Development and Evaluation of Monoclonal Antibodies for Paxilline

Paxilline (PAX) is a tremorgenic mycotoxin that has been found in perennial ryegrass infected with Acremonium lolii. To facilitate screening for this toxin, four murine monoclonal antibodies (mAbs) were developed. In competitive indirect enzyme-linked immunosorbent assays (CI-ELISAs) the concentrations of PAX required to inhibit signal development by 50% (IC₅₀s) ranged from 1.2 to 2.5 ng/mL. One mAb (2-9) was applied to the detection of PAX in maize silage. The assay was sensitive to the effects of solvents, with 5% acetonitrile or 20% methanol causing a two-fold or greater increase in IC₅₀. For analysis of silage samples, extracts were cleaned up by adsorbing potential matrix interferences onto a solid phase extraction column. The non-retained extract was then diluted with buffer to reduce solvent content prior to assay. Using this method, the limit of detection for PAX in dried silage was 15 µg/kg and the limit of quantification was 90 µg/kg. Recovery from samples spiked over the range of 100 to 1000 µg/kg averaged 106% ± 18%. The assay was applied to 86 maize silage samples, with many having detectable, but none having quantifiable, levels of PAX. The results suggest the CI-ELISA can be applied as a sensitive technique for the screening of PAX in maize silage.     

The Occurrence of Mycotoxins in Raw Materials and Fish Feeds in Europe and the Potential Effects of Deoxynivalenol (DON) on the Health and Growth of Farmed Fish Species—A Review

The first part of this study evaluates the occurrence of mycotoxin patterns in feedstuffs and fish feeds. Results were extrapolated from a large data pool derived from wheat (n = 857), corn (n = 725), soybean meal (n = 139) and fish feed (n = 44) samples in European countries and based on sample analyses by liquid chromatography/tandem mass spectrometry (LC-MS/MS) in the period between 2012–2019. Deoxynivalenol (DON) was readily present in corn (in 47% of the samples) > wheat (41%) > soybean meal (11%), and in aquafeeds (48%). Co-occurrence of mycotoxins was frequently observed in feedstuffs and aquafeed samples. For example, in corn, multi-mycotoxin occurrence was investigated by Spearman’s correlations and odd ratios, and both showed co-occurrence of DON with its acetylated forms (3-AcDON, 15-AcDON) as well as with zearalenone (ZEN). The second part of this study summarizes the existing knowledge on the effects of DON on farmed fish species and evaluates the risk of DON exposure in fish, based on data from in vivo studies. A meta-analytical approach aimed to estimate to which extent DON affects feed intake and growth performance in fish. Corn was identified as the ingredient with the highest risk of contamination with DON and its acetylated forms, which often cannot be detected by commonly used rapid detection methods in feed mills. Periodical state-of-the-art mycotoxin analyses are essential to detect the full spectrum of mycotoxins in fish feeds aimed to prevent detrimental effects on farmed fish and subsequent economic losses for fish farmers. Because levels below the stated regulatory limits can reduce feed intake and growth performance, our results show that the risk of DON contamination is underestimated in the aquaculture industry.     

The influence of feeding crimped kernel maize silage on growth performance and intestinal colonization with Campylobacter jejuni of broilers

An infection trial and a production trial over 35 days were conducted in parallel to study the influence of feeding crimped kernel maize silage (CKMS) on the intestinal Campylobacter jejuni colonization and broiler performance, respectively. The CKMS was used at dietary inclusion levels of 15% and 30% in maize-based diets. Broilers were orally inoculated with 2?×?10⁵?log?cfu/ml C. jejuni on day 14. Four birds from each pen were randomly selected and killed by cervical dislocation on days 3, 6, 9, 14 and 21 post infection and intestinal contents from ileum, caeca and rectum as well as liver samples were taken. Body weight and feed consumption of broilers were registered on days 13, 22 and 35. On day 35, litter dry matter (DM) was measured and the condition of the foot pads was evaluated. There was no significant effect of CKMS on the colonization of C. jejuni. Body weight of the broilers supplemented with 15% CKMS was comparable with the control maize-based feed, whereas addition of 30% CKMS reduced broiler body weight (P?Campylobacter colonization, but improved the foot pad health of broilers.     

