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Background: This study aimed to evaluate the suppressive effects of β-hydroxybutyrate (BHB) administration on lipopolysaccharide (LPS)-induced inflammation in broiler chickens. Methods: Twenty-day-old male broiler chickens were randomly allocated to three groups, each of which was treated with saline (control), intraperitoneal administration of LPS [1.5 mg/kg body weight (BW), Escherichia coli O127:B8], or LPS plus BHB (3 mmol/kg BW). Results: Plasma albumin and total protein concentration were significantly reduced by LPS administration, while BHB co-treatment partially attenuated the effects. The LPS treatment significantly induced plasma aspartate and alanine aminotransferase activities, and interleukin (IL)-6 concentration, with the increases suppressed by BHB co-treatment (p < 0.05). The LPS treatment significantly increased the gene expression levels of IL-1β, IL-6, and IL-18 in the spleen and peripheral blood monocytes (PBMC), while the increases were partially attenuated by BHB in the spleen. Relatively higher levels of BHB dehydrogenase 1 and succinyl-CoA:3-ketoacid CoA transferase were observed in the spleen and skeletal muscle, while these gene levels were lower in PBMC and the liver. Conclusions: The present results suggest that BHB can suppress LPS-induced inflammation, in which ketolytic enzyme expression levels may be involved in broiler chickens.

This study aimed to measure the effects of trehalose (Tre) supplementation on the growth, intestinal morphology, gut bacteria, and footpad dermatitis (FPD) of broiler chickens reared at different stocking densities (SD). Four hundred newly hatched Ross 308 male chicks were randomly allocated to four groups of eight, following a 2 × 2 factorial arrangement in a randomized complete block design using two SDs (normal, 11; high, 14 birds/m2) and two diets: basal with and without 0.5% Tre. Tre supplementation was provided during the starter/grower phase, but not the finisher phase. Data were analyzed using a two-way analysis of variance. We observed no significant effects of SD or Tre, individually or combined, on body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) during the starter/grower period. However, high SD decreased both BWG (P < 0.001) and FI (P < 0.05), and increased FCR (P < 0.001), during the finisher period. Whereas Tre reduced FCR (P < 0.05) as a main effect, no combined effect was observed on FCR. Over the total period, high SD negatively affected BWG and FCR (P < 0.001), and Tre significantly reduced FCR, with its effect unaffected by SD. No significant effects of SD or Tre were observed on jejunal morphology. The ileal abundance of Clostridium perfringens (P > 0.05) was not affected by high SD but was significantly reduced by Tre. Neither high SD nor Tre altered Lactobacillus spp. counts; however, high SD increased FPD lesion scores, whereas Tre had no effect. The study showed that Tre supplementation during the starter/grower period improved FCR during the finisher period, possibly by decreasing the abundance of C. perfringens in broiler chickens.

Poultry meat and egg production benefits from a smaller carbon footprint, as well as feed and water consumption, per unit of product, than other protein sources. Therefore, maintaining a sustainable production of poultry meat is important to meet the increasing global demand for this staple. Heat stress experienced during the summer season or in tropical/subtropical areas negatively affects the productivity and health of chickens. Crucially, its impact is predicted to grow with the acceleration of global warming. Heat stress affects the physiology, metabolism, and immune response of chickens, causing electrolyte imbalance, oxidative stress, endocrine disorders, inflammation, and immunosuppression. These changes do not occur independently, pointing to a systemic mechanism. Recently, intestinal homeostasis has been identified as an important contributor to nutrient absorption and the progression of systemic inflammation. Its mechanism of action is thought to involve neuroendocrine signaling, antioxidant response, the presence of oxidants in the diet, and microbiota composition. The present review focuses on the effect of heat stress on intestinal dysfunction in chickens and the underlying causative factors. Understanding these mechanisms will direct the design of strategies to mitigate the negative effect of heat stress, while benefiting both animal health and sustainable poultry production.

