Control Ducklings Research Articles

The effect of XIVb strain of Newcastle disease virus on the haematology of Muscovy ducks and local chickens

Introduction: Anseriform species such as Muscovy ducks, Mallard ducks and geese are commonly known to be susceptible to some of Newcastle disease virus (NDV) strains, while resistant to others. This study was designed to determine and compare the effect of XIVb strain of NDV on the haematological parameters of Muscovy ducks in relation to the local chickens. Methods: Forty experimental birds consisting of twenty Muscovy ducklings and twenty local chicks at five weeks of age were divided into four groups of 10 subjects each, designated as infected chickens (IC), control chickens (CC), infected ducklings (ID) and control ducklings (CD) and were inoculated orally with 107.8/ 0.1ml /bird as the embryo lethal dose (ELD50/ml) of the strain obtained from the National Veterinary Research Institute, Vom. The means of haematological parameters were used to determine the response of the birds in each group and were compared to their controls (at days 0, 3, 7, 10, 14, 21, 28, and 35). Results: The result showed reduction in some of the haematological parameters, such as RBC and PCV, MCV, HB concentration, MCH and leukocyte count of both the IC and ID. RBC was (1.71±0.26×1012/l) and (2.77±0.20×1012/l) in the IC and ID against their control groups (3.69±0.31×1012/l) and (3.71±0.31×1012/l) on day 7PI, respectively. The IC also showed significant (p < 0.05) lymphopenia on days 7, 10 and 21 than the CC while the ID showed significant (p < 0.05) lymphocytosis on days 14, 21, 28 and 35 than the CD. Significance: The haematological parameters of the local chickens are more affected when infected with XIVb strain of NDV than that of the Muscovy ducks.

Muscovy Duck Reovirus Infection Disrupts the Composition of Intestinal Microbiota in Muscovy Ducklings.

Muscovy duck reovirus (MDRV) is highlypathogenic to young Muscovy ducklings. Although MDRV infection results in ducklings' acute watery diarrhea, the effect of MDRV infection on the composition of host's intestinal microbiota remains poorly understood. This study was conducted to investigate the impacts of MDRV on the composition of Muscovy ducklings' intestinal bacterial community. Three-day-old Muscovy ducklings were inoculated with either the virulent MDRV strain MW9710 or sterile Hank's solution, respectively. The cecal microbiota was analyzed between control and mock MDRV-infected ducklings using Illumina MiSeq sequencing at 6 dpi and 17 dpi, respectively. The results indicated that MDRV infection damaged the intestinal mucosa. In addition, MDRV infection caused severe perturbations of gut microbiota by decreasing microbial richness, altering the abundance of certain genera of the gut microbiota at 6 dpi. Specifically, the relative abundance of short chain fatty acids-producing bacteria (including Shuttleworthia, Streptococcus, and Ruminococcus) was reduced in MDRV-infected ducklings than those of control group, whereas, with an enrichment of Enterobacteriaceae (including Plesiomonas, Escherichia_Shigella and Proteus). Furthermore, microbiota analysis showed that the gut microbiota dysbiosis caused by MDRV infection was basically recovered at 17 dpi. Collectively, this study demonstrated that the gut microbiota of Muscovy ducklings were altered due to MDRV infection, mainly featuring as a net loss of beneficial bacteria and a compensatory proliferation of pathogenic bacteria, which may lead to severe pathology to the intestinal mucosa, and ultimately acute diarrhea. These results will provide insights into the pathology of MDRV infection.

Experimental Infection of Common Eider Ducklings with Wellfleet Bay Virus, a Newly Characterized Orthomyxovirus

Wellfleet Bay virus (WFBV), a novel orthomyxovirus in the genus Quaranjavirus, was first isolated in 2006 from carcasses of common eider (Somateria mollissima) during a mortality event in Wellfleet Bay (Barnstable County, Massachusetts, USA) and has since been repeatedly isolated during recurrent mortality events in this location. Hepatic, pancreatic, splenic, and intestinal necrosis was observed in dead eiders. We inoculated 6-week-old common eider ducklings with WFBV in an attempt to recreate the naturally occurring disease. Approximately 25% of inoculated eiders had onset of clinical disease and required euthanasia; an additional 18.75% were adversely affected based on net weight loss during the trial. Control ducklings did not become infected and did not have clinical disease. Infected ducklings with clinical disease had pathologic lesions consistent with those observed during natural mortality events. WFBV was reisolated from 37.5% of the inoculated ducklings. Ducklings surviving to 5 days postinoculation developed serum antibody titers to WFBV.

