Manish Mehra

In Ovo Administration of Silver Nanoparticles and/or Amino Acids Influence Metabolism and Immune Gene Expression in Chicken Embryos

Due to their physicochemical and biological properties, silver nanoparticles (NanoAg) have a wide range of applications. In the present study, their roles as a carrier of nutrients and an immunomodulator were tested in chicken embryos. Cysteine (Cys)+NanoAg injected embryos had smaller livers but heavier breasts on the 19th day of embryogenesis. Cys injected embryos had lower oxygen consumption compared to threonine (Thr) or NanoAg injected embryos. The energy expenditure in Thr+NanoAg, or NanoAg injected embryos was higher than Cys or Cys+NanoAg but was not different from uninjected control embryos. Relative expression of the hepatic insulin-like growth factor-I (IGF-I) gene was higher in Cys or NanoAg injected embryos after lipopolysaccharide (LPS) induction. The gene expression of hepatic tumour necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) did not differ among amino acids, NanoAg and uninjected controls in the non-LPS groups, but increased by many folds in the LPS treated NanoAg, Cys and Cys+NanoAg groups. In LPS treated spleens, TNF-α expression was also up-regulated by NanoAg, amino acids and their combinations, but interleukin-10 (IL-10) expression was down-regulated in Thr, Cys or Thr+NanoAg injected embryos. Toll like receptor-2 (TLR2) expression did not differ in NanoAg or amino acids injected embryos; however, toll like receptor-4 (TLR4) expression was higher in all treated embryos, except for Cys+NanoAg, than in uninjected control embryos. We concluded that NanoAg either alone or in combination with amino acids did not affect embryonic growth but improved immunocompetence, indicating that NanoAg and amino acid complexes can act as potential agents for the enhancement of innate and adaptive immunity in chicken.

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.

In ovo trace element supplementation enhances expression of growth genes in embryo and immune genes in post-hatch broiler chickens

BACKGROUND Differential expression of growth- and immunity-related genes and post-hatch performances were evaluated in in ovo zinc (Zn), iodine (I) or selenium (Se) supplemented chicken embryos. RESULT There was about 9-18% reduction in hatchability of Zn, I or Se supplemented eggs. In ovo trace element supplementation did not improve post-hatch growth. Two-way analysis of data revealed significant effect (P > 0.01) of period, trace elements and their interactions. Expression of hepatic somatotropin, insulin-like growth factor-II and mucin gene was highest at 20(th) embryonic day but decreased during post-hatch periods. In ovo Zn or I supplemented embryos had higher expression of growth-related genes compared to the Se or un-injected control group. Expression of interleukin-6 was higher (P < 0.01) in in ovo I supplemented chicks (2.5-fold) but lower in the Zn and Se groups than in the un-injected control group. However, Zn and Se supplemented chicks had higher cellular immune gene expression. In vivo response to mitogen phytohaemaglutinin was also higher (P < 0.01) in Zn or Se supplemented chicks CONCLUSION In ovo supplementation of Zn, I and Se did not improve the post-hatch growth, but increased growth-related gene expression. Iodine improved humoral immune gene expression whereas Zn and Se enhanced cell-mediated immune gene expression in broiler chickens.

Delayed Post Hatch Feeding Affects Performance, Intestinal Morphology and Expression Pattern of Nutrient Transporter Genes in Egg Type Chickens

Effect of post-hatch (PH) feed deprivation (FD) for 6, 12, 24 and 36 hrs., on the performance, gut development and differential expression of nutrient transporter genes in egg type chickens (crosses of White Leghorn) was studied. Significant decrease (P=0.001) in yolk utilization (in all the FD chicks) and relative weight of gizzard, intestine, liver and pancreas was observed in 24 and 36 hrs FD chicks. The 36 hrs FD chicks recorded lower (P=0.001) body weight, lower feed intake and inferior FCR, decreased serum glucose, but higher cholesterol and uric acid level than the control (immediate fed group) or 6 hrs FD chicks. Villi height in duodenum, jejunum and ileum decreased (P=0.001) but villi width increased (P=0.001) with increase in FD period and significant changes were observed particularly in 24 or 36 hrs FD chicks. Relative expression of Cdx gene decreased with age of the bird and the feed restriction period. Expression of SGLT, FABP gene was not associated with the feed deprivation period, while that of EAAT3 gene increased in 24 or 36 hrs FD chicks. No difference was observed in bursa, spleen and thymus weight. In vivo humoral and cellular immune response was significantly better in chicks FD for 6, 12 and 24 hrs than control and 36 hrs FD chicks. Expression of immunity related genes IL-6 and TLR-2 increased as the FD period increased. It may concluded that PH feed deprival for first 12 hrs did not affect growth performance, intestinal morphology and immune response but feed withdrawal for 24 or 36 hrs adversely affect the intestinal morphology and few nutrient transporter genes expression in egg type chickens.

