#08-075

Complete

Date Full Report Received

06/30/2010

Date Abstract Report Received

06/30/2010

Investigation

Institution:
Primary Investigator:

Aflatoxins, especially aflatoxin B1 (AFB1), can be high in dried distillers grains with solubles (DDGS) when 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 objectives of this study were to determine the effects of AFB1 on 1) the health, performance, and serum profiles and 2) the hepatic gene expression of growing barrows. Ninety Duroc x Yorkshire crossbred barrows (age = 35 ± 5 d; initial BW = 14.2 ± 3.0 kg) were randomly assigned to receive 0 (CON), 250 ppb AFB1 (LOW), or 500 ppb AFB1 (HIGH) for 7, 28, or 70 d. Feed intake was measured daily, and pigs were weighed and blood samples collected weekly. Serum was analyzed for concentrations of liver specific enzymes, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (BILI), and blood urea nitrogen (BUN). Average feed intake was less in HIGH barrows than in CON barrows from wk 5 to 10, and was less in LOW barrows than in CON barrows in wk 5 and again from wk 8 to 10. Also, ADFI was lower in HIGH barrows than LOW barrows in wk 10. Lower ADG was observed in HIGH barrows than in CON barrows in wk 8 and 10; no differences in ADG were noted between CON and LOW barrows. There was no effect 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 in LOW barrows than CON barrows in wk 5, and serum BUN was greater in CON barrows than LOW barrows in wk 3. Both ADFI and ADG were negatively affected by AFB1 treatment. Liver samples were fixed and stained for detection of cellular damage and inflammation. No statistical differences in liver health as assessed by histological grading were observed among the 70 d treatment groups. These results demonstrate that performance and blood parameters in young growing barrows are affected by consumption of an aflatoxin-contaminated diet, especially when the concentration of aflatoxin is high (≥ 500 ppb); however, even lower concentrations (250 ppb) are detrimental to performance when administered for a more chronic period. Liver samples from d 70 barrows were used for RNA-Sequencing (RNA-Seq). Genomic analysis indicates considerable variation in the number of transcripts, with most probed sequences having low levels of transcription. Changes in the expression of genes involved in a variety of functions related to cellular stress and toxicity responses, such as apoptosis, regulation of cell growth and proliferation, and mRNA processing, are differentially regulated in response to AFB1. Of specific interest, 15 genes with apoptotic roles were differentially expressed after long-term aflatoxin exposure (70 d). Of those 15 genes, 4 (CDKN1A, ZMAT3, YWHAZ, and AEN) were also differentially expressed after only a short-term exposure (7 d), indicating those genes may be early indicators of an apoptotic response to aflatoxins. Further study of these differentially expressed genes may lead to prevention strategies and treatments for aflatoxicosis. Additionally, early response genes may prove to be useful for early diagnosis of aflatoxicosis, or even indicate differences in tolerance to dietary aflatoxins.