FTH1 expression is affected by promoter polymorphism and not DNA methylation in response to DHV-1 challenge in duck

Ferritin heavy polypeptide 1 (FTH1) plays a pivotal role in response to viral infections. FTH1 expression is modulated by various pathogens, but the regulatory mechanisms are unknown. We firstly construct duck hepatitis virus 1 (DHV-1) infection model, including morbid ducklings, non-morbid ducklings and control ducklings. Then the mRNA expression of duck FTH1 (duFTH1) was measured mRNA expression of duck FTH1 (duFTH1) in the liver and spleen after duck hepatitis virus 1 (DHV-1) infection using quantitative polymerase chain reaction (qPCR) and found that duFTH1 mRNA was down-regulated significantly in morbid ducklings (liver, P < 0.01; spleen, P < 0.05) compared with the control ducklings. We also found that duFTH1 expression was significantly higher in the spleen (P < 0.01) and liver (P < 0.05) of non-morbid ducklings than in morbid ducklings. Moreover, DNA methylation of the duFTH1 promoter was examined by bisulfite sequencing (BSP) and we found that the duFTH1 promoter was hypomethylated, the relative methylation was only 5.9% and 2.0% in the morbid ducklings and non-morbid ducklings, respectively. The promoter contained a −55 C/T mutation in 75% of non-morbid ducklings, and this polymorphism affected promoter activity. Further analysis suggested that this mutation altered the binding site of the transcription factor NRF1. Binding of NRF1 to the FTH1 promoter was confirmed by electrophoretic mobility shift assay (EMSA) analysis. Thus, our findings revealed the NRF1 was a negative regulator, and lossed of binding of NRF1 to duFTH1 promoter due to −55C/T mutation enhances duFTH1 expression in non-morbid ducks, which provided molecular insights into the effect of duFTH1 expression via promoter polymorphisms, but not DNA methylation, in response to DHV-1 challenge.

Up-regulation of avian uncoupling protein in cold-acclimated and hyperthyroid ducklings prevents reactive oxygen species production by skeletal muscle mitochondria

BackgroundAlthough identified in several bird species, the biological role of the avian homolog of mammalian uncoupling proteins (avUCP) remains extensively debated. In the present study, the functional properties of isolated mitochondria were examined in physiological or pharmacological situations that induce large changes in avUCP expression in duckling skeletal muscle.ResultsThe abundance of avUCP mRNA, as detected by RT-PCR in gastrocnemius muscle but not in the liver, was markedly increased by cold acclimation (CA) or pharmacological hyperthyroidism but was down-regulated by hypothyroidism. Activators of UCPs, such as superoxide with low doses of fatty acids, stimulated a GDP-sensitive proton conductance across the inner membrane of muscle mitochondria from CA or hyperthyroid ducklings. The stimulation was much weaker in controls and not observed in hypothyroid ducklings or in any liver mitochondrial preparations. The production of endogenous mitochondrial reactive oxygen species (ROS) was much lower in muscle mitochondria from CA and hyperthyroid ducklings than in the control or hypothyroid groups. The addition of GDP markedly increased the mitochondrial ROS production of CA or hyperthyroid birds up to, or above, the level of control or hypothyroid ducklings. Differences in ROS production among groups could not be attributed to changes in antioxidant enzyme activities (superoxide dismutase or glutathione peroxidase).ConclusionThis work provides the first functional in vitro evidence that avian UCP regulates mitochondrial ROS production in situations of enhanced metabolic activity.

