BACKGROUND: Phytase enzyme (EC 3.1.3.8), is used to increase the availability of phosphorus in the feeding of monogastric animals. Increasing public attention to environmental issues, improving livestock nutrition and human health have led to considerable attempts to increase its activity or prevent its inhibition as a food additive. OBJECTIVES: Determination of inhibitory or activating effect of methanolic extract from aerial parts of some herbs, as rich sources of secondary metabolites. METHODS: Phytase was partially purified from wheat barn. After preparation of methanolic extracts from aerial parts of plants, their effects on phytase activity were measured at four concentrations of 0.001, 0.01, 0.1 and 1 mg/ml. Micro plate assays were performed at 405 nm. RESULTS: Among analysed plant samples, extracts from Pedicularis sibthorpii Boiss, Phlomis persica Boiss, Solenanthus Circinatus Ledeb, Stachys lavandulifolia Vahl, had appreciable inhibitory effect, while extracts from Astragalus caraganae Hohe, Hypericum scabrum L, Linum album Ky.ex Boiss, Valeriana sisymbriifolia Vahl, Euphorbia denticulate Lam, Rindera lanata (Lam.) Bge, had a considerable activation effect. CONCLUSIONS: According to the results of this report, plants with positive effect on phytase activity, could be used as food additive along with phytase to improve phosphoros uptake. On the other hand, plants with negative effect on phytase could be viewed as unwanted sources in monogastric animals feeding.

This study aimed to characterise the effects of ketosis on milk yield and composition and digestive capacity in transition dairy cows. Seven ketotic and seven healthy cows were housed in individual stalls for six days. Samples of plasma, milk, refused total mixed ration, and faeces were collected, and the blood biochemical parameters, milk yield and composition, dry matter intake, and faecal dry matter (FDM) production were determined. Compared with healthy cows, the ketotic cows had significantly higher concentrations of milk fat and citrate, but lower levels of milk protein and lactose. The cows exhibited a need for acid detergent fibre in forage and better digestion of neutral detergent fibre, starch, crude protein, and phosphorus than healthy cows, but more fat and gross energy were excreted in their faeces. Ketotic cows had higher energy-corrected milk yields and lower FDM than healthy cows. Lower feed intake coinciding with the requirement to maintain high milk production is considered to be the cause of ketosis in dairy cows. Ketotic cows exhibited lower dry matter fat digestion.