A study of aflatoxicosis in laying hens

Response of the hepatic transcriptome to aflatoxin B1 in domestic turkey (Meleagris gallopavo)

Dietary exposure to aflatoxin B₁ (AFB₁) is detrimental to avian health and leads to major economic losses for the poultry industry. AFB₁ is especially hepatotoxic in domestic turkeys (Meleagris gallopavo), since these birds are unable to detoxify AFB₁ by glutathione-conjugation. The impacts of AFB₁ on the turkey hepatic transcriptome and the potential protection from pretreatment with a Lactobacillus-based probiotic mixture were investigated through RNA-sequencing. Animals were divided into four treatment groups and RNA was subsequently recovered from liver samples. Four pooled RNA-seq libraries were sequenced to produce over 322 M reads totaling 13.8 Gb of sequence. Approximately 170,000 predicted transcripts were de novo assembled, of which 803 had significant differential expression in at least one pair-wise comparison between treatment groups. Functional analysis linked many of the transcripts significantly affected by AFB₁ exposure to cancer, apoptosis, the cell cycle or lipid regulation. Most notable were transcripts from the genes encoding E3 ubiquitin-protein ligase Mdm2, osteopontin, S-adenosylmethionine synthase isoform type-2, and lipoprotein lipase. Expression was modulated by the probiotics, but treatment did not completely mitigate the effects of AFB₁. Genes identified through transcriptome analysis provide candidates for further study of AFB₁ toxicity and targets for efforts to improve the health of domestic turkeys exposed to AFB₁.

Aflatoxicosis chemoprevention by probiotic Lactobacillius and lack of effect on the major histocompatibility complex

Turkeys are extremely sensitive to aflatoxin B1 (AFB1) which causes decreased growth, immunosuppression and liver necrosis. The purpose of this study was to determine whether probiotic Lactobacillus, shown to be protective in animal and clinical studies, would likewise confer protection in turkeys, which were treated for 11 days with either AFB1 (AFB; 1 ppm in diet), probiotic (PB; 1 × 10(11) CFU/ml; oral, daily), probiotic + AFB1 (PBAFB), or PBS control (CNTL). The AFB1 induced drop in body and liver weights were restored to normal in CNTL and PBAFB groups. Hepatotoxicity markers were not significantly reduced by probiotic treatment. Major histocompatibility complex (MHC) genes BG1 and BG4, which are differentially expressed in liver and spleens, were not significantly affected by treatments. These data indicate modest protection, but the relatively high dietary AFB1 treatment, and the extreme sensitivity of this species may reveal limits of probiotic-based protection strategies.

Effect of tryptophan supplementation on aflatoxicosis in laying hens

Two experiments were conducted to determine the relationship of supplemental Trp on liver fat accumulation and egg production during aflatoxicosis in laying hens. In Experiment 1, two levels of Trp (0 and 2,000 ppm; basal = .16% Trp) and two levels of aflatoxin (AFLA) (0 and 10 ppm) were supplemented to a complete layer ration. In Experiment 2, a third level of AFLA (5 ppm) was added to the design. Single Comb White Leghorn hens (58 and 68 wk old) were fed the diets for 3 wk for Experiments 1 and 2, respectively. Henday production and egg weights were measured daily. Feed intake was measured weekly. Liver weights, liver moisture, and liver total lipids were determined at the end of each trial. In Experiment 1, supplemental Trp by itself caused a significant (P less than .01) reduction in total liver lipids compared to the controls (no Trp or AFLA). Adding trp and AFLA increased total liver lipids and caused a significant (P less than .05) decrease in egg production compared with adding AFLA alone. Total liver lipids were 41.1, 32.8, 54.8, and 62.4% (dry weight basis) for 0 Trp:0 AFLA, 2,000 Trp:0 AFLA, 0 Trp:10 AFLA, and 2,000 Trp:10 AFLA, respectively. Similar results were observed in Experiment 2. It was concluded that supplemental Trp by itself caused a reduction in total liver lipids, but when supplemented to a diet containing AFLA, Trp caused an increased severity of lesions associated with aflatoxicosis in layers.

Aflatoxin and aflatoxicosis. II. Effects of aflatoxin on ovaries and testicles in mature domestic fowls

The present study aimed at: 1. Examination of commercial chicken and duck eggs for the possible presence of aflatoxins. 2. Study of the sex susceptibility of mature chickens when fed on ration containing aflatoxins. 3. Study of clinicopathological effects on their ovaries and testicles. In this investigation, 100 chicken and 50 duck eggs collected from markets in the vicinity of Assiut Governorate, were examined individually for the presence of aflatoxins in the whites and yolks. The study revealed that the examined eggs contained no aflatoxins. Experimentally, aflatoxin BV(8.1 ppm) and G. (1.6 ppm) were incorporated into the feed of five laying hens and five mature cooks for three weeks duration. The layers showed cessation of egg production during the whole feeding period. Histopathological examinations revealed that, the ovaries showed follicular atresia while testicles were normal. It was shown that, aflatoxicosis cause pathological changes in the chicken ovaries, which has a detrimental effect on egg production.

Delayed reproductive development resulting from aflatoxicosis in juvenile Japanese quail

Aflatoxicosis was induced in young Japanese quail. In the first experiment five replicates of 30 birds per treatment were fed a soy-corn basal ration containing 0, 5, or 10 microgram aflatoxin per gram of feed from 1 to 3 weeks of age. At 3 weeks, the animals were sacrificed and mesurements taken. In the second experiment, 0 to 10 microgram aflatoxin per gram of diet were fed from either 1 to 3 weeks of age or 2 to 4 weeks of age. At 3 weeks of age body weights were significantly (P < .05) reduced and relative liver weights were significantly (P < .05) increased. Testicular weights relative to body weight were depressed by up to 50%. Ovary wet weights, but not relative weights, were reduced. Testicular development (weight) was impaired through 6 weeks of age. Ovarian development, determined both by weight and number of developing follicles, was delayed as long as 3 weeks following withdrawal of aflatoxin from the diet. Radioimmunoassay for circulating androgens revealed that aflatoxin suppressed both the onset of production and the final concentratin of male hormone. The data demonstrate that aflatoxin can exert a deleterious inhibition of sexual development in quail with subsequent impairment of reproductive capacity. These findings raise the implication of potential reproductive failure in economically important species such as broiler breeders.

