Mechanisms Regulating Feed Intake, Energy Expenditure, and Body Weight in Poultry

Pathology and Plasma Biochemistry of Common Eider (Somateria mollissima) Males Wintering in the Danish Part of the Western Baltic

Blood biochemistry, body mass, and gross pathology of male eiders (Somateria mollissima) wintering in the Inner Danish Waters of the western Baltic Sea (the Great Belt Strait) were assessed in this study. In November 2015, 14 specimens were obtained from the area defined for examination. Of the subject animals captured, 1 had dilated intestines and 2 had granulomas with encapsulated shotgun pellets considered to be chronic in nature. All 14 males were determined to have enteritis along with acanthocephalan and trematode endoparasites. Compared with reference values for captive eiders, plasma values of alanine aminotransferase (93%), total bilirubin (45%), gamma-glutamyl transferase (41%), and alkaline phosphatase (92%) showed significant increases in all 14 male birds. Altogether, the plasma biochemistry and gross pathology findings suggest that up to as many as 20% of the eider males in the Inner Danish Waters of the western Baltic Sea may suffer from liver and bile duct lesions and enteritis. The overall effect on the bird's survival from the results of this investigation is unknown. Therefore, the authors emphasize that more research is required on wintering eiders in the western Baltic to obtain a better understanding of their overall health status during winter, as well as their responses to wound-related lesions associated with gunshot pellets.

A grape seed extract maternal dietary supplementation improves egg quality and reduces ovarian steroidogenesis without affecting fertility parameters in reproductive hens

In broiler hens, the genetic selection increased susceptibility to metabolic disorders and reproductive dysfunctions. In human ovarian cells, grape seed extracts (GSE) improved steroid production. Here, we investigated the effects of a GSE dietary supplementation on egg production and quality, fertility parameters, Reactive Oxygen Species (ROS) and steroid content in yolk egg associated to plasma adipokines in broiler hens. For this, we designed two in vivo experiments, the first one included three groups of hens: A (control), B and C (supplemented with GSE at 0.5% and 1% of the total diet composition, respectively, since week 4), and the second one used two groups of hens: A (control) and D (supplemented with GSE at 1% of the total diet composition since hatching). We assessed the egg production from 23^th to 40^th weeks and quality at 33^th week. After artificial inseminations, the fertility parameters were calculated. In egg yolk, Reactive Oxygen Species (ROS) level and steroid production were evaluated by Ros-Glo H202 and ELISA assay, respectively. Expression of steroidogenic enzymes and adipokines and their receptors was determined by RT-qPCR in ovarian cells and plasma adipokines (RARRES2, ADIPOQ and NAMPT) were evaluated by specific ELISA assays. The fertility parameters and egg production were unaffected by GSE supplementation whatever the experiment (exp.). However, the rate of double-yolk eggs decreased for all GSE supplemented groups (exp. 1 P <0.01, exp.2, P<0.02). In exp.1, C group eggs were bigger and larger (P<0.0001) and the shell elasticity was higher for both B and C (P<0.0003) as compared to control. In the egg yolk, GSE supplementation in both exp. reduced ROS content and steroidogenesis consistent with a decrease in P450 aromatase and StAR mRNA expression and basal in vitro progesterone secretion in granulosa cells (P<0.001). Interestingly, in both exp. RARRES2 plasma levels were positively correlated while ADIPOQ and NAMPT plasma levels were negatively correlated, with steroids and ROS in yolk (P<0.0001). Taken together, maternal dietary GSE supplementation did not affect egg production and fertility parameters whereas it reduced ROS content and steroidogenesis in yolk egg. Furthermore, it ameliorated egg quality by decreasing the number of double-yolk eggs and by improving the size of normal eggs and the elasticity of the shell. Taken together, our data suggest the possibility of using dietary maternal GSE to improve egg quality.

Effect of Feed Restriction on the Behaviour and Welfare of Broiler Chickens

Under intensive rearing conditions, the welfare of broiler chickens may be at risk depending on genotype and sex, due to their different growth rates. The practice of quantitative feed restriction may also impact on welfare. This study aimed to evaluate behaviour and corticosterone content in plasma and faeces at different ages using 896 one-day-old chicks housed in 32 pens, allocated to 8 groups, i.e., 2 genotypes (standard vs. high breast yield) × 2 sex × 2 feeding plans (ad libitum vs. restricted, AL vs. FR). The feeding system affected the percentage of standing (9.84% vs. 11.7% in AL vs. FR; p ≤ 0.001), feeding (7.51% vs. 8.17%; p ≤ 0.01) and sitting/lying (67.0% vs. 64.1%; p ≤ 0.001), and the faeces corticosterone content (12.2 vs. 13.6 ng/g in AL vs. FR; p ≤ 0.10). Sex affected the percentage of pecking other chickens, standing and comfort behaviours. Changes in behaviour were recorded between high and standard breast yield genotypes with faeces corticosterone which tended to be higher in the former (p ≤ 0.10). Significant interactions between the main factors and age were observed. Major changes in behaviour were due to feed restriction, which stimulated activity during restriction.

A grape seed extract maternal dietary supplementation in reproductive hens reduces oxidative stress associated to modulation of plasma and tissue adipokines expression and improves viability of offsprings

In reproductive hens, a feed restriction is an usual practice to improve metabolic and reproductive disorders. However, it acts a stressor on the animal. In mammals, grape seed extracts (GSE) reduces oxidative stress. However, their effect on endocrine and tissue response need to be deepened in reproductive hens. Here, we evaluated the effects of time and level of GSE dietary supplementation on growth performance, viability, oxidative stress and metabolic parameters in plasma and metabolic tissues in reproductive hens and their offsprings. We designed an in vivo trial using 4 groups of feed restricted hens: A (control), B and C (supplemented with 0.5% and 1% of the total diet composition in GSE since week 4, respectively) and D (supplemented with 1% of GSE since the hatch). In hens from hatch to week 40, GSE supplementation did not affect food intake and fattening whatever the time and dose of supplementation. Body weight was significantly reduced in D group as compared to control. In all hen groups, GSE supplementation decreased plasma oxidative stress index associated to a decrease in the mRNA expression of the NOX4 and 5 oxidant genes in liver and muscle and an increase in SOD mRNA expression. This was also associated to decreased plasma chemerin and increased plasma adiponectin and visfatin levels. Interestingly, maternal GSE supplementation increased the live body weight and viability of chicks at hatching and 10 days of age. This was associated to a decrease in plasma and liver oxidative stress parameters. Taken together, GSE maternal dietary supplementation reduces plasma and tissue oxidative stress associated to modulation of adipokines without affecting fattening in reproductive hens. A 1% GSE maternal dietary supplementation increased offspring viability and reduced oxidative stress suggesting a beneficial transgenerational effect and a potential use to improve the quality of the progeny in reproductive hens.

