this leads to chronic hunger resulting in poor welfare. A challenge in these studies is to account for possible daily rhythms or the effects of time since last meal on measures relating hunger. To address this, we used 3 feed treatments: AL (ad libitum fed), Ram (restricted, fed in the morning), and Rpm (restricted, fed in the afternoon) to control for diurnal effects. We then conducted foraging motivation tests and collected home pen behavior and physiological samples at 4 times relative to feeding throughout a 24-h period. The feed treatment had the largest influence on the data, with AL birds weighing more, having lower concentrations of plasma NEFA, and mRNA expression of AGRP and NPY alongside higher expression of POMC in the basal hypothalamus than Ram or Rpm birds (P < 0.001). R birds were more successful at and had a shorter latency to complete the motivation test, and did more walking and less feeding than AL birds in the home pen (P < 0.01). There was little effect of time since last meal on many measures (P > 0.05) but AGRP expression was highest in the basal hypothalamus shortly after a meal (P < 0.05), blood plasma NEFA was higher in R birds just before feeding (P < 0.001) and glucose was higher in Ram birds just after feeding (P < 0.001), and the latency to complete the motivation test was shortest before the next meal (P < 0.05). Time of day effects were mainly found in the difference in activity levels in the home pen when during lights on and lights off periods. In conclusion, many behavioral and physiological hunger measures were not significantly influenced by time of day or time since the last meal. For the measures that do change, future studies should be designed so that sampling is balanced in such a way as to minimize bias due to these effects.

Comparison of the effects of intracerebroventricular administration of glucagon-like peptides 1 and 2 on hypothalamic appetite regulating factors and sleep-like behavior in chicks

Glucagon-like peptide (GLP)-1 and GLP-2, proglucagon-derived brain-gut peptides, function as anorexigenic neuropeptides in mammals. We previously showed that central administration of GLP-1 and GLP-2 potently suppressed food intake in chicks. GLP-1 and GLP-2 specifically activate their receptors GLP-1 receptor (GLP1R) and GLP-2 receptor (GLP2R), respectively in chickens. In adult chickens, GLP1R and GLP2R are expressed in different brain regions. These findings raise the hypothesis that both GLP-1 and GLP-2 function as anorexigenic peptides in the chicken brain but the mechanisms underlying the anorexigenic effects are different between them. In the present study, we compared several aspects of GLP-1 and GLP-2 in chicks. GLP1R mRNA levels in the brain stem and optic lobes were significantly higher than in other parts of the brain, whereas GLP2R mRNA was densely expressed in the telencephalon. Intracerebroventricular administration of either GLP-1 or GLP-2 significantly reduced the mRNA levels of corticotrophin releasing factor and AMP-kinase (AMPK) α1. The mRNA level of proopiomelanocortin was significantly increased, and those of AMPKα2 and GLP2R were significantly decreased by GLP-2, whereas the mRNA level of pyruvate dehydrogenase kinase 4 was significantly increased, and that of GLP1R was significantly decreased by GLP-1. Intracerebroventricular administration of either GLP-1 or GLP-2 induced sleep-like behavior in chicks. Our findings suggest that the anorexigenic peptides GLP-1 and GLP-2 induce similar behavioral changes in chicks, but the mechanism may differ between them.

Effects of exogenous α-(1,4)-amylase on the utilisation of corn starch and glucose metabolism in broiler chickens

