[Show abstract][Hide abstract] ABSTRACT: The effects of lutein and conjugated linoleic acid (CLA) on growth performance and immune response of broiler chickens were
evaluated in the presence and absence of Salmonella lipopolysaccharide (LPS) immune challenge. Cobb chicks (360; 1 to 22 d of age) were used in a 3 × 2 factorial arrangement
of CLA (0, 1, and 2%) and lutein (0 and 50 mg/kg) dietary levels. At d 8 and 15, birds were injected with BSA to assess IgY
production. At d 20, birds were injected with LPS. Samples of liver, spleen, and duodenum were collected at 3 and 16 h post-LPS
challenge for RT-qPCR analysis of RXRα, RXRγ, PPARα, PPARγ, TLR-4, IL-1β, IL-2, IL-10, and IL-12 gene expression. CLA decreased
BW, BW gain (BWG), and G:F from d 1 to 20, but these effects were reversed when lutein was included in the 1% CLA diet (P < 0.001). The production of IgY anti-BSA increased following a 2% CLA supplementation (P < 0.01). LPS increased the liver:BW ratio at 3 h post-injection (P < 0.001) and decreased BWG at 3, 16, and 40 h (P < 0.001). Lutein decreased plasmatic nitric oxide levels (P < 0.01). LPS downregulated PPARα mRNA in the duodenum (P = 0.02) and liver (P = 0.04), and PPARγ (P = 0.01) and RXRα (P = 0.08) in the spleen; these effects were not reversed by CLA or lutein as initially hypothesized. Although LPS upregulated
IL-1β (P = 0.02) and IL-12 (P = 0.07) expression, lutein downregulated these pro-inflammatory cytokines in the liver (P = 0.03 and P = 0.07, respectively). Lutein decreased splenic (P = 0.09) but increased hepatic (P = 0.06) TLR-4 mRNA. A dietary CLA supplementation of 2% increased hepatic RXRα (P = 0.10). In conclusion, CLA decreased broiler chicken growth performance, but lutein could prevent this negative effect (depending
on CLA dose). Lutein had an anti-inflammatory effect, and a 2% CLA supplementation improved the humoral immune response.
[Show abstract][Hide abstract] ABSTRACT: Critical care for aquatic birds undergoing rehabilitation as a result of oil spills currently proceeds with minimal information about the nutritional status and needs of the affected animals, and lack of such information may substantially affect the survival of birds through the rehabilitation process and after their release. To objectively evaluate the nutritional condition of aquatic birds undergoing rehabilitation, we performed proximate analyses on carcasses of adult Common Murres Uria aalge (COMU), Western Grebes Aechmophorus occidentalis (WEGR) and Surf Scoters Melanitta perspicillata (SUSC) that died or were euthanized during rehabilitation. Carcasses were selected to capture the widest available range of body conditions. A regression analysis of protein, fat, ash mass and liver and leg muscle mass against total carcass mass examined changes related to presumed loss of body mass. WEGR and COMU were found to have a nadir of fat that illustrates the boundary between phase II and III starvation, at which fat stores have been exhausted. The bird mass at this boundary was approximately 900 g for male WEGR and 675 g for both female WEGR and COMU, which corresponds to 63.0%, 56.3% and 66.0% of their wild mean masses, respectively. For comparison purposes, the mean body mass of WEGR and COMU received for care during the S.S. Jacob Luckenbach oil spill were 70.9% and 70.5% of the wild mean mass, respectively. Protein mass showed a linear decline as carcass mass declined in all comparisons, and the slope of the relationship did not change at a critical point, as would be expected from species that conserve protein while mobilizing fat stores. This suggests the phases of starvation in these species, or in faunivorous birds in general, may vary from that in better-studied omnivorous species. This work shows that birds commonly affected by oil spills in California may not be healthy animals in need of washing, but a large proportion may be presented for care in extreme catabolic states. Rapid capture of oiled animals is advisable to initiate treatment before excessive tissue catabolism results in severe nutritional depletion.