Post-photostimulation energy intake accelerated pubertal development in broiler breeder pullets

The effect of ME intake (MEI) on the reproductive system was evaluated. Ross 308 broiler breeder pullets (n = 140) were assigned to 2 treatments from 22 to 26 wk of age: (1) Low-energy diet fed restricted (2,807 kcal/kg, low MEI) and (2) high-energy diet fed unrestricted (3,109 kcal/kg, high MEI). Daylength was increased from 8 to 14 h at 22 wk of age with a light intensity of 30 lux. Daily palpation was used to detect sexual maturity via the presence of a hard-shelled egg in the shell gland. Expression of gonadotropin releasing hormone-I (GnRH) and gonadotropin inhibitory hormone (GnIH) genes in the hypothalamus and GnRH receptor (GnRH-RI) and GnIH receptor (GnIH-R) genes in the anterior pituitary gland of each pullet was evaluated from 22 to 26 wk of age using quantitative real time-PCR. Blood samples were taken weekly and luteinizing hormone (LH), follicle stimulating-hormone (FSH), and 17-beta-estradiol (E2) determined using commercial ELISA kits. Carcass samples were used for determination of CP and fat content. Data were analyzed using the MIXED procedure in SAS, and differences were reported where P ≤ 0.05. High MEI treatment pullets had 2.3-fold higher GnRH and 1.8-fold higher GnRH-RI mRNA levels than low MEI pullets. MEI affected neither expression of GnIH and GnIH-R nor carcass protein content. For high MEI (489 kcal/D) and low MEI treatments (258 kcal/D), respectively, from 22 to 26 wk of age (P ≤ 0.05), LH concentration was 3.05 and 1.60 ng/mL; FSH concentration was 145 and 89.3 pg/mL; E2 concentration was 429 and 266 pg/mL, and carcass lipid was 13.9 and 10.3%. The onset of lay for pullets in the high MEI treatment advanced such that 100% had laid by 26 wk of age compared with 30% in the low MEI treatment. We concluded that higher MEI advanced the activation of the hypothalamic–pituitary–gonadal axis and also increased body lipid deposition, and moreover, stimulated reproductive hormone levels which overall accelerated puberty in broiler breeder pullets.

Effects of feed form and energy levels on growth performance, carcass yield and nutrient digestibility in broilers

Feed form is well recognized to improve broiler performance, specially by increasing feed intake (FI). However, when different diet energy levels are used, the results differ in the literature. Therefore, this experiment was conducted to evaluate the influence of feed form and dietary metabolizable energy (ME) levels on broiler performance, carcass yield and on the digestibility of DM, CP, starch and gross energy. In total, 1152 male Cobb 500 broilers were evaluated between 35 and 47 days. The birds were distributed according to a completely randomized design in a 2 × 4 factorial arrangement, consisting of two feed forms (mash or pellet) and four ME levels (12.73, 13.06, 13.40 or 13.73 MJ/kg), totaling eight treatments with eight replicates of 18 birds. Broilers fed the lowest ME level presented the lowest weight gain (WG) and worst feed per unit gain (P < 0.01). Metabolizable energy intake increased (P < 0.01) with progressive increments of ME, which, however, did not affect caloric conversion (CC, P > 0.05). Pelleted diets promoted higher FI, WG, ME intake (P < 0.01) and better feed per unit gain and CC (P < 0.05) compared with mash. In mash diets, increasing dietary ME levels promoted a linear increase in WG (P < 0.01) and reduced feed per unit gain (P ≤ 0.05), but did not affect FI (P > 0.05). In pelleted diets, on the other hand, increasing ME levels linearly reduced FI (P < 0.05) and feed per unit gain (P < 0.01). Broilers fed pelleted diets presented higher abdominal fat deposition than those fed mash (P < 0.05). Increasing ME levels reduced the coefficients of ileal apparent digestibility of DM (P < 0.01) and total starch (P < 0.05) but did not affect the digestibility of other evaluated nutrients. The digestibility of all nutrients was lower when pelleted diets were fed compared with mash. Increasing inert material inclusion in the diets at the expense of soybean oil to reduce dietary ME levels promoted higher pellet durability index values (P < 0.05) and the percentage of fines (P < 0.01). Overall, the results suggest that pelleted diets promote better broiler performance because they increase FI, since the digestibility of dietary fractions is reduced. Chickens consuming low-energy pelleted diets may increase FI to compensate for energy deficit. In contrast, broilers fed mash diets may have reached their maximum intake capacity and did not regulate FI by changing feed energy density. When feeding pelleted diets, dietary energy reduction should be considered to reduce feed costs and to improve the carcass quality of broilers.

Dietary supplementation of 25-hydroxycholecalciferol improves livability in broiler breeder hens

The study aimed to examine the effects of 25-hydroxycholecalciferol (25-OH-D3) on reproductive performance and livability in broiler breeder hens. Hens at age of 26 wk were continued on restricted rations (R) or allowed ad libitum feeding (Ad) to 60 wk of age. Ad-feed intake greatly impaired egg production and hens' livability. The survival rate in both R- and Ad-hens was improved (86.7 vs.78.9% and 48.2 vs.29.1%, respectively) as was egg production in R-hens (P < 0.05) by inclusion of 69 μg 25-OH-D3/kg feedin the basal diet. Sudden death (SD) was the cause of hen mortality; hens died earlier with heavier BW and greater absolute and relative abdominal fat weights than surviving hens. Interestingly, feed intake of SD hens became less than that of surviving hens after 37 and 42 wk in Ad- and R-groups, respectively, and led to a progressive decline in SD hen BW with a ratio (relative to surviving hens of the same age) equaled 1 around 34 to 38 wk in Ad-groups and 52 to 53 wk in R-groups. Supplementation of 25-OH-D3 ameliorated untoward changes of heart and respiratory rate of Ad-survivors after 29 wk (P < 0.05), but had no significant effects on SD AD-hens. In contrast to the surviving counterparts, all SD hens experienced persistently higher respiratory rates in conjunction with declining heart rates (P < 0.05), suggesting compromised cardiac function as the cause of SD, in which hens increased heart and respiratory rate for more blood and oxygen supply to meet the need for rapid BW gain and/or adiposity in response to Ad-feed intake or due to genetically better feed efficiency even under R-feed intake. As the cardiorespiratory derangements advanced, compromised cardiac function ultimately led to heart failure and sudden death despite spontaneous reductions in feed intake and BW loss in all SD hens. Provision of 69 μg 25-OH-D3/kg feed is an effective and practical method to improve livability in broiler breeder hens.

Interaction between leptin and glutamatergic system on food intake regulation in neonatal chicken: role of NMDA and AMPA receptors

Objective: The aim of the current study was to determine the possible interaction of the central leptin and Glutamatergic systems on feeding behavior in neonatal 3-hours food deprived (FD₃) broilers chickens.Methods: In experiment 1, FD₃ chicken received intracerebroventricular (ICV) injection of control solution (group i) and 2.5, 5 and 10 µg of Leptin (groups ii-iv). In experiment 2, FD₃ chicken were ICV injected with (group i) control solution and groups ii-iv with 2.5, 5 and 10 nmol of AG-490 (JAK₂ antagonist). In experiment 3, injections were (i) control solution, (ii) Leptin (10 µg), (iii) AG-490 (2.5 nmol) and (iv) Leptin + AG-490. In experiment 4, broiler chickens were ICV injected with (i) control solution, (ii) Leptin (10 µg), (iii) MK-801 (NMDA glutamate receptors antagonist; 15 nmol) and (iv) Leptin + MK-801. Experiments 5-9 were similar to experiment 1, except chicken were ICV injected with CNQX (AMPA receptor antagonist, 390 nmol), UBP-302 (Kainate receptor antagonist, 390 nmol), AIDA (mGluR1 antagonist, 2 nmol), LY341495 (mGluR2 antagonist, 150 nmol) and UBP1112 (mGluR3 antagonist, 2 nmol) instead of MK-801. Then, food intake was measured until 120 min after injection.Results: ICV injection of leptin (2.5, 5 and 10 µg) significantly decreased food intake in a dose dependent manner (p < 0.05). Also, ICV injection of the JAK₂ antagonist (2.5, 5 and 10 nmol) had hyperphagic effect in chicken (p < 0.05). Co-administration of leptin + AG-490, partially decreased leptin-induced hypophagia in broiler chicken (p < 0.05). In addition, co-injection of leptin + MK-801 significalty inhibited leptin-induced hypophagia in neonatal chicken (p < 0.05). Also, co-administration of leptin + CNQX partially attenuated hypophagic effect of leptin in chicken (p < 0.05).Conclusion: The results of present study suggest that leptin has hypophagic effect in neonatal chicken and this effect is probably mediated via NMDA and AMPA glutamatergic receptors.

