Effects on poultry and livestock of feed contamination with bacteria and fungi

https://doi.org/10.1016/j.anifeedsci.2006.08.006Get rights and content

Abstract

Animal feed may serve as a carrier for a wide variety of microorganisms. The primary mode of inoculation of feed materials is the transference of soil by wind, rain, mechanical agitation, or insects to standing crops. Some of the microorganisms are adapted to the desiccated and relatively nutrient-poor conditions in soil and survive in similar niches on growing crops. Gastrointestinal pathogens can also introduced into the food chain by animals defecating in the farm environment or by fertilization of crops with manures. Other microorganisms are introduced during storage. In general, the amount of available water in the feed matrix determines whether a microorganism will grow or survive. Some microorganisms, primarily moulds, are adapted to the low amount of available moisture and grow actively within stored seeds and grains. Others will produce spores or enter survival state until the moisture is high enough for bacterial action. There are numerous ways contaminating microorganisms can affect feed quality negatively including reducing dry matter and nutrients, causing musty or sour odours, causing caking of the feed and producing toxins. Finally, feed can act as a carrier for animal and human pathogens. The type of feed, processing treatments and storage conditions can all be factors that influence the population levels and types of microorganisms present. The incidence and variation in the microflora found in animal feed and feed materials are reviewed. A select number of important human and animal pathogens are discussed. Finally there is a brief overview over the detection, surveillance and management strategies of microbial contamination in feed and feed materials.

Introduction

The chemical and nutritional constituents of animal feeds are important for livestock nutrition and growth, but are only part of the animal feed matrix. From an ecological standpoint, harvested grains are not only ingredients for livestock diets, but can act as substrate and transmission vectors for simple unicellular prokaryotic and eukaryotic organisms. Feeds may contain diverse microflora that is acquired from multiple environmental sources, including dust, soil, water, and insects. Feed materials may be inoculated at any time during growing, harvesting, processing, storage and dispersal of the feed. The microflora found in feed materials come from a variety of ecological niches, such as soil and gastrointestinal tracts, and have to adapt to the conditions found in animal feed and feed components in order to survive and/or grow. The microbial diversity found in different feeds is dependent on the water activity, oxygen tension, pH and nutrient composition of the feed matrix. Microfloral growth is dependent on the moisture content of the feed material. Some microorganisms, primarily moulds, have adapted to conditions without free water and can actively grow in stored grains. However, the majority of microorganisms must exercise various strategies to survive until there is sufficient water to support microbial activity. Microflora can decrease grain value through nutritional changes, physical damage, or the production of toxins deleterious to animal health.

Section snippets

Origins of bacteria found in feed

Grains and oilseed crops possess a diverse microflora, with populations ranging from 5 × 103 to 1.6 × 108 CFU/g, that are highly resistant to low moisture conditions (Richard-Molard, 1988, Multon, 1988). Plant material is primarily inoculated by dust generated when soil is disturbed during mechanical harvesting, strong wind or rain. The soil environment is a collection of microhabitats comprised of clay particles, organic matter and aqueous domains that vary in pH, redox potential, ionic strength,

Important bacterial pathogens found in feed

An overview of clinically important foodborne pathogens found in feed can be found in Table 1.

Origins of feed mycoflora

Mycoflora (moulds) can also be present in feed and present a potential threat to feed quality and seed survival. Moulds may cause a decrease in seed germination, musty or sour odours, dry matter and nutrient loss, caking, mycotoxin formation and, ultimately, a reduction in feed monetary value (Beuchat, 1978, Sauer et al., 1992).

Different populations of moulds may be found in growing versus stored grain and can be divided into two large groups: field fungi and storage fungi. Field fungi may

Presence of indicator organisms

Given the difficulty of monitoring the myriad of microorganisms which may contaminate animal feeds, tracking a variety of indicator organisms have been proposed as a means to monitor overall hygiene and fecal contamination. Toranzos and McFeters (1997) reviewed several indicators of fecal contamination, including total coliforms (Gram-negative, nonsporeforming rods that ferment lactose and produce acid and gas within 48 h at 35 °C), fecal coliforms (coliforms that produce gas and acid at 44.5 °C),

Control of bacterial contamination

An overview of several methods used to control bacterial contamination of feeds may be found in Table 3. Several strategies that have been tried to overcome feed degradation including: shortening storage time to prevent browning and caking of the feed, and supplementation with soybean oil to overcome fat losses (Bartov et al., 1982). To prevent overgrowth by storage microorganisms, rapid drying has been widely used to preserve grain (ICMSF, 1998). Zinc bacitracin can be added to feed to control