No preview · Article · Jan 2015 · Marine Ornithology
[Show abstract][Hide abstract] ABSTRACT: The nutritional demands of the immune system may result in tradeoffs with competing processes such as growth and reproduction. The magnitude of the nutritional costs of immunity is largely unknown. Thus, we examine the lysine content of the systemic components of the immune system in adult male chickens (Gallus gallus domesticus) in a healthy condition (maintenance) and following a robust Escherichia coli-specific immune response. Lysine was used as a metric, because it is found both in leukocytes and in protective proteins. The dynamics of subsets of leukocytes were monitored in primary and secondary immune tissues (thymus, bone marrow, and spleen) that would be expected to be involved in the response following iv injection of E. coli. The systemic immune system at maintenance has the same lysine content as 332 average-sized feathers, 16% of an egg, or 5.4% of a pectoralis muscle from an adult chicken. During the acute-phase response to E. coli, the additional lysine needed would equal 355 feathers, 17% of an egg, or 5.5% of a pectoralis muscle. The acute-phase proteins accounted for the greatest proportion of lysine in the immune system at maintenance and the proportion increased substantially during an acute-phase response. Hypertrophy of the liver required more lysine than all of the leukocytes and protective proteins that were produced during the acute-phase response. Size of the liver and levels of protein during the acute phase returned to normal during the time when the adaptive response began to utilize significant quantities of lysine. The catabolism would release a surfeit of lysine to provision the anabolic processes of the adaptive response, thus making proliferation of lymphocytes and production of immunoglobulins very cheap.
No preview · Article · Sep 2014 · Integrative and Comparative Biology
[Show abstract][Hide abstract] ABSTRACT: Sensory systems define an animal's capacity for perception and can evolve to promote survival in new environmental niches.
We have uncovered a noncanonical mechanism for sweet taste perception that evolved in hummingbirds since their divergence
from insectivorous swifts, their closest relatives. We observed the widespread absence in birds of an essential subunit (T1R2)
of the only known vertebrate sweet receptor, raising questions about how specialized nectar feeders such as hummingbirds sense
sugars. Receptor expression studies revealed that the ancestral umami receptor (the T1R1-T1R3 heterodimer) was repurposed
in hummingbirds to function as a carbohydrate receptor. Furthermore, the molecular recognition properties of T1R1-T1R3 guided
taste behavior in captive and wild hummingbirds. We propose that changing taste receptor function enabled hummingbirds to
perceive and use nectar, facilitating the massive radiation of hummingbird species.
[Show abstract][Hide abstract] ABSTRACT: Research that advances the practice of poultry nutrition covers a wide range, including fundamental studies that explore mechanisms
in cells or a small number of birds and applied research that determines product yield in authentic production facilities.
Ultimately, the applied research informs the economic analysis necessary for implementation of novel nutritional strategies
or products. Nutritional controversies arise from applied research experiments that were not designed and interpreted based
on the realities learned from mechanistic work. The experimental design and measurements selected for comparing nutrient sources
or setting nutrient recommendations should be informed by underlying mechanistic information, such as the relative priorities
of cells and tissues for the nutrient and the shape of the dose response relationship across a wide range of added dietary
levels of the nutrient. Integrating mechanistic and applied research provides more robust results that can be used across
wider ranges of diets and husbandry conditions.
