Early Post-hatch Period Research Articles

Biological motion facilitates filial imprinting

To study the functional role of the predisposed preference for Johansson's biological motion (BM) at an early stage of life, newly hatched domestic chicks, Gallus gallus domesticus, were exposed to a variety of motion pictures composed of light points (in red or yellow), and then tested for their learned colour preference. Point-light animations depicting the BM of a walking hen successfully facilitated both the approach activity during imprinting and the learned preference in the test, although significant positive correlations did not appear between these at the individual level. Furthermore, scrambling the light points did not significantly reduce the effects, whereas linear motion of a hen-shaped set of points had no effect. If pretreated with the linear motion, those chicks primed with a high BM preference score showed a high learning score in subsequent imprinting. We conclude that the local movement feature of the BM animation is critical in making chicks approach and learn the associated colour. We propose a scenario wherein naive chicks have an innate preference for BM, which arises prior to imprinting through nonspecific visual experience in the early posthatch period. The induced BM preference then allows chicks to form a learned colour preference for the associated colour more effectively, leading to the development of tighter social attachment.

Salmonella enterica Serovars Enteritidis Infection Alters the Indigenous Microbiota Diversity in Young Layer Chicks.

Avian gastrointestinal (GI) tracts are highly populated with a diverse array of microorganisms that share a symbiotic relationship with their hosts and contribute to the overall health and disease state of the intestinal tract. The microbiome of the young chick is easily prone to alteration in its composition by both exogenous and endogenous factors, especially during the early posthatch period. The genetic background of the host and exposure to pathogens can impact the diversity of the microbial profile that consequently contributes to the disease progression in the host. The objective of this study was to profile the composition and structure of the gut microbiota in young chickens from two genetically distinct highly inbred lines. Furthermore, the effect of the Salmonella Enteritidis infection on altering the composition makeup of the chicken microbiome was evaluated through the 16S rRNA gene sequencing analysis. One-day-old layer chicks were challenged with S. Enteritidis and the host cecal microbiota profile as well as the degree of susceptibility to Salmonella infection was examined at 2 and 7 days post infection. Our result indicated that host genotype had a limited effect on resistance to S. Enteritidis infection. Alpha diversity, beta diversity, and overall microbiota composition were analyzed for four factors: host genotype, age, treatment, and postinfection time points. S. Enteritidis infection in young chicks was found to significantly reduce the overall diversity of the microbiota population with expansion of Enterobacteriaceae family. These changes indicated that Salmonella colonization in the GI tract of the chickens has a direct effect on altering the natural development of the GI microbiota. The impact of S. Enteritidis infection on microbial communities was also more substantial in the late stage of infection. Significant inverse correlation between Enterobacteriaceae and Lachnospiraceae family in both non-infected and infected groups, suggested possible antagonistic interaction between members of these two taxa, which could potentially influences the overall microbial population in the gut. Our results also revealed that genetic difference between two lines had minimal effect on the establishment of microbiota population. Overall, this study provided preliminary insights into the contributing role of S. Enteritidis in influencing the overall makeup of chicken’s gut microbiota.

Reduced protein availability by albumen removal during chicken embryogenesis decreases body weight and induces hormonal changes.

What is the central question of this study? Prenatal protein undernutrition by albumen removal in an avian model of fetal programming leads to long-term programming effects, but when do these effects first appear and are these programming effects regulated by the same candidate genes as in mammals? What is the main finding and its importance? The present results indicate that prenatal protein undernutrition by albumen removal induces phenotypical and hormonal changes in the early posthatch period, when the mismatch between the prenatal and postnatal environment first arises, but these changes are not accompanied by an altered gene expression of the selected candidate genes. Studies of the chicken offer a unique model for investigation of the direct effects of reduced prenatal protein availability by the partial replacement of albumen with saline in eggs at embryonic day1 (albumen-deprived group). The results were compared with mock-treated sham chicks and non-treated control chicks. Although no differences in hatch weight were found, body weight and growth were reduced in the albumen-deprived chicks until 3weeks of age. The feed intake of the albumen-deprived chicks, however, was increased compared with the control (day13-21) and the sham chicks (day16-18). In the albumen-deprived chicks, the ratio of thyroxine to 3,5,3'-triiodothyronine in the plasma was increased compared with the control chicks, whereas the plasma corticosterone level was increased only at day 7 compared with both other groups. The plasma glucose concentration and glucose tolerance were not affected by treatment. Several candidate genes previously associated with effects of prenatal protein deprivation in mammals were examined in the liver of newly hatched chicks. Gene expression of glycogen synthase2, glycogen phosphorylase1, peroxisome proliferator-activated receptor α and γ and glucocorticoid receptor was not affected by the treatment. In conclusion, reduction of prenatal protein availability led to differences in body weight and influenced hormones involved in metabolism and growth. Gene expression of the selected candidate genes was not altered, in contrast to mammals.