There has been an upsurge of interest in the phytobiotics coincident with the onset of the potential ban on the use of antibiotic growth promoters (AGPs) in the broiler industry and because many kinds of nutraceuticals play an important role in improving growth performance, feed efficiency, and gut health of broilers. In the previous years, significant biological activities of essential oils (EOs) belonging to phytobiotics were observed, including antibacterial, antifungal, antiviral, and antioxidant properties. We found new perspectives on the roles of EOs, particularly extracts from the Apiaceae family, which is one of the largest plant families, in potential replacement of AGPs, and on the chemical composition involved in regulating microorganism activity and oxidative damage. Furthermore, the positive effects of EOs on broiler production and the possible mechanisms inducing the involvement of gut health and growth performance have been studied.

Phytobiotics, also known as phytochemicals or phytogenics, have a wide variety of biological activities and have recently emerged as alternatives to synthetic antibiotic growth promoters. Numerous studies have reported the growth-promoting effects of phytobiotics in chickens, but their precise mechanism of action is yet to be elucidated. Phytobiotics are traditionally known for their antioxidant activity. However, extensive investigations have shown that these compounds also have anti-inflammatory, antimicrobial, and transcription-modulating effects. Phytobiotics are non-nutritive constituents, and their bioavailability is low. Nonetheless, their beneficial effects have been observed in several tissues or organs. The health benefits of the ingestion of phytobiotics are attributed to their antioxidant activity. However, several studies have revealed that not all these benefits could be explained by the antioxidant effects alone. In this review, I focused on the bioavailability of phytobiotics and the possible mechanisms underlying their overall effects on intestinal barrier functions, inflammatory status, gut microbiota, systemic inflammation, and metabolism, rather than the specific effects of each compound. I also discuss the possible mechanisms by which phytobiotics contribute to growth promotion in chickens.

Broiler chickens reared under heat stress (HS) conditions have decreased growth performance and show metabolic and immunologic alterations. This study aimed to evaluate the effect of supplementation with a standardized blend of plant-derived isoquinoline alkaloids (IQ) on the growth performance, protein catabolism, intestinal barrier function, and inflammatory status of HS-treated chickens. Three hundred sixty 0-day-old Ross 308 male broiler chickens were randomly distributed into 2 treatment groups: control diet (no additives) or diet supplemented with 100 ppm IQ. At day 14, the chicks in each diet group were further divided into 2 groups, each of which was reared under thermoneutral (TN) (22.4°C) or constant HS (33.0°C) conditions until day 42. Each group consisted of 6 replicates with 15 birds per replicate, and chickens were provided ad libitum access to water and feed. During days 15–21, the body weight gain (BWG) and feed intake (FI) were significantly lower in the HS treatment group than in the TN group, and feed conversion ratio was higher (P

A study using pair-feeding technique was conducted to determine whether heat exposure directly or indirectly (via reduced feed intake) increases intestinal mucosal damage and permeability to endotoxin in broiler chickens. Male broiler chickens (Ross 308), 27-d-old, were subjected to one of the three treatments (n=8): 1) thermo-neutral conditions (24°C) with ad libitum feed intake, 2) heat stress conditions (33°C) with ad libitum feed intake, or 3) pair-feeding under thermo-neutral conditions, with the feed intake identical to that of heat-stressed chickens. Using these groups, two experiments were performed to evaluate temporal changes in the intestinal morphology in response to each treatment. In experiment 1, chickens were sacrificed after 24 h of exposure to the treatment conditions, while in experiment 2, chickens were sacrificed after 12 or 72 h of exposure to the treatment conditions. In experiment 1, exposure to heat stress conditions for 24 h significantly decreased both the villus height to crypt depth ratio and number of proliferating cell nuclear antigen (PCNA)-positive cells in the duodenum and increased the plasma endotoxin concentration. These findings were not observed in pair-fed chickens. In experiment 2, intestinal integrity and function were unaffected by 12 h of heat stress. On the other hand, chickens exposed to heat stress for 72 h exhibited significantly damaged intestinal morphology in the duodenum as well as increased plasma endotoxin concentration; these negative effects were not observed in pair-fed chickens. These findings suggest that the intestinal morphology and permeability changes observed in chickens that are heat-stressed for 24–72 h are due to the heat stress conditions and not due to reduced feed intake.