Starch is the most important energy source in corn-based diets for broiler chickens, however, some proportion of dietary starch may be partially digested, leading to a decrease in feed utilisation. Therefore, supplementing exogenous amylase might be a feasible way to improve the utilisation of dietary starch for poultry. This study investigated the effects of exogenous α-(1,4)-amylase supplementation on the utilisation of corn starch and glucose metabolism in broiler chickens. A total of 560, 4-d-old Arbour Acres plus male broiler chicks were randomly divided into five treatment groups and fed a corn-soybean meal diet supplemented with 0, 400, 600, 800 and 1 200 U/kg α-(1,4)-amylase to evaluate growth. The growth performance, nutrient digestibility coefficients, digestive enzyme activity, glucose transporter transcription and cecal microbiota composition were evaluated in this study. Starch digestibility coefficient showed a quadratic response to α-(1,4)-amylase at 14 d and 42 d (P < 0.05). However, the endogenous α-amylase activity in jejunal content was linearly decreased (P = 0.045). Also, exogenous α-(1,4)-amylase linearly decreased ileal Na+-dependent glucose and galactose transporter 1 mRNA expression at 42 d (P < 0.001). Exogenous α-(1,4)-amylase generated higher insulin and glucagon serum concentrations in fasted birds (P < 0.05) and following re-feeding for 2 h (P < 0.001). BW gain and feed intake were strongly positively correlated with starch digestibility coefficient at both 14 d (r = 0.87) and 42 d (r = 0.91); whereas, the relative weight of the gizzard was weakly negatively correlated with starch digestibility coefficient (r = -0.35). The relative abundance of Unclassified_Bacillaceae was moderately positively correlated (r > 0.50) while Oscillospira, Ornithobacterium and Unclassified_Barnesiellaceae were moderately negatively correlated (-0.50 < r -0.39) with starch digestibility coefficient. In conclusion, exogenous α-amylase modulates metabolic function by increasing insulin and glucagon concentrations, influenced gut microbiota which may impact starch digestibility in the jejunum and ileum. The results of this study showed that excessive addition of exogenous α-(1,4)-amylase was not beneficial for the utilisation of starch in broiler chickens. Supplement more than 600 U/kg α-(1,4)-amylase inhibited glucose transporters, decreases the coefficients of starch and organic matter digestibility in the small intestine to a varying degree, thereby limiting the growth performance of broiler chickens.

Impact of Different Durations of Fasting on Intestinal Autophagy and Serum Metabolome in Broiler Chicken

Simple Summary

Fasting is usually used before metabolizable energy assessment in poultry. Recently, fasting-induced autophagy has been of concern because of the beneficial function of autophagy. In this study, we found that the intestinal autophagy gene Atg7 has a good quadratic fitting with fasting duration. We found that the serum metabolism pathways involved in glycerophospholipid, phenylalanine, GnRH signaling pathways, glycosylphosphatidylinositol anchor biosynthesis, autophagy, and ferroptosis changed with fasting. Furthermore, we found a correlation between intestinal autophagy and serum metabolite PE (18:3(9Z,12Z,15Z)/P-18:0).

Abstract

Fasting-induced autophagy in the intestine is beneficial for body health. This study was designed to explore the relationship between the host metabolism and intestinal autophagy. Broilers were randomly assigned into 48 cages. At 0 (CT), 12 (FH12), 24 (FH24), 36 (FH36), 48(FH48), and 72 h (FH72) before 09:00 a.m. on day 25, eight cages of birds were randomly allotted to each fasting time point using completely random design, and their food was removed. At 09:00 a.m. on day 25, the blood and jejunum were sampled for serum metabolome and autophagy gene analyses, respectively. The results showed that the autophagy gene Atg7 has a good quadratic fit with fasting duration (R² = 0.432, p < 0.001). Serum phosphatidylethanolamine (PE) and lyso-PE were decreased in the birds that were fasted for 24 h or longer. Conversely, the serum phosphatidylcholine (PC) and lyso-PC were increased in the birds that were fasted for 36 h or longer. Metabolism pathway analysis showed that the serum glycerophospholipid, phenylalanine, and GnRH signaling pathways were downregulated with the extended fasting duration. The serum metabolites involved in glycosylphosphatidylinositol anchor biosynthesis, autophagy, and ferroptosis were upregulated in all of the fasted groups. Correlation analysis showed that serum PE (18:3(9Z,12Z,15Z)/P-18:0) was a potential biomarker for intestinal autophagy. Our findings provide a potential biomarker related to intestinal autophagy.

Effects of fasting and re-feeding on the expression of CCK, PYY, hypothalamic neuropeptides, and IGF-related genes in layer and broiler chicks

Cholecystokinin (CCK) and peptide YY (PYY) have been investigated as gut hormones that send satiation signals to the brain in mammals. There is evidence that chicken PYY mRNA expression was the highest in the pancreas compared to other tissues. We recently suggested that insulin-like growth factor (IGF)-1 and its binding proteins (IGFBPs) may be involved in the appetite regulation system in chicks. In the present study, in order to evaluate the possible roles of CCK, PYY, and IGF-related proteins in the appetite regulation system in chicks, we analyzed changes in the mRNA levels of these genes in response to fasting and re-feeding in layer and hyperphagic broiler chicks. In layer chicks, 12 h of fasting reduced the mRNA levels of intestinal CCK, PYY, Y2 receptor, and pancreatic PYY, and these changes were reversed by 12 h of re-feeding. On the other hand, in broiler chicks 12 h of fasting reduced the mRNA levels of intestinal PYY and Y2 receptor, but not intestinal CCK and pancreatic PYY, and these changes were reversed by 12 h of re-feeding. Hypothalamic NPY mRNA significantly increased by 12 h of fasting in both chicks, and these changes were reversed by re-feeding. Also, 12 h of fasting significantly increased the mRNA levels of hypothalamic agouti-related protein and reduced the mRNA levels of hepatic IGF-1 only in broiler chicks, and 12 h of re-feeding did not change these. IGFBP-1 and -2 mRNA levels were markedly increased by 12 h of fasting in both chicks, and these changes were reversed by re-feeding. IGFBP-3 mRNA levels were increased by 12 h of fasting only in layer chicks, while re-feeding reduced the mRNA levels of IGFBP-3 in both types of chicks. These results suggest that several peripheral hormones, such as pancreatic PYY and intestinal CCK, may not play important roles in the regulation of food intake in broiler chicks.

