An experiment was condncted to measure the effects of differrat ryegrass companion grasses and red-clover varieties on the productivity of red-clover swards. Three sOage harvests per year were taken over a 2-year period.The addition of a companion grass increased total herbage yields; S24 perennial ryegrass gave the highest herbage yield over the two years, followed by Reveille perennial ryegrass. Because of lack of persistence, Tetila Italian ryegrass yielded poorly the second year. A companion grass had Uttle effect on red-clover yields in the mixed swards but improved percentage digestibility of the OM of the total herbage and lowered the CP percentage. Its presence also reduced the ingress of unsown species.The variety of red clover used had little effect on total herbage yields or red-clover yields in the first harvest year. In the second year, Hungaropoly and Tilo persisted better and so gave higher total herbage yields and red-clover yields than Dorset Marl or Essex. The fall in total herbage yields from the first to the second year was entirely due to a fall in red-clover yield since yields of the 'non-red clover' fraction of the total herbage increased.A red-clover/grass sward may have advantages over a pure red-clover sward nutritionally, for silage-making and for its effect in diluting the oestrogenic activity of a pure clover sward. A major reappraisal of the role and potential of red-clover swards in the UK is warranted because of their many valuable attributes, particularly their ability to give high herbage yields of high nutritive value without the addition of fertilizer N. The improved persistency of some of the tetraploid varieties of red clover enhances the value of the plant.

Four legumes-white clover cv. Blanca, red clover cvs Violetta (diploid) and Hungaropoly (tetraploid) and lucerne cv. Eurojje-were established as pure-sown swards and with each of five companion grasses: timothy cv. Timo, meadow fescue cv. Bundy, sweet brome cv. Deborah and perennial ryegrass cvs Talbot (diploid) and Barlatra (tetraploid), both ryegrasses being of 'intermediate' heading date. Two 'silage' crops and an 'aftermath grazing' crop were harvested in each of three successive years.In the first harvest year, total herbage DM production of red clover ranged from 15-03 to 17-01 I ha"'. White clover and lucerne swards produced considerably less at 7-12 to 11 -011 ha"'. In the second harvest year, lucerne swards were the highest producing at 1554 to 1714 t ha"', while DM production from red clover and white clover swards ranged from 6-75 to 1187 t ha"'. Lucerne swards maintained Iheir production superiority in the third year at 16-48 to 17-87 t ha'', while production from white clover swards ranged from 6-41 to 10-23 t ha""'. However, red clover swards declined to 3-30 to 5 81 tha"'; this above-average decline was mainly caused by the onset of red clover necrotic mosaic virus which affected all red clover plots uniformly in the second harvest year, and by winter conditions before the third harvest year. Total herbage DOM and CP yields of the swards were influenced in a similar manner to DM production.Correspondence: DrJ. Frame, Agronomy Deparimeni, Wesl of Scotland Agricultura! College, Auchincruive, Ayr KA6 5HW, UK.Compared with pure-sown legume, the addition of a companion grass to a legume resulted in increased total herbage production but decreased legume content and production. In spite of the differing grass types represented by the companion grasses, they did not difFer greatly in their effects; however, meadow fescue did prove to be the most suitable companion grass for lucerne.The results highlighted some ofthe advantages and disadvantages of legume and legume/grass swards. Noteworthy features were (a) the unsuitability of pure-sown white clover swards, (b) the high production levels achievable from red clover swards in the short term and the need to choose disease-resistant varieties, (c) the high production levels achievable from lucerne swards, at least in selected soil and climatic conditions and (d) the advantage of using compatible companion grasses with legumes.

White-clover herbage proved to be of relatively high digestibility and it was possible to predict the digestibility of mixed grass and clover herbages from a knowledge of the digestibility and proportions of the components. Lucerne proved to be of low digestibility. Aftermath herbage was not so highly digestible as first cuts; and in autumn digestibility falls slowly as herbage ages. Digestibility was unrelated to the nitrogen content of herbage. In three trials no significant differences were found between the digestive efficiencies of wether sheep and dairy cows, while hormone implantation, although aflecting animal metabolism, failed to influence feed digestibility. Restricted feeding at 50% of the ad lii)itttnt intake resulted in a slight increase in the apparent digestibility of herbage.