The skeletal muscle growth rate is a major feature differentiating meat- and laying-type chickens. A large amount of ATP is required during skeletal muscle synthesis, in which mitochondrial energy production capacities play a significant role. Additionally, mitochondria may participate in muscle protein degradation via reactive oxygen species generation. To investigate the differences in mitochondrial energetic characteristics between chickens exhibiting different growth rates, this study evaluated respiratory capacities in response to different types of respiratory substrate, protein abundances, assembly of individual respiratory complexes (I–V) and supercomplexes, and reactive oxygen species generation rates. These characteristics were compared between mitochondria from the breast muscle (M. pectoralis superficialis) of seven-week-old meat- and laying-type male chickens. Blue native polyacrylamide gel electrophoresis analysis revealed that meat-type chickens exhibited a significantly lower protein abundance of complex III (cytochrome bc1 complex), complex V (F0F1 ATP synthase), and total amount of supercomplexes than did laying-type chickens. There were no differences between chicken types in the respiration rate of mitochondria incubated with either pyruvate/malate or succinate, each of which drives complex I- and complex II-linked respiration. Carnitine palmitoyltransferase-1-dependent and -independent respiration during ATP synthesis and carnitine palmitoyltransferase-2 enzymatic activity were significantly lower in meat-type chickens than in layingtype chickens. For mitochondria receiving pyruvate/malate plus succinate, the reactive oxygen species generation rate and its ratio to the oxygen consumed (the percentage of free radical leak) were also significantly lower in meat-type chickens than in laying-type chickens. These results suggested that the mitochondrial energetic capacities of the breast muscle of meat-type chickens could be lower than those of laying-type chickens at seven weeks of age. Furthermore, the lower reactive oxygen species generation rate in meat-type chickens might have implications for rapid muscle development, which is possibly related to their lower muscle protein degradation rates.

Hot, humid weather causes heat stress (HS) in broiler chickens, which can lead to high mortality. A recent study found that HS causes endoplasmic reticulum (ER) stress. However, the possible involvement of ER stress in HS-induced physiological alterations in broiler chickens is unclear. This study aimed to evaluate the effect of the dietary supplementation of 4-phenylbutyric acid (4-PBA), an alleviator of ER stress, in acute HS-exposed young broiler chickens. Twenty-eight 14-day-old male broiler chickens (ROSS 308) were divided into two groups and fed either a control diet or a diet containing 4-PBA (5.25 g per kg of diet feed) for 10 days. At 24 days old, each group of chickens was kept in thermoneutral (24 ± 0.5 °C) or acute HS (36 ± 0.5 °C) conditions for 2 h. The results showed that thermoneutral birds supplemented with 4-PBA exhibited no negative effects in terms of broiler body weight gain and tissue weight compared to non-supplemental birds. HS increased body temperature in both the control and 4-PBA groups, but the elevation was significantly lower in the 4-PBA group than in the control group. The plasma non-esterified fatty acid concentration was significantly increased by HS treatment in non-supplemental groups, while the increase was partially attenuated in the 4-PBA group. Moreover, 4-PBA prevented HS-induced gene elevation of the ER stress markers GRP78 and GRP94 in the skeletal muscle. These findings suggest that the 4-PBA effect may be specific to the skeletal muscle in HS-exposed birds and that 4-PBA supplementation attenuated HS-induced muscle ER stress, which could be associated with a supplementation of the body temperature elevation and lipolysis.