Effects of taurine on growth performance, antioxidant capacity, and lipid metabolism in broiler chickens

To investigate the effects of dietary taurine supplementation on growth performance, antioxidant status, and lipid metabolism in broilers, 384 male broilers (Arbor Acres, 1 D of age) were randomly allocated into 4 groups with 8 replicates of 8 birds. Dietary treatments were supplemented with taurine at the level of 0.00, 2.50, 5.00, and 7.50 g/kg of the diet (denoted as CON, TAU1, TAU2, TAU3, respectively). The BW gain from 1 to 21 D and from 22 to 42 D were all increased linearly (linear, P < 0.001) by taurine supplementation. Throughout the trial period, the highest BW gain and favorable gain-to-feed ratio were observed in the TAU2 group. Taurine supplementation increased the antioxidant enzyme activities and decreased (linear, P < 0.001) the content of malondialdehyde in both serum and the liver of broilers and alleviated oxidative damage through enhancing (P < 0.05) the hepatic genes expression of nuclear factor erythroid-2-related factor 2 (NRF2), glutathione peroxidase (GPX), and heme oxygenase-1 (HO-1). Correspondingly, in serum, the activities of hepatic lipase and total lipase were decreased linearly and quadratically (linear and quadratic, P < 0.001) with the increasing inclusion of taurine in the diet. Meanwhile, in serum, the content of triglycerides was significantly decreased (P < 0.05), and except for TAU3, the total cholesterol content was also significantly decreased (P < 0.05) by taurine supplementation. In addition, the hepatic content of triglycerides was significantly decreased (P < 0.05) in the TAU1 and TAU2 groups. Compared with the CON group, the hepatic genes expression of adenosine monophosphate-activated protein kinase alpha (AMPKα), silent 1, (SIRT1) and carnitine palmitoyltransferase 1 (CPT-1) were all increased (P < 0.05), and sterol regulatory element-binding protein-1 (SREBP-1) expression was decreased (P < 0.05) in the TAU2 group. These results indicated that taurine supplementation improved the growth performance, antioxidant capacity, and lipid metabolism of broilers.

Regulating appetite in broilers for improving body and muscle development - A review

Appetite is the desire for feed and water and the voluntary intake of feed and is an important regulator of livestock productivity and animal health. Economic traits such as growth rate and muscle development (meat deposition) in broilers are directly correlated to appetite. Factors that may influence appetite include environmental factors, such as stress and temperature variation, and animal‐specific factors, such as learning period, eating capacity and preferences. Feed preferences have been reported to be determined in early life, and this period is important in broilers due to their fast growth and relatively short growth trajectories. This may be of importance when contemplating the use of more circular and sustainable feeds and the optimization of appetite for these feeds. The objective of this review was to review the biological mechanisms underlying appetite using data from human, animal and bird models and to consider the option for modulating appetite particularly as it relates to broiler chickens.