Effect of Lactic Acid Bacteria on the Fermentation Quality and Mycotoxins Concentrations of Corn Silage Infested with Mycotoxigenic Fungi

This study was conducted to evaluate the effect of lactic acid bacteria (LAB) on fermentation quality, mycotoxin concentrations, and microbial communities of whole-crop corn silages infested with mycotoxigenic fungi. Cultured spores (10⁶ cfu/mL) of mycotoxigenic Aspergillus flavus and Fusarium graminearum were sprayed (5 mL) on corn forage on 27 July and 10 August 2018. On 21 August 2018, sprayed (FI; 3 plots) and unsprayed (NFI; 3 plots) corn forage were harvested at the 1/2 kernel milk line stage, followed by chopping and ensiling without inoculants (CON), or with Lactobacillus buchneri (LB, 1 × 10⁶ cfu/g FW), Lactobacillus plantarum (LT, 1 × 10⁶ cfu/g FW), or L. buchneri + L. plantarum (BT: both L. buchneri and L. plantarum applied at 0.5 × 10⁶ cfu/g FW). After 90 d of ensiling, FI silages had a higher (p < 0.05) pH value and higher acetic acid (ACA), ethanol, and ammonia nitrogen (ammonia N) concentrations, but lower (p < 0.05) lactic acid (LA) concentrations than NFI silage. The inoculants decreased pH and increased LA concentration and LA/ACA compared with CON. The aflatoxin B₁ (AFB₁) was only detected in FI fresh corn and silages; ensiling decreased (p < 0.05) AFB₁ concentration compared with fresh corn, and LB and BT decreased AFB₁ concentration compared with CON. The zearalenone (ZEN), deoxynivalenol (DON), and fumonisin B₁ (FB₁) concentrations were similar (p < 0.05) for NFI silages, while ZEN concentration in BT was the lowest (p < 0.05) among all FI silages; DON and FB₁ concentrations in LB, LT, and BT silages were significantly lower (p < 0.05) than those of CON in FI silages. The fungal infestation increased the bacterial and fungal diversity of silages compared with NFI silages. The FI silages had a higher relative abundance (RA) of Lactobacillus, Weissella, Wickerhamomyces, Pichia, and Epicoccum than the corresponding NFI silages. The RA of Aspergillus and Fusarium markedly decreased after 90 d of ensiling, and the inoculation expanded this trend irrespective of fungal infestation. The Penicillium in FI silages survived after 90 d of ensiling, while the inoculants decreased the RA of Penicillium. Inoculants mitigate the adverse effects of fungal infestation on corn silage quality by changing the bacterial and fungal communities.     

青贮饲料的优点及制作技术

国内外畜牧业发展成功的经验证明,青贮饲料是现代畜牧业发展不可替代的重要饲料形式。笔者从长期的科研工作实践,结合相关资料分析整理总结出了青贮饲料的优点及贮制方法,饲喂要点等。可供广大农牧民在生产实际操作中参用。     

优质青贮饲草料调制与品质鉴定及利用技术探讨

调制青贮饲料优越性很多。营养损失少,消化率高,适口性好,能保持营养平衡。要大力推广青贮饲料的调制技术。优质青贮饲料的调制,需要有相关的技术和制作工艺,掌握好其要领才能调制出优质的青贮饲料。如科学、合理的利用青贮饲料饲喂家畜,定会收到良好经济效益。     

Quality,Functional, and Sensory Properties of Cookies from Sweet Potato–Maize Flour Blends

This study was carried out to determine the quality, functional, and sensory properties of cookies from sweet potato–maize flour blends. Substitution of maize flour with sweet potato flour was done at 10–100%. Values of bulk density, water binding capacity, dispersability of flour samples, swelling power of starches, starch content, sugar content, cookie flow, calorific values, and proximate composition were determined. The results revealed that substitution of sweet potato flour with maize flour significantly (p < 0.05) reduced the protein from 6.8–4.4%, moisture from 5.3–5.0%, crude fiber from 3.4–2.5%, and fat from 9.8–8.5% of the composite flours and the cookies. The ash and sugar contents were increased from 4.3–5.8% for ash and 2.1–3.9% for sugar with increase in sweet potato flour substitution. The calorific value of the cookies decreased from 457–397cal/100 g as the percentage of sweet potato flour increased in the maize flour cookies. The water binding capacity increased from 0.9–1.7 and the starch swelling power decreased from 10.1–5.3 at 95°C with increase in sweet potato flour content in the flour mixture. The bulk density and dispensability decreased from 4.6–3.3 g/ml and 48.3–47.1 ml/g, respectively, in the flour as the content of the sweet potato flour in the composite flour increased. Sensory evaluation results showed that the colour, texture, taste and overall acceptability changed significantly (p ≤ 0.05) with increase in sweet potato flour substitution. The optimum substitution level was 40%. Above this level of substitution, the product becomes less acceptable to the consumer in terms of all the variables studied.     