Effects of experimentally increased in ovo lysozyme on egg hatchability, chicks complement activity, and phenotype in a precocial bird.

In birds, spectrum of egg white proteins deposited into the egg during its formation are thought to be essential maternal effects. Particularly, egg white lysozyme (LSM), exhibiting great between and within species variability, is considered to be essential for developing avian embryos due to its physiological, antimicrobial, and innate immune defense functions. However, there have been few studies investigating effects of LSM on early post-hatching phenotype, despite its broad physiological and protective role during embryogenesis. Here, we test how experimentally increased concentrations of egg white LSM affect hatchability in Japanese quail (Coturnix japonica) and chick phenotype immediately after hatching (particularly body weight, tarsus length, plasma LSM concentration, and plasma complement activity). Chicks from eggs with increased LSM concentration displayed reduced tarsus length compared to chicks from control eggs while hatchability, body weight and plasma LSM concentration were unaffected. It is worth noting that no effect of increased in ovo lysozyme on eggs hatchability could be related to pathogen-free environment during artificial incubation of experimental eggs causing minimal pressure on embryo viability. While tangible in vivo mechanisms during avian embryogenesis remain to be tested, our study is the first to document experimentally that egg white LSM appears to have growth-regulation role during embryo development, with possible underlying phenotypic consequences in the early post-hatching period in precocial birds.

Characterization of primary structure and tissue expression profile of the chicken apical sodium-dependent bile acid transporter mRNA

The ileal apical sodium-dependent bile acid cotransporter (ASBT) plays an essential role in the absorption of bile acids from intestinal lumina. ASBT cDNA has been cloned from mammalian and fish species, and the primary structure of the protein and expression properties of the mRNA have been characterized. In this study, we identified chicken ASBT mRNA by cDNA cloning. Chicken ASBT cDNA consisted of 91 bp of the 5′-untranslated region, 1,083 bp of the coding region, and 1,896 bp of the 3′-untranslated region. The cDNA encoded a protein of 360 amino acids showing significant sequence identity with mammalian and fish ASBT. The amino acid residues known to participate in the functions of mammalian ASBT were conserved in chicken ASBT. Real-time polymerase chain reaction analysis revealed that chicken ASBT mRNA was expressed at markedly higher levels in the ileum and proximal colon/rectum, relatively lower levels in the kidney, and very low levels in the jejunum and cecum. Expression levels in the ileum markedly increased after hatching, reached the highest levels on day 7 posthatching, and then decreased to adult levels. A similar expression pattern was observed in the proximal colon/rectum except for the significant decrease from day 7 posthatching to day 21 posthatching. These results suggest that chicken ASBT functions as a bile acid transporter in the ileum and proximal colon/rectum, particularly during the early posthatching period.