Preview · Article · May 2014 · The Journal of Applied Poultry Research
[Show abstract][Hide abstract] ABSTRACT: Consistent, stable behavioural differences in how individuals respond to novel situations can lead to variation in exposure to pathogens. To minimize the costs associated with pathogen infection, animals have evolved behavioural and immunological strategies to avoid infection. However, because both behavioural and immunological defences are costly, host individuals should benefit from balancing investment in these defence strategies. It has been suggested that one such behavioural defence strategy is hesitancy to engage with novel objects and environments. In particular, exploratory individuals appear more likely to be exposed to novel pathogens than less exploratory individuals. Here, we tested the hypothesis that immune function is inversely related to behaviours with the potential to decrease exposure to pathogens (i.e. forgoing exploratory behaviours). We found an inverse association between aspects of innate immune function and exploratory behaviours. These observations suggest that individuals that engage in low-risk behaviours when experiencing a novel situation may invest less in some aspects of innate immune function than individuals that engage in high-risk behaviours. This individual variation in pathogen defence strategy is expected to affect the dynamics of pathogen spread through populations, and ultimately the course of epidemics.
No preview · Article · Mar 2014 · Animal Behaviour
[Show abstract][Hide abstract] ABSTRACT: Gene targeting by homologous recombination or by sequence-specific nucleases allows the precise modification of genomes and genes to elucidate their functions. Although gene targeting has been used extensively to modify the genomes of mammals, fish, and amphibians, a targeting technology has not been available for the avian genome. Many of the principles of humoral immunity were discovered in chickens, yet the lack of gene targeting technologies in birds has limited biomedical research using this species. Here we describe targeting the joining (J) gene segment of the chicken Ig heavy chain gene by homologous recombination in primordial germ cells to establish fully transgenic chickens carrying the knockout. In homozygous knockouts, Ig heavy chain production is eliminated, and no antibody response is elicited on immunization. Migration of B-lineage precursors into the bursa of Fabricius is unaffected, whereas development into mature B cells and migration from the bursa are blocked in the mutants. Other cell types in the immune system appear normal. Chickens lacking the peripheral B-cell population will provide a unique experimental model to study avian immune responses to infectious disease. More generally, gene targeting in avian primordial germ cells will foster advances in diverse fields of biomedical research such as virology, stem cells, and developmental biology, and provide unique approaches in biotechnology, particularly in the field of antibody discovery.
Preview · Article · Nov 2013 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: High doses of Zn are widely used for prevention and treatment of diarrhoea in weaning piglets; however, the mechanism of action of Zn against diarrhoea is still not well understood. The objective of this study was to evaluate whether weaning induces Zn deficiency in piglets. Eight litters of primiparous sows were selected for the experiment, and 3 piglets presenting similar weights were selected within each litter. Two of the three selected piglets from each litter were weaned at 21d of age and fed two different diets: a commercial control diet (WCt) and the same diet plus 2000 ppm of Zn as ZnO (WZn). The third selected pig from each litter was kept unweaned (Uw) with the sow and the rest of the litter. All 24 selected animals were killed at 28 d of age, and blood, gastrointestinal content, liver, pancreas and spleen were sampled for Zn, Fe and Cu analysis (mg/kg or L of sample). Data were analysed using anova including treatment as a fixed factor. Weaned pigs fed WCt diet presented a lower Zn concentration in plasma than Uw animals (0.76 ± 0.091 vs. 1.10 ± 0.099 mg/L, p = 0.05). Zinc levels in liver, pancreas and spleen were not affected by weaning. Total concentration of Zn was higher in gastrointestinal contents of weaned animals fed WCt diet than in Uw pigs (p ≤ 0.001 for stomach, jejunum, ileum, caecum and colon). Supplementation with high doses of ZnO increased levels of Zn in gastrointestinal content (p < 0.001), liver (p < 0.001) and pancreas (p < 0.001) compared to WCt diet. It also increased plasma Zn to non-deficient levels (1.32 ± 0.086), but the increase was not as marked as in other locations and final concentration was not different than that in Uw animals (p = 0.231). Weaning creates a Zn deficiency situation in weaned pigs as observed by plasma Zn concentrations. ZnO supplementation counteracts Zn deficiency.