Trehalose (Tre) is a natural disaccharide. A laboratory-scale investigation showed that Tre supplementation increased the growth rate in juvenile chicks, possibly via the improvement of innate intestinal immune responses. In this study, two trials were conducted to evaluate the growth-promoting effect of Tre supplementation in broiler chickens. In experiment-1, two thousand day-old male and female broiler chicks (Ross) were fed 0 (control), 0.25, 0.50, and 0.75% Tre-supplemented pellet-form diets from d 1–17, and subsequently, they were provided grower (d 18–30) and finisher (d 31–37) diets without Tre supplementation. Over the trial period, there was no significant difference in body weight (BW), feed intake and feed conversion ratio (FCR) between chickens in the control and Tre-fed groups. Tre treatment increased villus height (VH)/crypt depth (CD) ratio and villus surface in jejunum; decreased CD and increased VH/CD ratio in ileum on d 17, when these results were compared to the control group. In experiment-2, two hundred day-old female broiler chicks were fed an antibiotics-free and mash-form diet supplemented with 0.5% Tre from d 1–21, before being fed a non-supplemental diet until d 43. There was no difference in BW on d 21 between the control and Tre-0.5% groups; however, from d 22–43, Tre-0.5% group showed significantly higher BW gain and lower FCR compared to the control group. From these results, we suggest that Tre feeding can be beneficial for intestinal morphology and growth performance in broiler chickens. However, these outcomes did not occur in parallel owing to the different feeding conditions observed.

Broiler chickens are highly sensitive to high ambient temperatures due to their feathers, lack of skin sweat glands, and high productivity. Heat stress (HS) is a major concern for the poultry industry because it negatively affects growth as well as immune functions, which increase the potential risk of infectious disease outbreaks. Therefore, it is vital to elucidate HS's effect on the avian immune system, especially considering the global rise in average surface temperature. Our study identified a series of immunological disorders in heat-stressed broiler chickens. We exposed 22-day-old broiler chickens to a continuous HS condition (34.5 ± 0.5°C) for 14 days and immunized them with a prototype bovine serum albumin (BSA) antigen. The plasma and lymphoid tissues (thymus, bursa of Fabricius, and spleen) were harvested at the end of the experiments to investigate the induction of BSA-specific immune responses. Our results revealed that plasma titers of immunoglobulin (Ig)Y, IgM, and IgA antibodies specific for BSA were lower than those of thermoneutral chickens immunized with BSA. Furthermore, the spleens of the heat-stressed broiler chickens displayed severe depression of Bu1+ B cells and CD3+ T cells, including CD4+ T cells and CD8+ T cells, and lacked a fully developed germinal center (GC), which is crucial for B cell proliferation. These immunological abnormalities might be associated with severe depression of CD4−CD8− or CD4+CD8+ cells, which are precursors of either helper or killer T cells in the thymus and Bu1+ B cells in the bursa of Fabricius. Importantly, HS severely damaged the morphology of the thymic cortex and bursal follicles, where functional maturation of T and B cells occur. These results indicate that HS causes multiple immune abnormalities in broiler chickens by impairing the developmental process and functional maturation of T and B cells in both primary and secondary lymphoid tissues.

