Aflatoxin production in supplemental feeders provided for northern bobwhite in Texas and Oklahoma.

Mycotoxins are toxic metabolites produced by varous species of fungi. Aflatoxin (AF), a particular type of mycotoxin, can negatively impact many wildlife species in the laboratory; however, the magnitude of the problem in the field environment is unclear. Wild birds generally consume a combination of native foods and agricultural grains. A common practice in which birds, such as northern bobwhite (Colinus virginianus), contact stored agricultural grain is through supplemental feeding. This feeding practice may promote the production of AF. The objectives of this study were to (1) examine AF production in supplemental feeders and (2) examine the relationship between weather and AF production in supplemental feeders. Samples were collected from supplemental feeders from November through February of 1996-97 and 1997-98. Mean monthly AF concentration of samples from feeders ranged from 0.57+/-2.86 to 15.47+/-14.69 ppb. Aflatoxin concentration in supplemental feeders increased from pre-sample to one month after filling the feeders each year. AF production in supplemental feeders was highly variable among months with no real temporal pattern between years. Instead, AF production was related to the highly variable relative humidity of the study area which influences moisture content of grain. Average relative humidity can be used to predict AF production.

Aflatoxin contamination in supplemental and wild foods of northern bobwhite.

Esophagi were removed from northern bobwhite (Colinus virginianus) that were killed by hunters during the 1996-1997 (n = 39) and 1997-1998 (n = 27) hunting seasons in Wheeler County, Texas and Roger Mills County, Oklahoma to determine if they were exposed to aflatoxin (AF) by consuming either wild or supplemental food. Esophagi were segregated into three categories based upon their contents: all wild seeds (n = 11), all supplemental foods (n = 21), and mixed foods (n = 18). Contents of esophagi were then analyzed for AF concentration. Mean (+/- SE) AF concentration (ppb) of wild seeds was 2.44 +/- 0.54; supplemental foods, 0.12 +/- 0.41; and mixed foods, 0.53 +/- 0.40. Wild seeds had higher (P = 0.004) AF concentrations than either the supplemental or mixed categories, although these levels are below those found to cause damage to northern bobwhite. This information suggests that northern bobwhite may consume contaminated food much more often than previously thought.

Exposure of game birds to ochratoxin A through supplemental feeds.

Thirty randomly selected game bird feeders were sampled at 25-33-day intervals from November 1996 to March 1997 to quantitate ochratoxin A concentrations in supplemental feed. Monthly mean ochratoxin A concentration of grain in feeders was 8.3 +/- 0.8 ppb (n = 167). Ochratoxin A concentrations from individual feeders ranged from <5 to 109.9 ppb, levels that have not been demonstrated to negatively affect game birds in a laboratory environment. Stress may increase the chance of ochratoxin-induced mortality or morbidity for wild game birds. Only mean relative humidity was significantly correlated with monthly mean ochratoxin A concentration.

Use of body measurements and serum metabolites to estimate the nutritional status of mallards wintering in the Mississippi Alluvial Valley, USA.

We collected mallards (Anas platyrhynchos) from bottomland hardwood habitats on the Bayou Meto Wildlife Management Area and the White River National Wildlife Refuge, Arkansas County, Arkansas during the winter of 1990 to 1991 to determine if measures of physiological condition could be predicted from structural size, serum metabolite levels, or from direct measures of carcass composition. Serum triglyceride levels were correlated (r = 0.57, P = 0.007) with total body fat in males and slightly increased the value (from R2 = 0.64 to 0.76) of intact body mass alone for predicting total body fat in males. Overall, however, serum metabolites appeared to be poor indicators of the magnitude of nutrient masses in mallards. Three potential indices of nutritional status were developed from carcass composition data: protein/total ash, fat/ total ash, and fat/fat-free body mass. Protein masses of male mallards changed over winter (P = 0.02). Consequently, fat-free masses are not constant and represent poor indicators of structural size for mallards wintering in the Mississippi Alluvial Valley.

Examination of the dietary methionine requirements of breeding northern bobwhite, Colinus virginianus.

Adult Northern bobwhite were used to test the hypothesis that dietary methionine levels recommended by the NRC for breeding quail are excessive for wild bobwhite. We tested the hypothesis by comparing immunocompetence, reproductive performance, and chick viability of Northern bobwhite hens fed diets containing low (0.31%), moderate (0.39%), or high (0.47%) concentrations of methionine. Chick viability was determined by assessing immunocompetence, including evaluating the ability of hens to passively transfer immunity to their chicks. Hens were fed the experimental diets for 6 wk on an ad libitum basis. After 6 wk, methionine treatment had no measurable effect (P > or = 0.20) on hen phytohemagglutinin wing web indices, organ weights, or serum anti-Pasteurella multocida titer indices. Mean egg weight, percentage egg production, total cumulative egg production, yolk weight, yolk volume, and percentage fertile and percentage hatch of fertile eggs did not differ (P > or = 0.12) among diet treatments. Amount of albumen in eggs produced by hens fed the high methionine diet averaged 0.27 g more (P = 0.003) than eggs of hens fed the low methionine diet. Anti-P. multocida titer of yolks from eggs in Week 6 were not different (P = 0.36) between birds fed the high and the low methionine diets. The mortality rate of chicks after challenge with 23 cfu of P. multocida was not different (P > or = 0.05) among diets. Chicks hatched from eggs laid by vaccinated hens during Weeks 2 and 3, however, had lower (P < 0.05) mortality than chicks of unvaccinated hens. It appears a dietary methionine concentration of 0.3% may be sufficient for wild Northern bobwhite to produce viable chicks.

