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Scientists say there is an urgent need for aflatoxin control strategies in Pakistan's feed supply chain to improve animal health, productivity, food safety and exports of animal-based products.

In the CABI One Health journal, the researchers argue that aflatoxins—toxic metabolites produced by certain fungi—are frequently found in animal feed due to poor storage and handling practices. Their presence, they say, not only compromises animal health but also leads to transfer through contaminated milk, meat and eggs, posing serious risks to public health.

A review article written by the scientists aimed to assess the impact of aflatoxin contamination in livestock feed on animal health, productivity and food safety, with a special focus on Pakistan, where the livestock industry in 2024 contributed 60.84% to overall agriculture and 14.36% to the Gross Domestic Product.

Prevalence of aflatoxins in livestock feed and their residues in food products

Dr. Abeera Umar, Project Coordinator based at CABI's center in Pakistan and an author of the review, said, "Despite the crucial role of livestock in Pakistan's economy, this sector remains largely overlooked, particularly concerning animal feed quality.

"This review synthesizes findings from national and international studies, highlighting the prevalence of aflatoxins in livestock feed and their residues in food products. It also discusses the regulatory standards for aflatoxins, identifies major gaps in compliance in Pakistan, and evaluates various control strategies—ranging from pre-harvest interventions and proper storage to the use of mycotoxin binders and regular feed monitoring.

"The findings underscore that aflatoxin levels in many feed samples often exceed permissible limits, resulting in adverse health effects on both livestock and human health."

Various health risks

The review outlines that the effects of mycotoxins depends upon various factors, one of which is the extent of exposure, which may result in acute to chronic health implications including genotoxicity, hepatotoxicity, neurotoxicity, carcinogenicity and reproductive effects.

Extended exposures to low-dose aflatoxins over time may result in stunted growth, decreased production (egg or milk), carcinogenicity and immunosuppression. Prolonged exposure of aflatoxins has been reported to cause liver damage, manifesting as jaundice with a swollen gall bladder.

Additionally, aflatoxin exposure has also been reported to cause the birth of smaller and unhealthy calves, acute mastitis, rectal prolapse and hair loss.

Aflatoxins consumed by children in milk may lead to growth impairment, wasting, immunosuppression and hepatic impairments.

Dr. Umar added, "In developing countries, like Pakistan, milk is a major source of aflatoxin exposure to the public. It is very difficult to check aflatoxin levels in milk due to the raw milk channeled by informal market channels. To address the issue, farmers' awareness on aflatoxins is essential so that they can willingly participate in aflatoxin mitigation."

The scientists emphasize a study conducted in Quetta to determine the prevalence of aflatoxicosis in broiler birds in 2009-2010 based on examination of sick and dead birds.

The post-mortem findings of dead birds indicated 8.78% of birds to be aflatoxin-positive, with postmortem lesions like congested and edematous carcass, yellowish brown and hemorrhagic liver, swollen kidneys along with atrophy of bursa and thymus. Some 8.78% of birds were found to be positive for aflatoxicosis.

Meanwhile, in 2011, a study was conducted to assess the quality of layer and broiler feed manufactured by 10 different commercial feed mills. A study was conducted on 50 layer and 50 broiler feed samples manufactured by 10 different commercial feed mills; 40 samples in total contained aflatoxin content above permissible limits.

Measures that can be taken to limit exposure and consumption of aflatoxins

However, the scientists say there are a range of measures that can be taken to limit exposure and consumption of aflatoxins. For example, the removal of aflatoxins from silage is possible by adding absorbents, which are safe and inexpensive.

They can simply be mixed in animal rations, lowering the bioavailability of aflatoxins, reducing the toxic metabolites in animal products as well.

Mitigation of aflatoxins at farm level by adopting Good Agricultural Practices (GAP) can also play a significant role in the mitigation of aflatoxins in animal feed at farm level, the scientists say.

One of the GAPs is the time of harvest, which is a key factor in the growth of the aflatoxin-producing fungi, Aspergillus flavus. Increased levels of Vitamin A, D, E, K and B bind the toxins and cause fewer aflatoxin effects.

Dr. Umar said, "Despite numerous challenges in the livestock feed industry, particularly concerning aflatoxin contamination in feed, there exist some key opportunities that could facilitate successful and healthy livestock production in Pakistan.

"Although several studies document the presence and impact of aflatoxins, there is an urgent need for more standardized, widespread monitoring and data collection. Mitigation strategies are available, but their adoption remains limited due to challenges, such as lack of awareness, cost constraints and inadequate infrastructure."

The scientists conclude by suggesting that ensuring toxin-free feed will improve livestock productivity, reduce public health risks and enhance the export potential of animal-derived products, ultimately supporting national food security and economic growth.