Effects of phytogenic inclusion level on broiler carcass yield, meat antioxidant capacity, availability of dietary energy, and expression of intestinal genes relevant for nutrient absorptive and cell growth–protein synthesis metabolic functions

Context Phytogenic applications in animal nutrition currently attract worldwide scientific attention for their potential to contribute positively to sustainable and high-quality animal production. However, further understanding and substantiation of dietary phytogenic functions is required. Aims The inclusion level of a phytogenic premix (PP) comprising functional flavouring substances from ginger, lemon balm, oregano and thyme was studied for its effects on broiler growth performance, carcass traits, nutrient digestibility, liver and meat total antioxidant capacity (TAC), and lipid oxidation. The expression of genes for nutrient transporter proteins (SGLT1, GLUT2, PEPT1, BOAT and LAT1), for FABP2 involved in cellular fatty acid uptake and metabolism, and for the mTORC1 complex relevant for protein synthesis were profiled along the intestine. Methods One-day-old Cobb broiler chickens (n = 500) were assigned to four treatments with five replicates of 25 chickens each. Starter (1–10 days), grower (11–22 days) and finisher (23–42 days) basal diets were supplemented with four levels of PP inclusion as treatments: 0, 750, 1000 and 2000 mg/kg diet, termed control, PP750, PP1000 and PP2000. Feed and water were available ad libitum. Data were analysed by ANOVA, taking the treatment as fixed effect. Statistically significant (P ≤ 0.05) effects were further analysed and means were compared using Tukey’s HSD test. Polynomial contrasts tested the linear and quadratic effect of PP inclusion levels. Key results Growth performance responses were not improved significantly (P &gt; 0.05) by PP inclusion level. However, carcass (P = 0.030) and breast meat yield (P = 0.023) were higher in PP1000 than in the control. In addition, PP1000 had higher (P = 0.049) apparent metabolisable energy than PP2000 and the control. Increasing PP inclusion level increased breast (P = 0.005), thigh (P = 0.002) and liver (P = 0.040) TAC. Breast and thigh meat TAC reached a plateau at PP1000, whereas liver TAC continued to increase linearly. Lipid oxidation in breast meat and liver was delayed linearly (P ≤ 0.05) with increasing PP inclusion level. Expression of genes SGLT1, GLUT2, PEPT1, BOAT and FABP2 were not affected by PP inclusion. However, PP inclusion affected the expression of LAT1 (P &lt; 0.001) in jejunum and of mTORC1 in duodenum (P = 0.010) and ceca (P = 0.025). In particular, expression increased with increasing PP inclusion level in a linear and quadratic pattern depending on the intestinal segment. Conclusions Overall, PP inclusion at 1000 mg/kg diet improved carcass and breast yield, dietary available energy, and overall meat and liver TAC. Preliminary evidence was highlighted for effects of PP in promoting expression of genes relevant for muscle protein synthesis. Implications This study has contributed new information on effects of a phytogenic premix on broiler meat yield and antioxidant capacity, digestibility, absorption and metabolic functions, further supporting phytogenic benefits for broiler production.

Effect of dietary supplementation with phytogenic blend on growth performance, apparent ileal digestibility of nutrients, intestinal morphology, and cecal microflora of broiler chickens

The effects of dietary supplementation with phytogenic blend (PB) of Aerva lanata, Piper betle, Cynodon dactylon, and Piper nigrum on growth performance, ileal nutrient digestibility, intestinal morphology, and cecal microflora were determined in a 42-day broiler feeding trial. A total of 192 broilers were assigned to 4 dietary treatments (6 replicates and 8 birds/replicate): basal diet, basal diet supplemented with antibiotic (chlortetracycline), 1% and 2% PB, respectively. The body weight gain (BWG) of starter chicks increased linearly (P = 0.023) as dietary supplementation levels of PB increased. At grower phase, broilers fed diet supplemented with 1% PB had similar BWG with the antibiotic group, but other treatments had reduced (P = 0.0001) BWG. Dietary supplementation with 1% PB resulted in the highest (P < 0.0001) BWG during the study. Feed intake was not affected by the treatments during the starter, finisher, and overall rearing periods. Broilers fed diet supplemented with 1% PB had the best (P < 0.0001) feed conversion ratio during the study. Overall, broilers fed only basal diet had the highest (P = 0.0450) mortality. Ileal organic matter (OM) digestibility increased linearly (P = 0.044) with broilers fed diet supplemented with PB, but reduced with antibiotic group. Dietary supplementation with 1% PB had the highest (P = 0.0402) ileal digestibility of tryptophan. In the duodenum, broilers fed diet supplemented with PB had longer (P = 0.0006) villi heights than the birds fed only basal diet, but similar with antibiotic group. Broilers fed diet supplemented with PB had longer (P = 0.0064) villi height in the jejunum than the antibiotic group. Bifidobacterium concentration of the cecum content showed a slight increase (P = 0.053) with increasing supplementation levels of PB. In conclusion, the current study shows that dietary supplementation with PB improves growth performance, intestinal morphology, and apparent ileal digestibility of OM and tryptophan in a dose-dependent manner with the best response at 1% inclusion level.

Assessment of the body development kinetic of broiler breeders by non-invasive imaging tools

In order to determine the body composition of parental broilers during growth from hatching to adulthood (32 wk of age), we evaluated the kinetics of fattening, growth rate, reproduction parameters, and body composition of the animals by using non-invasive tools such as medical imaging (ultrasound and CT scan) and blood sample analysis. The use of CT scanner allowed us to monitor the development of the body composition (fatness, bone, muscle, ovary, and testis growth) of these same animals. These analyses were accompanied by biochemical blood analyses such as steroids, metabolites, and some adipokines concentration. Difference in the body composition between males and females appeared at 16 wk of age. From 20 wk of age, shortly before the onset of lay, the females had 1.6-fold more adipose tissues than males (P < 0.001) and 8-fold more elevated plasma triglycerides levels. In addition, females, from 16 wk of age, presented a weakened bone quality in comparison to males (P < 0.001). The ratio of the tibia volume/tibia length was 33.2% lower in female compared to male chicken at 32 wk of age (P < 0.001). However, the pectoral muscle had the same volume in both sexes. The production of steroids by gonad started at 16 wk of age for both sexes, and the testis and ovary development could be measured by imaging tools at 24 wk. The follicle development was correlated to the ovarian fat tissue (r = 0.80) and fatness. In conclusion, the use of CT scanner and ultrasound system has allowed investigate the body composition of live animals and actual parental breeds with to the aim of using them for genetic selection.