Mitochondrial content is regarded a useful feature to distinguish muscle-fiber types in terms of energy metabolism in skeletal muscles. Increasing evidence suggests that specific mitochondrial bioenergetic phenotypes exist in metabolically different muscle fibers. A few studies have examined the energetic properties of skeletal muscle in domestic fowls; however, no information on muscle bioenergetics in broiler chickens selectively bred for faster growth is available. In this study, we aimed to characterize the mitochondrial contents and functions of chicken skeletal muscle consisting entirely of type I (oxidative) (M. pubo-ischio-femoralis pars medialis), type IIA (glycolytic/oxidative) (M. pubo-ischio-femoralis pars lateralis), and type IIB (glycolytic) (M. pectoralis) muscle fibers. Citrate synthase (CS) activity was the highest in type IIA muscle tissues and isolated mitochondria, among the muscle tissues tested. Although no difference was registered in mitochondrial CS activity between type IIB and type I muscles, tissue CS activity was significantly higher in the latter. Histochemical staining for NADH tetrazolium reductase and the ratio of muscle-tissue to mitochondrial CS activity indicated that type I, type IIA, and type IIB muscle-fiber types showed decreasing mitochondrial content. Mitochondria from type I muscle exhibited a higher coupled respiration rate induced by pyruvate/malate, palmitoyl-CoA/malate, and palmitoyl-carnitine, as respiratory substrates, than type IIB-muscle mitochondria, while the response of mitochondria from type IIA muscle to those substrates was comparable to that of mitochondria from type I muscle. Type IIA-muscle mitochondria exhibited the highest carnitine palmitoyltransferase-2 level among all tissues tested, which may contribute to the higher fatty acid oxidation in these mitochondria. The results suggest that mitochondrial abundance is one of the features differentiating metabolic characteristics of different chicken skeletal muscle types. Moreover, the study demonstrated that type IIA-muscle mitochondria may have distinct metabolic capacities.

Mitochondrial dysfunction increases oxidative stress and depletes ATP in a variety of disorders. Several antioxidant therapies and drugs affecting mitochondrial biogenesis are undergoing investigation, although not all of them have demonstrated favorable effects in the clinic. We recently reported a therapeutic mitochondrial drug mitochonic acid MA-5 (Tohoku J. Exp. Med., 2015). MA-5 increased ATP, rescued mitochondrial disease fibroblasts and prolonged the life span of the disease model “Mitomouse” (JASN, 2016). To investigate the potential of MA-5 on various mitochondrial diseases, we collected 25 cases of fibroblasts from various genetic mutations and cell protective effect of MA-5 and the ATP producing mechanism was examined. 24 out of the 25 patient fibroblasts (96%) were responded to MA-5. Under oxidative stress condition, the GDF-15 was increased and this increase was significantly abrogated by MA-5. The serum GDF-15 elevated in Mitomouse was likewise reduced by MA-5. MA-5 facilitates mitochondrial ATP production and reduces ROS independent of ETC by facilitating ATP synthase oligomerization and supercomplex formation with mitofilin/Mic60. MA-5 reduced mitochondria fragmentation, restores crista shape and dynamics. MA-5 has potential as a drug for the treatment of various mitochondrial diseases. The diagnostic use of GDF-15 will be also useful in a forthcoming MA-5 clinical trial.

Previously, we showed that the growth of chicks fed a diet containing 43% whole-grain paddy rice and 10% soybean oil was retarded relative to a control group fed a corn-based diet containing 6% soybean oil. However, feeding chicks with 43% whole-grain paddy rice containing 6% soybean oil resulted in normal growth. It is possible that the observed growth retardation was caused by the high soybean oil content or resulted from the combination of whole-grain paddy rice and the high level of soybean oil which was added to the diet to maintain the overall energy content. The present study was therefore carried out to identify the reasons for the observed growth retardation. Thirty-six chicks (0-day-old) were divided into six equal-sized groups that were fed one of the following six experimental diets ad libitum for 28 d: two kinds of dehulled rice-based diets containing 5% or 10% soybean oil (DS5% or DS10%), another three whole-grain paddy rice-based diets containing 10% soybean oil, corn oil, or rendering oil (WS10%, WC10%, WR10%, respectively), and a WS10% diet supplemented with vitamin B12, methionine and ethoxyquin. The body weight gain of groups fed the WS10% and WC10% diets was significantly lower than the weight gain of birds fed the DS5% diet (control). In addition, the liver of birds fed the WS10% and WC10% diet exhibited significantly higher lipid peroxidation than that of the control group. In comparison, supplementation of the WS10% diet with vitamin B12, methionine and ethoxyquin dramatically improved growth and hepatic oxidation status. These results indicate that diets combining whole-grain paddy rice and high levels of soybean and corn oil adversely affect performance, presumably via lipid peroxidation in the liver.

