Genetic resistance to aflatoxin in Japanese quail.

Progress was rapid in attempts to develop lines of quail resistant to acute aflatoxicosis induced by oral dosing with aflatoxin. After five generations of selection, 8- and 11-fold differences were present in mortality between two selected lines and their respective control lines. These quail lines should be of value in investigating the physiological basis of resistance to aflatoxin.

Effect of dietary aflatoxin concentration on the assessment of genetic variability of response in a randombred population of chickens.

The effect of graded levels of dietary aflatoxin on the assessment of genetic variability of body weight and gain and plasma protein response was tested utilizing the Athens-Canadian randombred population of chickens. Dietary aflatoxin was administered at levels of either 0, 1.25, 2.50 or 5.0 microg/g of diet ad libitum from 7 to 21 days of age to progeny from 58 sire families. Twenty-one-day body weights, gain and plasma protein concentration were used to assess the variation in response.-The administration of increasing levels of aflatoxin resulted in a dose-related decrease of gains and plasma protein concentrations. Plasma protein concentrations were significantly higher among males than females within the control group; however, this difference was reversed as the severity of the aflatoxin challenge increased. Heritability estimates for all responses increased as the level of aflatoxin administered increased. This change was most notable for total plasma protein concentration. Phenotypic correlations for plasma protein concentration and growth measurements tended to diminish with increasing levels of aflatoxin. A similar trend was noted for the genetic correlations; however, a moderate correlation between growth responses and plasma protein response was detected in the 5.0-microg/g aflatoxin treatment group. Genetic correlations were calculated for the same characters between the different levels of aflatoxin. Regardless of which aflatoxin challenges were compared, a very high genetic correlation for 21-day body weight and 7- to 21-day gain was estimated. This variation in growth potential in the toxic environment paralleled that observed in the control environment but at a lower plane. Genetic correlations for plasma protein response across aflatoxin levels diminished as the difference between the levels of aflatoxin administered increased. Plasma protein concentration in the control environment was positively correlated with plasma protein response in groups fed a low level of aflatoxin, but negatively correlated when an aflatoxin challenge of 2.5 microg/g or more was given, suggesting that selection for aflatoxin resistance using plasma protein response as a selection criterion should be made under an aflatoxin stress environment.

The antifungal activity of natamycin toward molds isolated from commercially manufactured poultry feed.

The antifungal activity of natamycin, a polyene antifungal compound, was evaluated on molds isolated from commercial poultry feed. The antifungal activity was measured by determination of the minimal inhibitory concentration (MIC) for natamycin on molds growing on semisolid microbiological medium (potato dextrose agar) containing pure natamycin at concentrations ranging from 0 to 200 mg/liter. Natamycin exhibited a high degree of antifungal activity against the 191 isolates of aspergilli used in this study, with average MIC values ranging from 5.08 to 40.1 mg/liter for Aspergillus fumigatus and Aspergillus parasiticus, respectively. Natamycin was also equally effective in inhibiting the growth of nonaflatoxigenic compared with aflatoxigenic isolates of Aspergillus flavus and A. parasiticus. Natamycin was also efficacious against molds other than aspergilli, with MIC values ranging from 2.15 to 5.80 mg/liter for Paecilomyces and Rhizopus spp., respectively. Natamycin exhibited apparent sporicidal activity against spores of toxigenic strains of Fusarium moniliforme and A. parasiticus but not Penicillium rubrum. This sporicidal activity was evident only when spores were exposed to an in vitro concentration of natamycin of 25 mg/liter or higher for a period of time of at least 12 hr. The growth inhibiting activity of natamycin was more pronounced compared with the sporicidal activity.

An improved microbiological assay for chlortetracycline in avian plasma.

Bacillus cereus was used as the assay organism for the quantification of chlortetracycline (CTC) in avian plasma. Antibiotic medium #8 gave significantly larger zones of inhibition than nutrient agar 1.5% when used as the assay medium (P less than or equal to 0.05). When the CTC concentration was measured in serum, citrated plasma, heparinized plasma, and oxalated plasma, no significant differences were found between the inhibition zone diameters produced on antibiotic medium #8. However, there was a significant decrease in the zone diameters produced on this medium when citrated whole blood, oxalated whole blood, and heparinized whole blood were used instead of plasma. The length of incubation of assay plates was inversely related to the inhibition zone diameter, with an incubation time of 8 hr giving the largest and most distinct zones. Storing prepared assay plates at 4 C for 24 hr before use appeared to decrease the variability of the inhibition zone diameters. Storage of citrated plasma at 4 C for 48 hr and at -60 C for 9 days resulted in no significant decreases in CTC concentrations.