Summary

Feed may serve as a substrate for a wide variety of microorganisms. Some of the microflora are adapted to the desiccated conditions in soil and are transferred by insects, dust, and wind to similar niches in feed. Some bacteria are adapted to a niche where they are capable of degrading organic matter and/or exist in a survival state until the moisture is high enough for bacterial action. While other microorganisms, primarily moulds, actively grow within stored seeds and use seed nutrients and

Acknowledgements

This research was supported by the Texas Higher Education Coordinating Board's Advanced Technology Program (Grant #999902-165) and the Research Enhancement Program grant of the Texas Agricultural Experiment Station of the Texas A&M University System (Grant #2-102). This research was also supported by Hatch grant H8311 administered by the Texas Agricultural Experiment Station. K.G.M. was supported by an Endowed Graduate Fellowship from Pilgrim's Pride, Inc., Pittsburg, TX, and the Heep

References (167)

  • P.B. Hamilton

    Proof of mycotoxicoses being a field problem and a simple method for their control

    Poultry Sci.

    (1975)
  • D.E. Herriott et al.

    Association of herd management factors with colonization of dairy cattle by shiga toxin-positive Escherichia coli O157

    J. Food Prot.

    (1998)
  • M.H. Hinton

    Infections and intoxications associated with animal feed and forage which may present a hazard to human health

    Vet. J.

    (2000)
  • F.T. Jones et al.

    Association of low levels of aflatoxin in feed with productivity losses in commercial broiler operations

    Poultry Sci.

    (1982)
  • F.T. Jones et al.

    Research note: relationship of feed surface area to fungal activity in poultry feeds

    Poultry Sci.

    (1987)
  • C. Lin et al.

    Epiphytic microflora on alfalfa and whole-plant corn

    J. Dairy Sci.

    (1992)
  • T.V. Lynn et al.

    The occurrence and replication of Escherichia coli in cattle feeds

    J. Dairy Sci.

    (1998)
  • M. Alexander

    Introduction to Soil Microbiology

    (1977)
  • C.B. Annett et al.

    Necrotic enteritis: effect of barley, wheat and corn diets on proliferation of Clostridia perfringens type A

    Avian Pathol.

    (2002)
  • K.E. Ashelford et al.

    In situ population dynamics of bacterial viruses in a terrestrial environment

    Appl. Environ. Microbiol.

    (1999)
  • P. Aureli et al.

    An outbreak of febrile gastroenteritis associated with corn contaminated by Listeria monocytogenes

    N. Engl. J. Med.

    (2000)
  • L.R. Bakken

    Culturable and nonculturable bacteria in soil

  • E.M. Barnes et al.

    The intestinal flora of chicken in the period 2 to 6 weeks of age, with particular reference to the anaerobic bacteria

    Br. Poultry Sci.

    (1972)
  • I. Bartov et al.

    Effect of early stages of fungal development on the nutritional value of diets for broiler chicks

    Br. Poultry Sci.

    (1986)
  • L. Bass et al.

    Incidence and characterization of integrons, genetic elements mediating multiple-drug resistance, in avian Escherichia coli

    Antimicrob. Agents Chemother.

    (1999)
  • B.T. Bennett et al.

    Acute gastric dilatation in monkeys: a microbiologic study of gastric contents, blood and feed

    Lab. Anim. Sci.

    (1980)
  • G.A. Bennett et al.

    Distribution of fumonisins in food and feed products prepared from contaminated corn

  • A.E. Bernhard et al.

    Identification of nonpoint sources of fecal pollution in coastal waters by using host-specific 16S ribosomal DNA genetic markers from fecal anaerobes

    Appl. Environ. Microbiol.

    (2000)
  • L.R. Beuchat

    Microbial alterations of grains, legumes, and oilseeds

    Food Technol.

    (1978)
  • D. Billi et al.

    Engineering desiccation tolerance in Escherichia coli

    Appl. Environ. Microbiol.

    (2000)
  • I. Birlouez-Aragon et al.

    The FAST method, a rapid approach of the nutritional quality of heat-treated foods

    Nahrung/Food

    (2001)
  • N.K. Bohra et al.

    Fungal toxicity with special reference to mycotoxins

    J. Environ. Biol.

    (2003)
  • J. Borneman et al.