Enriching the Diet In N‐3 Polyunsaturated Fatty Acids Reduces Adiposity and Adipocyte Size in a Broiler Chick Model for Childhood Obesity

Epidemiological studies suggest that enriching prenatal and perinatal diets in long‐chain omega‐3 polyunsaturated fatty acids (LC n‐3 PUFA) may be a tool with which to reduce adiposity, improve metabolic status and reduce the risk of childhood obesity. We used broiler chickens, which rapidly deposit adipose tissue post‐hatch and share a number of metabolic features with humans, to test the hypothesis that consumption of diets enriched in LC n‐3 PUFA during the early post‐hatch period of rapid adipose development reduces adiposity. From seven to 21 days of age,Cobb500 broiler chicks (n=10/group) were fed isocaloric diets formulated using either lard (primarily saturated), corn oil (primarily monounsaturated), flaxseed oil (PUFA, enriched in alpha linolenic acid (ALA, 18:3, n‐3)), or fish oil (PUFA, enriched in eicosapentaenoic acid (EPA, 20:5, n‐3) and docosahexaenoic acid (DHA, 22:6, n‐3)), each at 8% by weight. Abdominal fat pad weight, but not body weight, was significantly (p=0.0327) lower in birds fed the fish oil diet (21.3g±5.5) than those fed lard (26.7g±5.9), but did not differ in birds fed flax and corn‐oil based diets relative to lard. Fish oil also significantly reduced abdominal adipocyte size compared to all other diets (p<0.05). Subcutaneous adipocyte size was significantly smaller in corn, flax and fish oil groups relative to lard (p<0.05). Plasma non‐esterified fatty acid levels, as a reflection of lipolysis, increased in birds fed fish oil diets as compared to lard diets (p=0.0194). Collectively, our data suggest that altering the type of fatty acids consumed during childhood may attenuate adipose deposition and adipocyte size, which could have benefits in reducing childhood obesity.

Insulin-induced hypoglycemia associations with gene expression changes in liver and hypothalamus of chickens from lines selected for low or high body weight

Chickens selected for low (LWS) or high (HWS) body weight for more than 56 generations now have a 10-fold difference in body weight at 56days of age and correlated responses in appetite and glucose regulation. The LWS chickens are lean and some are anorexic, while the HWS are compulsive feeders and have a different threshold sensitivity of food intake and blood glucose to both central and peripheral insulin, respectively. We previously demonstrated that at 90-days of age, insulin-induced hypoglycemia was associated with reduced glucose transporter expression in the liver of both lines, and differences in expression of neuropeptide Y (NPY) and NPY receptor sub-type genes between LWS and HWS in the hypothalamus. The objective of this study was to determine effects of insulin-induced hypoglycemia on gene expression in the hypothalamus and liver of early post-hatch LWS and HWS chicks. On day 5 post-hatch chicks from each line were fasted for 3h and injected intraperitoneally with insulin or vehicle. At 1h post-injection, chicks were euthanized, blood glucose was measured, and hypothalamus and liver were removed. Total RNA was isolated and real time PCR performed. Insulin injection was associated with a more pronounced reduction in blood glucose in HWS compared with LWS chicks (two-way interaction; P<0.05). Aromatic L-amino acid decarboxylase, NPY, and NPY receptor sub-types 2 and 5 mRNA quantities were greater in LWS than HWS chicks in the hypothalamus (P<0.05), whereas pro-opiomelanocortin mRNA was greater in the hypothalamus of HWS than LWS (P<0.05). In the liver, glucose transporter 1, 2 and 3 (GLUT 1, 2 and 3, respectively) mRNA abundance was greater in HWS than LWS chicks (P<0.05). Compared to the vehicle, insulin treatment was associated with an increase in tryptophan hydroxylase 2 mRNA in the hypothalamus of both lines (P=0.02). In the liver of both lines, insulin treatment was associated with decreased (P=0.01) GLUT2 mRNA and increased (P=0.01) GLUT1 mRNA, compared to vehicle-treated chicks. Results suggest that NPY-associated factors and glucose transporters are differentially-expressed between LWS and HWS chickens and that HWS chicks display greater sensitivity to exogenous insulin during the early post-hatch period.

Sexual difference of eggshell hormone contents during the early post hatch period in the Japanese quail (Coturnix coturnix japonica)

Sexual difference of eggshell hormone contents during the early post hatch period in the Japanese quail (Coturnix coturnix japonica)

In ovo carbohydrate supplementation modulates growth and immunity-related genes in broiler chickens.