Effects of Eimeria tenella infection and dietary aflatoxin on blood coagulation of young broiler chicks.

Eimeria tenella, aflatoxicosis, and a combination of the two prolonged the prothrombin times of male Cobb broilers. Factor V added to the plasmas of birds infected with E. tenella corrected the prothrombin time. E. tenella infection did not significantly alter the levels of plasma calcium, total plasma protein, or fibrinogen. Adding Factors V, VII, and X to plasma from birds with aflatoxicosis or aflatoxicosis plus E. tenella infection did not correct prothrombin times. Partial correction was achieved by adding normal plasma containing Factor II and fibrinogen. Plasma calcium and fibrinogen levels were not significantly altered in either group whereas total protein levels of these groups were significantly lower. The hemorrhage and mortality in birds infected with E. tenella may be explained in part by the longer prothrombin time resulting from deficiency of Factor V.

Effect of decreased feed intake on serum and pancreatic alpha-amylase of broiler chickens.

Removal of feed from 20-day-old broiler chicks for 24 hours caused serum and pancreatic alpha-amylase activities to increase almost twofold. A 24-hour feeding period following feed removal caused a reduction in serum alpha-amylase to basal levels and a sixfold reduction in pancreatic alpha-amylase activity. Serum alpha-amylase levels remained elevated after long-term feed restriction in adult broilers compared with levels in full-fed controls. Reduction in feed intake in chicks caused by coccidial infections also resulted in increased serum alpha-amylase. In all cases, the degree of change in serum alpha-amylase corresponded inversely to feed intake. It is proposed that the pancreas synthesizes a specific quantity of alpha-amylase, which does not change even under conditions of extended underconsumption of feed. The rate of alpha-amylase secretion is determined, at least indirectly, by the rate of carbohydrate metabolism, and the remainder of the enzyme is stored in the pancreatic cells. A small percentage of the stored enzyme diffuses into the blood and thus directly reflects increased secretion or accumulation of alpha-amylase in the pancreas in response to conditions of carbohydrate utilization.

Relationship of serum alpha-amylase to aflatoxin resistance in Japanese quail.

Serum alpha-amylase (S alpha A) activities were examined in a non-selected population (NS) of Japanese quail and in two lines genetically selected for resistance to aflatoxin. Normal S alpha A activities of both selected lines were significantly lower than that of the NS line (P less than or equal to 0.05). An oral dose of 2.5 mg aflatoxin/kg body weight significantly lowered S alpha A activity in NS quails after 24 hours; 18.0 mg/kg body weight was required to decrease the activity in selected lines to a similar degree. The two selected lines did not differ significantly in response. Disc tube gel electrophoresis of the serum revealed eight bands of S alpha A activity and six S alpha A zymogram phenotypes in the total population using an iodine-staining technique. Neither migration distance nor band width varied with genetic line, but the frequency of quails with at least one of three specific anodic bands was significantly higher in the selected lines (75% and 100%) than in the NS line (27%). The frequencies of the zymogram phenotypes with these bands were similarly increased in the resistant populations. Although there are differences in total S alpha A activity between the selected aflatoxin-resistant lines and the NS line, the presence of specific electrophoretic anodic band types and the S alpha A zymogram may be more useful indicators of aflatoxin resistance.

Microscopic and ultrastructural renal pathology of oosporein-induced toxicosis in broiler chicks.

Kidneys from broiler chicks receiving 300 micrograms of oosporein K salt per gram of feed continuously from 0 to 21 days of age were examined by light and electron microscopy. Chicks that died at 3 days had nephrosis of initial proximal tubular segments with an early pyogranulomatous interstitial response. Macula densa cells had cytoplasmic accumulations of periodic-acid-Schiff-positive granules. Kidneys from chicks surviving 21 days had hypercellular or atrophic glomeruli and hyperplastic dilated proximal tubules. Centrilobular distal tubules were dilated and filled with hyaline basophilic casts. Interstitial fibrosis was prominent in cortical and medullary zones. These findings indicate that oral oosporein is a severe nephrotoxin which can cause visceral urate deposition and severe nephrosis of initial proximal tubular segments. The histopathology of this mycotoxicosis was compared with those of infectious-bronchitis-induced nephrosis and avian urolithiasis syndrome.

