THE USE OF CATTLE WITH OESOPHAGEAL FISTULAE IN GRASSLAND EXPERIMENTS

Oesophageal-fistulated calves and cattle were used in various experiments during 1963 to 1966; results for 1966 are reported.
The method of inserting the fistula, the routine care of the animals and the methods of sampling through the fistula, are described.
Individual stall-feeding experiments in 1966 gave recovery values of 99.7% for herbage extruded through the fistulae, in relation to herbage eaten. The in vitro organic-matter digestibility of the grass offered and of the extrusa samples were identical. The digestibility of the grass fed in these experiments was high, but was comparable with that of herbage used in the grazing experiments reported. Grazing studies on grass/white clover pastures are reported. The digestibility was determined on all samples and they were separated into various plant fractions. Results obtained were compared with herbage samples cut at the same time. In most cases the digestibility and % N of the extrusa sample was higher than that of the corresponding herbage sample. The quantity of dead material present increased, and more was eaten, as the season advanced; it was of low digestibility. Results of intake studies with grazing animals are presented and the use of oesophagea-istulated cattle as an aid in such studies is discussed.     

A NEW TECHNIQUE FOR THE ACCURATE AERIAL APPLICATION OF HERBICIDES TO DRAINAGE CHANNELS WITH NEGLIGIBLE SPRAY DRIFT

Summary. Difficulties of access met with in Britain when applying dalapon to emergent water weeds in drainage channels led to work starting in 1964 on the development of a method of accurate aerial application of aqueous solutions of herbicide. The narrow, sinuous nature of the targets and the proximity of susceptible crops made it necessary to minimize spray drift and maintain a constant height and a slow speed. Nozzles designed to give large droplets were tested for droplet size and distribution. Selected nozzles were then tested from a helicopter in the field and the effect of their spray characteristics on the biological performance of dalapon was assessed. No daman occurred as a result of spray drift and satisfactory control of Phragmites communis, Typha angustifolia and T. latifolia was achieved with a lower dose of dalapon in a lower volume of spray than previously considered necessary for ground applications.
Une nouvelle technique pour l'application précise d'herbicides par voie aérienne sur les canaux de drainage, avec des risques négligeables d'entrainement     

THE EFFECTS ON DAIRY COWS OF GRAZING PASTURE CONTAINING HIGH LEVELS OF NITRATE-NITROGEN

Two paddocks each received a total of 412 kg N/ha (371 lb/ac) between April and July in four equal applications. The paddocks were grazed four times for four days by two groups of 5 Friesian cows starting 14 and 21 days after each N applica tion. The nitrate-N content of the herbage DM reached a peak of 0·76 % in the third grazing 14 days after N application. There was a significant (P < 0·001) correlation (r =0·67) between water soluble carbohydrates and nitrate-N in the herbage DM. No marked changes occurred in eitber the methaemoglobin or packed cell volume of the blood samples from either group. No detrimental effects on animal health or production were recorded during the experiment.