Enhanced reproduction in mallards fed a low level of methylmercury: An apparent case of hormesis

Breeding pairs of mallards (Anas platyrhynchos) were fed a control diet or a diet containing 0.5 microg/g mercury (Hg) in the form of methylmercury chloride. There were no effects of Hg on adult weights and no overt signs of Hg poisoning in adults. The Hg-containing diet had no effect on fertility of eggs, but hatching success of eggs was significantly higher for females fed 0.5 microg/g Hg (71.8%) than for controls (57.5%). Survival of ducklings through 6 d of age was the same (97.8%) for controls and mallards fed 0.5 microg/g mercury. However, the mean number of ducklings produced per female was significantly higher for the pairs fed 0.5 microg/g Hg (21.4) than for controls (16.8). Although mercury in the parents' diet had no effect on mean duckling weights at hatching, ducklings from parents fed 0.5 microg/g Hg weighed significantly more (mean = 87.2 g) at 6 d of age than did control ducklings (81.0 g). The mean concentration of Hg in eggs laid by parents fed 0.5 microg/g mercury was 0.81 microg/g on a wet-weight basis. At this time, one cannot rule out the possibility that low concentrations of Hg in eggs may be beneficial, and this possibility should be considered when setting regulatory thresholds for methylmercury.

Effects of feed- and water-based enrichment on activity and cannibalism in Muscovy ducklings

Cannibalism is a major problem for commercial production of Muscovy ducks ( Cairina moschata). Surprisingly little is known about the ontogeny of cannibalism in ducks or how to reduce/prevent the problem in a welfare-friendly way. The preventative method typically used by the industry is bill-trimming, which causes acute pain. We hypothesised that cannibalism in Muscovy ducks is a form of redirected foraging, and therefore investigated the effects of different types of environmental enrichment designed to promote foraging behaviour on general activity patterns and the ontogeny of cannibalism. Groups of 17 bill-intact female Muscovy ducklings were randomly assigned from day-old to one of three treatments (5 replicate groups/treatment): (1) water-enriched treatment (water + plastic strings, water + plastic objects + gravel, water + grain mixture, and pure water), (2) feed-enriched treatment (corn silage, alfalfa, grain mixture + gravel, and Astroturf mats + grain mixture + occasionally mealworms), and (3) control (empty troughs). Floors were covered with wood shavings, and feed and water were available ad libitum. Behaviour was recorded during daylight hours on days 7, 11, 14, and 18 of age. Water- and feed-enriched ducklings foraged significantly more than control ducklings and spent significantly less time inactive during the observations. There were no significant differences between water- and feed-enriched ducklings on these measures, or between any of the treatments for preening and locomotion. Water-enriched ducklings used their enrichments significantly more than feed-enriched ducklings. Although time spent foraging was increased in both the water- and feed-enriched ducklings, cannibalism developed in all treatments beginning at 15–17 days of age. At the end of the experiment (35 days of age), there was no significant difference among treatments in the total number of ducklings with injuries inflicted by cannibalism. Feather pecking was also observed in all three treatments, but the frequency was significantly higher at some ages in the control groups than in the water- and feed-enriched groups. Thus, our findings do not support the hypothesis that cannibalism in Muscovy ducks develops from an unfulfilled motivation for foraging.

Role of catecholamines in glucagon-induced thermogenesis.

The present work was undertaken in order to investigate whether the observed thermogenesis following glucagon injection requires the participation of catecholamines. Our experiments aim at studying the effects of intraperitoneal injection of glucagon on metabolic rates, plasma catecholamine and fuel metabolites in guanethidine-treated ducklings reared at thermoneutrality (25 degrees C). The chronic guanethidine treatment induced a marked decrease in catecholamines levels in peripheral tissues (heart, muscle and intestine) but not in adrenals. At thermoneutrality, intraperitoneal injection of glucagon had lower thermogenic effects in guanethidine-treated compared to control ducklings. Glucagon injection elicited a concomitant increase of plasma norepinephrine, metabolic rate and energy metabolites in control ducklings, whereas in guanethidine-treated ducklings, the plasma catecholamines and metabolic rate did not undergo any consistent change. The thermogenic action of glucagon in birds involves at least the mobilization of lipids and catecholaminergic system stimulation.

Responsiveness of plasma catecholamines to intracerebroventricular injection of glucagon in Muscovy ducklings.

