Elizabeth A. Koutsos

Nutrition of Birds in the Order Psittaciformes: A Review

Abstract Over 350 species of birds make up the order Psittaciformes; many of these are maintained in captive environments. Malnutrition is commonly diagnosed in captive psittacine birds; therefore, providing nutritionally adequate diets must be a primary concern. This review integrates quantitative information on the dietary habits and nutritional requirements of psittacine birds to facilitate the formulation and evaluation of diets for birds in captivity. Initially, characterization of the diet and feeding strategy of a particular species in the wild can provide insight into appropriate diet choices in captivity. Knowledge of the gastrointestinal anatomy and physiology can be used to elucidate the capacity of that species to utilize various feedstuffs. For example, the presence of a highly muscularized gizzard may allow a bird to utilize a seed-based diet, whereas a species possessing a small gizzard may be unable to process such a diet. Finally, nutrient requirements determined in a particular species or a related species (eg, similar digestive physiology and feeding strategy) may be applied to create a nutritionally adequate diet. Understanding the factors involved in selecting appropriate diets enables aviculturists, veterinarians, and nutritionists to maintain and propagate these birds with increased success.

The effect of an acute phase response on tissue carotenoid levels of growing chickens (Gallus gallus domesticus)

Plasma, liver and skin carotenoids decrease following infectious disease challenges. Since these challenges often involve substantial host pathology and chronic immune responses, the mechanism underlying altered carotenoid deposition is unclear. Therefore, changes in tissue carotenoid levels were examined during an acute phase response induced by lipopolysaccharide (LPS) or interleukin-1 (IL-1). In two experiments, chicks were hatched from carotenoid-deplete eggs (n=28, n=64, respectively) and fed 0, 8 or 38 mg carotenoids (lutein+canthaxanthin)/kg diet. For chicks fed 38 mg carotenoids, but not those fed 0 or 8 mg, LPS generally reduced plasma lutein, canthaxanthin and total carotenoids (P<0.05), and liver lutein, zeaxanthin, canthaxanthin and total carotenoids (P<0.05). Additionally, LPS reduced thymic total carotenoids (P=0.05) and increased thymocyte lutein (P=0.07), zeaxanthin (P=0.07) and total carotenoids (P=0.07). Finally, LPS increased bursal canthaxanthin (P<0.01), but had no effect on shank carotenoids (P>0.5). In chicks hatched from carotenoid-replete eggs (n=36) and fed dietary lutein (38 mg/kg diet), LPS reduced plasma and liver zeaxanthin and liver total carotenoids (P<0.05); IL-1 reduced plasma and liver lutein, zeaxanthin and total carotenoids (P<0.05). Therefore, an acute phase response plays a role in reduced tissue carotenoids during infectious disease.

The acute phase response in Japanese quail (Coturnix coturnix japonica)

Experiments were conducted to determine the effect of injection of lipopolysaccharide (LPS, from S. typhimurium) or muramyl dipeptide (MDP, N-acetylmuramyl-L-ala-isoglutamine) in Japanese quail. Doses of MDP between 0.3 and 10 mg/kg body wt. had no effect on body temperature. In contrast, doses of 1.0-22.5 mg LPS/kg body wt. caused significant increases in body temperature. None of the doses of LPS or MDP resulted in mortality. The febrile response to LPS was diminished following a second injection 48 h after the first, and was absent following a third injection. Plasma zinc, an indicator of the acute phase response, was significantly reduced by either LPS or MDP after the first injection (P<0.001), but not after the second or third injection. Splenic interleukin 1-beta (IL-1beta) mRNA expression was increased after the first and last injection of LPS (P<0.001), but only after the first injection of MDP (P<0.005). Hepatic IL-1beta mRNA expression was increased after the first, but not the third injection of LPS (P<0.001), while MDP had no effect. These data indicate that Japanese quail are less sensitive to MDP than LPS, and that quail demonstrate tolerance to LPS following repeated injections.

AVIAN IRON STORAGE DISEASE: VARIATIONS ON A COMMON THEME?

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.