Interaction of aflatoxin with Eimeria tenella infection and monensin in young broiler chickens.

Young broiler chicks inoculated with Eimeria tenella and given a diet containing 2.5 mug aflatoxin/g had significantly higher mortality than birds with aflatoxicosis or coccidiosis alone or uninoculated controls. This effect was seen even when a light coccidial infection alone did not increase mortality or cause weight depression. In addition this higher mortality with the combination began earleir and occurred at a higher rate than did mortality from aflatoxin or cecal coccidiosis alone. Dietary monensin sodium (99 umg/g) did not completely prevent mortality and weight depression when aflatoxin and E. tenella were in combination. Aflatoxin and E. tenella singly significantly depressed three-week body weights; however, the depression was most severe when the two were in combination. Both dietary aflatoxin and E. tenella significantly reduced hemoglobin, packed cell volume, and plasma pigmentation, and in combination resulted in more severely reduced hemoglobin, packed cell volume, and plasma pigmentation. Coccidial lesion scores were significantly less for the combination of E. tenella and aflatoxicosis than for coccidiosis alone. This atypical response of the ceca to E. tenella in the presence of dietary aflatoxin was characterized by less distended ceca, very little coagulated blood in the ceca, and apparently more profuse cecal hemorrhage.

Induced systemic candidiasis in young broiler chickens.

Systemic candidiasis was induced in broiler chickens 14 days old by intravenous injection of a suspension of viable Candida albicans cells. Injection resulted in decreased body weight, moderate mortality, swollen and reddened livers and kidneys, pancreatitis, and disturbances of the nervous system. Three types of neutral disturbances were observed: 1) extreme opisthotonus with spasmodic tremors; 2) extreme torticollis with cranial rotation of 270 degrees: and 3) extreme torticolis which resulted in the head being drawn in a medial-ventral direction. None to 50% of the inoculated birds exhibited these neural disturbances, depending on the isolant of C. albicans used. Microbiological examination of internal organs and blood revealed that C. albicans localized in the meninges of the brain. There was also a significant isolant-related effect of C. albicans on the growth rate of the inoculated birds. These easily quantitated differential effects of various isolants of C. albicans offer the prospect of correlating biochemical characteristics with virulence and obtaining information about the mechanism of pathogenicity of this microorganism.

Oosporein-toxicosis in the turkey poult.

Turkey poults were fed diets containing oosporein at concentrations of 0, 500, 1,000, and 1,500 micrograms/g from hatching until three weeks of age. Low feed consumption resulted in poor growth rates at every dietary level of oosporein; however, a dose-related increase in water consumption was observed. The most significant effect of dietary oosporein was severe visceral and articular gout, with death ensuing in 24 and 52% of the poults at the 1,000 and 1,500 micrograms/g levels, respectively. Gout and mortality were absent at 0 and 500 micrograms/g. In addition to tissue urate deposition, necropsies revealed dehydration, swollen pale kidneys, hemorrhagic proventriculitis with mucosal necrosis, gizzard enlargement and lining discoloration, an increase in gall bladder size, and focal hepatic necrosis. The relative weights of the kidney, liver, proventriculus, gizzard, and pancreas were increased in a dose-related fashion; spleen and bursa weights were unaffected. Among plasma constituents, uric acid, urea, and the activities of glutamic-oxalacetic transaminase and lactic dehydrogenase were elevated in response to dietary oosporein; albumin, potassium, phosphorus, and calcium were decreased. The toxin had no effect on plasma total protein, sodium, glucose, cholesterol, triglycerides, alkaline phosphatase, or creatine phosphokinase. These data substantiate the original classification of oosporein as a nephrotoxin and etiologic agent of gout in avian species.

Acute toxicity of boric acid and boron tissue residues after chronic exposure in broiler chickens.

The acute oral mean lethal dose of boric acid in 1-day-old chickens was found to be 2.95 +/- 0.35 g/kg of body weight, which classifies this product as only slightly toxic to chickens. One-day-old broiler chicks were housed in floor pens in which litter had been treated with 0, 0.9, 3.6, or 7.2 kg of boric acid per 9.9 m2 of floor space. Boron residue levels in brain, kidney, liver, and white muscle were not statistically elevated following a 15-day exposure period. Boron residue levels in the same types of tissue were not significantly elevated in chicks fed 500 ppm or 1250 ppm boric acid in feed ad libitum for 3 weeks; however, residues were significantly higher in chicks fed 2500 ppm or 5000 ppm boric acid. These data indicate that broilers grown on boric acid-treated litter do not consume enough boric acid to cause elevated boron levels in tissues.

