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Hereford heifers were fed a diet (7-0 MJ ME/kg D.M.) containing 0-09 % phosphorus but complete with regard to other nutrient constituents. Only after 19 weeks wore the effects of subclinical aphosphorosis evident in the form of reduction in feed intake, cessation of weight gain, increased feed conversion and decreases in tho concentration of inorganic phosphorus in blood and saliva. Heifers supplemented daily with 12 g phosphorus sustained a weight gain of about 0-2 kg/day over 62 weeks as did other supplemented heifers whose feed intake was restricted to that of tho low phosphorus treatment. The effects of phosphorus supplementation were thus demonstrated without being confounded by concomitant increases in feed intake.Phosphorus supplementation resulted in significantly lowered apparent crude protein digestibility and a slight increaso in cell wall digestibility.

Clinical signs of ephemeral fever, which were observed in individual cattle during two successive epidemics in 1973 and 1976, were related to biochemical, cellular and serological changes in the blood. The rise in peripheral blood neutrophil counts in sampies collected from 12 sentinel cattle on a daily basis before, during and after natural disease in the two epidemics to mean peaks of 9 . 6-12 . 5 X 10 9 per litre, and fall in counts of lymphocytes to a trough of 5-7 X 10 9 per litre was found to occur on the same day as the fever peak. A fall in serum calcium levels from a normal mean of 2·55 mmol/l to 2·0 mmol/I occurred on the day clinical signs were most pronounced. Serum magnesium levels were affected to only a minor degree. Plasma fibrinogen rose from a normal mean of 5·0 g/I to a peak of 18 g/I on the second day of disease and fell towards normal in the week after recovery. Neutralizing antibodies to bovine ephemeral fever virus were detected up to 63 days prior to clinical disease, and the rise of antibody after recovery was secondary in pattern. Serological evidence of a prior infection with an antigenically related virus, Kimberley virus, was found in these animals. In more severe clinical cases of ephemeral fever serum calcium levels were as low as 1·95 mmol/l. Treatment of cattle showing clinical signs of the disease with phenylbutazone and calcium borogluconate was favourable.

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