Unravelling fatty liver haemorrhagic syndrome: 2. Inflammation and pathophysiology

To study the role of inflammation in the pathophysiology of the fatty liver haemorrhagic syndrome (FLHS), mature laying hens were treated with oestrogen (β-oestradiol-17-dipropionate or E₂) and challenged with lipopolysaccharide (LPS). Oestrogen injections induced FLHS, but the incidence and severity of the condition was increased with a combination of E₂ & LPS. Hepatic mRNA levels of the genes encoding key regulators of inflammation, such as interleukin-1β (IL-1β), interleukin-6 (IL-6) and interleukin-18 (IL-18), were evaluated. The expression of IL-6 mRNA in hepatocytes of all treated groups (E₂, LPS and E₂ & LPS hens) was elevated from 6-fold to 56-fold (P < 0.01), when compared to baseline and control values, with the highest fold change at 3 h post-treatment. The mRNA levels for IL-1β were better expressed at 24 h post-treatments with E₂, LPS and E₂ & LPS. The expression of IL-18 mRNA in the liver tissue was lower than IL-1β and IL-6 mRNA in all treated birds. At 24 h post-treatment, total white blood cell (WBC) counts and fibrinogen levels were elevated (P < 0.05) in E₂-, LPS- and E₂- & LPS-treated hens. Histologically, livers of hens from E₂- and E₂- & LPS-treated groups revealed inflammatory alterations with areas showing mononuclear aggregations, vacuolar fatty degeneration of hepatocytes, and increased sinusoidal congestion and haemorrhages. It was concluded that liver lipid accumulation and injury were associated with incidences of local (hepatic) and systemic inflammation, which could have initiated liver blood vessel and capsule rupture and, subsequently, the onset of FLHS.

Differential expression of genes implicated in liver lipid metabolism in broiler chickens differing in weight

1. Lipid parameters and expression of ACACA, APOA1, CPT1A, FASN, FOXO1, LIPG, PPARα and SIRT1 genes involved in lipid metabolism were investigated in two groups of high (HW) and low (LW) weight broilers from the same strain.2. Blood cholesterol and liver triglyceride levels were significantly increased in HW chickens compared to LW broilers, while other parameters, i.e. blood triglyceride, blood HDL/LDL, liver cholesterol and total liver fat showed no significant changes in either group.3. The relative expression of ACACA, APOA1 and CPT1A genes was significantly lower in the liver tissues of HW broilers than in the LW group. The mRNA levels of these three genes showed a significant negative correlation with abdominal fat deposition and live weight of broilers. However, relative expression of FASN, FOXO1, LIPG, PPARα and SIRT1 hepatic genes did not differ among broilers.4. It was concluded that, of eight hepatic genes implicated in lipid metabolism, only the expression of three (ACACA, APOA1 and CPT1A) were significant for fat and leanness within the same strain of chicken. Since reducing body fat is a major goal in the broiler industry, these data can provide fresh insight into the molecular processes underlying the regulation of fat deposition in broilers.

Role of Insulin-like Growth Factor-1 in the Central Regulation of Feeding Behavior in Chicks

Insulin-like growth factor-1 (IGF-1) is a key regulator of muscle development and metabolism in chickens. Recently, we have demonstrated that intracerebroventricular administration of IGF-1 significantly decreased food intake in broiler chicks. However, the molecular mechanisms underlying the IGF-1-induced anorexia and the anorexigenic effect of IGF-1 in different strains of commercial chicks have not been investigated. Neuropeptide Y (NPY, a hypothalamic orexigenic neuropeptide), agouti-related protein (AgRP, a hypothalamic orexigenic neuropeptide), and proopiomelanocortin (POMC, the precursor of hypothalamic anorexigenic neuropeptides) play important roles in the regulation of food intake in both mammals and chickens. Evidence shows that several cell signaling pathways in the hypothalamus are involved in regulating the feeding behavior of mammals. In the present study, we first investigated the effects of IGF-1 on the expression of appetite-regulating neuropeptides and phosphorylation of signaling molecules in the hypothalamus of broiler chicks. Intracerebroventricular administration of IGF-1 significantly increased the mRNA levels of POMC, whereas the mRNA levels of NPY and AgRP were not significantly altered. IGF-1 also significantly induced the phosphorylation of v-Akt murine thymoma viral oncogene homolog 1 (AKT) in the hypothalamus of chicks, but did not influence the phosphorylation of forkhead box O1, S6 protein, AMP-activated protein kinase, and extracellular signal-regulated kinase 1/2. We also compared the effect of IGF-1 on food intake in broiler chicks (a hyperphagic strain of chickens) and layer chicks. Results demonstrated that the threshold of IGF-1-induced anorexia in broiler chicks was higher than that in layer chicks. Our observations suggest that hypothalamic POMC and AKT may be involved in the IGF-1-induced anorexigenic pathway and that high threshold of IGF-1-induced anorexia in broiler chicks might be one of the causes of hyperphagia in broiler chicks. Overall, it appears that IGF-1 plays important roles in the central regulation of feeding behavior in chicks.

Central administration of insulin and refeeding lead to the phosphorylation of AKT, but not FOXO1, in the hypothalamus of broiler chicks

Several studies in rodents and layer chickens have demonstrated that insulin upregulates hypothalamic AKT-mediated signaling and expression of proopiomelanocortin (POMC, the precursor of alpha-melanocyte stimulating hormone, an anorexigenic peptide) and suppresses appetite in these animals. However, a previous study has also reported that insulin fails to suppress food intake in broiler chicks. In the present study, no significant differences were observed in hypothalamic AKT and forkhead box O1 (FOXO1) phosphorylation levels between broiler and layer chicks. The phosphorylation rate of AKT, but not that of FOXO1, increased in the hypothalami of broilers refed for 1 h after a 24-h fast, with a corresponding increase in plasma insulin concentration. Intracerebroventricular (ICV) administration of 50 pmol insulin, which could decrease food intake in broiler chicks, significantly increased the AKT phosphorylation rate, whereas no significant change was observed in FOXO1 phosphorylation or POMC expression after ICV insulin administration. These findings suggest that hypothalamic AKT responds to insulin in broiler chicks, but FOXO1-mediated regulation of POMC expression is not induced by insulin, which may be one of the causes of excessive food intake in broiler chickens.

Heat stress management in poultry farms: A comprehensive overview

Heat stress causes significant economic losses in poultry production, especially in tropical and arid regions of the world. Several studies have investigated the effects of heat stress on the welfare and productivity of poultry. The harmful impacts of heat stress on different poultry types include decreased growth rates, appetites, feed utilization and laying and impaired meat and egg qualities. Recent studies have focused on the deleterious influences of heat stress on bird behaviour, welfare and reproduction. The primary strategies for mitigating heat stress in poultry farms have included feed supplements and management, but the results have not been consistent. This review article discusses the physiological effects of heat stress on poultry health and production and various management and nutritional approaches to cope with it.

Role of gamma-aminobutyric acid in regulating feed intake in commercial broilers reared under normal and heat stress conditions

This study was conducted to investigate the effects of dietary GABA supplementation on blood biochemical parameters, the overall growth performance, and the relative mRNA expression of some FI- regulating genes in broiler chickens. A total of 192, three-day old chicks of mixed sex from two commercial broiler strains (Ross 308 and Cobb 500) were distributed into 2 groups; a control group and GABA-supplemented group (100 mg/kg diet). When the chicks reached 21 days of age, each group of each strain was randomly subdivided into two subgroups: one was exposed to HS (33 ± 2 °C for 5 h/day for 2 weeks), while the other remained at thermoneutral temperature (24 °C). GABA significantly improved bird growth performance under normal and HS conditions, by increasing body weight (BW), weight gain (WG), and FI and significantly reduced the elevated body temperature of birds under HS. GABA supplementation increased FI by reducing the mRNA expression levels of FI-inhibiting neuropeptides, such as POMC, leptin, Ghrelin, and CCK, during HS and by increasing the expression of FI-stimulating neuropeptides such as AgRP and NPY. Moreover, GABA significantly altered FAS and ACC gene expression, resulting in significant increases in abdominal fat content in birds reared normally. In contrast, GABA lowered fat content in Cobb birds and increased it in Ross birds under HS. Therefore, GABA (100 mg/kg diet) is a strong FI-stimulating neurotransmitter and its regulatory effects depend on broiler strain and housing temperature.