Should I Lay or Should I Grow: Photoperiodic Versus Metabolic Cues in Chickens

While photoperiod has been generally accepted as the primary if not the exclusive cue to stimulate reproduction in photoperiodic breeders such as the laying hen, current knowledge suggests that metabolism, and/or body composition can also play an influential role to control the hypothalamic-pituitary gonadal (HPG)-axis. This review thus intends to first describe how photoperiodic and metabolic cues can impact the HPG axis, then explore and propose potential common pathways and mechanisms through which both cues could be integrated. Photostimulation refers to a perceived increase in day-length resulting in the stimulation of the HPG. While photoreceptors are present in the retina of the eye and the pineal gland, it is the deep brain photoreceptors (DBPs) located in the hypothalamus that have been identified as the potential mediators of photostimulation, including melanopsin (OPN4), neuropsin (OPN5), and vertebrate-ancient opsin (VA-Opsin). Here, we present the current state of knowledge surrounding these DBPs, along with their individual and relative importance and, their possible downstream mechanisms of action to initiate the activation of the HPG axis. On the metabolic side, specific attention is placed on the hypothalamic integration of appetite control with the stimulatory (Gonadotropin Releasing Hormone; GnRH) and inhibitory (Gonadotropin Inhibitory Hormone; GnIH) neuropeptides involved in the control of the HPG axis. Specifically, the impact of orexigenic peptides agouti-related peptide (AgRP), and neuropeptide Y (NPY), as well as the anorexigenic peptides pro-opiomelanocortin (POMC), and cocaine-and amphetamine regulated transcript (CART) is reviewed. Furthermore, beyond hypothalamic control, several metabolic factors involved in the control of body weight and composition are also presented as possible modulators of reproduction at all three levels of the HPG axis. These include peroxisome proliferator-activated receptor gamma (PPAR-γ) for its impact in liver metabolism during the switch from growth to reproduction, adiponectin as a potential modulator of ovarian development and follicular maturation, as well as growth hormone (GH), and leptin (LEP).

Investigation of the effects of dichlorvos poisoning on AMPK signaling pathway in chicken brain tissues

Dichlorvos is a common crop insecticide widely used by people which causes extensive and serious environmental pollution. However, it has been shown that organophosphorus poisoning causes energy metabolism and neural disorders. The overall purpose of this study was to investigate the damage to brain tissue and the changes in AMPK signaling pathway-related gene expression after dichlorvos poisoning in chickens. White-feathered broiler chickens, as the research subjects of this experiment, were divided into three groups: control group, low-dose group (77.5% dichlorvos at 1.13 mg/kg dose) and high-dose group (77.5% dichlorvos at 10.2 mg/kg dose). Clinical symptoms were observed after modeling, and an integrative analysis was conducted using HE staining microscopy, immune-histochemical microscopy, electron microscopy and PCR arrays. The results showed that the high-dose group had more obvious dyspnea, salivation, convulsion and other neurological phenomena. Pathological sections showed that nuclear disintegration of neurons was most obvious in the low-dose group, and apoptosis of brain cells was most obvious in the high-dose group, and the mitochondrial structure was destroyed in the two poisoned group, i.e. low-dose group and high-dose group. PCR arrays showed that AMPK signaling pathway was inhibited and the expressions of genes involved in energy metabolism (ACACA and PRKAA1) were significantly changed. Furthermore, genes associated with protein synthesis (EIF4EBP1) were significantly upregulated. FASN and HMGCR expressions were significantly increased. There were significant changes in the expressions of cell cycle-related genes (STK11, TP53 and FOXO3). Organophosphate poisoning can cause a lot of nuclear disintegration of brain neurons, increases cell apoptosis, disrupts the energy metabolism of mitochondrial structure, and inhibits the AMPK signaling pathway. These results provide a certain idea and basis for studying the mechanism of AMPK signaling after organophosphorus poisoning and provide a research basis for the prevention and treatment of organophosphorus poisoning.

Transcriptome analyses of liver in newly-hatched chicks during the metabolic perturbation of fasting and re-feeding reveals THRSPA as the key lipogenic transcription factor

Background

The fasting-refeeding perturbation has been used extensively to reveal specific genes and metabolic pathways that control energy metabolism in the chicken. Most global transcriptional scans of the fasting-refeeding response in liver have focused on juvenile chickens that were 1, 2 or 4 weeks old. The present study was aimed at the immediate post-hatch period, in which newly-hatched chicks were subjected to fasting for 4, 24 or 48 h, then refed for 4, 24 or 48 h, and compared with a fully-fed control group at each age (D1-D4).

Results

Visual analysis of hepatic gene expression profiles using hierarchical and K-means clustering showed two distinct patterns, genes with higher expression during fasting and depressed expression upon refeeding and those with an opposing pattern of expression, which exhibit very low expression during fasting and more abundant expression with refeeding. Differentially-expressed genes (DEGs), identified from five prominent pair-wise contrasts of fed, fasted and refed conditions, were subjected to Ingenuity Pathway Analysis. This enabled mapping of analysis-ready (AR)-DEGs to canonical and metabolic pathways controlled by distinct gene interaction networks. The largest number of hepatic DEGs was identified by two contrasts: D2FED48h/D2FAST48h (968 genes) and D2FAST48h/D3REFED24h (1198 genes). The major genes acutely depressed by fasting and elevated upon refeeding included ANGTPL, ATPCL, DIO2, FASN, ME1, SCD, PPARG, SREBP2 and THRSPA—a primary lipogenic transcription factor. In contrast, major lipolytic genes were up-regulated by fasting or down-regulated after refeeding, including ALDOB, IL-15, LDHB, LPIN2, NFE2L2, NR3C1, NR0B1, PANK1, PPARA, SERTAD2 and UPP2.

