Effects of dietary aflatoxin on the hepatic expression of apoptosis genes in growing barrows.

The most common and toxic form of aflatoxin, aflatoxin B(1) (AFB(1)), is produced by molds growing on crops. Use of moldy corn can result in high concentrations of AFB(1) in swine diets, which could potentially lead to an increased incidence of aflatoxicosis, a disease associated with decreased health and performance through reduced feed intake, reduced BW gain, and impaired liver function. The objective of this study was to determine the effects of AFB(1) on the hepatic gene expression of growing barrows. Ninety Duroc × Yorkshire crossbred barrows (age = 35 ± 5 d; initial BW = 14.2 ± 3.0 kg) were allocated to 9 pens with 10 pigs per pen, and randomly assigned in a 3 × 3 factorial arrangements of treatments to receive diets containing 0 µg/kg of AFB(1), 250 µg/kg of AFB(1), or 500 µg/kg of AFB(1) for 7, 28, or 70 d. Because performance was most affected in animals administered AFB(1) for an extended period, liver samples from d 70 animals were used for RNA-sequencing analysis. Of 82,744 sequences probed, 179 had transcripts that were highly correlated (r ≥ |0.8|; P < 0.0001) with treatment. Of the 179 significant transcripts, 46 sequences were negatively and 133 sequences positively related to treatment. Forty-three unique functional groups were identified. Genes within the apoptosis regulation functional group were selected for 1) confirmation of d 70 gene expression differences using real-time reverse-transcription (RT)-PCR (n = 4 genes), and 2) investigation of d 7 expression to identify early responses to AFB(1) (n = 15 genes) using real-time RT-PCR. Expression of the 4 apoptosis genes selected for confirmation, cyclin-dependent kinase inhibitor 1A, zinc finger matrin type 3, kininogen 1, and pim-1 oncogene, was confirmed with real-time RT-PCR. Of the 15 genes tested in d 7 liver samples, 4 were differentially expressed: cyclin-dependent kinase inhibitor 1A; zinc finger matrin type 3; tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide; and apoptosis enhancing nuclease. Results from this study demonstrate that administration of an AFB(1)-contaminated diet to growing barrows alters hepatic gene expression, and in particular apoptosis genes.

Effects of dietary aflatoxin on the health and performance of growing barrows.

Aflatoxins, especially aflatoxin B1 (AFB1), can be greater in dried distillers grains with solubles (DDGS) because it can be concentrated during the ethanol production process. Increased use of DDGS in swine diets could potentially lead to an increased incidence of aflatoxicosis, a disease associated with decreased feed intake, reduced BW gain, and impaired liver function. The objective of this study was to determine the effects of AFB1 on the health, performance, and serum profile of growing barrows. Ninety Duroc × Yorkshire crossbred barrows were purchased (age = 35 ± 5 d; BW = 14.2 ± 3.0 kg), allocated to 9 pens with 10 pigs per pen, and randomly assigned to receive diets containing 0 µg/kg of AFB1 (CON), 250 µg/kg of AFB1 (LO), or 500 µg/kg of AFB1 (HI) for 7, 28, or 70 d in a 3 × 3 factorial arrangement of treatments. Feed intake was measured daily, and pigs were weighed and blood samples collected weekly. Serum was analyzed for concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (BILI), and blood urea nitrogen (BUN). Both ADFI and ADG were negatively affected (P ≤ 0.001) by AFB1 treatment. Average daily feed intake was less (P < 0.05) in HI barrows than in CON barrows from wk 5 to 10 and was less (P < 0.05) in LO barrows than in CON barrows in wk 5 and again from wk 8 to 10. Also, ADFI was less (P = 0.022) in HI barrows than LO barrows in wk 10. Decreased ADG (P < 0.05) was observed in HI barrows than in CON barrows in wk 8 and 10; no differences (P ≥ 0.665) in ADG were noted between CON and LO barrows. There was no effect (P ≥ 0.080) of AFB1 treatment on ALT or BILI concentrations. However, both AST and BUN were affected (P < 0.05) by AFB1 treatment. Serum AST was greater (P = 0.010) in LO barrows than CON barrows in wk 5, and serum BUN was greater (P = 0.004) in CON barrows than LO barrows in wk 3. Results from this study demonstrate that the performance and health of young growing barrows were affected by consumption of an AFB1-contaminated diet, especially when fed for a more extended period.