Berberine attenuates sodium palmitate-induced lipid accumulation, oxidative stress and apoptosis in grass carp(Ctenopharyngodon idella)hepatocyte in vitro

The objective of this work was to investigate the effect of berberine (BBR) on the Cell viability, lipid accumulation, apoptosis, cytochrome c, caspase-9 and caspase-3 in lipid accumulation-hepatocytes induced by sodium palmitate in vitro. The lipid accumulation-hepatocytes (induced by 0.5 mM sodium palmitate for 24 h) were treated with 5 μM berberine for 12 h. Then, the Cell viability, intracellular triglyceride (TG) content, lipid peroxide (LPO), malonaldehyde (MDA) content, cytochrome c, caspase-9, caspase-3 and apoptosis were detected. Sodium palmitate decreased Cell viability and increased intracellular TG content, lipid droplet accumulation, LPO and MDA concentrations, caused caspase-3 and caspase-9 activation, then led to apoptosis accompanied by cytochrome c release from mitochondria into the cytoplasm. Beberine could improve intracellular lipid droplet accumulation and oxidative stress, while reduce apoptosis induced by sodium palmitate.

Feed preference and feeding behaviours in grower broilers fed diets containing wheat naturally contaminated with fusarium mycotoxins

1. Two trials were conducted to determine the effect of feeding diets contaminated with fusarium mycotoxins (primarily deoxynivalenol (DON)) on broiler chicken feed preference, feeding behaviour and growth performance. 2. A total of 120 male Ross 308 chicks (4 birds/cage, 30 cages) were fed a common corn-based starter diet from 1 to 20 d of age. At 21 d, 15 cages were randomly assigned to the feed preference trial or a feeding behaviour trial. Three wheat-based experimental diets (0.14, 2.27 and 5.84 mg/kg DON) were prepared with a clean wheat and a naturally contaminated wheat. Broilers were ad libitum fed the experimental diets during 21-27 d. 3. In the preference trial, each cage's feeder was split into two equal-sized compartments so birds were provided a choice of two diets (control vs. low, control vs. high and low vs. high DON). In the feeding behaviour trial, diets were randomly assigned to 15 cages (5 cages/diet). Feeding and drinking behaviour was recorded for 1 h before and after the dark period and 1-h period at 9 h after the light was turned on (middle of day). Growth performance was assessed at 27 d. 4. In the preference trial, broilers preferred the control diet over low (93.0 vs. 66.1 g/d, P < 0.01) and high (104.4 vs. 50.4 g/d, P < 0.01) DON diets. At all three timepoints, where behaviour was recorded, birds offered the DON diets spent more time at the feeder compared to birds provided control diets (P < 0.05). Control birds had lower feed to gain ratio (1.65) than birds fed low (1.82) and high (1.94) DON diets (P < 0.01). 5. It is clear that broilers are sensitive to the presence of fusarium mycotoxins and that moderate levels of DON negatively affect feed preference and growth performance when fed during the grower period.

Oxidative Stress in the Poultry Gut: Potential Challenges and Interventions

The gastrointestinal tract (GIT) provides the biological environment for nutrient digestion and absorption, and protection from pathogens and toxins. Broilers are fast growing because of the great potential of intestinal epithelia for nutrient absorption, and efficient conversion of nutrient to muscle. Physiologically, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated by GIT epithelial cells either from oxygen metabolism or by enteric commensal bacteria and regulate gut health. However, increased production of ROS elevates free radical production and antioxidant insults resulting in oxidative stress. Oxidative stress in poultry GIT is derived from nutritional, environmental heat stress, and pathological factors, which alters overall performance as well as meat and egg quality. Supplementation of exogenous vitamins, antioxidants, and plant extract having antioxidant properties scavenge ROS and are beneficial in mitigating oxidative stress in the GIT. This review highlights the involvement of oxidative stress in the gastrointestinal functionality of poultry and potential intervention strategies to maintain redox balance in the GIT.

Performance, diameter of muscle fibers, and gene expression of mechanistic target of rapamycin in pectoralis major muscle of broilers supplemented with leucine and valine

Two experiments were performed to study the interaction between the standardized ileal digestible (SID) leucine (Leu) and valine (Val) levels on the mRNA expression of genes involved in the mechanistic target of rapamycin (mTOR) pathway (experiment I) and determine the requirement of these amino acids in low-protein diets, and their effects on performance, serum parameters and muscle fiber diameters of broilers (experiment II) from day 1 to day 21 post hatch. Broiler chickens were distributed in a completely randomized design in a 3 × 3 and 5 × 5 factorial arrangement for a total of 9 and 25 treatments in experiments I and II, respectively. There was no (P > 0.05) interaction between the SID Leu and Val levels on mRNA expression of mTOR, S6 kinase 1 (S6K1), 4E-binding protein-1 (4EBP1), eukaryotic elongation factor 2 (eEF2), and insulin-like growth factor-1 (IGF-1) genes in pectoralis major muscle. Leucine supplementation increased (P < 0.05) mRNA expression of mTOR and S6K1 genes in muscle tissue, whereas Val supplementation did not affect (P > 0.05) mRNA expression of the genes investigated. Interaction was observed (P < 0.05) between dietary Leu and Val levels on feed intake and gain:feed. Leucine supplementation may stimulate mRNA expression of mTOR and S6K1 genes in pectoralis major muscle of broilers from day 1 to day 21 post hatch. The SID Leu and Val levels required for the optimization of feed intake, weight gain, and gain:feed in low-crude protein diets for broiler chickens from day 1 to 21 post hatch were estimated at 1.29% and 0.96%, 1.28% and 0.92%, and 1.27% and 0.91%, respectively; however, these requirements may be greater to maximize muscle fiber growth.

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.

Fatty liver haemorrhagic syndrome occurrence in laying hens: impact of production system

Surveys were conducted with cage and alternative layer production systems to assess the prevalence of fatty liver haemorrhagic syndrome (FLHS). Commercial caged laying hens of different ages from three farms in Queensland were monitored for three months. The mortality rate of flocks ranged from 0.8% (the youngest flock) to 11.6% (the oldest flock). Six hundred and fifty-one birds were necropsied, and approximately 40% of hens died due to FLHS. Hens kept in cages in a controlled environment shed, were at a similar risk of developing FLHS to hens kept in naturally controlled sheds, however, the heavier birds in a flock were more likely to have the condition than lighter birds. In another study, layer flocks kept in cage, barn and free-range housing systems at the University of Queensland facility, were monitored for 50 weeks. Data from necropsies and performance records showed no significant differences in mortality rates between the housing systems (6.1%, 6.4% and 5.8%, for cages, barns and free-range, respectively), but the cause of mortality was different. In cages, 74% of necropsied hens died due to FLHS. In the other systems, only 0-5% of dead hens were diagnosed with the condition. These results are in agreement with previous Australian and overseas findings which have shown that FLHS is one of the main causes of hen death in caged flocks. Factors associated with husbandry practices in different production systems, such as restricted movement, increased production and temperature variations, influence hepatic lipid metabolism and predispose hens to FLHS.