Conclusions

Transcriptional profiling of liver during fasting/re-feeding of newly-hatched chicks revealed several highly-expressed upstream regulators, which enable the metabolic switch from fasted (lipolytic/gluconeogenic) to fed or refed (lipogenic/thermogenic) states. This rapid homeorhetic shift of whole-body metabolism from a catabolic-fasting state to an anabolic-fed state appears precisely orchestrated by a small number of ligand-activated transcription factors that provide either a fasting-lipolytic state (PPARA, NR3C1, NFE2L2, SERTAD2, FOX01, NR0B1, RXR) or a fully-fed and refed lipogenic/thermogenic state (THRSPA, SREBF2, PPARG, PPARD, JUN, ATF3, CTNNB1). THRSPA has emerged as the key transcriptional regulator that drives lipogenesis and thermogenesis in hatchling chicks, as shown here in fed and re-fed states.

Induction of hypothalamic GABA synthetic enzymes mRNA (Gad 1 and Gad 2) expression by negative energy balance in broiler and layer chicks

Broiler and layer chicks have been selected for higher and lower food intake and body weight gain, respectively. It has recently been reported that glutamate decarboxylase (Gad1) mRNA, a gamma-aminobutyric acid (GABA) synthetic enzyme gene, is a reliable proxy for GABA release. Previous studies have revealed that GABAergic system has a stimulatory role on food intake in both mammals and birds. Over the recent years, evidence has identified the presence of GABAergic neurons as either the first- or second-order neurons within the various feeding nuclei of hypothalamus of laboratory rodents. They respond to the negative energy balance representing a critical role for GABA in the regulation of food intake. In the current study, the mRNA abundance of Gad 1 and Gad 2 was measured within the hypothalamus of both broiler and layer free fed, 12 h-fasted and 12 h-fasted / 3 h refed chicks. Furthermore, the effect of intracerebroventricular (ICV) injection of GABA was studied on food intake of chicks. The results indicated an increase in both Gad 1 and 2 expressions during fasting which tended to return to the baseline after refeeding. However, this increase was greater in broilers than in layers. The results also showed that ICV injection of GABA had no effect on food intake with the exception of an increase in free fed broilers. This study suggests a role for hypothalamic GABAergic system in birds that respond to negative energy balance, which seems to be more considerable in broilers than in layers.

Antioxidant Defence Systems and Oxidative Stress in Poultry Biology: An Update

Poultry in commercial settings are exposed to a range of stressors. A growing body of information clearly indicates that excess ROS/RNS production and oxidative stress are major detrimental consequences of the most common commercial stressors in poultry production. During evolution, antioxidant defence systems were developed in poultry to survive in an oxygenated atmosphere. They include a complex network of internally synthesised (e.g., antioxidant enzymes, (glutathione) GSH, (coenzyme Q) CoQ) and externally supplied (vitamin E, carotenoids, etc.) antioxidants. In fact, all antioxidants in the body work cooperatively as a team to maintain optimal redox balance in the cell/body. This balance is a key element in providing the necessary conditions for cell signalling, a vital process for regulation of the expression of various genes, stress adaptation and homeostasis maintenance in the body. Since ROS/RNS are considered to be important signalling molecules, their concentration is strictly regulated by the antioxidant defence network in conjunction with various transcription factors and vitagenes. In fact, activation of vitagenes via such transcription factors as Nrf2 leads to an additional synthesis of an array of protective molecules which can deal with increased ROS/RNS production. Therefore, it is a challenging task to develop a system of optimal antioxidant supplementation to help growing/productive birds maintain effective antioxidant defences and redox balance in the body. On the one hand, antioxidants, such as vitamin E, or minerals (e.g., Se, Mn, Cu and Zn) are a compulsory part of the commercial pre-mixes for poultry, and, in most cases, are adequate to meet the physiological requirements in these elements. On the other hand, due to the aforementioned commercially relevant stressors, there is a need for additional support for the antioxidant system in poultry. This new direction in improving antioxidant defences for poultry in stress conditions is related to an opportunity to activate a range of vitagenes (via Nrf2-related mechanisms: superoxide dismutase, SOD; heme oxygenase-1, HO-1; GSH and thioredoxin, or other mechanisms: Heat shock protein (HSP)/heat shock factor (HSP), sirtuins, etc.) to maximise internal AO protection and redox balance maintenance. Therefore, the development of vitagene-regulating nutritional supplements is on the agenda of many commercial companies worldwide.

