Alexandra Weaver

Dr. Alexandra Weaver

orcid

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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23 July 2021 in Toxins
Verified
Journal Article
Open access
PDF file
AWAlexandra Weaver
Alexandra Weaver
DWDaniel M. Weaver
Daniel M. Weaver
NANicholas Adams
Nicholas Adams
AYAlex Yiannikouris
Alex Yiannikouris
Mycotoxins contaminate crops worldwide and play a role in animal health and performance. Multiple mycotoxins may co-occur which may increase the impact on the animal. To assess the multiple mycotoxin profile of corn (Zea mays), we conducted a 7-year survey of new crop corn grain and silage in the United States. A total of 711 grain and 1117 silage samples were collected between 2013 and 2019 and analyzed for the simultaneous presence of 35 mycotoxins using ultra-performance liquid chromatography–tandem mass spectrometry. The measured mean number of mycotoxins per sample were 4.8 (grain) and 5.2 (silage), ranging from 0 to 13. Fusaric acid (FA) was most frequently detected in 78.1 and 93.8% of grains and silages, respectively, followed by deoxynivalenol (DON) in 75.7 and 88.2% of samples. Fumonisin B1 (FB1), fumonisin B2 and 15-acetyl-deoxynivalenol (15ADON) followed. The greatest (p < 0.05) co-occurrence was between FA and DON in 59.1% of grains and 82.7% of silages, followed by FA with FB1, DON with 15ADON, and FA with 15ADON. Although many samples had lower mycotoxin concentrations, 1.6% (grain) and 7.9% (silage) of tested samples had DON ≥ 5000 µg/kg. Fumonisins were detected ≥ 10,000 µg/kg in 9.6 and 3.9% of grain and silage samples, respectively. Concentrations in grain varied by year for eight mycotoxin groups (p < 0.05), while all 10 groups showed yearly variations in silage. Our survey suggest that multiple mycotoxins frequently co-occur in corn grain and silage in the United States, and some of the more prevalent mycotoxins are those that may not be routinely analyzed (i.e., FA and 15ADON). Assessment of multiple mycotoxins should be considered when developing management programs.

1 October 2020 in Toxins
Verified
Journal Article
Open access
PDF file
AWAlexandra Weaver
Alexandra Weaver
WKW. D. King
W. D. King
MVMorgan Verax
Morgan Verax
UFUrsula Fox
Ursula Fox
MKManoj Kudupoje
Manoj Kudupoje
AYAlex Yiannikouris
Alex Yiannikouris
The chronic intake of naturally multi-mycotoxin contaminated feed by broilers with or without titers of Yeast Cell Wall Extract (YCWE, a.k.a Mycosorb A+®), was investigated. Day-old male Cobb chicks (1600 birds, 64 pens, 25 birds/pen) were randomly allocated to diets of control (CON); diet containing mycotoxins (MT); CON + 0.2% YCWE; MT + 0.025% YCWE; MT + 0.05% YCWE; MT + 0.1% YCWE; MT + 0.2% YCWE; and MT + 0.4% YCWE. Growth performance, blood biochemical parameters and gut health were recorded over 42 days. Compared with CON, MT had reduced body weight (BW) and increased feed conversion ratio (FCR) on days 35 and 42 with increased duodenal crypt depth and fewer goblet cells. Furthermore, European Poultry Production Efficiency (EPEF) was reduced for MT versus CON. Feeding MT + 0.2% YCWE improved BW, lowered FCR, reduced crypt depth, increased goblet cell count and improved EPEF. Considering titration of YCWE (0 to 0.4%) during mycotoxin challenge, a cubic effect was observed for FCR with NC + 0.2% YCWE having the lowest FCR. These findings suggest that chronic consumption of multiple Fusarium mycotoxins present in common field concentrations can negatively impact broiler performance and gut health while inclusion of YCWE, particularly 0.2%, could be effective in counteracting mycotoxins.

2 July 2022 in Poultry Science
Verified
Journal Article
Open access
AWAlexandra Weaver
Alexandra Weaver
DWDaniel M. Weaver
Daniel M. Weaver
AYAlex Yiannikouris
Alex Yiannikouris
NANicholas Adams
Nicholas Adams
The effect of mycotoxins (MT) on broiler performance without or with the inclusion of yeast cell wall extract (YCWE, Mycosorb, Alltech, Inc., KY) was evaluated in a random-effects meta-analysis. Data was extracted from 25 research experiments with a total of 10,307 broilers. Broilers fed MT had lower (P < 0.001) body weight gain (BWG, −217 g), reduced feed intake (FI, −264 g), increased feed conversion ratio (FCR, 0.12), and greater mortality by 2.01%. Inclusion of YCWE improved (P < 0.001) BWG (59 g) and FI (65 g), lowered FCR (−0.05), and reduced mortality by 1.74%. Additionally, change in European Production Efficiency Factor (EPEF) was assessed. Feeding MT lowered (P < 0.001) EPEF while YCWE increased (P < 0.001) EPEF. Finally, the carbon footprint of production was evaluated. Control fed birds produced an estimated 1.93 kg CO2-equivalent/kg liveweight (LW), while MT fed broilers produced 2.13 kg CO2-equivalent/kg LW and YCWE inclusion lowered this to 2.03 kg CO2-equivalent/kg LW which resulted in −25 tonnes less CO2-equivalent output per 100,000 birds with YCWE. In conclusion, mycotoxins can play a role in reducing broiler performance and farm production output, as well as increase the carbon footprint. Inclusion of YCWE in feed under a mycotoxin challenge can improve broiler performance and output, as well as lower carbon footprint, which could play a role in farm efficiency, profitability, and environmental sustainability.

