BACKGROUND: Subclinical mastitis plays an important role in the economic losses of dairy cattle farms. Staphylococcus aureus is one of the most important causes of this disease. Treatment of this disease with synthetic antibiotics has complications like antibiotic resistance. Using herbal antibiotics can be an excellent way to reduce these side effects.OBJECTIVES: This study aimed to determine the minimum inhibitory concentration of alcoholic extract of olive leaf on Staphylococcus aureus isolated from milk of cows with subclinical mastitis to achieve herbal treatment.METHODS: This study was conducted on 175 Holstein female cattle. The milk samples of 60 cows were obtained with the sterilized method, and Subclinical mastitis-positive cases were determined using the California mastitis test. Staphylococcus aureus bacteria were isolated from positive samples by culture method, and the minimum inhibitory concentration of olive (Olea europaea L.) leaves alcoholic extract on isolated bacteria was determined by microdilution method.RESULTS: From 175 cows under study, 60 cows had a positive California mastitis test, and Staphylococcus aureus separated from milk samples of 14 cows. The minimum inhibitory concentration of olive (Olea europaea L.) leaves extract on this bacterium was 12000 ppm.CONCLUSIONS: Alcoholic extract of olive (Olea europaea L.) leaves has an antimicrobial effect on Staphylococcus aureus as a cause of mastitis. The minimum concentration required for this effect was 12000 ppm. Further studies on the impact of this plant on other bacterial causes of subclinical mammary inflammation in cows and investigation of the effective substances in the extract are needed.

Two various kinds of olive mill solid residues (Crude and partly destoned) were used to investigate the adsorbing property of olive mill solid residues (OMSR) to heavy metals. 100 adult albino rats were classified into four groups. One group served as (–ve) control group (10 rats), received balanced ration and supplied tap water; in addition to three equal groups (each of 30 rats) received water polluted with1/100LD50 of either lead, cadmium or copper at concentration levels( 107.2 mg/L, 8.8mg/L or 58.4mg/L respectively). Each main group was divided into 3sub- groups, one (+ve) control and two experimental groups fed either 20 % crude olive mill or 20% partly destoned olive mill. Polluted water administration extended for 1 month, meanwhile feeding 20% crude or partly destoned (OMSR) continued for further 30 days after cessation of polluted water as a withdrawal period. Samples of serum, muscle, liver and kidney were collected at one month of the experiment and at the end of the withdrawal period after one month. Level of metals were determined by atomic absorption spectrophotometer. Results indicate that crude olive mill exhibit higher adsorption capacities to Pb, cd, and cu than partly destoned especially at withdrawal period. In conclusion, the main advantage of this process is the conversion of this waste product to a useful adsorbent material with low coast in minimizing the toxic hazard of environmental pollution with heavy metals.