Impact of an energy- and nutrient-reduced diet containing 10% lignocellulose on animal performance, body composition and egg quality of dual purpose laying hens

In response to ethical concerns regarding the killing of day-old male chicks of layer breeds, the use of dual purpose chickens is increasingly discussed in public while data on nutritional requirements of dual purpose laying hens are not available. The present study examined the impact of an energy- and nutrient-reduced diet containing lignocellulose on performance, body composition and egg quality of dual purpose hens. Female Lohmann Dual chicks were allocated to 12 pens and fed two different diets for 52 weeks: a control (CON) and a treatment diet (LC), based on CON but diluted with 10% lignocellulose. During the trial, animal performance, whole-body composition and egg quality parameters of hens were consistently ascertained. The results showed that LC-fed hens had lower body weights compared to those receiving CON (p < 0.05). During the laying period, feed intake was increased in LC-fed hens (p < 0.001). LC-fed hens showed a higher egg production and egg mass resulting in an improved feed efficiency (p < 0.05) and laid smaller eggs compared to CON-fed hens (p < 0.001). At 52 weeks of age, bodies of LC-fed hens had higher protein and lower fat contents than those fed with CON diet (p ≤ 0.001). Mean body weight was positively correlated to the body fat content (p = 0.004) and body fat content was negatively correlated to the egg production (p = 0.043). Analyses of the egg quality showed that yolk mass at all sampling points and albumen mass at 27 and 42 weeks were lower in hens fed with diet LC compared to those fed with diet CON (p< 0.05). In conclusion, the feeding of energy- and nutrient-reduced diets containing 10% lignocellulose reduced the body fat content and simultaneously improved the laying performance in dual purpose hens.

Neuroendocrine mechanism of food intake and energy regulation in Japanese quail under differential simulated photoperiodic conditions: Involvement of hypothalamic neuropeptides, AMPK, insulin and adiponectin receptors

Neuroendocrine coordination between the reproductive and energy regulatory hypothalamic circuitries not only tightly regulates food intake and energy expenditure but also maintains the body weight and reproduction. The effect of different simulated photoperiodic conditions on food intake and neuroendocrine mechanism of energy homeostasis in Japanese quail is not investigated till date. Hence, our present study is designed to elucidate the effect of different simulated photoperiodic conditions on food consumption and neuroendocrine mechanism(s) of energy regulation in this poultry species. The alterations in hypothalamic energy balancing neuropeptides (NPY/AgRP/CART), polypeptide hormone precursor (POMC), protein kinase (AMPK-p-AMPK) as well as receptors of insulin and adiponectin [Insulin Receptor (IR), Adiponectin Receptor 1 & 2] have been investigated in photosensitive (PS), scotorefractory (SR),photorefractory (PR) and scotosensitive (SS) quail. Immunofluorescence and western blotting were used to quantify the expression of these peptides and proteins. Results showed increased food consumption and body weight gain, along with increased expression of NPY, AgRP, IR, adiponectin receptors and p-AMPK, decreased CART and POMC in the hypothalamus of photosensitive and scotorefractory quail. While, opposite findings were observed in photorefractory and scotosensitive quail. Hence, this study may suggest the hypothalamic energy channelization towards reproductive axis in photosensitive and scotorefractory quail to support the full breeding conditions, while hypothalamic energy deprivation in photorefractory and scotosensitive quail leads to reproductive quiescence.

Effect of dietary resveratrol supplementation on meat quality, muscle antioxidative capacity and mitochondrial biogenesis of broilers

BACKGROUND

The naturally occurring polyphenol resveratrol has been acknowledged with many beneficial biological effects. The aim of this study was to evaluate the influence of dietary resveratrol supplementation on meat quality, muscle antioxidative capacity and mitochondrial biogenesis of broilers. One hundred and eighty 21-day-old male Cobb broilers were randomly assigned to two groups and fed on a 0 mg kg^-1 or 400 mg kg^-1 resveratrol-supplemented diet for 21 days. Then, chickens were slaughtered and pectoralis major muscle (PM) samples were collected for analysis.