30 May 2021 in Toxins
Verified
Journal Article
Open access
PDF file
YSYan-Bin Shen
Yan-Bin Shen
AWAlexandra Weaver
Alexandra Weaver
Sung Woo KimSung Woo Kim
Sung Woo Kim
This study investigated the impact of deoxynivalenol (DON) from naturally contaminated feed on pig growth, immune status, organ health, brain serotonin (5-Hydroxytryptamine, 5-HT) and behavior. Sixteen individually housed pigs (25.57 ± 0.98 kg, age 9 weeks) were randomly allotted to two dietary treatments: without DON (CON) or with 3.8 mg/kg of DON (MT). Pigs were pair-fed to eliminate differences in feed intake (equal tryptophan (Trp) intake). Pigs fed CON received a daily ration based on the ad libitum feed consumption of their MT pair-mate. Performance was determined over 21 days and blood collected for immunological and oxidative stress parameters. Behavior was recorded for 12 h on days 0, 7, 14 and 21. After 21 days, pigs were euthanized to collect tissues for immune parameters, gut morphology and brain serotonin levels. Overall, pigs fed MT had greater weight gain compared with CON. Immunological and oxidative stress parameters were unaffected, but pigs fed MT had reduced villus height, crypt depth and villus-to-crypt ratio in the jejunum. Pigs consuming MT had reduced concentration of 5-HT and increased 5-HT turnover in the hypothalamus. Mycotoxin-fed pigs spent more time lying and sitting, and less time standing and drinking. In conclusion, consumption of DON impacted gastrointestinal tract structure, altered behavior and changed Trp metabolism through increasing 5-HT turnover in hypothalamus.

30 March 2024 in Toxins
Verified
Journal Article
Open access
PDF file
AWAlexandra Weaver
Alexandra Weaver
DWDaniel M. Weaver
Daniel M. Weaver
NANicholas Adams
Nicholas Adams
AYAlex Yiannikouris
Alex Yiannikouris
A random-effects meta-analysis was conducted to investigate the effect of mycotoxins (MT) without or with the inclusion of yeast cell wall extract (YCWE, Mycosorb®, Alltech, Inc., Nicholasville, KY, USA) on laying hen performance. A total of 25 trials were collected from a literature search, and data were extracted from 8 of these that met inclusion criteria, for a total of 12 treatments and 1774 birds. Laying hens fed MT had lower (p < 0.05) body weight (BW) by −50 g, egg production by −6.3 percentage points, and egg weight by −1.95 g than control fed hens (CTRL). Inclusion of YCWE during the mycotoxin challenges (YCWE + MT) resulted in numerically greater (p = 0.441) BW by 12.5 g, while egg production and egg weight were significantly (p < 0.0001) higher by 4.2 percentage points and 1.37 g, respectively. Furthermore, economic assessment calculations indicated that YCWE may not only support hen performance but also resulted in a positive return on investment. In conclusion, mycotoxins can play a role in negatively impacting laying hen performance and profitability. Inclusion of YCWE in feed with mycotoxin challenges provided benefits to egg production and egg weight and may support profitability. As such, the inclusion of YCWE could play an important role in minimizing mycotoxin effects and in turn aid farm efficiency and profitability.

20 December 2025 in Toxins
Verified
Journal Article
Open access
PDF file
AWAlexandra Weaver
Alexandra Weaver
DWDaniel M. Weaver
Daniel M. Weaver
LCLuiz Victor Ferrato Melo de Carvalho
Luiz Victor Ferrato Melo de Carvalho
AYAlex Yiannikouris
Alex Yiannikouris
Mycotoxins are global contaminants of feedstuffs and feeds that are linked to animal health and performance challenges and subsequently lead to economic burden. Negative effects of mycotoxin consumption may increase as a result of multiple mycotoxin co-occurrences. To assess mycotoxin challenge in Europe, a seven-year survey (2018 to 2024) of 1867 samples of grains (barley, maize, and wheat) and 818 forages (maize silage and grass silage) was conducted to assess the simultaneous presence of 54 mycotoxins using ultra-pressure liquid chromatography–tandem mass spectrometry. Results were categorized by feedstuff, harvest year, and climatic region to gain insight on mycotoxin occurrence, concentration and co-occurrence. Grains contained a mean 3.6 to 6.7 mycotoxin types per sample, while silages contained 3.1 to 6.0. Barley in the Nordic climate region had some of the highest Fusarium mycotoxin concentrations, while maize silage had consistently higher mycotoxin concentrations across all climate regions. The B trichothecenes and emerging mycotoxins had the highest rates of co-occurrence (52.4% to 74.2% of samples) in grains and maize silage. Co-occurrence data can serve as an initial framework for identifying or reasserting known environmental conditions that favor mycotoxin biosynthesis in distinct fungal taxa and for refining risk assessment of animals simultaneously exposed to multiple mycotoxins. Collectively, this survey shows that mycotoxin contamination and co-occurrence in grains and silages from Europe is expected, with differences occurring by feedstuff type and climatic region.