A study was undertaken to investigate the role of in ovo administrated carbohydrates on the expression pattern of growth and immune-related genes. In ovo injections (n = 400) were carried out on the 14th day of incubation into the yolk sac/amnion of the broiler chicken embryos. Expression of growth-related genes: chicken growth hormone (cGH), insulin-like growth factor-I & II (IGF-I & II) and mucin were studied in hepatic and jejunum tissues of late-term embryo and early post-hatch chicks. Expression of candidate immune genes: Interleukin-2, 6, 10 and 12 (IL-2, IL-6, IL-10 and IL-12), Tumour necrosis factor-alpha (TNF-α) and Interferon gamma (IFN-γ) were studied in peripheral blood monocyte cells of in ovo-injected and control birds following antigenic stimulation with sheep RBC (SRBC) or mitogen concanavalin A (Con-A). Glucose injection significantly increased the expression of IGF-II gene during embryonic period and both cGH and IGF-II in early post-hatch period, while ribose-injected chicks had higher expression of IGF-II gene during embryonic stage. Enhanced mucin gene expression was also observed in fructose-injected chicks during embryonic age. Glucose-injected chicks had higher expression of IL-6 or IL-10, while those injected with fructose or ribose had higher expression of IL-2, IL-12 and IFN gamma. It is concluded that in ovo supplementation of carbohydrates might help in improving the growth of late-term embryos and chicks. In ovo glucose could modulate humoral-related immunity, while fructose or ribose might help in improving the cellular immunity in broiler chickens.

Skeletal muscle characterization of Japanese quail line selectively bred for lower body weight as an avian model of delayed muscle growth with hypoplasia.

This study was designed to extensively characterize the skeletal muscle development in the low weight (LW) quail selected from random bred control (RBC) Japanese quail in order to provide a new avian model of impaired and delayed growth in physically normal animals. The LW line had smaller embryo and body weights than the RBC line in all age groups (P<0.05). During 3 to 42 d post-hatch, the LW line exhibited approximately 60% smaller weight of pectoralis major muscle (PM), mainly resulting from lower fiber numbers compared to the RBC line (P<0.05). During early post-hatch period when myotubes are still actively forming, the LW line showed impaired PM growth with prolonged expression of Pax7 and lower expression levels of MyoD, Myf-5, and myogenin (P<0.05), likely leading to impairment of myogenic differentiation and consequently, reduced muscle fiber formation. Additionally, the LW line had delayed transition of neonatal to adult myosin heavy chain isoform, suggesting delayed muscle maturation. This is further supported by the finding that the LW line continued to grow unlike the RBC line; difference in the percentages of PMW to body weights between both quail lines diminished with increasing age from 42 to 75 d post-hatch. This delayed muscle growth in the LW line is accompanied by higher levels of myogenin expression at 42 d (P<0.05), higher percentage of centered nuclei at 42 d (P<0.01), and greater rate of increase in fiber size between 42 and 75 d post-hatch (P<0.001) compared to the RBC line. Analysis of physiological, morphological, and developmental parameters during muscle development of the LW quail line provided a well-characterized avian model for future identification of the responsible genes and for studying mechanisms of hypoplasia and delayed muscle growth.

Delayed feeding after hatch caused compensatory increases in blood glucose concentration in fed chicks from low but not high body weight lines

This experiment used 2 lines of chickens that have been selected 54 generations for either low (LWS) or high (HWS) 8-wk BW from the same founder population, sublines (HWR and LWR) in which selection was relaxed in generation 43 in the selected lines, and crosses (HL and LH) made from generation 54 of HWS and LWS. For 8-wk BW, the difference between lines LWS and HWS in generation 54 was approximately 10-fold, whereas for the relaxed contemporary lines they were approximately 7-fold. Three trials were designed to measure developmental, nutritional, and genetic aspects of blood glucose homeostasis during the first 2 wk posthatch. In trial 1, we measured BW, whole blood glucose (BG), and weights (relative to BW) of liver, pancreas, and yolk sac of chicks fed from day of hatch to d 15. In trial 2, we compared those traits in chicks feed-delayed 72 h posthatch and in chicks without feed delay. In trial 3, we evaluated the effect of a 16-h fast on BW and BG on d 3, 8, and 15. There were higher levels of BG in HWS than LWS, and males than females in the fed state. Delayed access to feed for 72 h after hatch was associated with a dramatic reduction in BG. Feeding triggered a compensatory response whereby LWS displayed greater BG but smaller pancreases (% BW; d 15), compared with the controls. There were maternal effects for BW in both fed and fasted states and the reciprocal crosses exhibited heterosis for BG in the fasted state. These results show that chickens selected for high or low BW differ in BG regulation during the early posthatch period.