Differences in productive performance and intestinal transcriptomic profile in two modern fast-growing chicken hybrids

This study aimed to characterize growth performance and ileum transcriptomic profile of two fast-growing chicken hybrids (HA and HB). A total of 1,170 one-day-old female chicks (n = 585 per genotype) were weighed and randomly divided into 18 pens (9 replications/group). Both the groups received the same commercial diet (starter, 0-9 days; grower I, 10-21 days; grower II, 22-34 days; and finisher, 35-43 days). Body weight (BW), daily feed intake (DFI) and feed conversion ratio (FCR) were determined on a pen basis at the end of each feeding phase. At the processing (43 days), incidence of footpad dermatitis (FPD) was evaluated on all the birds and ileum mucosa was collected from 1 bird/replication. Total mRNA was extracted to perform microarray analysis (Chicken Gene 1.1^ST Array Strip), and an exploratory pathway analysis was then conducted (Gene Set Enrichment Analysis software). The two genotypes showed different growth patterns throughout the study. HA birds exhibited higher BW and better FCR than HB after 9 days (228 vs. 217 g and 1.352 vs. 1.419, respectively, p < 0.05). At 21, 34 and 43 days, HB birds reported higher BW (807 vs. 772 g; 1,930 vs. 1,857 g and 2,734 vs. 2,607 g, respectively; p < 0.01), DFI (74.9 vs. 70.6 g bird^-1  day^-1 , p < 0.01; 144.4 vs. 139.6 g bird^-1  day^-1 , p = 0.06; and 196.5 vs. 182.4 g bird^-1  day^-1 , p < 0.01) and similar FCR compared to HA ones. HB group showed a higher percentage of birds with no FPD (75% vs. 48%; p < 0.001). Transcriptomic analysis revealed enriched gene sets for mitochondria, cellular energy metabolism, and cell structure and integrity in ileum mucosa of HA broilers and enriched gene sets for immune system activation, cell signalling and inflammation in HB ones. In conclusion, these results indicated that the two chicken genotypes are characterized by different growth patterns, feeding behaviour and gene expression profiles in the intestinal mucosa.

Application of omics technologies for a deeper insight into quali-quantitative production traits in broiler chickens: A review

The poultry industry is continuously facing substantial and different challenges such as the increasing cost of feed ingredients, the European Union's ban of antibiotic as growth promoters, the antimicrobial resistance and the high incidence of muscle myopathies and breast meat abnormalities. In the last decade, there has been an extraordinary development of many genomic techniques able to describe global variation of genes, proteins and metabolites expression level. Proper application of these cutting-edge omics technologies (mainly transcriptomics, proteomics and metabolomics) paves the possibility to understand much useful information about the biological processes and pathways behind different complex traits of chickens. The current review aimed to highlight some important knowledge achieved through the application of omics technologies and proteo-genomics data in the field of feed efficiency, nutrition, meat quality and disease resistance in broiler chickens.

Transcriptional shifts account for divergent resource allocation in feed efficient broiler chickens

Considerable variation in feed efficiency (FE) has been observed in indigenous and selected meat-type chicken populations. Although this variation could be partially linked to extrinsic factors like diet, housing environment and microbiota, it further illustrates the existence of strong molecular mechanisms enabling the differential allocation of resources for various physiological processes. To further deepen the molecular basis of individual allocation capacity in male and female broilers, an RNA-seq experiment was conducted which based on a phenotyped chicken population divergent in FE. Transcriptional differences linked to FE were pronounced in intestinal and muscular tissue sites of male animals. Specifically, signalling pathways of farnesoid X receptor (FXR) and retinoid X receptor (RXR) might contribute to mediate individual FE. The transcriptional profiles suggested ACSBG2 (muscular lipid utilisation), ASBT (intestinal bile salt transport), CLEC2B (natural killer cell activation), HMGCS2 (jejunal, duodenal and muscular ketogenesis), and SCARB1 (jejunal lipid uptake) as potential mediators driving FE. Results indicate that improvements in FE exploit shifts in resource allocation which might occur at the expense of general immune responsiveness in high efficient male chickens. Consequently, to further improve FE traits and to explore causative molecular patterns, effects originating from sex-dimorphism in chickens need to be taken into consideration.

Proteomic analysis of hypothalamus and liver proteins affected by dietary l-arginine supplementation in laying hens

The goal of this study was to investigate the influence of l-arginine (l-Arg) supplementation on diet-induced changes in hypothalamus and liver proteome of laying hens. Layers were fed either an isonitrogenous control diet or a l-Arg diet. The test included a 2-week acclimation period and a 12-week experimental period. Eight layers per group were sacrificed at terminal of the experiment underwent 12 fasting. Blood and tissue samples of hypothalamus and liver were collected for further analysis. The levels of serum nitric oxide and hypothalamus neuropeptide Y of layers in l-Arg group were increased in comparison with those in control group. Quantitative proteomic analyses showed that a total of 3,715 hypothalamus proteins (235 differentially expressed) and 3797 liver proteins (373 differentially expressed) were detected between control and l-Arg-fed groups. A further enriched Gene Ontology term analysis of proteins found that 17 hypothalamus proteins (11 upregulated and six downregulated) and 29 liver proteins (14 upregulated and 15 downregulated) were altered differentially between the two groups. Our findings revealed the changes in metabolic and hormonal signals in central nervous system and peripheral tissues by responding to l-Arg feeding, which provides a possible way to gain a better understanding of l-Arg function in laying hens.

Effect of elevated dietary amino acid levels in high canola meal diets on productive traits and cecal microbiota population of broiler chickens in a pair-feeding study

A pair-feeding study was conducted to determine if reduced feed intake (FI) in broiler chickens fed high canola meal (CM) diets per se accounts for reduced growth performance and whether this lower growth rate can be mitigated by increasing dietary amino acid (AA) levels. Five experimental wheat-based diets were formulated as follows: soybean meal (SBM) diet, high CM diet with normal AA concentration, and high CM diets with 3, 6, or 9% additional AA concentration (Lys, Met+Cys, Thr, Ile, Arg, and Val). Another group of birds was pair-fed with SBM diet to the consumption levels of birds fed CM diet with normal AA. There were 6 replicates of 17 male 10-day-old Ross 308 chicks per treatment over grower and finisher periods. Birds fed the CM diets had reduced FI and BWG, but improved FCR (P < 0.01) compared to SBM ad libitum fed birds. The SBM pair-fed birds gained the same weight and exhibited similar FCR compared to CM fed birds. Additional 9% AA improved FCR (P < 0.01) compared to SBM and CM diets with normal AA. No significant differences were observed in ileal digestibility of DM, energy, crude protein, and AA between CM with normal AA and SBM diets. The additional 6 and 9% AA in CM diets increased digestibility of crude protein and some AA (P < 0.05). SBM ad libitum and CM + 6 and 9% AA fed birds had the highest and lowest relative weight of abdominal fat, respectively (P < 0.05). Addition of 6 and 9% AA in CM diets increased relative carcass and breast yields (P < 0.01). Serum triglyceride level was higher in SBM ad libitum fed birds (P < 0.05). The composition of microbiota in the ceca was not affected by treatments. This study showed that reduced growth of birds fed high CM diets is primarily mediated through reduced FI. This growth depression could partially be ameliorated by increasing dietary AA levels.

