The health and performance of the grazing animal in relation to fertilizer nitrogen usage. I. Calves

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Abstract
1. An experiment was carried out in 1961 and 1962 to test the effect of the application of high levels of fertilizer N to S 23 ryegrass swards on the health and performance of grazing calves. A uniform application of 47 kg. P and 75 kg. K/ha. was used in each year. Nitro-chalk was applied at monthly intervals from February to September, at rates equivalent to 22.4 kg. (Nl) and 112 kg. (N3) per hectare in 1961; in 1962 an intermediate rate (N2) of 67.2 kg./ha./month was also used. The total quantities of N applied per hectare in 1961 were 185 and 1042 kg. and in 1962, 192, 576 and 961 kg.2. Male calves, 2-6 months old when introduced to the experiment, grazed in rotation round a series of four paddocks on each treatment. In 1961 Friesian, Aberdeen Angus cross and Shorthorn twin calves were used; in 1962 all the calves were unrelated Friesians.