Heat stress (HS) stimulates mitochondrial reactive oxygen species (ROS) production and protein degradation in skeletal muscle. The present study investigated the stimulatory effects of HS-induced mitochondrial ROS production on the ubiquitin-proteasome protein degradation system in primary cultured avian muscle cells. Cells were isolated from the breast muscle of neonatal chicks, and then grown for 48 h. Thereafter, the cells were subjected to 37°C or 41°C (HS). Exposure to 6 h of HS treatment significantly decreased the cellular protein content compared to that of normal cells, an effect was completely suppressed by the addition of a proteasome-specific inhibitor. Whereas the mRNA levels of the 20S proteasome C2 subunit, which is one of the subunits of the 26S proteasome, did not change at any time during HS treatment (1, 3, 6 h), the mRNA levels of atrogin-1 and muscle ring-finger protein 1, both of which are muscle-specific ubiquitin ligases, increased after 1 h of HS but then decreased to near-normal values with time. Intracellular ROS production (the sum of H2O2, hydroxyl radicals, peroxyl radicals, peroxynitrite) did not change in the 1 h HS-exposed cells, but was significantly increased after 3 h and 6 h of HS. Mitochondrial superoxide production was significantly increased after 1 h of HS, which might increase the mRNA expression of ubiquitin ligase in muscle cells. In cells pretreated with 4-hydroxy TEMPO, which is able to decrease mitochondrial superoxide production, the increases in mitochondrial superoxide production and ubiquitin ligase mRNA levels observed after 1 h of HS were suppressed. The protein content of these cells was not decreased, which was observed after the longest period of HS (6 h). These findings suggest that mitochondrial superoxide production may play an important role in activating the ubiquitin-proteasome system, probably via the induction of ubiquitin ligases, in HS-exposed muscle cells.

We have previously shown that, under thermoneutral conditions, the growth performance of chicks fed a rice-based diet containing 6% soybean oil [metabolizable energy (ME): 2,800 kcal/kg] for 28 days was comparable to that obtained with a corn-based diet containing 6% soybean oil (ME: 3,100 kcal/kg). However, there is no information available concerning how such diets compare with respect to growth performance under heat stress conditions. The present study was therefore conducted to clarify differences in dietary effectiveness between corn-based and whole-grain paddy rice-based diets [formulated to be equivalent in terms of fat (6%), but not iso-caloric] under the two conditions of acute and chronic heat stress (Experiment 1 and Experiment 2, respectively). In Experiment 1, the body weight gain of a corn- and rice-fed group of chickens exposed to acute heat (33°C-12 h) were significantly decreased compared with that of a corn-fed control group (24°C), with similar results obtained for the two heat-treated groups. Malondialdehyde (MDA) levels in the M. pectoralis superficialis were significantly increased in corn-fed birds exposed to acute heat stress, but not in the rice-fed group (33°C-12 h). In Experiment 2, body weight gains in the corn- and rice-fed groups exposed to chronic heat (33°C-6 d) were significantly decreased, and to a similar extent, compared with the corn-fed control group (24°C). Muscle MDA levels in the corn- and rice-fed groups were similarly increased by the chronic heat exposure compared with the control group. These results suggest that, in response to acute heat stress (but not chronic heat stress) conditions, the feeding of whole-grain paddy rice diet to chickens may attenuate skeletal muscle oxidative damage compared with that in corn-fed chickens. The possible involvement of intestinal morphology (such as the villus height: crypt depth ratio observed here) on growth performance is also discussed.