Full-text · Article · May 2013 · J Anim Physiol a Anim Nutr
[Show abstract][Hide abstract] ABSTRACT: Taste has evolved largely as a mechanism to identify nutritious foods and is important for detecting nutritionally relevant carbohydrates, amino acids, lipids, salts and toxic compounds. Species differences in the taste system are intimately related to ecological niche and food availability. It has been argued that birds have a lower taste acuity compared to mammals due to their low taste bud numbers. In addition, chickens seem to have fewer taste receptor genes: the sweet taste receptor is missing and their bitter taste receptor repertoire is very small, consisting of only three members. Furthermore, chickens compared to pigs show a lower sensitivity to glucosinolates. However, chickens are able to quickly adapt their feeding behaviour based on taste cues and the ratio of the number of taste buds/oral cavity volume is higher than in most mammals. Compared to ruminants, chickens show higher aversion to glucosinolates and compared to humans a similar avoidance to quinine chloride. Moreover, many birds (including commercial chicken breeds) seem to have high acuity for dietary calcium. Emerging knowledge mostly derived from genome sequencing, shows that birds have a well-developed taste system. Predicted taste genes for umami, sour, salt, bitter, calcium and lipids are present in the chicken, turkey and zebra finch genomes. Preliminary data indicate that the umami taste receptor may be intact in chickens and that the bitter taste receptor repertoire is small in chickens, but in some bird species it is as large as in mammals. Some of the novel findings outlined in the review have the potential to bring important innovations to the practice of poultry nutrition such as reduction in phosphorus excretion, optimize the use of amino acids and fats, use of alternative feedstuffs or the short and long term manipulation of feed intake. In conclusion, the avian taste system is well developed but differs significantly with different species. Behavioural and genetic evidence show that birds have an accurate capacity to detect different taste modalities challenging the broad consensus that birds have lower taste acuity than mammals. Finally, avian taste is intimately related to nutrient sensing and, consequently, to poultry nutrition practices.
No preview · Article · Mar 2013 · Animal Feed Science and Technology
[Show abstract][Hide abstract] ABSTRACT: The immune response is thought to be costly and deters from growth and reproduction, but the magnitude and sources of these costs are unknown. Thus, we quantified the changes in mass of leukocytes (CD4(+) and CD8(+) T cells, Bu1(+) IgM(+) and Bu1(+) IgG(+) B cells, monocytes/macrophages, heterophils and thrombocytes) and protective plasma proteins in systemic (non-mucosal) components of adult chickens injected intravenously with dead E. coli. During the first day after E. coli injection most types of blood leukocytes decreased and α-1-acid glycoprotein increased. Specific IgM, specific IgY, total IgM, Bu1(+) lymphocytes in the spleen and bone marrow and thymic CD8(+) lymphocytes increased at 5d post-injection. Quantitatively, the increases in the weight of cells and antibodies due to E. coli were dwarfed by the increase in the weight of the liver and acute phase proteins. Thus the acute phase response was markedly more costly than the subsequent adaptive response. The weight of the cells and proteins of the systemic immune system prior to challenge was 0.14% of body weight. Following E. coli injection, the additional weight of the immune components and the hypertrophy of the liver resulted in a 3.6-fold increase in weight which is equivalent to 18.5% of a large egg.
No preview · Article · Mar 2013 · Developmental and comparative immunology
[Show abstract][Hide abstract] ABSTRACT: In many oviparous animals, bursting type atresia of ovarian follicles occurs during the reproductive cycle resulting in the escape of yolk into the extracellular compartment. In birds, this ectopic yolk is rapidly cleared by an unknown process that involves the appearance of yolk-engorged macrophage-like cells. To study this unique type of lipid transport, we injected young male chickens intra-abdominally with egg yolk. Absorption of egg yolk from the body cavity markedly increased the triacylglyceride-rich fraction (TRL) of plasma lipoproteins and was coincident with increased levels of plasma triacylglycerides (TAG) but not non-esterified fatty acids (NEFA). Thus, the transport of yolk lipids from the abdominal cavity appears to occur in lipoproteins and be more similar to the transport of hepatic TAG to the periphery via lipoproteins than to transport of adipose TAG to the periphery via NEFA released by the action of lipases. When macrophages were exposed to yolk in vitro, they quickly phagocytized yolk; however, it is unclear if this level of phagocytosis contributes significantly to total yolk clearance. Instead, the chicken macrophage may function more as a facilitator of yolk clearance through modification of yolk lipoproteins and the regulation of the local and systemic immune response to ectopic yolk. Yolk appears to be anti-inflammatory in nature. Yolk did not increase inflammatory cytokines IL-1, IL-6 and IFNγ either in vivo or in vitro; in fact, yolk dampened many inflammatory changes caused by lipopolysaccharide (LPS). Conversely, LPS-induced inflammation retarded yolk clearance from the abdominal cavity and plasma TAG levels.