Recent investigations have demonstrated a modulatory action of glucagon on shivering via the central nervous system in ducklings. The aim of this study was to investigate the effects of intracerebroventricular injection (i.c.v.) of glucagon on metabolic rates (MR) and plasma catecholamines in control ducklings (TN) and in ducklings exhibiting nonshivering thermogenesis after chronic glucagon treatment: (GT). At thermoneutrality (25 degrees C, Ta), i.c.v. injection of glucagon had no thermogenic effects in TN and GT ducklings. At cold (+4 degrees C, Ta), i.c.v. glucagon injection elicited a concomitant decrease of plasma norepinephrine (NE) and MR in TN ducklings, whereas in GT ducklings, the plasma catecholamines and the MR remained unchanged. These results indicate that glucagon treatment rendered the catecholaminergic system of GT ducklings insensitive to cold or i.c.v. glucagon injection.

Effects of cold acclimation and palmitate on energy coupling in duckling skeletal muscle mitochondria

Gastrocnemius subsarcolemmal and intermyofibrillar mitochondria were isolated from 5-week-old cold-acclimated and thermoneutral control ducklings. In vitro respiration (polarography) and ATP synthesis (bioluminescence) were determined at 25°C. Subsarcolemmal mitochondria showed a higher state 4 respiration and lower respiratory control and ADP/O ratio in cold-acclimated than in thermoneutral ducklings. Palmitate decreased the rate of ATP synthesis in both mitochondrial populations to about 30% of maximal but failed to abolish this process even at high concentrations. It is suggested that both expensive ATP synthesis and increased ATP hydrolysis could contribute synergistically to muscle non-shivering thermogenesis in cold-acclimated ducklings.

Hormonal control of thermogenesis in perfused muscle of Muscovy ducklings.

Endocrine stimulation of muscle nonshivering thermogenesis (NST) in ducklings was investigated in vitro using a perfused hindlimb preparation maintained at 25 degrees C. Effects of flow rate, norepinephrine (NE), epinephrine, and glucagon on perfused muscle oxygen consumption (MO2) and perfusion pressure were studied. Control ducklings (Cairina moschata, 5 wk old) reared at thermoneutrality (25 degrees C, TN) were compared with two age-matched groups exhibiting muscle NST in vivo: cold-acclimated ducklings (4 degrees C, 4 wk, CA) and glucagon-treated ducklings (103 nmol/kg twice-daily, intraperitoneally, GT). Basal MO2 was higher in CA than in TN or GT ducklings and increased in all groups with elevated flow rates. Catecholamines increased both MO2 and perfusion pressure. The maximal effect on MO2 was higher in CA (+ 36%) and GT ducklings (+ 43%) than in controls (+ 31%), but was associated with reduced vasoconstriction. Flow rate did not consistently potentiate the NE response. At high doses, catecholamines became inhibitory on MO2 while a monotonous increase of pressure was still observed. Glucagon, by contrast, slightly decreased both MO2 and pressure. This vasodilatory effect was greater in CA ducklings than controls in preconstricted preparations. In vivo, low-dose epinephrine induced a modest thermogenic effect (+ 10%) in CA ducklings. These findings showed that duckling muscle thermogenesis is directly stimulated in vitro by catecholamines but not by glucagon. Higher in vitro thermogenic effects of NE in ducklings that were expected to exhibit muscle NST in vivo suggests catecholamine involvement in muscle NST in vivo. Potential vascular control of avian muscle NST is discussed.

Effect of chronic cold exposure on Na-dependent D-glucose transport along small intestine in ducklings.