Validation and Application of a Low-Cost Sorting Device for Fumonisin Reduction in Maize

Fumonisin mycotoxins are a persistent challenge to human and livestock health in tropical and sub-tropical maize cropping systems, and more efficient methods are needed to reduce their presence in food systems. We constructed a novel, low-cost device for sorting grain, the “DropSort”, and tested its effectiveness on both plastic kernel models and fumonisin-contaminated maize. Sorting plastic kernels of known size and shape enabled us to optimize the sorting performance of the DropSort. The device sorted maize into three distinct fractions as measured by bulk density and 100-kernel weight. The level of fumonisin was lower in the heaviest fractions of maize compared to the unsorted samples. Based on correlations among fumonisin and bulk characteristics of each fraction, we found that light fraction 100-kernel weight could be an inexpensive proxy for unsorted fumonisin concentration. Single kernel analysis revealed significant relationships among kernel fumonisin content and physical characteristics that could prove useful for future sorting efforts. The availability of a low-cost device (materials~USD 300) that can be used to reduce fumonisin in maize could improve food safety in resource-limited contexts in which fumonisin contamination remains a pressing challenge.     

Gradual domestication of root traits in the earliest maize from Tehuacán

Efforts to understand the phenotypic transition that gave rise to maize from teosinte have mainly focused on the analysis of aerial organs, with little insights into possible domestication traits affecting the root system. Archeological excavations in San Marcos cave (Tehuacán, Mexico) yielded two well-preserved 5,300 to 4,970 calibrated y B.P. specimens (SM3 and SM11) corresponding to root stalks composed of at least five nodes with multiple nodal roots and, in case, a complete embryonic root system. To characterize in detail their architecture and anatomy, we used laser ablation tomography to reconstruct a three-dimensional segment of their nodal roots and a scutellar node, revealing exquisite preservation of the inner tissue and cell organization and providing reliable morphometric parameters for cellular characteristics of the stele and cortex. Whereas SM3 showed multiple cortical sclerenchyma typical of extant maize, the scutellar node of the SM11 embryonic root system completely lacked seminal roots, an attribute found in extant teosinte and in two specific maize mutants: root with undetectable meristem1 (rum1) and rootless concerning crown and seminal roots (rtcs). Ancient DNA sequences of SM10—a third San Marcos specimen of equivalent age to SM3 and SM11—revealed the presence of mutations in the transcribed sequence of both genes, offering the possibility for some of these mutations to be involved in the lack of seminal roots of the ancient specimens. Our results indicate that the root system of the earliest maize from Tehuacán resembled teosinte in traits important for maize drought adaptation.