Insulin immuno-neutralization decreases food intake in chickens without altering hypothalamic transcripts involved in food intake and metabolism

In mammals, insulin regulates blood glucose levels and plays a key regulatory role in appetite via the hypothalamus. In contrast, chickens are characterized by atypical glucose homeostasis, with relatively high blood glucose levels, reduced glucose sensitivity of pancreatic beta cells, and large resistance to exogenous insulin. The aim of the present study was to investigate in chickens the effects of 5 h fasting and 5 h insulin immuno-neutralization on hypothalamic mRNA levels of 23 genes associated with food intake, energy balance, and glucose metabolism. We observed that insulin immune-neutralization by administration of anti-porcine insulin guinea pig serum (AI) significantly decreased food intake and increased plasma glucose levels in chickens, while 5 h fasting produced a limited and non-significant reduction in plasma glucose. In addition, 5 h fasting increased levels of NPY, TAS1R1, DIO2, LEPR, GLUT1, GLUT3, GLUT8, and GCK mRNA. In contrast, AI had no impact on the levels of any selected mRNA. Therefore, our results demonstrate that in chickens, food intake inhibition or satiety mechanisms induced by insulin immuno-neutralization do not rely on hypothalamic abundance of the 23 transcripts analyzed. The hypothalamic transcripts that were increased in the fasted group are likely components of a mechanism of adaptation to fasting in chickens.

Nutrient sensing, taste and feed intake in avian species

The anatomical structure and function of beaks, bills and tongue together with the mechanics of deglutition in birds have contributed to the development of a taste system denuded of macrostructures visible to the human naked eye. Studies in chickens and other birds have revealed that the avian taste system consists of taste buds not clustered in papillae and located mainly (60 %) in the upper palate hidden in the crevasses of the salivary ducts. That explains the long delay in the understanding of the avian taste system. However, recent studies reported 767 taste buds in the oral cavity of the chicken. Chickens appear to have an acute sense of taste allowing for the discrimination of dietary amino acids, fatty acids, sugars, quinine, Ca and salt among others. However, chickens and other birds have small repertoires of bitter taste receptors (T2R) and are missing the T1R2 (related to sweet taste in mammals). Thus, T1R2-independent mechanisms of glucose sensing might be particularly relevant in chickens. The chicken umami receptor (T1R1/T1R3) responds to amino acids such as alanine and serine (known to stimulate the umami receptor in rodents and fish). Recently, the avian nutrient chemosensory system has been found in the gastrointestinal tract and hypothalamus related to the enteroendocrine system which mediates the gut-brain dialogue relevant to the control of feed intake. Overall, the understanding of the avian taste system provides novel and robust tools to improve avian nutrition.

Obesity-associated cardiac pathogenesis in broiler breeder hens: Pathological adaption of cardiac hypertrophy

Broiler hens consuming feed to appetite (ad libitum; AL) show increased mortality. Feed restriction (R) typically improves reproductive performance and livability of hens. Rapidly growing broilers can exhibit increased mortality due to cardiac insufficiency but it is unknown whether the increased mortality of non-R broiler hens is also due to cardiac compromise. To assess cardiac growth and physiology in fully mature birds, 45-week-old hens were either continued on R rations or assigned to AL feeding for 7 or 21 days. AL hens exhibited increased bodyweight, adiposity, absolute and relative heart weight, ventricular hypertrophy, and cardiac protein/DNA ratio by d 21 (P < 0.05). Increased heart weights due to hypertrophic growth was attributed to enhanced IGF-1-Akt-FoxO1 signaling and its downstream target, translation initiation factor 4E-BP1 in conjunction with down-regulation of ubiquitin ligase atrogin-1/MAFbx (P < 0.05). Reduced activation of cardiac AMPK and downstream activation of ACC-1 in parallel with increased cardiac nitric oxide levels, calcineurin activity, and MAPK activation in AL hens (P < 0.05) suggested that metabolic derangement develops along the cardiovascular remodeling. These indictors of cardiac maladaptive hypertrophic growth were further supported by uregulation of heart failure markers, BNP and MHC-β (P < 0.05). Hens allowed AL feeding for 70 d exhibited a higher incidence of mortality (40% vs. 10%) in association with ascites, pericardial effusion, and ventricle dilation. A higher incidence of irregular ECG patterns and rhythmicity consistent with persistently elevated systolic blood pressure and ventricle fibrosis were observed in AL hens (P < 0.05). These observations support the conclusion that AL feeding in broiler hens results in maladaptive cardiac hypertrophy that progresses to overt pathogenesis in contractility and thereby increases mortality. Feed restriction provides clear physiological benefit to heart function of adult broiler hens.

Comparative transcriptome analysis of hypothalamus-regulated feed intake induced by exogenous visfatin in chicks

Background

The intracerebroventricular injection of visfatin increases feed intake. However, little is known about the molecular mechanism in chicks. This study was conducted to assess the effect of visfatin on the feeding behavior of chicks and the associated molecular mechanism.

Results

In response to the intraventricular injection of 40 ng and 400 ng visfatin, feed intake in chicks was significantly increased, and the concentrations of glucose, insulin, TG, HDL and LDL were significantly altered. Using RNA-seq, we identified DEGs in the chick hypothalamus at 60 min after injection with various doses of visfatin. In total, 325, 85 and 519 DEGs were identified in the treated chick hypothalamus in the LT vs C, HT vs C and LT vs HT comparisons, respectively. The changes in the expression profiles of DEGs, GO functional categories, KEGG pathways, and PPI networks by visfatin-mediated regulation of feed intake were analyzed. The DEGs were grouped into 8 clusters based on their expression patterns via K-mean clustering; there were 14 appetite-related DEGs enriched in the hormone activity GO term. The neuroactive ligand-receptor interaction pathway was the key pathway affected by visfatin. The PPI analysis of DEGs showed that POMC was a hub gene that interacted with the maximum number of nodes and ingestion-related pathways, including POMC, CRH, AgRP, NPY, TRH, VIP, NPYL, CGA and TSHB.

Conclusion

These common DEGs were enriched in the hormone activity GO term and the neuroactive ligand-receptor interaction pathway. Therefore, visfatin causes hyperphagia via the POMC/CRH and NPY/AgRP signaling pathways. These results provide valuable information about the molecular mechanisms of the regulation of food intake by visfatin.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4644-7) contains supplementary material, which is available to authorized users.

Effects of Fasting and Refeeding on the mRNA levels of Insulin-like Growth Factor-binding Proteins in Chick Liver and Brain

The physiological functions of insulin-like growth factor-binding proteins (IGFBPs) in mammals have been evaluated in several studies. However, the physiological roles of IGFBPs in chickens have not yet been elucidated. In this study, we examined the effects of short-term (6 h) fasting and refeeding on the mRNA levels of IGFBPs in chick liver and brain. Eighteen 8-day-old chicks were weighed and allocated to three groups on the basis of body weight, and subjected to ad libitum feeding, 6 h of fasting, or 6 h of fasting followed by 6 h of refeeding. After the chicks were euthanized by decapitation, the liver and brain were excised, and the brain was dissected into six segments (telencephalon, optic lobes, cerebellum, rostral part of the brainstem, middle part of the brainstem, and caudal part of the brainstem). IGFBP mRNA levels were determined by qRT-PCR. Fasting significantly increased the mRNA levels of IGFBP-1 and -2 in the chick liver, and these changes were reversed by 6 h of refeeding. The mRNA levels of IGFBP-3 in the middle part of the brainstem and IGFBP-5 in the optic lobes were decreased by 6 h of fasting and were not reversed after 6 h of refeeding. These findings suggest that IGFBP-1 and -2 in the liver, IGFBP-3 in the middle part of the brainstem, and IGFBP-5 in the optic lobes may play physiological roles in response to short-term changes in the nutritional status of chicks.