Experiments were conducted to determine the effects of different types of paddy rice (dehulled, crushed and untreated whole-grain forms) on growth performance in broiler chickens. In Experiment 1, a control diet containing 41.6% corn (control), and three experimental diets containing 40.7% dehulled, 43% crushed or 43% whole-grain paddy rice, were formulated to be iso-caloric (3,100 kcal/kg ME) and iso-nitrogenous (20% crude protein), but to contain different levels of fat (6%, 5.6%, 10.7%, 10.7%, respectively). Groups of 0-day-old chickens were the fed experimental diets ad libitum for 28 d. The average final body weight of groups fed the crushed and untreated whole-grain paddy rice was significantly lower (P

Heat stress (HS) causes poor growth, immunosupression and high mortality, through physiological dysfunction. We have reported that ‘acute’ HS increases mitochondrial reactive oxygen species (ROS) and oxidative damage in the skeletal muscle of broiler chickens (Cobb), but that this is not for the case for males of the laying-type white leghorn (WLH) strain of chickens (Mujahid et al., 2005b). We have now studied the effects of ‘chronic’ HS on performance and oxidative damage to skeletal muscle in different strains of chickens. Meat-type male chickens (Ross and Cobb) and male laying-type chickens (WLH) of 14d of age were arranged according to a factorial design (3 strains×4 conditions): control (24°C), cyclic (32-24-32°C: 32°C for 8h/d, 32-24-32HS), constant (32 and 34°C, 32HS and 34HS, respectively) for 14d. Feed consumption and body weight gain were measured. Thiobarbituric acid reactive substances (TBARS) content in skeletal muscle was measured colorimetrically with BHT (butylated hydroxytoluene) and expressed as malondialdehyde (MDA) equivalent. Body weight gain and feed consumption for the 3 strains (Ross, Cobb and WLH) were decreased by 32HS and 34HS, but not by 32-24-32HS. The decrease in weight gain of WLH chickens for the 32HS and 34HS conditions was smaller than for broiler chickens (Ross and Cobb). The 32HS and 34HS groups showed slightly enhanced MDA levels (P

Heat stress is an environmental factor that causes oxidative stress. We found previously that acute heat stress stimulates the production of reactive oxygen species (ROS) in the skeletal muscle mitochondria of birds, and that this was accompanied by an increase of the mitochondrial membrane potential (ΔΨ) due to increased substrate oxidation by the electron transport chain. We also showed that avian uncoupling protein (avUCP) expression is decreased by the heat exposure. The present study clarifies whether ΔΨ is a major determinant of the overproduction of ROS due to acute heat stress, and if the decrease in avUCP expression is responsible for the elevation in ΔΨ. Control (24°C) and acute heat-stressed (34°C for 12 h) birds exhibited increased succinate-driven mitochondrial ROS production as indicated by an elevation of ΔΨ, with this increase being significantly higher in the heat-stressed group compared with the control group. In glutamate/malate-energized mitochondria, no difference in the ROS production between the groups was observed, though the mitochondrial ΔΨ was significantly higher in the heat-stressed groups compared with the control group. Furthermore, mitochondria energized with either succinate/glutamate or succinate/malate showed increased ROS production and ΔΨ in the heat-stressed group compared with mitochondria from the control group. These results suggest that succinate oxidation could play an important role in the heat stress-induced overproduction of mitochondrial ROS in skeletal muscle. In agreement with the notion of a decrease in avUCP expression in response to heat stress, proton leak, which was likely mediated by UCP (that part which is GDP-inhibited and arachidonic acid-sensitive), was reduced in the heat-exposed group. We suggest that the acute heat stress-induced overproduction of mitochondrial ROS may depend on ΔΨ, which may in turn result not only from increased substrate oxidation but also from a decrease in the mitochondrial avUCP content.