    Molecular microbial diversity of an agricultural soil in Wisconsin

    Appl. Environ. Microbiol.

    (1996)
  • M.R. Bragulat et al.

    A mycological survey on mixed poultry feeds and mixed rabbit feeds

    J. Sci. Food. Agric.

    (1995)
  • M.D. Buser et al.

    Effects of extrusion temperature and dwell time on aflatoxin levels in cottonseed

    J. Agric. Food Chem.

    (2002)
  • D. Carr et al.

    Excessive mortality in market-age turkeys associated with cellulitis

    Avian Dis.

    (1996)
  • P.J. Christensen

    The history, biology, and taxonomy of the Cytophaga group

    Can. J. Microbiol.

    (1977)
  • J.A. Crump et al.

    Bacterial contamination of animal feed and its relationship to human foodborne illness

    Clin. Infect. Dis.

    (2002)
  • E.A. Curl et al.

    Effects of soil insects on populations and germination of fungal propagules

  • F. Diez-Gonzalez et al.

    Grain feeding and the dissemination of acid-resistant Escherichia coli from cattle

    Science

    (1998)
  • J.E. Dohms et al.

    Cases of type C botulism in broiler chickens

    Avian Dis.

    (1982)
  • W. Dorn et al.

    Bewertung von verfahren der aufbereitung von h-hnerkot aus veteran-rhygienischer sicht (Veterinary—hygenic aspects of assessment on processes of handling poultry faeces)

    J. Vet. Med. B

    (1997)
  • S.G. Edwards et al.

    Quantification of trichothecene-producing Fusarium species in harvested grain by competitive PCR to determine efficacies of fungicides against Fusarium head blight of winter wheat

    Appl. Environ. Microbiol.

    (2001)
  • A.A. El-Daraway et al.

    Hazards and control of aflatoxins

  • A.A. Elfadil et al.

    A prospective study of cellulitis in broiler chickens in southern Ontario

    Avian Dis.

    (1996)
  • A.A. Elfadil et al.

    Description of cellulitis lesions and associations between cellulitis and other categories of condemnation

    Avian Dis.

    (1996)
  • A.A. Elfadil et al.

    Farm management risk factors associated with cellulitis in broiler chickens in southern Ontario

    Avian Dis.

    (1996)
  • I.A. El-Kady et al.

    Survey of mycoflora and mycotoxins in Egyptian soybean seeds

    J. Basic Microbiol.

    (1993)
  • A.M. Erickson et al.

    Optimisation of enzyme treatment for the degradation of feed proteins for an Escherichia coli auxotroph lysine availability assay

    J. Sci. Food Agric.

    (1999)
  • A.M. Erickson et al.

    Antibiotic amendment for suppression of indigenous microflora in feed sources for an Escherichia coli auxotroph lysine assay

    J. Appl. Microbiol.

    (1999)
  • Cited by (125)

    • Recent developments in antimicrobial growth promoters in chicken health: Opportunities and challenges

      2022, Science of the Total Environment
      Citation Excerpt :

      Pathogen diversity varies with feed type and moisture content. Mycotoxin production in the feed by fungi is responsible for various diseases (Maciorowski et al., 2007). Natural progressive changes (prevalence, abundance, and absence) in the microbial community occur in response to available oxygen concentration in the gut, feed, and water intake.

    • Spirulina platensis and biosynthesized selenium nanoparticles improve performance, antioxidant status, humoral immunity and dietary and ileal microbial populations of heat-stressed broilers

      2022, Journal of Thermal Biology
      Citation Excerpt :

      However, some microbes, particularly molds, grow at a low level of moisture. Other microbes can form spores, which enhance the microbes' survival until the appropriate conditions for growth are available (Maciorowski et al., 2007). The contamination of poultry feed with microbes may negatively affect the feed quality, such as reducing the nutrient value, altering the physical and chemical properties, and producing toxins (Hafez and Attia, 2020; Gernat et al., 2021).

    • Microbial pathogen contamination of animal feed

      2022, Present Knowledge in Food Safety: A Risk-Based Approach through the Food Chain
    View all citing articles on Scopus
    1

    Current address: Department of Agriculture and Natural Resources, 1200 North DuPont Highway, Delaware State University, Dover, DE 19901, United States.

    2

    Current address: Department of Food Science, 2650 N. Young Ave., University of Arkansas, Fayetteville, AR 72704, United States.

    View full text