No preview · Article · Jan 2013 · Journal of Experimental Biology
[Show abstract][Hide abstract] ABSTRACT: Nutrition is an important determinant of the development and efficacy of the immune system. Nutrition is also sometimes used as a management tool to affect changes in the type or magnitude of an immune response. These developments have been the result of difficult research that relies on accepted principles of nutrition to inform the somewhat unknown frontiers of immunology and disease resistance. Historically, plethoric levels of nutrients were thought to boost, improve, or stimulate immunity and these claims were a tool of nutrient marketing because of the intellectual vacuum. These claims illustrate sloppiness in thinking, which fortunately has diminished due to our new appreciation for the role of nutrients in the immune system.
[Show abstract][Hide abstract] ABSTRACT: High doses of ZnO are used to treat diarrhea in weaning pigs but are also an environmental concern. The mechanism of action of Zn against diarrhea is still not well understood. The amount of solubilized Zn, the relation of Zn with Fe and Cu, and the concentration of these elements in the gastrointestinal tract (GIT) are key data to understanding its mechanism of action and optimize its use. Therefore, we studied the Zn, Fe, and Cu concentrations in the GIT content of unweaned, weaned, and ZnO-treated pigs. Eight litters were used and 3 piglets were selected within each litter. Two piglets from each litter were weaned at 21 d of age and fed a commercial control diet (WCt) or WCt + 2000 mg/kg of Zn as ZnO (WZn). The third pig was kept unweaned (Uw) with the sow. All 24 pigs were killed at 28 d of age, GIT contents were sampled, soluble and insoluble fractions of the content were separated, and Zn, Fe, and Cu concentrations were analyzed. Concentration of Zn increased 3 to 5 fold along the GIT (2 to 10 fold in the soluble fraction) for weaned pigs on WZn compared to WCt and Uw pigs (P < 0.01 in all cases). The proportion of total Zn that was present in the soluble fraction was 4 to 10 folds higher in jejunum, ileum, and cecum of Uw pigs than in those weaned (P < 0.01 in all cases) but was not affected by ZnO treatment. Concentration of Fe in the soluble fraction was higher for Uw pigs compared to weaned pigs along the GIT (P < 0.05 in all cases) even when concentration in total content was lower for Uw pigs in stomach (P = 0.001) and jejunum (P = 0.029). Concentrations of Cu were lower in Uw pigs than in weaned pigs along the GIT (P < 0.05 in all cases). Surprisingly, animals on WZn showed a 5 to 10 fold increase of Cu solubilized in distal parts of the GIT (cecum and colon; P < 0.001) compared to other groups. Differences in Zn, Fe, and Cu concentrations found among treatments will be useful in future studies for understanding mechanism of action of ZnO and optimizing its use in order to avoid environmental concerns.
