Preventing ectoparasite infestations reduces glucocorticoid concentrations in the hair of cows - short communication.

The aim of this study was to compare hair corticosteroid concentrations in ectoparasiticide-treated (n = 10) and non-treated (n = 12) Holstein cows. Animals in the treated group received cyfluthrin three times, on days 0, 28 and 56 of the experiment. Hair samples were collected from all cows on days 0, 21, 42, 63, and 84 of the experiment for the determination of cortisol and corticosterone concentrations using immunoassays. The respective hair cortisol concentrations in the treated group averaged 209.78, 165.10, 260.78, 177.44 and 183.11 ng/g, while in the non-treated group hair cortisol concentrations averaged 172.58, 243.58, 309.73, 199.75 and 207.09 ng/g. These results indicate that the control of ectoparasites reduced hair cortisol levels in dairy cows. The respective hair corticosterone concentrations in the treated group averaged 19.06, 22.95, 21.95, 21.60 and 24.84 ng/g and in the non-treated group the hair corticosterone concentrations averaged 17.28, 21.94, 34.05, 26.27 and 26.91 ng/g. The results suggest that longterm stress can be estimated better by the determination of hair cortisol rather than corticosterone concentrations.

Degradation and dissipation of the veterinary ionophore lasalocid in manure and soil.

Lasalocid is a veterinary ionophore antibiotic used for prevention and treatment of coccidiosis in poultry. It is excreted from the treated animals mostly in its active form and enters the environment with the use of contaminated manure on agricultural land. To properly assess the risk that lasalocid poses to the environment, it is necessary to know its environmental concentrations as well as the rates of its degradation in manure and dissipation in soil. These values are still largely unknown. A research was undertaken to ascertain the rate of lasalocid degradation in manure under different storage conditions (aging in a pile or composting) and on agricultural soil after using lasalocid-contaminated manure. The results have shown that there is considerable difference in lasalocid degradation between aging manure with no treatment (t1/2=61.8±1.7 d) and composting (t1/2=17.5±0.8 d). Half-lives in soil are much shorter (on average 3.1±0.4 d). On the basis of the measured concentrations of lasalocid in soil after manure application, we can conclude that it can potentially be harmful to soil organisms (PEC/PNEC ratio of 1.18), but only in a worst-case scenario of using the maximum permissible amount of manure and immediately after application. To make certain that no harmful effects occur, composting is recommended.

Sex steroid levels in urine of cattle of different ages: evaluation of abuse control procedures.

Levels of several natural urinary steroids have been determined in the urine of a large number of animals of different cattle categories in the context of steroid abuse in beef production. Bovine animals of different breeds, sex and age included in the Slovene national residue detection plan for steroid abuse were studied. Urine from 120 males and 174 females was analysed. Urinary boldenone, boldione, androstenedione, equiline, medroxyprogesterone, medroxyprogesterone acetate, melengestrol acetate, progesterone, stanozolol, trenbolone, trenbolone acetate, 17α-ethinylestradiol, 17α-methyltestosterone, epitestosterone, 17ß-estradiol, testosterone, and nandrolone were determined by LC-MS/MS. Epitestosterone was found in all bulls; while the proportion of animals containing testosterone and androstenedione increased with age. Testosterone was not detected in bulls less than 5 months of age. Epitestosterone levels, however, were not age dependent. The ratio of testosterone to epitestosterone thus increased with age, from 0.13 ± 0.09 at 1-7 months to 0.42 ± 0.10 at 25-38 months. It was significantly (p < 0.01) higher in bulls above 13 months than in younger animals. In contrast to males, no urinary testosterone was found in females, whereas epitestosterone, androstenedione, progesterone and estradiol were present. The proportion of animals of various age groups in which epitestosterone was detected ranged from 68% to 100%, but the differences were not significant. The presence of both estradiol and progesterone in the same sample was not observed in any animal. The results of this study could be helpful in determining physiological urinary steroid levels in order to provide a baseline for the control of steroid abuse in beef production.

Retrospective study of bull semen quality - possible correlation with pesticide use?

Decline in semen quality in humans and increased incidence of male reproductive problems could be caused by different factors, including pesticides that could mimic or block the action of endogenous hormones. If the decline in semen quality is real, and environmental chemicals are at least partially responsible for this decline, similar changes should be observed in animals that live in close connection with humans and are exposed to similar levels of pollutants. In the present study, the semen quality of bulls in the last 30 years was examined with respect to the year of birth. Furthermore, semen quality results were correlated to the total pesticide use in a limited geographical area. The results indicate a notable decrease in both ejaculate volume and total number of spermatozoa in ejaculates of bulls born in the late 1970s, while after that (until 2006) there was no obvious downward or upward trend either in ejaculate volume or in the total number of sperm cells. The amount of pesticides released into the environment increased about twofold in the given period, and linear regression analysis revealed a strong and statistically significant correlation between the amount of pesticides used and the total number of spermatozoa in the ejaculate.

Detection of trace amounts of abamectin used as an antiparasitic agent in fallow deer tissues.

A sensitive and reliable method for the determination of trace amounts of abamectin in muscles, kidneys and fat tissue of fallow deer is presented. Abamectin was extracted from the tissues with acetonitrile and the extract was cleaned up on a C8 solid-phase extraction cartridge. Abamectin residue was derivatised with trifluoroacetic acid anhydride and 1-methylimidazole, and determined using reversed-phase high-performance liquid chromatography under isocratic conditions and fluorescence detection. The recoveries of the method were high and consistent, ranging from 78% to 90%. The limit of detection of the method was below 1 microg/kg when analysing muscle, kidney and fat tissue. Matrix-matched calibration was used in order to obtain accurate values and to avoid matrix interference.

Abamectin effects on rainbow trout (Oncorhynchus mykiss).

The effect of abamectin (ABM) on rainbow trout (Oncorhynchus mykiss) was studied. The acute toxicity of ABM on rainbow trout was established, following the target 58-h water bath exposure of ABM concentrations from 0.6 to 4.5 microg/l, on the basis of which LD75 (4.0 microg/l) was calculated. The histological changes in organs showed a direct toxicity of ABM for rainbow trout since degenerative changes in brain and kidney and--to a minor extent--in liver were established. The values of the ABM residues in fish muscle tissue with skin were proportional to the exposed concentrations of ABM.

Serum T3 and T4 concentrations in the adult rats treated with herbicide 2,4-dichlorophenoxyacetic acid.

The influence of sublethal doses of 2,4-dichlorophenoxyacetic acid (2,4-D) on serum T3 and T4 concentrations in Hsd Cpb: Wistar rats of both sexes was studied. The trial was performed on 24 males and females respectively, each divided into three groups of 8 animals (control, groups 1 and 2). Aqueous solution of the compound (11 mg/kg body weight - group 1 and 110 mg/kg body weight - group 2) or clean tap water (control group) was used. Aliquots of 2.4 ml/kg body weight were administered with a stomach tube from the 1st to 10th day of the experiment. Three days before the first treatment and on the 6th and 13th day of the experiment the serum T3 and T4 concentrations were determined by commercial radioimmunoassay kits (Byk-Sangtec Diagnostica), validated for rats. A significant decrease of serum T4 (P < 0.01) and T3 (P < 0.001) was determined in males of groups 1 and 2 during the experiment. On the 6th day of experiment serum T4 and T3 values were significantly lower (P < 0.001 and 0.01 respectively) in group 2 than in the controls and group 1 of both males and females. During the whole experiment serum T4 levels were lower in females than in males (P < 0.05).