Occurrence of aflatoxins in animal feeds and raw milk: the case of Kondoa District in Dodoma Tanzania
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Date
2024
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Publisher
Sokoine University of Agriculture
Abstract
Aflatoxins in animal feeds and milk are common problem mostly
reported among many regions in Tanzania, in Africa, and worldwide.
Studies have revealed a high occurrence of aflatoxins in feeds and
milk, which is largely due to a lack of knowledge among various
stakeholders along the milk value chain, particularly smallholder dairy
farmers (SHDF), animal feed processors, and feed suppliers. This
has led to aflatoxins contamination of animal feeds during processing,
storage, and feeding. The most common and highly carcinogenic
aflatoxins is aflatoxin B1 (AFB1), which, when consumed, is
metabolized into aflatoxin M1 (AFM1) and can be found in milk, meat,
and eggs. Other types of aflatoxins include aflatoxin B2, G1, G2, and
M2. The formation of aflatoxins is mostly caused by Aspergillus flavus
or Aspergillus parasticus, which, under adverse environmental
temperatures and humidity, can grow in livestock feeds such as
maize bran, sunflower seedcakes, silage, hay, and, rarely, in the
grass, leading to the production of toxins that referred to as aflatoxins.
This study was conducted to assess the level of awareness of
aflatoxins in animal feeds and fresh milk among smallholder dairy
farmers and to determine the contamination of AFB1 in animal feeds
and the occurrence of AFM1 in milk. The study involved both
qualitative and quantitative methodologies, including surveys and
laboratory determinations of aflatoxins in animal feeds and milk.
Semi-structured questionnaires were used, involving 120 SHDFs who
had at least one dairy cow from six wards in Kondoa district namely
Soera, Kikiro, Haubi, Kolo, Borisa, and Kondoa mjini. In the
laboratory, 20 feed samples and 25 milk samples were collected from
25 SHDFs selected among 120 SHDFs and analysed for aflatoxin B1
and M1 respectively using High-Performance Liquid Chromatography
(HPLC), with samples prepared following various steps before
injection into the HPLC for aflatoxins detection and quantification. The
results of this study provide a basis for the recommendation of more
training programs and awareness campaigns on aflatoxins
supplemented with close monitoring of the dairy value chain by
extension officers across regions in Tanzania. The results of this
study demonstrate that, majority of SHDFs have awareness of aflatoxins. About 88.3% of the surveyed SHDFs have heard of
aflatoxins through village meetings coordinated in collaboration with
extension staff, where aflatoxins awareness was one of the agenda.
Other sources of information included seminars, newspapers, radio,
and television. Additionally, 77.5% were aware of the possible factors
and control measures for aflatoxins in animal feeds and milk, and
68.2% understand that aflatoxins can harm both animal health and
human health resulting in liver cancer. Furthermore, 63.3% knew the
possible transmission of aflatoxins from animal feeds to milk.
Additionally, more than 55% of the surveyed farmers were aware of at
least one factor for aflatoxins contamination and control measures to
prevent aflatoxins.
The results by High Performance Liquid Chromatograph (HPLC)
analysis of animal feeds and milk revealed that 55% of all samples
tested positive for AFB1 in animal feeds, where only 5% were above
the permissible safe limit of 20 μg/kg for dairy cattle feeding. The
mean AFB1 was found to be 8.6 (±5.9) μg/kg, ranging from the lowest
limit of detection (LOD) to 21.1 μg/kg. The analysis of milk samples
revealed that 44% of the samples tested were positive for AFM1, with
12% of the sample above the level recommended by the Tanzania
Bureau of Standards (TBS), the European Union (EU) and the World
Health Organization (WHO). The mean AFM1 was found to be 0.07
(±0.08) μg/L, ranging from the limit of detection to 0.23 μg/L.
However, there was no milk sample that exceeded the US Food and
Drug Administration (USFDA) and Codex standards of 0.5 μg/L for
milk to be consumed by the public.
Findings from this study demonstrate that the majority of farmers had
information about aflatoxins in animal feeds and raw milk, despite
many awareness programs conducted for agricultural crop producers.
Some farmers were aware of factors and the control measures for
aflatoxins, also they were able to mention at least one sign of
possible aflatoxins-contaminated feeds. This helped in their routine
practices of feed preparation, storage, and feeding cattle. The
findings of the survey reflect the real situation in the field, as the
majority of feeds and milk samples were within the levels recommended by TBS, EU, WHO, USFDA, and Codex Alimentarius
standards for dairy cattle feeding and milk for public consumption.
In conclusion, it was found, smallholder dairy farmers were aware of
aflatoxins animal feeds and milk. However, there are some fees and
milk samples contain aflatoxin calling for more training programs to
be established and implemented to spread awareness on aflatoxins
causes and effects, and hence ensure that the community is aware of
the problem and contribute to the effort to prevent aflatoxins.
Monitoring of SHDFs practices along the dairy value chain is also
recommended to encourage voluntary participation to prevent
aflatoxins contamination in animal feeds and milk and throughout the
food system in general
Description
Dissertation
Keywords
Aflatoxins, Awareness, Aflatoxin B1, Aflatoxin M1, Animal feeds, Raw/fresh milk, Occurrence, Smallholder dairy farmers, and High-Performance Liquid Chromatography.