Adaptive and innate immune molecules in developing rainbow trout, Oncorhynchus mykiss eggs and larvae: Expression of genes and occurrence of effector molecules

The ontogenetic development of the immune system was studied during the egg phase and the early post-hatch period of rainbow trout. Quantitative real-time PCR (qPCR) was used to assess the timing and degree of expression of 9 important immune relevant genes and EF1-α. Further, immunohistochemical staining using monoclonal antibodies was applied on rainbow trout embryos and larvae in order to localize five different protein molecules (MHCII, CD8, IgM, IgT and SAA) in the developing tissue and immune organs. Maternally transferred transcripts of EF1-α mRNA were detected in the unfertilized egg. Early onset of expression was seen for all immune genes at very low levels. The amount of mRNA slowly increased and peaked around and after hatching. The highest increases were seen for MHCII, C3, C5 and SAA. Immunohistochemistry using five monoclonal antibodies showed positive staining from day 84 post fertilization. Skin, gills, intestine, pseudobranch and thymus showed reactivity for MHCII, thymus for CD8, gill mucus for IgT and pseudobranch and cartilage associated tissue for SAA. The importance of detected factors for early protection of eggs and larvae is discussed.

Changes in expression levels of neurotensin precursor and receptor mRNA in chicken intestinal tissues and liver during late embryonic and early posthatching development

Neurotensin is a tridecapeptide that has multiple functions as a neurotransmitter and as a circulating hormone. Neurotensin and its related peptide, LANT6, have been isolated in the chicken, but the mRNA encoding these peptides has not been identified. In this study, we first cloned the cDNA for the chicken neurotensin precursor mRNA from the duodenum and characterized its primary structure and then investigated tissue expression patterns of neurotensin precursor and receptor mRNA. The cDNA encoded a protein of 495 amino acids that contains the sequences of chicken neurotensin and LANT6 in the C-terminal region. Real-time PCR analysis showed that the neurotensin precursor mRNA is preferentially expressed in intestinal tissues, such as the duodenum, jejunum, ileum, and colon/rectum, with temporal increases during the hatching period. The expression levels of neurotensin receptor 1 mRNA were relatively higher during the late embryonic period compared with the posthatching period in the duodenum and jejunum, whereas the expression levels were higher in the colon/rectum during the posthatching period. In the liver, the expression levels of neurotensin receptor 1 were markedly increased during the early posthatching period. These results suggest that chicken neurotensin is involved in the regulation of gastrointestinal and hepatic functions, especially during the hatching period.

The effect of monochromatic photostimulation on growth and development of broiler birds