Nutrition and health in amphibian husbandry

Amphibian biology is intricate, and there are many inter-related factors that need to be understood before establishing successful Conservation Breeding Programs (CBPs). Nutritional needs of amphibians are highly integrated with disease and their husbandry needs, and the diversity of developmental stages, natural habitats, and feeding strategies result in many different recommendations for proper care and feeding. This review identifies several areas where there is substantial room for improvement in maintaining healthy ex situ amphibian populations specifically in the areas of obtaining and utilizing natural history data for both amphibians and their dietary items, achieving more appropriate environmental parameters, understanding stress and hormone production, and promoting better physical and population health. Using a scientific or research framework to answer questions about disease, nutrition, husbandry, genetics, and endocrinology of ex situ amphibians will improve specialists understanding of the needs of these species. In general, there is a lack of baseline data and comparative information for most basic aspects of amphibian biology as well as standardized laboratory approaches. Instituting a formalized research approach in multiple scientific disciplines will be beneficial not only to the management of current ex situ populations, but also in moving forward with future conservation and reintroduction projects. This overview of gaps in knowledge concerning ex situ amphibian care should serve as a foundation for much needed future research in these areas.

Leaping forward in amphibian health and nutrition

The Epidemiology Working Group, a subgroup of the participants of the Disneys Animal Kingdom Workshop on Ex situ Amphibian Medicine and Nutrition, identified a critical need to design and implement approaches that will facilitate the assessment and evaluation of factors impacting amphibian health. In this manuscript, we describe and summarize the outcomes of this workshop with regards (a) the identified gaps in knowledge, (b) identified priorities for closing these gaps, and (c) compile a list of actions to address these priorities. Four general areas of improvement were identified in relation to how measurements are currently being taken to evaluate ex situ amphibian health: nutrition, infectious diseases, husbandry, and integrated biology including genetics and endocrinology. The proposed actions that will be taken in order to address the identified gaps include: (1) identify and quantify major health issues affecting ex situ amphibian populations, (2) identify and coordinate laboratories to conduct analyses using standardized and validated protocols to measure nutritional, infectious diseases, genetic, and hormonal parameters, (3) determine in situ baseline distribution of parameters related to amphibian health, and (4) establish an inter-disciplinary research approach to target specific hypotheses related to amphibian health such as the effects of population genetics (e.g., relatedness, inbreeding) on disease susceptibility, or how environmental parameters are related to chronic stress and hormone production. We think is important to address current gaps in knowledge regarding amphibian health in order to increase the probability to succeed in addressing the issues faced by in situ and ex situ amphibians populations. We are confident that the recommendations provided in this manuscript will facilitate to address these challenges and could have a positive impact in both the health of in situ and ex situ amphibian populations, worldwide.

Effect of varying dietary starch and fiber levels and inoculum source (mule deer vs. dairy cow) on simulated rumen fermentation characteristics

This study measured starch and fiber digestion and microbial fermentation of three commercial exotic animal feeds using mule deer (MD) or dairy cow (DC) rumen inoculum. Diets were formulated to provide either high starch/low fiber (based on neutral detergent fiber fraction; NDF) with either alfalfa (diet A) or grain and oilseed byproducts (diet B) as the major fiber sources or low starch/high NDF (diet C). An initial batch culture incubation was run with diets inoculated with each rumen inoculum (nu2009=u20096; Nu2009=u200936) over a 48u2009hr period with samples taken at different hour points for ammonia, pH, lactate, and volatile fatty acids (VFA). A second experiment was conducted where two continuous culture incubations (MD or DC) were run with six single-flow polycarbonate fermentation vessels per dietary treatment. Diets were fed two times a day over an 8-day period and sampled for ammonia, pH, and VFA before and after feeding on the last 3 days. On day 8, fermenter and effluent contents were collected and analyzed for nitrogen, dry matter digestibility (DMD), and organic matter digestibility (OMD). OMD was greater in MD (Pu2009=u20090.02) and DMD tended to do the same (Pu2009=u20090.06), but there were no differences due to diet (Pu2009>u20090.05). Ammonia concentration was greater in DC (Pu2009<u20090.01), and diets A and B had greater concentrations than diet C (Pu2009<u20090.01). The greater digestibility, higher acetate:propionate (A:P) ratio and increased lactate levels prior to feeding likely led to diet C having a lower pH than diet A (6.59 vs. 6.66, respectively; Pu2009<u20090.01) and led the tendency of A to be lower than C after feeding (Pu2009=u20090.08). A:P ratio was greater in DC than MD before and after feeding (Pu2009<u20090.01) and was greater in diet C than diets A or B (Pu2009<u20090.01). Total VFA production tended to be greater in diets B and C in DC (Pu2009=u20090.06). Rumen fluid source did affect fermentation. Increasing fiber level did not negatively affect fermentation and may increase OMD by removal of negative associative affects by starch on cellulolytic bacteria.