Effect of different levels of feed restriction and fish oil fatty acid supplementation on fat deposition by using different techniques, plasma levels and mRNA expression of several adipokines in broiler breeder hens

Background

Reproductive hens are subjected to a restricted diet to limit the decline in fertility associated with change in body mass. However, endocrine and tissue responses to diet restriction need to be documented.

Objective

We evaluated the effect of different levels of feed restriction, with or without fish oil supplementation, on metabolic parameters and adipokine levels in plasma and metabolic tissues of reproductive hens.

Methods

We designed an in vivo protocol involving 4 groups of hens; RNS: restricted (Rt) unsupplemented, ANS: ad libitum (Ad, receiving an amount of feed 1.7 times greater than animals on the restricted diet) unsupplemented, RS: Rt supplemented, and AS: Ad supplemented. The fish oil supplement was used at 1% of the total diet composition.

Results

Hens fed with the Rt diet had a significantly (P < 0.0001) lower growth than Ad hens, while the fish oil supplementation had no effect on these parameters. Furthermore, the bioelectrical impedance analysis (BIA) and the fat ultrasonographic examinations produced similar results to the other methods that required animals to be killed (carcass analysis and weight of adipose tissue). In addition, the Rt diet significantly (P < 0.05) decreased plasma levels of triglycerides, phospholipids, glucose and ADIPOQ, and fish oil supplementation decreased plasma levels of RARRES2. We also showed a positive correlation between insulin values and ADIPOQ or NAMPT or RARRES2 values, and a negative correlation of fat percentage to RARRES2 values. Moreover, the effects of the Rt diet and fish oil supplementation on the mRNA expression depended on the factors tested and the hen age.

Conclusions

Rt diet and fish oil supplementation are able to modulate metabolic parameters and the expression of adipokines and their receptors in metabolic tissue.

Tibiotarsus bone characteristics and tibial dyschondroplasia incidence of broilers fed diets supplemented with leucine and valine

Two experiments were conducted to study the effect of standardized ileal digestible (SID) leucine and valine levels on tibiotarsus bone characteristics and the incidence of tibial dyschondroplasia of broilers from day 1 to 21 (Experiment I) and day 21 to 42 post-hatch (Experiment II). Each experimental phase was evaluated independently. In both experiments, a total of 1,500 one-day-old Cobb 500 male broiler chickens were distributed in a completely randomized design 5 × 5 factorial arrangement for a total of 25 treatments. The SID leucine and valine levels were ranged from 10.0 to 19.6 g/kg, and 6.0 to 12.0 g/kg from day 1 to 21 post-hatch, respectively, while day 21 to 42 post-hatch ranged from 10.0 to 18.0 g leucine/kg, and 5.2 to 11.2 g valine/kg. Serum calcium and phosphorus, bone concentrations of calcium, phosphorus and ash, diameter and Seedor index of the tibiotarsus were not affected (p > .05) by the treatments at 21 or 42 days of age. There was an interaction (p ≤.06) between the SID levels of leucine and valine on tibiotarsus breaking strength at 21 days, but not at 42 days of age (p > .05). Tibiotarsus breaking strength was maximized in broilers from day 1 to 21 with the dietary levels of leucine and valine at 14.2 and 9.0 g/kg respectively. Dietary leucine levels reduced linearly (p < .05) the hypertrophic zone of tibiotarsus cartilage at 21 days of age. Therefore, leucine and valine supplementation interact positively on bone strength of broilers from day 1 to 21 post-hatch. Leucine can be a useful amino acid for reducing the hypertrophic cartilage zone in broilers from day 1 to 21, but not from day 21 to 42 post-hatch.

Anti-parasite treatment and blood biochemistry in raptor nestlings

We investigated the effects of parasite removal on various blood clinical–chemical variables (BCCVs). BCCVs are indicators of health, reflecting, e.g., homeostasis of liver, kidney function, and bone metabolism. The study was conducted in Norway on chicks of two predatory birds: White-tailed Eagle (Haliaeetus albicilla (L., 1758)) and Northern Goshawk (Accipiter gentilis (L., 1758)). Chicks were treated against both endoparasites (internal parasites) and ectoparasites (external parasites). We treated against ectoparasites by spraying nests with pyrethrins. Within nests, chicks were randomly treated with either an anti-helminthic medication (fenbendazole) or sterile water (controls). Treatment against either ectoparasites or endoparasites led to higher levels of the bone and liver enzyme alkaline phosphatase. Bilirubin levels were lower when treated against ectoparasites, whereas bile acids were higher. Anti-endoparasite treatment led to higher creatinine levels. In Northern Goshawks, treating against endoparasites led to higher urea levels and lower potassium levels. Treatment against ectoparasites increased uric acid and urea levels and reduced bilirubin levels and protein:creatinine ratios. In conclusion, anti-parasite treatments led to changes in several BCCVs, suggesting differences in nutrient absorption and physiological state of chicks that are possibly related to the costs of parasitism, but maybe also to the parasite treatment itself.

Consequence of dopamine D2 receptor blockade on the hyperphagic effect induced by cannabinoid CB1 and CB2 receptors in layers

1. Endocannabinoids (ECBs) and their receptors play a regulatory function on several physiological processes such as feed-intake behaviour, mainly in the brain. This study was carried out in order to investigate the effects of the dopaminergic D1 and D2 receptors on CB1/CB2 ECB receptor-induced hyperphagia in 3-h feed-deprived neonatal layer chickens. 2. A total of 8 experiments were designed to explore the interplay of these two modulatory systems on feed intake in neonatal chickens. In Experiment 1, chickens were intracerebroventricular (ICV) injected with control solution, l-DOPA (levo-dihydroxyphenylalanine as precursor of dopamine; 125 nmol), 2-AG (2-arachidonoylglycerol as CB₁ receptor agonist; 2 µg) and co-administration of l-DOPA (125 nmol) plus 2-AG (2 µg). Experiments 2-4 were similar to Experiment 1 except birds were injected with either 6-OHDA (6-hydroxydopamine as dopamine synthesis inhibitor; 150 nmol), SCH23390 (D1 receptor antagonist; 5 nmol) and AMI-193 (D2 receptor antagonist; 5 nmol) instead of l-DOPA, respectively. Additionally, Experiments 5-8 followed the previous ones using the same dose of l-DOPA, 6-OHDA and dopamine antagonists except that birds were injected with CB65 (CB2 receptor agonist; 5 µg) instead of 2-AG. Coadministrations were at the same dose for each experiment. Cumulative feed intakes were measured until 120 min after each injection. 3. ICV administration of 6-OHDA and AMI-193 significantly attenuated 2-AG-induced hyperphagia. Interestingly, the hyperphagic effect of CB65 was significantly attenuated by administration of l-DOPA, whereas the administration of 6-OHDA and AMI-193 together amplified the hyperphagic effect of CB65. 4. It was concluded that cannabinoid-induced feeding behaviour is probably modulated by dopamine receptors in neonatal layer-type chickens. It seems that their interaction may be mediated by the D2-dopamine receptor.