In conditions of chronic cold exposure, ducklings develop a nonshivering thermogenesis that requires a high energy expenditure. Therefore, energy supply becomes essential to cold-acclimated ducklings, which increase their intake of carbohydrate-rich food. The aim of this work was to investigate the effect of cold acclimation on the activity of the intestinal brush-border Na(+)-D-glucose cotransport, which is the first major step controlling glucose entrance into an organism. Cotransport activity was determined by measuring D-glucose uptake in brush-border membrane vesicles isolated from different parts of the small intestine of thermoneutral control (25 degrees C) or cold-acclimated (4 degrees C) ducklings (Cairina moschata). Two D-glucose transport sites were described in ducklings: a high-affinity/low-capacity site and a low-affinity/high-capacity site. The former was mainly located in the ileum and the latter in the duodenum. These two transport sites were altered differently by cold exposure. Major alterations occur in the ileum where 1) a reduction in the Michaelis-Menten constant and maximal transport rate of the high-affinity site was observed, and 2) the occurrence of low-affinity site activity was noted in cold-acclimated ducklings, although it was not detected in the thermoneutral control group. Cold effect on the high-affinity site could be related to the changes in the ileal brush-border membrane vesicle lipids, whereas cold effect on the low-affinity site could be due, at least in part, to the higher glycosyl content found in this segment. The small intestine appears then able to react to cold exposure by increasing both its mucosa mass in proximal segments and D-glucose uptake capacity in ileum to respond to the higher energy demand induced by thermoregulatory requirements.

Runting of Ducklings Associated with Cochlosoma anatis Infection

Ducklings, especially common goldeneye (Bucephala clangula), experiencing poor weight gain and delayed development were reported from a waterfowl park during June and July of 1990. Runting was first noticed between days 5 and 10 post-hatch in the "brooder" building, and although ducklings appeared active and were feeding, they developed at a slower rate than other members of their clutch. Many ultimately died of emaciation and gram-negative bacterial septicemia. Necropsies of affected ducklings revealed large numbers of the intestinal flagellate Cochlosoma anatis, in both the small and the large intestine; however, autolysis impaired histological interpretation in many cases. Inoculation of 1-day-old Muscovy ducklings with feces containing large numbers of C. anatis resulted in poor weight gain and delayed tail-feather development compared with uninoculated control ducklings. Weight gain improved after treatment with metronidazole. Cochlosoma anatis is associated with the runting syndrome observed in ducklings at the waterfowl park.

Expression of sarcoplasmic reticulum Ca2+ transport proteins in cold-acclimating ducklings.

The relationship between the cold-induced increase in sarcoplasmic reticulum (SR) Ca2+ transport proteins and the development of muscular nonshivering theermogenesis (NST) was investigated by determining the time course of expression of the sarcoplasmic or endoplasmic reticulum Ca(2+)-ATPase (SERCA), Ca2+ release channel, and calsequestrin in control and cold-acclimating ducklings. 45Ca2+ uptake and [3H]ryanodine binding measurements with skeletal muscle homogenates showed that a cold acclimation period of approximately 4 wk was required to observe a substantial increase in Ca(2+)-ATPase activity and Ca2+ release channel content, which correlates well with NST development Immunoblot analysis of muscle homogenates showed no differences in calsequestrin levels but revealed that the decrease in SERCA2a content was delayed in cold-acclimating birds and that the SERCA1 level was increased after 4 wk of cold acclimation. The persistence of SERCA2a may be related to shivering thermogenesis occurring preferentially in slow-twitch fibers. SERCA1 may account for most of the cold-induced increase in 45Ca2+ uptake activity, suggesting the preferential occurrence of a Ca(2+)-dependent NST in fast-twitch fibers.

Increased role of skeletal muscle in the calorigenic response to glucagon of cold-acclimated ducklings

The site of the calorigenesis observed in birds after glucagon was sought in control and cold-acclimated (CA) ducklings. Twenty-four 6-wk-old muscovy ducklings were reared either at thermoneutrality (TN) (25 degrees C) or in the cold (4 degrees C) from the age of 1 wk. Glucagon-induced calorigenesis (GIC) was estimated at 25 degrees C after a peritoneal glucagon injection (103 nmol/kg). Glucagon induced a higher increase in animal heat production (indirect calorimetry) and body temperature in CA (+45% and +1.1 degrees C) than in control ducklings (+30% and +0.4 degree C). In CA ducklings, the perfusion rate (thermal clearance method) and temperature of gastrocnemius increased (+130% and +1.0 degree C) shortly after glucagon, whereas tissue oxygenation (polarography) decreased (-34%). There was no significant effect of glucagon in TN controls. These changes, which peaked 45-60 min after glucagon injection, indicated a prolonged increase of muscle O2 consumption in CA ducklings. Leg muscle blood flow (radioactive microspheres) measured 45 min after glucagon was slightly increased in controls (+20%; P < 0.05), while in CA ducklings, the increase was larger (+76%; P < 0.05). The arteriovenous difference in O2 content was not markedly affected by glucagon in both groups. These parameters indicated an increase in leg muscle O2 uptake in response to glucagon of +29% in controls and +76% in CA ducklings. In controls, 28% of the GIC measured in vivo could be attributed to whole body skeletal muscles, compared with 53% in CA ducklings. The remaining part might be accounted for mostly by the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical disinfection of duck hepatitis B virus: a model for inactivation of infectivity of hepatitis B virus.