The only light source for chickens in environmentally controlled houses is an artificial one. Thus, source, spectra, intensity and regimen of light supplementation became major factors in modern meat type bird management. Light spectra affect growth in meat type birds both in ovo and post hatch. Broilers photostimulated in ovo with green light gained significantly more weight than birds incubated under dark conditions. Furthermore, we defined the cellular and molecular events associated with the effect of in ovo green photostimulation on muscle growth. We found that in ovo photostimulation have a stimulatory effect on the proliferation and differentiation of satellite cells and a promoting effect on the uniformity of the muscle fibers in the early post-hatch period. How does in ovo photostimulation affect intracellular events, such as proliferation and differentiation of muscle cells, leading to post-hatch muscle growth? It is possible that the monochromatic green light penetrates the eggshell and has a direct effect on the embryo’s muscle. We were unable to detect any proliferative effect of monochromatic green light on cultured myoblasts derived from standard (un-illuminated) E17 embryos and 3-day-old chicks. A more likely explanation is that green light indirectly affects myoblast proliferation by activating the endocrine system; the latter receives photic cues from the retinal or extra-retinal photoreceptors. We gathered some evidence to support these findings; we have shown a higher expression of growth hormone (GH) receptor mRNA in satellite cells derived from green light illuminated chicks. In addition, plasma GH levels and IGF-I levels in muscle tissue, were higher in the green group relative to the dark one in early post-hatch. Another possible explanation for this phenomenon could be that growth factor secretion is activated in response to green light photostimulation. Both retinal and extra-retinal photoreceptors are active during embryogenesis and can be first detected at E14. Combinations of in ovo and post-hatch green light photostimulation to broilers and turkeys did not cause synergetic effect on growth. In a recent study, we found that in ovo green light photostimulation suppresses the green and red opsin receptors gene expression in the last three days before hatching, while red light enhances their expression. Furthermore, we found that the down-regulation of the green and red opsins in response to incubation under monochromatic green lighting lasted up to 9days post hatch, suggesting a possible epigenetic effect.

NATURAL ANTIOXIDANTS IN HENS' EMBRYOGENESIS AND ANTISTRESS DEFENCE IN POSTNATAL DEVELOPMENT (review)

The success of modern broiler industry is closely associated with breeding programs aimed at production of broiler chickens that show fast growth, high production yield, and efficient conversion of feed. These features of broilers often interfere with their health – as a rule, the higher is productivity, the more is birds’ susceptibility to various stresses, which poses a certain problem for breeding work (1). From a fertilized egg cell to farm housing of chicks, there are various factors (quality of incubation eggs, egg storage conditions, incubation technology, conditions in the period between hatching and delivery to a farm), and their interaction notably affects productivity of reared broilers. In general, all of these factors are significant determinants of the quality of chicks (2). In contrast to mammals, avian embryogenesis occurs in an egg, the semi-closed system with only exchange of gases and water. Today it’s a certainty that successful embryonic development of a chick depends on egg composition and conditions of incubation. Many facts from the available literature show that maternal diet is the main determinant of health and development of offspring in avians, as well as in humans and other mammals. Egg composition is such that it contains in yolk and albumen all the nutrients necessary for the development of future embryo (3). Polyunsaturated fatty acids (PUFA) and natural antioxidants of maternal diet are key important for the development of chick embryos and viability of chicks in early post-hatch period. Indeed, high content of endogenous antioxidants in the egg and embryonic tissues may be a major adaptive mechanism preventing the oxidative stress at hatching. Free radicals: formation, biological functions and control. Free radicals are atoms, or molecules of any compounds containing unpaired electrons (one or more). Most of biologically important free radicals are formed in the presence of oxygen and nitrogen – activators of this process. Both these elements play a significant role in metabolism of human and animals, but under certain conditions they may pass (directionally or randomly) into the molecules of free radicals. Free radicals are highly unstable and very reactive; they can damage DNA, proteins, lipids, carbohydrates, and disrupt cell signaling system (4). DNA damage is associated with mutations, errors of genetic data transfer, impaired protein synthesis, and, in some cases, it leads to cancer. Protein damage causes disorders of ion transport, functioning of receptors, and it changes properties of certain most important enzymes. The oxidation of PUFA in cell membranes affects their structure and properties (fluidity and permeability, etc.), and the activity of membrane-bound enzymes. Damage to biological molecules causes a notable negative effect on growth, development, reproduction, and immunocompetence. In general, for the last three decades the study of free radicals and their adverse effects on biomolecules was mainly focused on lipid peroxidation as a basis of the observed adverse effects. The modern trend of such researches is associated with negative effects of free radicals on proteins and DNA (5, 6). Cells are permanently attacked by free radicals, most of which are elements of a normal metabolism, or the agents of immune response in phagocytes that destruct microbes-invaders. Under normal physiological conditions, about 3-5% of the oxygen utilized by cells and passed to the mitochondrial electron-transfer chain, may leave it to be converted into free radicals (7). In rats, each cell has to process daily about 10 12

