In today’s changing world, safety and security remain basic human needs. Ensuring the safety of food has also been a major focus of international and national food safety authority like FAO (Food and Adulteration organization) and FSSAI (Food safety and Standard Authority of India). Animal feed is a critical component of the food chain that has a direct impact on animal health and welfare and also on food safety and public health. The slogan ‘healthy animals, healthy humans’ demonstrates the clear relationship that exists between health status of animals and humans. Experience shows that the transmission of diseases from domestic animals to man can only be prevented by improving the health care of animals, and feed plays an integral part of animal wellbeing. The quality of animal feeds is based on the quality of its constituents i.e. the raw material (cereals, cereal by products, oilseed meals, marine feeds, agro industrial by products), used to formulate the ration.
The main purpose of animal feed is to provide the nutrition necessary to support production of meat, milk and eggs. Unfortunately, on occasion, feed can be a source of contaminants that may adversely affect health/production of farm animals and/or the safety of food produced by farm animals. It is only when the contaminant present in the feed is of significant level that it is likely to harm animals or people consuming the meat, milk or eggs derived from the animals. Similarly, when certain essential nutrients are above recommended levels in an animal feed, this also could result in an unacceptable feed risk.
Feed Contaminants (or hazards)
Contaminants (or hazards) refer to microbiological, chemical or physical agents in animal feed capable of causing adverse human and/or animal health effects. Contaminants are substances that have not been intentionally added to feed. The risk profile of an animal feed is an estimation of the probability of an adverse occurrence multiplied by the severity of potential impact. To determine risk it is therefore necessary to first identify hazards in relation to animal feed.
These substances may be introduced in food at one of the stage of production, packaging, transport or holding.
a. Hazards in animal feed ingredients at source- These are microbiological contaminants that could cause infection or illness of the animal, or can be transferred to animal products destined for human consumption, or result in spread of pests,
b. Hazards in processing animal feed: processing hazards in animal feed may arise from ineffective processes not managing ingredient hazards, for example, faulty cooking or heating that were intended to remove microbiological contamination, or faulty formulation processes concentrating chemical contaminants or processing chemicals rather than reducing their concentration.
Contamination generally has a negative impact on the quality of feed and food and may imply a risk to human health. Contaminants of feed and food are mainly divided into three groups 1) Chemical contaminants: Chemical hazards that may occur in food and feed ingredients include naturally occurring chemicals (such as mycotoxins and heavy metals), industrial and environmental contaminants (such as dioxins, PCBs and nitrates), antimicrobial feed additives, residues of veterinary drugs and pesticides and also radionuclide. 2) Physical hazards: Physical hazards include foreign objects (such as pieces of glass, metal, plastic or wood). 3) Biological contaminants: pathogenic microbes like salmonella, mycotoxins (eg. aflatoxins). The potential contaminants (hazards), their health hazards and sources are summarized in Table 1.
Contamination by feed additives
The integrated animal production system uses varied feed additives, including coccidiostats and antibiotics. These additives are particularly important in the control of certain types of contamination that can have a serious impact in hot climates. However, excessive dosages and inappropriate use of these additives can pose a serious risk to public health through the development of resistances to certain antibiotics and the intrinsic toxicity of certain products (coloring agents, preservatives etc.). For chemicals employed in feeds, e.g., coccidiostats, acceptable daily intake (ADI), maximum residue limits (MRL) and withdrawal period are determined through the overall assessment of pharmacokinetics and toxicological studies. Another is the implementation of specific pre-slaughter feed practices: without using a weaning ration (non-enforceable), a required period could be imposed of feeding on ground maize-based feed.
Feed safety Measures:
Feed Safety implies high level of assurance that the feed will not cause harm to the farm animals when prepared or consumed according to the intended use, or to the final consumer. Factors involved in feed safety include the availability of safe feedstuffs, husbandry practices, immunization and the use of antimicrobials and other veterinary drugs. Strategies that have been explored to control foodborne human pathogens include the administration of selected microbial cultures to piglets and day-old chicks in order to establish a balanced gut microflora and increase colonisation resistance. In case of ruminants, attempts have been made to reduce carriage of E. coli using special dietary formulations. Important principles and practices as means of ensuring the safety of the feed are
1. Know what feed contaminants may be present in your animals’ feed and the measures known to prevent such contaminants from becoming unacceptable feed risks
2. Obtain feed from safe and reliable sources
3. Recognize unexpected changes in the feed at your farm (e.g., changes in color, smell, texture, or appearance)
4. Know where in your animal production system(s) unacceptable feed risks may occur
5. Monitor animal feed products for contaminants during receiving, holding, and handling
6. Be aware that other actions, such as limiting access to the premises to authorized personnel, following feed labeling directions, proper personnel training, and sampling and testing of feed, can help ensure feed safety.
Animal feed may be contaminated with organic and inorganic compounds as well as residue of pesticide and fungicide may enter food chain through feed raw materials. The effects of feed contaminants and toxins range from reduced intake to reproductive dysfunction and increased incidence of bacterial diseases. Residues transferred to edible animal products represent another reason for concern. Comprehensive legislation is required in place for the control of several of these chemical compounds, biological contaminants and pathogens in feed. Decontamination of feeds is generally uneconomic and practically unviable, hence prevention is an important strategy of provide safe feed to animals and food to human being.
by Dr. Kumar Kore, AB Vista South Asia