6. Estimation of deltamethrin residues in cow's and goat's environment and trials to reduce its level in milk

摘要

Aim: The present study was aimed to estimate deltamethrin residues in cow's and goat's environment over a certain period of time post-application, to identify the role of both feed and water as a source of pesticides, and to conduct some trials to reduce their levels in milk. Materials and Methods: A total of 80 water and feed samples (40 of each) and 120 milk samples (80 cow's milk and 40 goat's milk) were collected. Fresh milk samples were collected directly from the udder as well as from feed and water before application and 1st, 2nd, 3rd, 7th, 15th, 21st, and 35th days after insecticide application. Results: Deltamethrin residues were detected after its application in both water and feed at different levels up to the first 3 days and in all cow's and goat's milk samples at 35th day. The highest levels were detected in milk samples at the 2nd day then at the 7th day followed at the 15th day after application as such levels were above the maximum residual limits. By microwaving the polluted cow's milk samples, deltamethrin residues were not detected without influencing the chemical composition of the milk. However, on freezing of milk, the deltamethrin residues reached 12.6±3.24 μg/L in association with a significant decline in the concentration of fat. Conclusion: Microwaving of milk is an effective method to decline deltamethrin concentration in milk.