Deltamethrin: Impact on Livestock Health and Food Safety
The animal sector comprises a specific segment in the agricultural industry including rearing, breeding, and management of livestock. This sector includes various animals such as cattle, sheep, goats known as ruminants, and poultry. The primary goal of this sector is the production of meat, animal fat, and dairy products. Substances that are used to kill insects are called insecticides. Insecticides have a wide spectrum of applications in the field of medicine, agriculture, and industry. Some Insecticides have the potential to alter ecosystem components majorly and are toxic to animals as well as humans. Some insecticides become concentrated as they spread in the food chain. Less than 0.1% of pesticides applied for pest control reach their target pests. Thus, more than 99.9% of pesticides used move into the environment where they adversely affect public health and beneficial biota, and contaminate soil, water, and the atmosphere of the ecosystem.” David Pimentel Journal of Agricultural and Environmental Ethics”, this means forages which are typically used in the nutrition of animals are being highly contaminated with pesticides and therefore affecting animal health. In this article we will be discussing the mode of action of deltamethrin, and its uses in forages, and how it affects cow’s health.
At the start of 2019, Lebanon witnessed a high economic crisis where the products especially animal based had highly increased and the inflation of lira rates had increased. Moving to august 4thport explosion where it lost all the stored forages used for animals and moreover all the products used in food preparation. Based on according to the United Nations COMTRADE database on international trade, the total imports of Lebanon related to animal sector is equal to 870,530,000$M which includes live animals, dairy products, animal fat, fish, meat and seafood preparations and more. However, the total exports are equal to 50,858,674$ M.
According to LARI (Lebanese Agricultural Research Institute), more than twenty-seven diseases that affect ruminants, poultry, horses and pets are diagnosed at the Lab, with serological and molecular tools. The research focuses on pathogens and diseases of interest for animal health and/or public health (zoonosis). They concern both direct transmission diseases (avian influenza, Brucella, Rabies….) and vector-borne diseases (Flavivirus, Bluetongue).
Moreover, FAO is supporting the ministry of agriculture to face lumpy skin disease. Lebanon faces a livestock threat known as lumpy skin disease (LSD) due to outbreaks in neighboring Syria. Such infectious disease outbreaks can have severe economic consequences for herders. LSD is vector-borne and primarily controlled through vaccination. In the past, Lebanon successfully managed the disease using a heterologous LSD vaccine. However, in recent times, the country has been unable to supply the vaccine to local producers due to financial constraints. The absence of vaccinations could result in substantial economic losses and adversely impact the livelihoods of small-scale dairy farmers.
Actually, Deltamethrin is an insecticide in the chemical class of pyrethroids. Pyrethroids are synthetic chemicals modeled after the pyrethrin components of pyrethrum. Unlike other pyrethroids, deltamethrin consists of one pure compound. Deltamethrin is effective against insects via ingestion and direct contact. Pyrethroids, in general, interfere with normal production and conduction of nerve signals in the nervous system. Pyrethroids act on nerve membranes by delaying the closing of the activation gate for the sodium ion channel. Deltamethrin is registered for use on various crops including cotton, corn, cereals, alfalfa, soybeans, and vegetables for pests such as mites, ants, weevils, and beetles. On second thoughts Deltamethrin is also used to control Ticks (Acari: Ixodidae) which are ectoparasites infesting livestock in every geographic area in the world and they are vectors of several viral, bacterial, and protozoan pathogens to animals and humans worldwide
In 2011 a study was conducted by Melhorn (Elias 2013), and others aimed to investigate the efficacy of Deltamethrin (Butox® 7.5 pour on) against two species of ticks – Ixodes ricinus and Rhipicephalus sanguineus – which are important vectors of diseases in cattle and sheep. The researchers treated four sheep and four young cattle along the vertebral column with 10ml (about 0.34 oz) Butox® (deltamethrin) per sheep or 30ml (about 1.01 oz) Butox® per cattle.
The research team collected hair from various parts of the animals’ bodies (head, ears, back, belly, and feet) on days 7, 14, 21, and 28 after treatment. These hair samples were then brought into close contact with either adult and/or nymph stages of I. ricinus and R. sanguineus ticks to assess the acaricidal (tick-killing) and repellent effects of Deltamethrin. The results showed that Deltamethrin had strong acaricidal effects, but the efficacy varied depending on the tick species, the origin of the hair (which body part the hair was collected from), and the time elapsed after treatment.
In sheep, the acaricidal effect lasted for the entire 28-day period along the whole body against adults and nymphs of I. ricinus, while the acaricidal effects against R. sanguineus stages began to decline at day 21 after treatment.
In cattle, the full acaricidal effect was observed for 21 days (about 3 weeks) against I. ricinus stages and for 14 days (about 2 weeks) against R. sanguineus. After these periods of full action, the acaricidal efficacy decreased, especially when hair was taken from the legs. It’s worth noting that R. sanguineus adults did not show any reaction on day 28 after treatment.
A total of 272 adult hard ticks were randomly collected from domestic ruminants (cattle, sheep, and goats) located at 37 Lebanese farms, distributed among 30 villages.
Another study was conducted in 2018 (Halla E. Bahgy,vetworld.2018.606-611) which aimed to assess Deltamethrin residue levels in the surroundings of cows and goats after its application. It focused on identifying the sources of Deltamethrin contamination, particularly in feed and water, which could lead to exposure to the pesticide. Additionally, the researchers conducted experiments to lower Deltamethrin concentrations in milk, ensuring the safety of milk products for consumption. In the study, a total of 80 samples of water and feed (40 of each) and 120 milk samples (80 cow’s milk and 40 goat’s milk) were collected. Milk samples were taken directly from the udder, as well as from feed and water before the application of Deltamethrin, and at various time points after application (1st, 2nd, 3rd, 7th, 15th, 21st, and 35th days).
The results showed that Deltamethrin residues were detected in water and feed at different levels during the first 3 days after its application. In all cow’s and goat’s milk samples, Deltamethrin residues were found at the 35th day, with the highest levels observed on the 2nd day after application, followed by the 7th and 15th days. These levels exceeded the maximum allowable limits for residue levels.
Another study (M. Humayoun Akhtar, Nov 2008) involved lactating dairy cows being fed deltamethrin at different dosages (2 or 10 mg (about the weight of a grain of table salt)/kg of feed) for 28 consecutive days. The researchers then measured the levels of deltamethrin residues in the milk and various tissues of the cows.
They found that deltamethrin residues were higher in both the milk and tissues when higher doses of the pesticide were administered. Additionally, the study examined the relative concentrations of deltamethrin in the tissues at different time points after the last dose (1 day, 4 days, and 9 days). Based on the analysis, the researchers observed that the highest
relative concentrations of deltamethrin were found in renal fat, followed by subcutaneous fat, fore‐quarter muscle, hindquarter muscle, liver, and kidney.
In summary, Deltamethrin is an effective insecticide used to kill insects, but its residual effects in water and feed diminish after 7 days. However, high residues persist in milk, which could be later consumed by humans. To address contaminated milk, microwave treatment is more effective than freezing in removing deltamethrin residues without altering the milk’s composition. Despite its efficacy against ticks, the exposure of cows to deltamethrin has significant negative effects on their health. The study suggests that further attention is needed to mitigate the potential risks and adverse impacts on livestock due to deltamethrin exposure.
By Sara Mkahal – Agricultural Engineering Student at the Lebanese University