Effects of orally applied butyrate bolus on histone acetylation and cytochrome P450 enzyme activity in the liver of chicken – a randomized controlled trial

BackgroundButyrate is known as histone deacetylase inhibitor, inducing histone hyperacetylation in vitro and playing a predominant role in the epigenetic regulation of gene expression and cell function. We hypothesized that butyrate, endogenously produced by intestinal microbial fermentation or applied as a nutritional supplement, might cause similar in vivo modifications in the chromatin structure of the hepatocytes, influencing the expression of certain genes and therefore modifying the activity of hepatic microsomal drug-metabolizing cytochrome P450 (CYP) enzymes.MethodsAn animal study was carried out in chicken as a model to investigate the molecular mechanisms of butyrate’s epigenetic actions in the liver. Broiler chicks in the early post-hatch period were treated once daily with orally administered bolus of butyrate following overnight starvation with two different doses (0.25 or 1.25 g/kg body weight per day) for five days. After slaughtering, cell nucleus and microsomal fractions were separated by differential centrifugation from the livers. Histones were isolated from cell nuclei and acetylation of hepatic core histones was screened by western blotting. The activity of CYP2H and CYP3A37, enzymes involved in biotransformation in chicken, was detected by aminopyrine N-demethylation and aniline-hydroxylation assays from the microsomal suspensions.ResultsOrally added butyrate, applied in bolus, had a remarkable impact on nucleosome structure of hepatocytes: independently of the dose, butyrate caused hyperacetylation of histone H2A, but no changes were monitored in the acetylation state of H2B. Intensive hyperacetylation of H3 was induced by the higher administered dose, while the lower dose tended to increase acetylation ratio of H4. In spite of the observed modification in histone acetylation, no significant changes were observed in the hepatic microsomal CYP2H and CYP3A37 activity.ConclusionOrally added butyrate in bolus could cause in vivo hyperacetylation of the hepatic core histones, providing modifications in the epigenetic regulation of cell function. However, these changes did not result in alteration of drug-metabolizing hepatic CYP2H and CYP3A37 enzymes, so there might be no relevant pharmacoepigenetic influences of oral application of butyrate under physiological conditions.

The oral administration of meat and bone meal-derived protein fractions improved the performance of young broiler chicks

A study was designed to assess the impact of water-soluble proteins and peptides extracted from meat and bone meal (MBM) on broiler chick performance, following their oral delivery during the early post-hatch period. Proteinaceous material was fractionated by size exclusion filtration into weight ranges of &lt;3 kDa (Fraction 1; 0.5 mg protein/mL), 3–100 kDa (Fraction 2; 0.5 mg protein/mL) and &gt;100 kDa (Fraction 3; 0.8 mg protein/mL), which formed the three protein fraction treatments. A total of 1 mL of each of the respective preparations was delivered orally via gavage over 4 days (0.25 µL each day) to Cobb broiler hatchlings. Three control groups: control–unhandled, control–phosphate-buffered saline and control–handled were also included. Chicks were grown to 30 days of age. Feed intake, chick weight gain and feed conversion ratio were determined from day old through to 29 days of age. On Days 10, 16, 23 and 30, the weight of the breast and the small intestine was determined from 10 birds/treatment. For all parameters measured there was no interaction between experimental week and protein fraction treatment. Chicks receiving Fraction 2 had a statistically significant increase in feed intake and weight gain (P = 0.012) compared with the control–unhandled chicks. Chicks receiving Fraction 2 also demonstrated a numerically higher final bodyweight. Mass spectrometric analysis of all three fractions revealed that they each contained a wide array of proteinacious material. The results of this study suggests the likelihood that protein or protein-derived fragment components within the 3–100 kDa molecular weight range of MBM can generate improvements in broiler chick production, and thus promote the need for further research to identify the specific protein(s) responsible for the observed positive growth effects.

