SUMMARYMilled grass particles were coated with n-alkanes and suspended in a xanthan gum solution. Experiments snowed that grass particles could be coated uniformly with alkanes by means of a rotary evaporator. Further experiments showed that the grass particles, in stable xanthan gum suspension, could be accurately dispensed. The coefficients of variation of the alkane content per dose delivered by means of a dosing gun and syringe were 2·6 and 2·3%, respectively. There was no significant difference between the concentration of faecal alkanes derived from alkanes dosed in suspension-form and alkanes placed directly into the rumen.
A study was made of some of the factors responsible for the accumulation of excessive amounts of nitrate in certain Kikuyu pastures. Accumulation, mainly in stem tissue, is the nett result of several contributing processes. Climatic conditions causing a decline in the requirements of the plant for assimilated nitrogenous substances, stimulate accumulation. High fertilizer-N applications and the re-cycling of nitrogenous substances in the pasture seem to be of considerable significance. These high soil nitrogen levels in conjunction with high potassium levels in the soil, aiding nitrate absorption, translocation and accumulation, seem to be major factors responsible for the accumulation of nitrate, espeCially in old Kikuyu pastures.'n Studie is gemaak van enkele faktore wat die ophoping van oormatige hoeveelhede nitraat in sekere Kikoejoeweidings veroorsaak. Ophoping, hoofsaaklik in stingelweefsel, is die resultaat van verskeie bydraende prosesse. Klimaatstoestande wat 'n verlaging in die vraag na geassimileerde stikstofverbindings in die plant ve roo rsaak, stimuleer nitraatophoping. Toedienings van hoe paile stikstof en die hersirkulering van stikstofverbindings in die weidings blyk van aansienlike belang te wees. Hierdie ho~ nitraatvlakke tesame met hoe kaliumpeile in die grond, wat nitraat-absorpsie, translokasie en ophoping bevorder, blyk die belangrikste faktore te wees wat die ophoping van nit r,aat , veral in ou Kikoejoe-weidings, veroorsaak.
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