The individual and combined effects of citrinin and ochratoxin A on renal ultrastructure in layer chicks.

Layer chicks fed 3.0 micrograms of ochratoxin A (OA) and 300 micrograms of citrinin (CTN) per gram of feed, alone and in combination, were evaluated for changes in renal ultrastructure. Feeding OA from 0 to 21 days of age was associated with proximal tubular intranuclear membrane-bound inclusions, elongated tortuous and ring-shaped mitochondria, enlarged mitochondrial matrix granules with hyaline centers, and an increase in number and size of peroxisomes and secondary lysosomes. Birds fed OA from 0 to 7 days and then given untreated ration had similar changes but to a lesser degree. Feeding CTN from 0 to 21 days of age was associated with similar proximal tubular nuclear inclusions, elongated tortuous and ring-shaped mitochondria, and an increase in size and number of peroxisomes and secondary lysosomes. Hyalinized mitochondrial matrix granules were not present, and some proximal tubular cells had cytoplasmic aggregates of smooth endoplasmic reticulum. Birds fed CTN from 0 to 7 days had similar but milder changes. Birds fed CTN + OA for 21 days had changes similar to those fed OA alone and also had cytoplasmic aggregates of smooth endoplasmic reticulum similar to those of CTN-fed birds. Again, changes in birds fed CTN + OA for 7 days were similar but milder.

Experimental exposure of broiler chickens to boric acid to assess clinical signs and lesions of toxicosis.

One-day-old broiler chicks were housed on litter treated with 0, 0.9, 3.6, or 7.2 kg of boric acid per 9.3 m2 of floor space. After 15 days, average body weights were 340.7 g, 278.1 g, and 213.2 g for chickens exposed to 0, 3.6, and 7.2 kg boric acid/9.3 m2, respectively (P < or = 0.05). Feed conversion was 1.68 and 2.29 in chickens exposed to 0 and 7.2 kg boric acid/9.3 m2 (P < or = 0.05). In a second experiment, after birds ingested feed treated with 2500 and 5000 ppm of boric acid for 2 weeks, body weights were 254.8 g and 149.6 g, respectively. The chickens in the control group weighed an average of 285.0 g (P < or = 0.05). The 5000 ppm treatment group had a feed conversion of 1.70, vs. 1.45 in the controls (P < or = 0.05). A dose-related feathering abnormality was evident in treated chickens. No significant histopathologic changes were observed. Livability, weight gain, and feed conversion were not adversely affected in broilers as a result of exposure to litter treated with boric acid at recommended levels of 0.4-0.9 kg/9.3 m2.

Interaction of aflatoxin with infectious bursal disease virus infection in young chickens.

Young White Leghorn chickens fed 2.5 microgram of aflatoxin (Afl) per g of diet from hatching until 4 weeks old and infected with infectious bursal disease virus (IBDV) at 3 weeks old had significantly higher mortality and more severely depressed body weights than chicks with aflatoxicosis or IBD alone. Afl-IBDV chicks also had more extensive gross and microscopic changes characteristic of IBD than did IBDV-chicks. None of the treatments significantly reduced antibody responses to Newcastle disease(ND) and infectious bronchitis vaccines or increased susceptibility to challenge with virulent NDV. In a similar experiment chickens fed Afl from hatching to 7 weeks of age had no marked depression in immune response to ND vaccination.

The individual and combined effects of citrinin and ochratoxin A in broiler chicks.