The early influence of aflatoxin upon sexual maturation in the male Japanese quail

The effects of early exposure to aflatoxin on sexual maturation were investigated in young male Japanese quail. Quail in Treatment A were fed a soy-corn starter mash with 10 micrograms aflatoxin/g added from 7 to 21 days of age. Treatment B quail were fed this from 14 to 28 days of age. Animals from each treatment were sampled at intervals from 25 days to 70 days of age. Both behavioral and physiological indicators of sexual maturation were monitored including measurements of sexual behavior, cloacal gland area, testes weight, and peripheral concentrations of testosterone. Statistical estimation was conducted to determine the age at which occurred rapid increase in hormone concentrations and morphological variables indicative of sexual maturation. Control animals showed increased testosterone concentration at 26 days and increased testes weight at 27 days. The cloacal gland area enlarged by 34 days and sexual behavior was first observed at 31 days. Animals in the A treatment had rapid testicular growth at 29 days and testosterone concentrations rose after 27 days. Concentrations were depressed compared to those of controls. Cloacal gland hypertrophy occurred after 37 days; initial sexual activity began at 35 days. The B treatment animals began showing evidence of sexual maturation significantly later with increasing testes weight by 36 days, testosterone concentrations by 37 days, cloacal gland area by 37 days, and initial sexual activity at 35 days. This experiment indicates that exposure to aflatoxin at an early age results in a delay in physiological and behavioral sexual maturation. Animals exposed between 7 and 21 days recovered slightly earlier than those treated between 14 and 28 days.

Energy and nitrogen metabolism of diseased chickens: aflatoxicosis

1. New Hampshire chicks were fed on diets containing 0 (control), 0-7 (A), or 1-1 (B) ppm of aflatoxin B1. In two trials 1-d-old chicks were offered ad libitum the three diets for 14 d. The gaseous exchange of five chickens from each group was measured for 3 or 4 d, the same diets being fed, at 2, 3, 4 and 5 weeks of age in two series of experiments. The controls were fed at the lower intake of the two other groups. Following each series of experiments at the various ages, birds were starved for 24 h and their heat production was re-measured over the next 24 h. 2. Mortality was highest and growth and food conversion poorest where the diet with the highest aflatoxin concentration was fed. Mortality was confined to the first 2 weeks. 3. Performance of birds in the chambers was improved in the second series due to differences in food intake. It also improved with age suggesting some resistance to the toxin. 4. Mean respiratory quotient was 0-97 for fed chickens on diet B. This was significantly different from 0-92 for the two other groups. Similarly, during starvation the RQ was 0-76 compared with 0-73. 5. birds fed on diet B generally grew better, retained more nitrogen and had a better energy balance in the respiration chambers than the other two groups. Metabolisability of dietary energy was less (68.5%) for all groups at 2 to 3 weeks than when older (70%) but availability of ME was the same (71%) for all groups. 6. Heat production (kJ/kg0-75) of starved birds on diet B was significantly lower than the other two groups, while endogenous nitrogen excretion was higher. 7. Water consumption (ml/g food and g/100 g body weight) was greatest for birds on diet B. 8. Although aflatoxin in the diet substantially reduced intake there was no indication that at these reduced levels of intake, nitrogen or energy metabolism were measurably impaired.

Further characterization of tissue distribution and metabolism of (14C)aflatoxin B1 in chickens

The distribution and metabolism of [(14)C]aflatoxin B(1) in chicken tissues were further investigated. Previously dried and frozen ethyl acetate extracts of liver, heart, gizzard, breast, leg, blood, and fecal samples were obtained from either layer or broiler chickens fed subclinical levels of [(14)C]aflatoxin B(1). Treatment of these extracts with either carboxypeptidase A, leucine aminopeptidase, pepsin, or trypsin revealed that an average of 50% of the (14)C detected in the acetate extracts was a liberated peptide (or amino acid) conjugate of [(14)C]aflatoxin B(2a). When a prepared standard of B(2a) was made by incubation of B(1) with cold dilute aqueous HCl, the R(f) values and absorbance maxima were identical with those of the tissue extracts after enzymatic treatment.

Tissue distribution and metabolism of aflatoxin B 1 - 14 C in Broiler chickens

The effects of administering low levels of aflatoxin B(1)-(14)C by crop intubation daily for 14 days to broiler chickens were determined. Studies on the distribution of (14)C in the blood, selected organs, tissues, and excreta were conducted. No toxic effects were observed in broiler chickens during the 14 days of the experiment. The broiler chickens excreted 90.64% of the (14)C administered. Of the (14)C retained, 11.04, 9.83, 4.30, 12.52, 31.66, and 30.63% were detected in the blood, liver, heart, gizzard, breast, and leg, respectively. Chemical assay of those samples demonstrating radioactivity revealed that 81.2% of the radioactivity in these substrates was not extractable by classical extraction procedures while approximately 10% was extractable. Treatment of aqueous extracts for conjugated steroids by treatments with beta-glucuronidase revealed that 31.5% of the (14)C detected in the aqueous extract was a liberated glucuronide conjugate of aflatoxin M(1)-(14)C.