Tracebility And Residual Of Organophosphorus Pessticides In The Milch Milk

Organophosphorus pesticides(OPS) residual is an universal concerned topic. Because of slathering OPS in agricultural production, the environment and food resources are inevitably polluted. The available data on tracebility of OPS residual during the production of raw milk is very rare. It is therefore essential, to make clear the migration level of OPS into raw milk.Total four in vitro and in vivo trials were conducted in this paper, involving the detection of OPS residual in the feed, the OPS degradation in processing of corn straw silage, the OPS degradation by inculating with artificial rumen and a feeding trial to milking goats.In the 1^st trial, four types of OPS residual in two types of feed were detected in GC equiped with FPD detector under the conditions of acetonitrile as extraction solvent. The Vacuum pump equipped with 0.4μm organo-filter-membrane was adopted as vacuum filtration in the purification treatment. The coefficient of recovery was within the range of 72% to 94%, RSD 2.05% to 8.96%.The detection limit was in the range of 0.01 to 0.05μg/g.In the 2^st trial, the degradation of omethoate in artificial rumen was evaluated. Artificial rumen juice mixed with OPS was fermented for 72h, The OPS degradation was rapid within 12h and slow later. Regression analysis of OPS degradation in artificial rumen indicated that the relationship of residual concentration with initial concentration was expressed as the power function. Regression relation were extremely significant(p＜0.01, R²=0.956), the optimal equation for estimating OPS degradation in vitro is Y=244.571X^1.63.In the 3^th trial, the degradation of omethoate in corn straw silage was observed. The rapid degradation was found at 7d and 21d, extremely fast at 3d to 7d. During 3 to 7d, the growth of lactic acid bacteria was slow. But culture OD value of mixed culvativation for 3d in MRS of lactobacillus plantarum, lacbobacillus acidophilum and bacterium lacticum with different concentration omethoate was not significant (p＞0.05). the optimal equation for estimating OPS degradation is Y=0.188-0.013X+0.024X²(R²=1).the degradation of OPS in different initial concentration in procedure of corn straw silage meets exponential flow equation Y = ae^bt. The equations for the treated groups ,G1: y = 3.389e^-0.074t, half life is 9.4d; G2: y = 9.438e^-0.066t, half life is 10.5d; G3: y = 16.64e^-0.041t, half life is 14.1d; G4: y = 28.474e^-0.037t, half life is 18.7d; G5: y=55.419e^-0.041t,half life is 16.9d.In the 4^th trial, in vivo degradation of omethoate and migration was studied in milking goats The animals was divided into three group, G₁ group(low level of OPS), G₂ group (high level of OPS), and C group as control (normal), the concentration of detected omethoate was 0.131μg/ml in the G₂ group on the first day, but residual of omethoate was 0.132μg/ml in the G₁ group on the second day, none in the C group. Residual concentration increased obviously in the G₂ group on the second and third day. The concentration was 0.199μg/ml and 0.164μg/ml ,the tendency changed gently from the third day to later. The value was 0.131μg/ml-0.134μg/ml until the eigth day .No residual in the milk sample of G₂ group was detected on the ninth day, and G₁ group on the eigth day. This study indicated that concentration of serum cholinesterase had reduced obviously following the time and amount of adding pesticide. Feeding pesticide was stopped because of animal serious anorexia on the sixth day and at that moment concentration of serum cholinesterase was to be normal.The conclusion of this study was that migration of OPS into raw milk existed as primitive form. OPS was partly degraded in rumen and in silage process. It is extremely important to control pollution of OPS on the safety of raw milk.