Citrinin (CTN) and ochratoxin A (OA) were fed alone and in combination to broilers from day of hatch until 3 weeks of age. Dietary concentrations of 300 micrograms CTN/g and 3.0 micrograms OA/g were used. Birds fed CTN had significantly (P less than or equal to 0.05) lower body weights than controls on days 14 and 21 and increased water consumption on days 7, 14, and 21. Birds fed OA had significantly lower body weights than controls on days 7, 14, and 21 and increased water consumption on day 14. Birds fed CTN and OA in combination had lower body weights than controls and increased water consumption during the experiment, but the alterations were intermediate in severity when compared with those in birds fed CTN or OA alone. Birds fed OA alone or combined with CTN had higher liver and kidney weights than controls, but birds fed CTN alone had only higher kidney weights. Birds fed both CTN and OA had concentrations of serum constituents similar to those in birds fed OA alone, except the levels of cholesterol and triglycerides were not significantly different from those in the controls. Histological evaluation of the kidney indicated no lesions in birds fed CTN alone, but birds fed OA, alone or in combination with CTN, had increased tubular casts and tubular hyperplasia compared with controls. These data suggest that there were no additive or synergistic toxic interactions when 300 micrograms CTN/g and 3.0 micrograms OA/g were fed simultaneously to broiler chicks for 3 weeks. However, the severe growth depression resulting from OA and the increased water consumption associated with CTN toxicosis were ameliorated when CTN and OA were fed in combination. These data may be useful in diagnosing field cases of mycotoxicosis where both CTN and OA are involved.

Effect of coccidiosis on blood coagulation in broilers.

Severe infection with Eimeria acervulina, Eimeria maxima, Eimeria necatrix, and Eimeria tenella increased the prothrombin times in broilers compared with the times in uninfected birds. Recalcification time was not affected. The increase in prothrombin time was related to the severity of infection (as measured by lesion score), and was significant (P less than or equal to 0.05) only in the most severely infected birds. The increase was of short duration, lasting only 1 or 2 days, and first appeared on day 5 or 6 postinoculation. Restricting the feed intake of uninoculated birds to the amount of feed consumed by infected birds showed that the reduction in feed intake with coccidiosis was not responsible for the increase in prothrombin time.

The effect of diet on performance, digestibility, blood composition and intestinal microflora of weaned pigs.

Good evaluation variables are needed to study postweaning lag in early weaned pigs. In this study, performance, digestibility, concentration of blood components and aerobic fecal microflora under different dietary regimens from weaning at 3 wk of age to 35 d of age are reported. Treatment 1 (T1) consisted of a corn-soybean meal starter diet. Pigs in treatment 2 (T2) received a steamed, rolled oat groats-casein starter diet. Pigs in treatment 1 and 2 were weaned at 3 wk of age while those in treatment 3 remained with the sow. Treatment 1 pigs had lower average daily gains for the 2-wk trial as compared with T2 pigs (P less than .05). Three of the four animals consuming the corn-soybean meal diet were observed to have diarrhea during the experiment as compared with an occasional loose stool from the pigs fed oats-casein. There were no significant differences in digestibility of dry matter, crude protein or ether extract among pigs in T1 and T2. Digestibilities of ash and crude fiber were higher (P less than .05) in T1 pigs, while there was an increase (P less than .05) in digestibility of N-free extract by pigs in T2. Serum protein, Na, CO2 and blood hematocrit were not significantly different among treatments. Blood chloride was higher, whereas glucose was lower for pigs in T1 and T2 than T3 (P less than .05). Blood urea N was higher for pigs in T1 as compared with pigs in T2 or T3. Potassium was higher (P less than .05) for pigs in T1 as compared with those in T2 or T3.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of aflatoxin on the humoral and cell-mediated immune systems of the chicken.

Chickens fed 2.5 microgram of aflatoxin/g of diet from 2 to 4 weeks of age or from hatching to 4 weeks were deficient in cell-mediated immunity, as measured at 4 weeks of age by the graft-versus-host reaction. Delayed-type hypersensitive skin reactions to tuberculin were also reduced in chickens given dietary aflatoxin from hatching to 7 weeks of age. Humoral immunity, as measured by the ability of 4-week-old chicks to produce natural agglutinins to rabbit red blood cells, was not significantly altered by dietary aflatoxin. A significant decrease in concentrations of serum immunoglobulins (Ig) IgG and IgA, but no IgM, however, did occur in chicks given dietary aflatoxin from hatching to 4 weeks or between 2 and 4 weeks of age. Aflatoxin consumption from 0 to 2 weeks of age produced no marked effect on either cell-mediated or humoral immunity in 4-week-old chicks.

Leukoencephalomalacia in a white-tailed deer from North Carolina.

Leukoencephalomalacia similar to equine leukoencephalomalacia occurred in a white-tailed deer (Odocoileus virginianus) from North Carolina. The deer was recumbent and stuporous when presented for examination. It was believed that the disease resulted from ingestion of moldy field corn, infected with Fusarium moniliforme.