Full-text · Article · Dec 2012 · Journal of Animal Science
[Show abstract][Hide abstract] ABSTRACT: Infection with parasites and pathogens is costly for hosts, causing loss of nutritional resources, reproductive potential, tissue integrity and even life. In response, animals have evolved behavioural and immunological strategies to avoid infection by pathogens and infestation by parasites. Scientists generally study these strategies in isolation from each other; however, since these defences entail costs, host individuals should benefit from balancing investment in these strategies, and understanding of infectious disease dynamics would benefit from studying the relationship between them. Here, we show that Carpodacus mexicanus (house finches) avoid sick individuals. Moreover, we show that individuals investing less in behavioural defences invest more in immune defences. Such variation has important implications for the dynamics of pathogen spread through populations, and ultimately the course of epidemics. A deeper understanding of individual- and population-level disease defence strategies will improve our ability to understand, model and predict the outcomes of pathogen spread in wildlife.
[Show abstract][Hide abstract] ABSTRACT: Introduced disease has been implicated in recent wildlife extinctions and population declines worldwide. Both anthropogenic-induced change and natural environmental features can affect pathogen spread. Furthermore, environmental disturbance can result in changes in stress physiology, nutrition, and social structure, which in turn can suppress immune system function. However, it remains unknown whether landscape variation results in heterogeneity in host resistance to pathogens. Avian pox virus, a pathogen implicated in avian declines and extinctions in Hawaii, was introduced to the Galapagos in the 1890s, and prevalence (total number of current infections) has increased recently in finches. We tested whether prevalence and recovery trends in 7 species of Galapagos finches varied by elevation or human land use. To do so, we used infection data obtained from 545 wild-caught birds. In addition, we determined whether annual changes in 4 aspects of innate immune function (complement protein activity, natural antibody activity, concentration of PIT54 protein, and heterophil:lymphocyte ratio) varied by elevation or land use. Prevalence and recovery rates did not vary by elevation from 2008 to 2009. Avian pox prevalence and proportion of recovered individuals in undeveloped and urban areas did not change from 2008 to 2009. In agricultural areas, avian pox prevalence increased 8-fold (from 2% to 17% of 234 individuals sampled) and proportion of recovered individuals increased (11% to 19%) from 2008 to 2009. These results suggest high disease-related mortality. Variation in immune function across human land-use types correlated with variation in both increased prevalence and susceptibility, which indicates changes in innate immune function may underlie changes in disease susceptibility. Our results suggest anthropogenic disturbance, in particular agricultural practices, may underlie immunological changes in host species that themselves contribute to pathogen emergence.
No preview · Article · Oct 2012 · Conservation Biology
[Show abstract][Hide abstract] ABSTRACT: Many frugivorous avian species kept in captivity develop iron storage disease (ISD) as indicated by high concentrations of hepatic iron and hemosiderin deposits in hepatocytes or phagocytes. In several susceptible species fed diets containing moderate levels of iron, ISD develops because of an inability to match rates of iron absorption to tissue needs. Evidence suggests that the pathophysiologic basis of excess iron absorption is due to high levels of expression of divalent metal transporter-1 that transports iron into enterocytes in the proximal intestine, and ferroportin that exports iron to the circulation. The regulatory basis for this inability to sufficiently down-regulate iron absorption is unknown, but disruptions in the hepcidin-ferroportin axis are likely candidates based on recent research in humans and laboratory rodents. It is likely that ISD-susceptible avian species evolved on foods that were very low in bioavailable iron, so there was strong selection pressure for the efficient capture of the small amount of dietary iron but low selection pressure for preventing iron toxicities. Thus, the transporters and regulatory networks for iron absorption seem to be heavily skewed toward iron storage even when food items that are high in iron are consumed. Infections, trauma and neoplasias that trigger an acute phase response may exacerbate ISD in susceptible species and may be the primary cause in species that are normally resistant to ISD (i.e., those that are normally able to shut down intestinal iron absorption when iron stores are replete). The evolutionary basis that resulted in some avian species to be susceptible to ISD (e.g., dietary cause) seems to differ from many inherited ISD disorders in humans that are thought to have evolved to bolster protection against infectious diseases. However the evolutionary basis of ISD in other mammalian species might be more similar to that in ISD-susceptible avian species.
No preview · Article · Sep 2012 · Journal of Zoo and Wildlife Medicine