Poultry Services

Broiler Chick Bioassay

Knowledge of the nutrient value of dietary ingredients and the impact of supplement on broiler chickens is required by the broiler chicken industry and its allied partners. Based on this knowledge diets can be accurately formulated to provide the dietary nutrients and stimulants to enable a flock to uniformly reach its genetic potential and provide high quality safe food products in a sustainable manner.

The University of Sydney broiler chick bioassay is routinely used to establish the feed value of ingredients and the impact of dietary supplements on production, efficiency, health, physiology, and product quality and safety.


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The derivation of feed value includes determination of nutrient: level, intake, availability and retention (as meat or bioactive compounds). The bioassay may also be expanded to evaluate the impact of diet on health (immunity (cellular and humoural components, and response to antigenic challenge); gut tissue health (histopathology and histochemistry); metabolic disease (e.g. ascites and skeletal) and normal intestinal microflora (to be developed)).

Male broiler chicks are maintained in replicate groups and randomised in up to 96 bioassay cages for various dietary treatments.

Birds can be maintained on treatments for up to 28 d of age.
Replicates of 3 to 6 cages of six birds can be tested for each diet.
Allowing for comparison of 16 to 32 dietary treatments in any one bioassay.
Larger numbers of treatments (up to 96) are accommodated by replicating the bioassay to provide statistically meaningful results.
Test diets are formulated to meet the requirements of male broiler chicks and prepared in small scale feed mixing equipment on site.
Diets are full fed and feed intake and body weight measured at specific times and used to determine feed efficiency.
Diet and excreta and/or digesta are collected freeze-dried, ground and used in analysis. Insoluble ash markers are used.

Flexibility to Respond
  • Gut health and physiology
  • Immunological response
  • Skeletal integrity
  • Body composition and yield of high value breast muscle and/or bioactives.

The poultry staff are well trained in bird management, sampling of biological material and laboratory analysis. Our focus is on repeatability and accuracy of the bioassay; using it to provide materials for laboratories specifically designed to measure materials our laboratory is not equipped to analyse. A multidisciplinary approach is achieved by collaboration within the Sydney School of Veterinary Science and with other academic and industry labs.

Dr. Aaron Cowieson, Director Poultry Research Foundation
University of Sydney, 425 Werombi Road Camden, NSW 2570
02 4655 0612

Potential Bioassay Studies
  1. Feed value determination of different ingredients
    a. Evaluations to determine nutrient level, availability, intake and retention as saleable meat or bioactives
    b. Potential collaborators include cereal geneticists and feed processors
  2. Determine the impact of feed processing on feed value
    a. Typical processes (grind size, hydrothermal conditions)
    b. Alternative processes
  3. Impact of feed additives or supplements on feed value
    a. Enzymes, pharmaceuticals, minerals, vitamins, chemicals, nutraceuticals
    b. Identify effective level and or interactions with main ingredients
  4. Physiological studies to measure early broiler development
    a. Gut health
    b. Skeletal integrity
    c. Disease resistance and immunological modulation
    d. Development of supply organs (respiration, circulatory) on development of high value breast meat or bioactives
  5. Alternatives to antimicrobials
  6. Industry sustainability and manure/output modification
Working with industry

Industry-like conditions can be emulated in floor-pens to further evaluate treatments for industry applications.