The susceptibility of duck hepatitis B virus (DHBV) to the virucidal effects of sodium hypochlorite (NaOCl) and sodium dichloroisocyanurate (NaDCC) was compared to hepatitis B virus (HBV) with the aim of using the duck as a model for studying HBV disinfection. Using viral DNA polymerase (DNAP) as a target, inhibition of DNAP activity by chlorine disinfectants was found to be concentration-dependent but independent of contact time. Two minute exposure of minimal effective concentrations of sodium hypochlorite (domestic bleach: 3600 ppm and industrial bleach: 3180 ppm) and sodium dichloroisocyanurate (3000 ppm available chlorine) to DHBV- and HBV-rich plasma totally inhibited DNA polymerase activity. DHBV particles in DHBV-carrier duck plasma (10(4.5) ID50/mL) were treated with these concentrations and inoculated intravenously into 18 one-day old ducklings (six animals/disinfectant). Analysis of plasma (0, 7 and 14 days post-infection) and post-mortem liver (14 days post-infection) by DNA hybridization techniques showed that DHBV DNA was undetectable in samples from all animals inoculated with disinfected virus particles. However, post-inoculation plasma and liver of 18 of 18 control ducklings inoculated with untreated virions were positive for DHBV DNA. These results show for the first time that total inhibition in vitro of hepadnavirus DNA polymerase activity by chemical disinfectants is predictive of inactivation of infectivity in vivo.

Histochemical arguments for muscular non-shivering thermogenesis in muscovy ducklings.

1. The histochemical characteristics of gastrocnemius muscle were investigated in 6-week-old cold-acclimated (5 weeks, 4 degrees C) and glucagon-treated (5 weeks, 25 degrees C, 103 nmol/kg I.P. twice daily) muscovy ducklings, two groups able to develop non-shivering thermogenesis in vivo. A comparison was made with thermoneutral controls (25 degrees C) of the same age. All animals were fed ad libitum. Fibre type, fibre area and capillary supply have been studied. Further, a quantitative histochemical method for mitochondrial Mg(2+)-ATPase activity was developed to characterize the mitochondrial coupling state in situ. 2. White gastrocnemius was composed of fast glycolytic (FG) and fast oxidative glycolytic (FOG) fibres, while red gastrocnemius contained FOG and slow oxidative (SO) fibres. In white gastrocnemius, the proportion of FG fibres was higher in glucagon-treated than in control or cold-acclimated ducklings. In red gastrocnemius, the proportion of SO fibres was higher in both cold-acclimated and glucagon-treated ducklings than in controls. The area of all fibres was generally lower in glucagon-treated than in other ducklings. 3. The capillary density was higher in both red and white components of the gastrocnemius muscle in cold-acclimated and glucagon-treated than in control ducklings, as a result of an increased number of capillaries around each fibre. 4. In all fibres, except the FG type in cold-acclimated ducklings, the staining intensity of the Mg(2+)-ATPase reaction was higher in cold-acclimated and glucagon-treated than in control ducklings whereas the staining intensity with maximal decoupling of oxidative phosphorylation by dinitrophenol was unchanged. This indicated a more loose-coupled state of mitochondria in situ in all fibres of cold-acclimated ducklings, and in FOG fibres of white gastrocnemius and SO fibres of red gastrocnemius in glucagon-treated ducklings. 5. These results indicated a higher oxidative metabolism of skeletal muscle in both cold-acclimated and glucagon-treated than in control ducklings, and for most of the parameters studied, a similarity between cold acclimation and glucagon treatment. Because of the higher loose-coupled state of muscle mitochondria in cold-acclimated and glucagon-treated than in control ducklings, the higher oxidative capacity of skeletal muscle in these ducklings could be used for heat production rather than ATP synthesis and account for muscular non-shivering thermogenesis.

