1. Two experiments were carried out to compare spring-dried grass and autumn-dried grass. In both experiments a 3×3 Latin square changeover design was used with periods of 4 weeks. In the first the control ration was a home-grown concentrate mixture (S.E. 58, D.C.P. 12·5%), in the second a high-quality mixture of imported feeds (S.E. 73·5, D.C.P. 16·6%). The concentrates or dried grass were fed in addition to a basal ration which supplied only the maintenance requirements of the cow.

2. In both experiments the milk yield from spring grass was 3–5% higher than that from autumn grass, but the differences were not statistically significant. In Exp. 1 the yield from the home-grown mixture was the same as from spring grass. The yield from the imported mixture in Exp. 2 was significantly higher than from both grass rations. There was a significant increase in milk yield when the cows went on to spring grazing in Exp. 1.

3. Expression of the feed input as a percentage of the Woodman standards showed that the level of feeding was similar in all three rations in the first experiment, and that the increased milk yield from the high-quality ration in the second experiment could be explained by the increased level of feeding which it gave. It was considered that the increased yield on spring grazing might have been caused simply by an increase in the amount of nutrients consumed.