There has been an upsurge of interest in the phytobiotics coincident with the onset of the potential ban on the use of antibiotic growth promoters (AGPs) in the broiler industry and because many kinds of nutraceuticals play an important role in improving growth performance, feed efficiency, and gut health of broilers. In the previous years, significant biological activities of essential oils (EOs) belonging to phytobiotics were observed, including antibacterial, antifungal, antiviral, and antioxidant properties. We found new perspectives on the roles of EOs, particularly extracts from the Apiaceae family, which is one of the largest plant families, in potential replacement of AGPs, and on the chemical composition involved in regulating microorganism activity and oxidative damage. Furthermore, the positive effects of EOs on broiler production and the possible mechanisms inducing the involvement of gut health and growth performance have been studied. [ABSTRACT FROM AUTHOR]

Seventy-five individually fed barrows averaging 35 kg were used in a series of three experiments for 6-week growth assays (25 barrows each) to determine the effects of L-tryptophan (Trp) supplementation on growth performance and to establish the lower limits of dietary crude protein (CP) levels. Corn and soybean meal (SBM)-based diets containing 9% (Experiment 1), 10% (Experiment 2), and 11% CP (Experiment 3) fortified with deficient essential amino acids (AAs) except Trp were used as basal diets for each experiment. The experimental diets were supplemented with 0.00%, 0.02%, 0.04%, or 0.06% Trp. A 16% CP corn-SBM-based diet was set as a positive control in each experiment, and feed and water were provided ad libitum. Average daily gain and gain-to-feed ratio improved quadratically (P < 0.05) as supplemented Trp increased in the 9% and 10% CP group, although these positive effects were not observed in the 11% CP group. Because the maximum performance parameters in 9%, 10%, and 11% CP groups were not different from that of the 16% CP positive control group, the marginally reduced level of dietary CP without growth performance being affected appears to be around 9% at most. A potential reduction of nitrogen intake was clearly indicated. [ABSTRACT FROM AUTHOR]

Peptide transporter 1 (PepT1) is a transporter responsible for absorbing dipeptide and tripeptide in enterocytes and is upregulated by dipeptide in mammals. It has not been certain whether intestinal PepT1 expression is responsive to dipeptides in chickens because of the lack of in vitro study using the cultured enterocytes. This study established a primary culture model of chicken intestinal epithelial cells (IECs) in two-dimensional monolayer culture using collagen gel by which the response of chicken PepT1 gene expression to dipeptide stimuli was evaluated. The cultured chicken IECs showed the epithelial-like morphology attached in a patch-manner and exhibited positive expression of cytokeratin and epithelial cadherin, specific marker proteins of epithelial cells. Moreover, the chicken IECs exhibited the gene expression of intestinal cell type-specific marker, villin1, mucin 2, and chromogranin A, suggesting that the cultured IECs were composed of enterocytes as well as goblet and enteroendocrine cells. PepT1 gene expression was significantly upregulated by synthetic dipeptide, glycyl-l-glutamine, in the cultured IECs. From the results, we herein suggested that dipeptide is a factor upregulating PepT1 gene expression in chicken IECs. [ABSTRACT FROM AUTHOR]

Meat and bone meal (MBM) is an important protein source used in animal feeds. However, as the composition and availability of amino acids (AAs) in MBM fluctuate markedly, it is important to verify the magnitude of these parameters in different MBMs. In this study, the AA compositions of 19 MBMs were analyzed to confirm variations in lysine (Lys), threonine (Thr), and tryptophan (Trp), then which were compared with those of soybean meal (SBM) and fish meal (FM). Instability in Lys, Thr, and Trp availabilities in six MBMs were also considered after estimation using the slope‐ratio growth assay technique in rats. Variations in AA composition were evaluated using the coefficient of variance (CV: Standard deviation/Mean). CVs for Lys, Thr, and Trp content were 9.40, 11.83, and 18.12 in MBM, 2.71, 2.48, and 3.19 in SBM, and 10.09, 10.44, and 13.47 in FM. Furthermore, means and SDs for Lys, Thr, and Trp availabilities in MBM were 53.3 ± 10.4% (CV: 19.5), 65.9 ± 17.6% (CV: 26.6), and 83.2 ± 11.2% (CV: 13.5), respectively. These results provide the first evidence that variations in MBM AA compositions were 3.5 to 5.7 times higher than those in SBM, but similar to FM, and that the large variation in availability substantially existed. [ABSTRACT FROM AUTHOR]