RESULTS

The results showed that resveratrol not only tended to increase (P < 0.10) PM pH_24h but also significantly decreased (P < 0.05) PM L*_45min , pH decline, drip loss and lactate content. Meanwhile, PM total antioxidative capacity and catalase activity were significantly increased (P < 0.05) by resveratrol, while malondialdehyde content was decreased (P < 0.10). Moreover, resveratrol significantly increased (P < 0.05) PM peroxisome proliferator-activated receptor γ coactivator 1α and nuclear respiratory factor 1 mRNA levels, along with increased (P < 0.05) citrate synthase activity.

CONCLUSION

Resveratrol can be used as a feed additive to improve meat quality of broilers, which may be associated with improved muscle antioxidative status and mitochondrial biogenesis. © 2017 Society of Chemical Industry.

Mapping Molecular Datasets Back to the Brain Regions They are Extracted from: Remembering the Native Countries of Hypothalamic Expatriates and Refugees

This article focuses on approaches to link transcriptomic, proteomic, and peptidomic datasets mined from brain tissue to the original locations within the brain that they are derived from using digital atlas mapping techniques. We use, as an example, the transcriptomic, proteomic and peptidomic analyses conducted in the mammalian hypothalamus. Following a brief historical overview, we highlight studies that have mined biochemical and molecular information from the hypothalamus and then lay out a strategy for how these data can be linked spatially to the mapped locations in a canonical brain atlas where the data come from, thereby allowing researchers to integrate these data with other datasets across multiple scales. A key methodology that enables atlas-based mapping of extracted datasets-laser-capture microdissection-is discussed in detail, with a view of how this technology is a bridge between systems biology and systems neuroscience.

The effect of fasting on the appetite-associated factors and energy sensors expression in the hypothalamus of different TI broilers

Tonic immobility (TI) is a behaviour related to fear and stress response. Birds can exhibit a short (STI) or long (LTI) tonic immobility phenotype on the basis in TI duration. In this study, the differences in the hypothalamic appetite-associated factors and energy sensor gene expression between STI and LTI broilers were evaluated under free feed access or 16-h fasting. The results showed that the concentrations of cholesterol, high density lipoprotein-cholesterol, non-esterified fatty acid, malonaldehyde, lactate dehydrogenase, creatine kinase, alanine aminotransferase and aspartate aminotransferase in plasma were significantly increased (P < 0.05) in fasting broilers compared with broilers fed ad libitum, whereas plasma glucose, triglyceride, and total antioxidant capacity concentrations were decreased (P < 0.05). With respect to TI, however, only low density lipoprotein-cholesterol and glutathione peroxidase concentrations in plasma showed significant differences between LTI and STI broilers, with higher concentrations in LTI compared with STI. Real-time PCR results showed that only NPY mRNA expression demonstrated a tendency to increase in STI broilers compared with LTI (P = 0.095). Fasting downregulated SREBP-1 and its target gene FAS but upregulated CPT1 in the hypothalamus. Additionally, levels of hypothalamic p-GR and p-AMPK protein expression decreased after fasting. These results indicate that a 16-h fasting results in a negative energy status, and is accompanied with changes in expression of hypothalamic energy sensor and appetite-associated factors.

The physiological and neuroendocrine correlates of hunger in the Red Junglefowl (Gallus gallus)

The ability to regulate food intake is critical to survival. The hypothalamus is central to this regulation, integrating peripheral signals of energy availability. Although our understanding of hunger in rodents is advanced, an equivalent understanding in birds is lacking. In particular, the relationship between peripheral energy indices and hypothalamic 'hunger' peptides, agouti-related protein (AgRP), pro-opiomelanocortin (POMC) and neuropeptide Y (NPY) is poorly understood. Here, we compare AgRP, POMC and NPY RNA levels in the hypothalamus of Red Junglefowl chicks raised under ad libitum, chronic restriction and intermittent feeding regimens. Hypothalamic gene expression differed between chronically and intermittently restricted birds, confirming that different restriction regimens elicit different patterns of hunger. By assessing the relationship between hypothalamic gene expression and carcass traits, we show for the first time in birds that AgRP and POMC are responsive to fat-related measures and therefore represent long-term energy status. Chronically restricted birds, having lower indices of fat, show elevated hunger according to AgRP and POMC. NPY was elevated in intermittently fasted birds during fasting, suggesting a role as a short-term index of hunger. The different physiological and neuroendocrine responses to quantitative versus temporal feed restriction provide novel insights into the divergent roles of avian hunger neuropeptides.