Genetic evidence indicates that maize (Zea mays ssp. mays) populations arose from Balsas teosinte (Zea mays ssp. parviglumis, also named teosinte parviglumis) close to 9,000 y ago (1). This evolutionary transition caused important phenotypic changes in the aerial portion of the plant, including the partial suppression of lateral branching, a decrease in the number of male and female inflorescences per individual, the exposure of the kernel by absence of a cupulate fruitcase, and the transformation of a distichous female inflorescence that disarticulates naturally into a polystichous (3- to 12-ranked) cob with attached grains that require human intervention for dispersal (1–3). A close association has been established between some of these traits and the genes that underlie their developmental control (4, 5), or genomic regions that have lost genetic diversity as a consequence of progressive domestication (6–8). In some cases, paleogenomic analysis of millenary specimens dating to the earliest stages of Mesoamerican cultivation has allowed the establishment of reference time frame for the progression of their genetic diversity and stages of domestication (9–11).By contrast, and despite their importance for supplying water and nutrients during all stages of growth and development, the influence of domestication on the evolution of root architecture and anatomy has received little attention. A phenotypic analysis and comparison of maize landraces and teosintes concluded that their range of root architectural and anatomical traits was similar, however, a few specific traits permitted some distinction between both subspecies (12). In general, teosintes showed less variation for architectural traits such as root system dry weight, longest nodal root length, nodal system diameter, number of root tips, and number of seminal roots. They also showed smaller mean stele and xylem areas, shorter nodal roots, less frequent lateral root branching, and significantly fewer seminal roots than landraces (12), suggesting they could be important traits affected during domestication. Comparisons of physiological responses to limited nitrogen availability indicates that teosinte parviglumis shows an increase of the shoot:root biomass ratio as compared to maize, as well as an increase in the length of nodal and lateral roots, but also reduced nodal root number (13). A functional decrease in major domestication genes such as Teosinte Branched1 (Tb1) results in an increase of both lateral and nodal roots, although it remains unclear if the effect is direct or indirect (14).Root architecture is crucial for productivity by determining the temporal and spatial distribution of soil exploration and hence resource capture. Maize root architecture is comprised of embryonic and postembryonic components (15). After seed germination, the emergence of the radicle and the coleoptile is followed by the elongation of the mesocotyl. While the primary root develops from the radicle, the scutellar node gives rise to seminal roots located in a protuberance formed by the remnants of the pericarp and endosperm, located between the mesocotyl and the primary root. Seminal and primary roots are considered components of the embryonic root system. The first node forms the first nodal roots between the mesocotyl and the coleoptile. Subsequent elongation of the main vertical axis of the mesocotyl results in additional subterranean and root nodes (SI Appendix, Fig. S1). Aerial nodes will give rise to whorls of brace roots.The anatomy of a root transversal section is characterized by the presence of two concentric cellular cylinders: the stele and the cortex. In maize, the central region of the differentiated stele contains xylem vessels responsible for axial transport of water and nutrients. At the periphery of each late metaxylem bundle are the smaller early metaxylem bundles. Phloem vessels, necessary for photosynthate transport, are composed of smaller cells located between late metaxylem bundles. The intersection of the cortex and the stele is composed of two concentric cell files: the pericycle and the endodermis. The cortex is composed of the root epidermis and 6 to 19 files of outer, mid, and inner cortical cells (16, 17). Cortical aerenchyma can be formed via programmed cell death. In some cases, the outer cortex exhibits multiseriate cortical sclerenchyma (MCS) with thick lignified walls, a phenotype recently reported to improve root penetration ability as an adaptation to growth in hard soils (18). Interestingly, the MCS phenotype is present in some modern maize inbreds but not in accessions of teosinte parviglumis and Z. mays ssp. mexicana [teosinte mexicana; (18)], suggesting it might represent an adaptation acquired during domestication.Two maize genes have been shown to be important for development of seminal roots during the establishment of the embryonic root system. Mutations in ROOT WITH UNDETECTABLE MERISTEM1 (RUM1) result in the absence of seminal and postembryonic lateral roots on the primary root (19–21). RUM1 encodes a monocot specific AUX/IAA protein that can be induced by auxin. Similarly, mutants defective in ROOTLESS CONCERNING CROWN AND SEMINAL ROOTS (RTCS) completely lack seminal roots and the postembryonic shoot-borne root system (21). RTCS encodes a Lateral Organ Boundaries (LOB) domain protein preferentially expressed in roots. Two major quantitative loci contributing to 66% of seminal root number variation comapped with RUM1 and RTCS, suggesting both genes play key regulatory functions in the development of the embryonic root system (22).Pioneering excavations conducted in rock shelters of the Tehuacán Valley uncovered maize paleobotanical specimens dating back to the earliest stages of agriculture in Mesoamerica (23, 24), including hundreds of cob specimens, but only a few root crowns. Subsequent explorations of San Marcos cave yielded new nonmanipulated specimens dating to a similar age of 5,300 to 4,970 calibrated y B.P., including SM3, a well-preserved root crown that represents the earliest maize root specimen found to date (10). A paleogenomic analysis of SM3 and other specimens of equivalent age showed that the earliest maize from San Marcos genetically diverged from fully domesticated landraces and contained allelic variants absent from extant maize populations (10). Some domestication loci (teosinte branched1, brittle endosperm2) showed reduced nucleotide variability as compared to teosinte parviglumis, but others (teosinte glume architecture1, sugary1) showed conserved levels of nucleotide variability that are absent from extant maize. These temporally similar samples also showed unexpected levels of homozygosity and inbreeding, opening the possibility for Tehuacán maize cultivation evolving from reduced founder populations (10).To characterize in detail the architecture and anatomy of the earliest maize roots found to date, we conducted laser ablation tomography (LAT) of two paleobotanic specimens (SM3 and SM11) from San Marcos cave, dating at a similar age of 5,280 to 4,956 y B.P. We generated a three-dimensional (3D) reconstruction of a second node root segment for both specimens, confirming the exquisite preservation of their inner cellular organization, and comparing multiple anatomical parameters to extant maize and teosinte accessions. SM3 exhibited MCS proposed to be exclusive to domesticated maize. By contrast, the 3D reconstruction of the scutellar node of SM11 demonstrated the absence of seminal roots, a trait only reported in extant teosintes and two specific maize mutants. Partial sequencing of RUM1 and RTCS alleles present in the genome of SM10—a San Marcos specimen of equivalent age to SM3 and SM11—revealed mutations that could relate to the absence of seminal roots. Our overall results indicate that some of the most important root traits that distinguish extant maize landraces from teosinte were not fully present in the earliest maize from San Marcos.