Transfer of Chicken Immunoglobulin Y (IgY) from the Hen to the Chick

Chicks depend on maternal antibodies as the main source of passive natural humoral protection until they become immunocompetent. Immunoglobulin Y (IgY), the avian homologue of mammalian IgG is transferred from the circulation of the hen into the egg yolk and then absorbed by the embryo. In the post-hatching period, protein integrity within the yolk sac is critical for normal absorption of the yolk sac content and for IgY transfer to the circulation of the chick. Factors affecting transfer of IgY to the chick may threaten the chick's immune status and increase disease susceptibility during the early post-hatching period. Here we review basic concepts of IgY with special emphasis on the mechanisms of IgY transfer to egg yolk and yolk sac during embryonic development and first days post-hatching.

The effect of including Lactobacillus reuteri KUB-AC5 during post-hatch feeding on the growth and ileum microbiota of broiler chickens

The probiotic strain Lactobacillus reuteri KUB-AC5, which was originally isolated from chicken intestine, was fed to newborn broiler chicks for the first week post-hatch. The growth and ileum microbiota of the chickens were carefully monitored for 6 wk. The inclusion of 5 log cfu/g of feed statistically increased the BW gain in the first week compared with that of the control group, but this effect did not continue thereafter. Significant effects on host feed consumption and the feed-to-growth conversion ratio were not detected. The total amount and composition of ileum bacteria were investigated by quantitative PCR and pyrosequencing of the 16S rRNA gene (rDNA), respectively, and were compared between the control and the probiotic-treated groups. The amount of total bacterial 16S rDNA in ileum samples at d 42 was 5 times higher in the probiotic group than in the control, whereas no significant difference was observed at d 21. A composition analysis revealed the establishment of lactobacilli-enriched microbiota in the probiotic-treated chickens at d 42. At this point, the population level and species diversity of lactobacilli were significantly enhanced compared with those of the control group. In addition, Actinobacteria, mainly genera Corynebacterium and Dietzia, were also statistically higher in the probiotic group. However, Proteobacteria, including those of the family Campylobacterales and some other nonbeneficial bacterial groups, were decreased in the probiotic group at the growing stage. Therefore, with probiotic supplementation, it was demonstrated that Lactobacillus reuteri KUB-AC5 in the early post-hatching period had a delayed effect on ileum microbiota, which resulted in the enrichment of potentially beneficial lactobacilli and the suppression of Proteobacteria, including nonbeneficial bacterial groups.

Myogenesis – Possibilities of its Stimulation in Chickens

Due to selection for increased body weight modern broilers are 3-4 times heavier as compared with chickens of the laying type. The muscle mass is mainly determined by the total number of muscle fibres (hyperplasia), their thickness (hypertrophy) and different fibre types. Hyperplasia occurs during either embryogenesis or the early posthatching period. Skeletal muscles originate from the dermatomyotome, which differentiates into four myogenic cell populations: myotomal cells, embryonic myoblasts, fetal myoblasts and satellite cells; the latter are the adult myoblasts, present within adult skeletal muscles to serve as a cell source for both muscle regeneration and self-renewal. Pax3 keeps migrated precursor cells non-differentiated, thereby controlling transcription of the MyoD gene, whereas Pax7 is a significant regulator of the satellite cell population. Manipulation of temperature and light quality and quantity have been proposed as methods of both pre- and postnatal myogenesis stimulation. Being thermogenic stimulants, both thyroid and adrenal hormones substantially stimulate metabolism. Short-term exposure of embryos to increased temperature between days 16 and 18 of incubation directly influences the proliferation and differentiation of muscle fibres, which manifest themselves in increased hyperplasia. Ultraviolet radiation is an effective means for disinfection of hatching eggs, resulting in a change of embryonic mortality rate during breeding. Especially, green light influences both body weight and the satellite cell number in the first days posthatch, thereby enhancing the growth of embryos, and causing a significant increase in both muscle and body weight. In ovo green stimulation probably enhances the proliferation and differentiation of myoblasts, subsequently causing an increase in muscle weight. The present paper highlights the possibilities of enhancing growth and development of skeletal muscles in birds by manipulation of many aspects of their regulation, thereby contributing to a further increase in production efficiency.