Effects of dietary boron and arsenic on the behavior of mallard ducklings

AbstractHigh concentrations of boron and arsenic have been associated with irrigation drain water and aquatic plants consumed by waterfowl. Both compounds affect the central nervous system and cause generalized physiological distress in mammals and waterfowl. We examined sublethal effects of boron and arsenic on the behavior of developing mallard ducklings (Anas platyrhynchos). Day‐old ducklings received an untreated diet (control) or a diet containing 100, 400, or 1,600 ppm boron, added as boric acid, or 30, 100, or 300 ppm arsenic, added as sodium arsenate. Activity schedules and behavior durations were analyzed for effects at the various treatment levels. Both boron and arsenic at the highest levels had significant effects on the activity schedules of developing ducklings, including increased time at rest and under the provided heat lamp. We also observed decreases in the amount of time treated ducklings spent in alert behaviors and in the water in comparison to control ducklings. High levels of boron (1,600 ppm) increased feeding time overall but did not increase the amount of food consumed. Arsenic had no effect on feeding behavior. There were no differences found in the durations of behaviors as a result of treatment. These findings, in combination with reported effects on the growth and physiology of ducklings under identical treatments, suggest that reported concentrations of these compounds in aquatic plants in the Central Valley of California could adversely affect normal duckling development and survival.

Loose-coupled mitochondria in chronic glucagon-treated hyperthermic ducklings

In chronic glucagon-treated ducklings (GT) showing thermogenic and hyperthermic responses without shivering to glucagon test injection and in control ducklings (TN; both aged 44 +/- 1 days and reared at thermoneutrality), subsarcolemmal (S) and intermyofibrillar (I) mitochondria from gastrocnemius muscle and mitochondria from liver were isolated. Respiration and cytochrome oxidase activity were determined in these isolated mitochondria by polarography and creatine kinase activity by spectrophotometry, both at 25 degrees C. In GT ducklings, the powerful thermogenesis observed in vivo after a glucagon test injection may be due to the uncoupling effect of released free fatty acids (FFA) in loose-coupled mitochondria because their respiration increased as a function of FFA concentration, and the loose coupling of these mitochondria was reversed by addition of albumin. In all types of mitochondria from GT ducklings, the increase in respiration because of FFA was about double that in mitochondria from controls. There was no change in creatine kinase activity from liver and I mitochondria, but a 16% decrease in this enzyme activity (expressed per mg mitochondrial protein) from S mitochondria was shown despite a strong increase in cytochrome oxidase activity from liver mitochondria (+114% if expressed per g tissue) and from muscle mitochondria (I, +53 or +48%; S, +41 or +97% if expressed per mg mitochondrial protein or per g tissue, respectively). These results support a coupling defect in liver and skeletal muscle mitochondria from the GT hyperthermic ducklings and an uncoupling reinforcement by FFA.

Changes in mallard hen and brood behaviors in response to methyl parathion- induced illness of ducklings

Half the young in each of four broods of 5-d-old mallards (Anas platyrhynchos) were gavaged orally with 4 mg/kg methyl parathion and released with their mother and untreated siblings in pond enclosures. Four control broods received corn oil only. Activity categories (swimming, preening, feeding, loafing) of hens and broods were noted every 15 min and continuous observations were made of length of time to recovery or death (dosed ducklings) and of time spent in a behavior. Observations were made for 4 h following release, for an additional 2 to 4 h that afternoon, and for 2 h the following morning. Control broods were on water during 22 of 37 observations, while treated broods were on land more frequently than on water (43 of 51 observations). There was a significant difference (χ2 = 76.4, p < 0.001) between behaviors of treated and control broods; treated broods mostly preened and loafed on land while control broods primarily fed and swam in open water. Hens remained with their broods and kept all ducklings together even when dosed young were too sick to move (for 90 to 155 min posttreatment). Forty percent of dosed ducklings died the first day, whereas no control ducklings died. The results of this study indicate that methyl parathion can affect the brood-rearing phase of reproduction by direct mortality and through behavioral changes.