In ovo silver nanoparticle supplementation for improving the post-hatch immunity status of broiler chickens

ABSTRACT Silver nanoparticles (AgNano) are known for their unique physical, chemical and biological properties, enabling cell penetration and anti-inflammatory response. In Experiment 1, the effect of an in ovo administration of AgNano (15 µg/egg; n = 360) at different incubation times (d 7 and d 18) on hatchability parameters was explored. In Experiment 2, post-hatch performance of broilers (42 d, n = 250) was studied after in ovo AgNano administration: Group T1 remained un-injected, Group T2 was the sham control and Groups T3, T4 and T5 were injected with 12.5, 25 and 50 µg AgNano, respectively, at 18 d of incubation. Chick weight, chick to egg weight ratio and hatchability as well average daily gain, average daily feed intake and feed conversion ratio were similar in all treatment groups. No variation was seen in the weight of thymus; however, the bursa and spleen weight was increased (p < 0.05) in Groups T4 and T5 in comparison to Group T1. The in vivo immune response to phytohaemagglutinin-P was increased in Group T3 in comparison to Groups T1 and T2 (p < 0.05), while the response to sheep red blood cells was increased in all AgNano-treated groups in comparison with Group T1 (p < 0.01). The expression of toll-like receptors 2 and 4 genes was up-regulated in AgNano groups in comparison with Groups T1 and T2 (p < 0.01). In summary, an in ovo supplementation of AgNano carried out at d 18 of incubation is effective and modulates the post-hatch immune response without affecting the hatchability, growth and other performance parameters in broilers.

Delayed post-hatch feeding affects the performance and immunocompetence differently in male and female broiler chickens

ABSTRACT The effect of post-hatch (PH) feed deprival for 6, 12, 24 and 36 h was studied in male and female broiler chickens. At 21 d, lower body weight (BW) was recorded in 36 h feed-deprived (FD) birds; however, at 42 d PH, only 36 h FD female birds had lower BW compared to control and other FD birds. Feed intake during 0–21 d PH was lower in 36 h FD birds, but feed conversion ratio did not differ between control and FD birds. The H:L ratio significantly increased in 12–36 h FD male birds and 24–36 h FD females. The humoral immune response was similar in FD and control birds, but the cellular immune response was higher in 12 and 24 h FD female birds. At 36 h the expression of interleukin 6 (IL-6), toll-like receptor-2 (TLR-2) and tumour necrosis factor-α- gene was down-regulated in male birds only. However, the expression of IL-6 and TLR-2 was up-regulated in 12–36 h FD female birds at 7 and 14 d PH. It may be concluded that PH feed deprival for the first 24 h did not affect growth performance but improved immune response in slow-growing broiler females.

Effect of incubational thermal exposures on the hatchability and early posthatch growth performance of broiler chickens

Incubation temperature plays a crucial role in the embryo development, hatchability and post-hatch (PH) adaptability to varied climatic conditions. Effect of exposure to high (39.0°C) or low (36.0°C) temperatures during 4 to 7, 11 to 14 and 18 to 21 d of broiler chicken embryo development was studied. Exposures to high or low incubation temperature did not affect the embryo growth, but the early thermal exposed eggs had higher embryonic mortality. Exposure to high temperature during late incubation period causes early piping, but increased the piping time by four hours. Mid-period thermal exposed eggs recorded higher hatchability. Chick to egg weight ratio was higher in late-low temperature exposed egg. The 14th d PH body weight was lower in early-high temperature exposed chicks, however no difference was observed in 28th d body weight. Chicks having exposure to low temperature during late period had apparently improved FCR (1.60) than the control (1.65) chicks. Low temperature exposed chicks had higher body temperature. The present findings concluded that mid (11–14 d) and late period (18–21 d) exposure to high or low temperature for six hrs could improve the hatchability without affecting the post-hatch performances in broiler chicken.

Role of epigenetic modifications in improving the thermo-tolerance, growth and immuno-competence in poultry: current status and future applications

Epigenetics refer to the changes in gene expression that occur without any underlying change(s) in DNA sequence and can be transmitted through mitosis and/or meiosis across generations. These changes include the DNA methylation; a covalent modification of cytosine at CpGdinucleotides; role of small RNAs and chromatin modifications including histone acetylation, methylation, phosphorylation and others. Though a relatively naive concept in biological sciences, epigenetics has been more researched upon in mammalian species and there is scarcity of studies on poultry species. Epigenetics can also be thought of as those processes that regulate the gene expression in a given cell leading to a particular cellular phenotype. Nutrients, bioactive compounds, environmental factors and hormones trigger changes in the environment of the cell and affect epigenetic phenotype. Nutrigenomics and nutrigenetics are part of the epigenetic studies and are highly correlated to each other. Imprinting and silencing of genes are helpful in deciphering the secrets of natural diversity in different poultry species and variations in their performance and other attributes. By manipulating at gene regulation and expression steps, epigenetic mechanisms play important roles in improving production, immunocompetence, stress regulation as well as health and welfare of poultry. The present review is aimed at highlighting the current status and future applications of epigenetics for improving production, disease resistance and other attributes in poultry.