Regulation of Agouti-Related Protein and Pro-Opiomelanocortin Gene Expression in the Avian Arcuate Nucleus

The arcuate nucleus is generally conserved across vertebrate taxa in its neuroanatomy and neuropeptide expression. Gene expression of agouti-related protein (AGRP), neuropeptide Y (NPY), pro-opiomelanocortin (POMC), and cocaine- and amphetamine-regulated transcript (CART) has been established in the arcuate nucleus of several bird species and co-localization demonstrated for AGRP and NPY. The proteins encoded by these genes exert comparable effects on food intake in birds after central administration to those seen in other vertebrates, with AGRP and NPY being orexigenic and CART and α-melanocyte-stimulating hormone anorexigenic. We have focused on the measurement of arcuate nucleus AGRP and POMC expression in several avian models in relation to the regulation of energy balance, incubation, stress, and growth. AGRP mRNA and POMC mRNA are, respectively, up- and downregulated after energy deprivation and restriction. This suggests that coordinated changes in the activity of AGRP and POMC neurons help to drive the homeostatic response to replace depleted energy stores in birds as in other vertebrates. While AGRP and POMC expression are generally positively and negatively correlated with food intake, respectively, we review here situations in some avian models in which AGRP gene expression is dissociated from the level of food intake and may have an influence on growth independent of changes in appetite. This suggests the possibility that the central melanocortin system exerts more pleiotropic functions in birds. While the neuroanatomical arrangement of AGRP and POMC neurons and the sensitivity of their activity to nutritional state appear generally conserved with other vertebrates, detailed knowledge is lacking of the key nutritional feedback signals acting on the avian arcuate nucleus and there appear to be significant differences between birds and mammals. In particular, recently identified avian leptin genes show differences between bird species in their tissue expression patterns and appear less closely linked in their expression to nutritional state. It is presently uncertain how the regulation of the central melanocortin system in birds is brought about in the situation of the apparently reduced importance of leptin and ghrelin compared to mammals.

Regulation of the assembly and amyloid aggregation of murine amylin by zinc

The secretory granule of the pancreatic β-cells is a zinc-rich environment copopulated with the hormones amylin and insulin. The human amylin is shown to interact with zinc ions with major contribution from the single histidine residue, which is absent in amylin from other species such as cat, rhesus and rodents. We report here the interaction of murine amylin with zinc ions in vitro. The self-assembly of murine amylin is tightly regulated by zinc and pH. Ion mobility mass spectrometry revealed zinc interaction with monomers and oligomers. Nuclear magnetic resonance confirms the binding of zinc to murine amylin. The aggregation process of murine amylin into amyloid fibrils is accelerated by zinc. Collectively these data suggest a general role of zinc in the modulation of amylin variants oligomerization and amyloid fibril formation.

Effects of peripheral administration of ghrelin antagonist [D-Lys³]-GHRP-6 on growth performance and blood biochemical indices in broiler chickens

Abstract. In the present study, possible effects of peripheral administration of ghrelin antagonist [D-Lys3]-GHRP-6 on chicken performance, thyroid hormones level and serum biochemical parameters were investigated. Broiler chicks divided into five experimental groups were reared up to day 42. On day 21, a treatment was assigned to the five groups: group 1 (control), chickens without any administration of peptide or solution; group 2 (G50), chickens with intraperitoneal (IP) injection of 50 ng per 100 g body weight (BW) of D-Lys3 peptide on day 21; group 3 (G100), chickens with IP injection of 100 ng per 100 g BW of D-Lys3 peptide on day 21; group 4 (G150), chickens with IP injection of 150 ng per 100 g BW of D-Lys3 peptide on day 21; and group 5 (G200), chickens with IP injection of 200 ng per 100 g BW of D-Lys3 peptide on day 21. On days 21 (post-injection) and 42 (post-rearing), blood samples were obtained from the animals for laboratory analyses. Experimental groups administered the GHS-R antagonist showed less feed intake – i.e., administration of greater doses led to less feed intake (P < 0.01). Daily weight gains within groups G150 and G200 decreased (P < 0.01) in comparison with the control. The feed conversion ratio (FCR) did not differ among the groups. There was a significant difference between control and experimental groups for glucose, total cholesterol and phosphorus levels (P < 0.01) in post-injection samples. In post-injection and post-rearing blood samples, the thyroid hormone (T3 and T4) in 6 h increased in treated groups in comparison with the control (P < 0.01). The infusion of ghrelin antagonist [D-Lys3]-GHRP-6 reduces feed intake and body weight. With regard to increase in T4 level, it can be inferred that [D-Lys3]-GHRP-6 may increase metabolic rate, lipolysis and weight loss, which is similar to results obtained in mammalian species.