A pathogenic challenge model for adult northern bobwhite (Colinus virginianus) using a vaccine strain of Pasteurella multocida type 3.

A pathogenic challenge model causing approximately 50% mortality was developed in adult Northern bobwhite (Colinus virginianus) using Avichol, a live vaccine containing the Clemson University (CU) strain of Pasteurella multocida Type 3. A dose of 2300 or 3000 colony-forming units (CFU) of Avichol injected intramuscularly resulted in 30 to 75% mortality, whereas a dose of 230 CFU or less resulted in no mortality, and 58,720 CFU or more resulted in death in all birds challenged. Primary and secondary vaccination of Northern bobwhite with a formalinized anaculture of Avichol -derived P. multocida resulted in protection against challenge in three separate experiments. Dexamethasone treatment of birds during vaccination resulted in decreased protection against challenge exposure.

Proliferative responses of splenocytes from wild and domestic northern bobwhites (Colinus virginianus) to T- and B-cell mitogens.

Baseline information on the functional responses expected for assays used to assess immunocompetence in the Northern bobwhite (Colinus virginianus) are largely unavailable. Our primary objective was to develop an in vitro lymphoproliferative response assay for assessing cell-mediated immunocompetence in the Northern bobwhite. Culture conditions were optimised for domestic Northern bobwhites and field tested on splenocytes from wild-caught quail. Results indicated that increasing cell concentration and media volume in culture, as well as decreasing concentrations of serum in media, improved splenocyte responses to Con A stimulation. Optimum culture conditions were attained with 1 million cells per well cultured in 200 microliters of AIM-V serum-free media for 72 h. Five micrograms concanavalin A (Con A) or 2.5 micrograms Salmonella typhimurium mitogen (STM) per well provided maximum stimulation as measured by 3H-thymidine incorporation. Stimulation indices of splenocyte cultures of wild-caught Northern bobwhites to 5 micrograms Con A were approximately four-fold greater than levels observed for domestic quail (P = 0.0055). Alternatively, stimulation indices of splenocyte cultures obtained from wild-caught and domestic Northern bobwhites to 2.5 micrograms STM per well were not different (P = 0.3938).

High in vitro endotoxin responsiveness of macrophages from an endotoxin-resistant wild rodent species, Sigmodon hispidus.

It has been reported that macrophages primarily mediate endotoxin shock and cell death by synthesizing and releasing cytokines, largely tumor necrosis factor (TNF) and interleukin-1 (IL-1). However, macrophages from some laboratory mouse strains such as C3h/HeN are unresponsive to endotoxin both in vivo and in vitro. We found members of a wild rodent species, Sigmodon hispidus, to also be extremely resistant to bacterial endotoxin challenge. Intravenous administration of up to 100,000 micrograms/kg body mass of Escherichia coli O26:B6 endotoxin did not cause lethality in adult S. hispidus. In contrast to the endotoxin-resistant mouse strain, peritoneal macrophages derived from S. hispidus were responsive to in vitro endotoxin challenge as measured by high levels of TNF and IL-1 activity in supernatants of macrophage cultures. Thus, in vitro macrophage responsiveness to endotoxin does not always indicate high host sensitivity to endotoxin challenge.

Serum enzymes as indicators of capture myopathy in mallards (Anas platyrhynchos).

Serum concentrations of the enzymes creatine kinase (CK) and aspartate aminotransferase (AST) were measured in captive and wild mallards (Anas platyrhynchos) as indicators of muscle damage. Baseline values for both enzymes were determined from six captive male mallards. During winter 1990 to 1991, six diets (including controls) representative of food available in the Mississippi alluvial valley were fed to captive female mallards housed in an outdoor aviary at the White River National Wildlife Refuge, Arkansas County, Arkansas (USA). Controlled handling of penned mallards resulted in elevated serum CK (means = 1,352 IU/liter; SD = 1,212) and AST (means = 101 IU/liter; SD = 95) concentrations consistent with myopathies. These serum enzyme elevations were not affected (P > 0.3) by dietary selenium concentrations in the six diets or by energy malnutrition suffered by birds fed soybeans. Capture of wild mallards with an entanglement type rocket net resulted in serum CK and AST concentrations (means = 12,035 and 330 IU/liter; SD = 8,125 and 171, respectively) that were higher (P < 0.001) than those reported after capture with an enveloping type rocket net. Baseline values, controlled handling values, and entanglement rocket net values for serum CK and AST all differed (P < 0.0001).