Much of the published digestibility data refer to swards grown in the south of Britain. In order to study digestibility curves in a more northerly latitude, several pure swards were established in the west of Scotland in 1962 and 1963. Varieties included S22 and Tetila Italian ryegrass, S37 cocksfoot, S170 tall fescue, S215 meadow fescue, Scots timothy, English broad red clover, and SI00 white clover. In addition to primary growth in vitro digestibility, the effect of various cutting managements on digestibility and productivity was measured. Flowerhead emergence was delayed, with the result that the digestibility curve was later than is reported from southern Britain. Highest yields of digestible organic matter were obtained from the less frequent cutting regimes, but the mean digestibility of the herbage was lower. Predictibility of herbage digestibility is desirable as the basis of a reliable and planned herbage utilization programme, particularly for conservation.

quality parameters into consideration, timothy proved a better companion than tall fescue. A seed rate of2 or 4 kg ha"' timothyand 12 kg ha"' red clover proved the most satisfactory. AbstractTetraploid red clover (cv. Hungaropoly) was sown at seed rates of 6,12 or 18 kg ha"'alone and in mixture with timothy (cv. Scots) at 2, 4 or 6 kg ha"' or with tall fescue (cv. S170) at 6,12 or 18 kg ha"'. Two 'silage' crops and an 'aftermath grazing' crop were harvested in 2 successive years. In harvest years 1 and 2, total herbage production levels of 11 12 and 7-47 t dry matter (DM) ha"' respectively were obtained from pure-sown red clover compared with 11-84 and 8-78 t DM ha"' for red clover-timothy and 12-23 and 9-64 t DM ha"' for red clover-tall fescue. Corresponding red clover production levels were 10-93 and 5-30 t DM ha-' (red clover swards), 8-04 and 3-131 ha"' (red clover-timothy), and 6-42 and 1-09 t ha"' (red clover-tall fescue).Total herbage organic matter digestibility was improved by the timothy companion grass but not consistently by the tall fescue, whereas crude protein (CP) concentration was decreased by the addition of either grass. Increased seed rate intensified these effects, as well as the general effect of the companion grass in depressing red clover DM, digestible organic matter (DOM) and CP production.Total herbage DM, DOM and CP were not markedly affected by increasing red clover seed rate but red clover DM, DOM and CP were increased as red clover seed rate was raised, due to increases in the red clover component.The potential for silage cropping of red clover swards was confirmed but there was advantage in sowing a companion grass. Taking yield and

A reassessment of the potential productivity of 37 varieties of red eiover suggests that DM productivity is equivalent to grass given fertilizer N at 252 kg/ha for the 1st year, 209 kg/ha for 2nd year and 144 kg/ha for 3rd year of production. Corresponding equivalents for CP productivity of the red clover swards were 298, 228 and 206 kg N/ha. Varietal differences in productivity were significant Average yields of total herbage DM in the 1st, 2nd and 3rd harvesting years were 10-9, 8-7 and 8-2 t/ha, containing 6*5, 5-9 and 6-0 t/ha red clover, respectively. For two harvesting years, the most productive varieties were Essi, Kuhn, Hungaropoly, Robina, Tilo Daehnfeldt, Redhead and Corona Otofte. Rea 4N and a few other tetraploid varieties were very productive in the 3rd year. Hungaropoly, although showing a decline in the 3rd year, was the most productive over 3 years, with an average yield of 1I>5 t/ha per year total herbage DM containing 10>2 t/ha per year red clover DM.Such high potential DM production warrants further investigation into the persistence of red clover, its conservation and the problems of its utilization by livestock.

Two different sizes of seed of a tetraploid and a diploid Italian ryegrass were sown in pure stands. Harvests were made at frequent intervals from 14 to 54 days after sowing, the rootand shoot-yields and numbers of leaves and tillers being recorded at each harvest. The results suggest that seed size per se has little influence on leaf-and tiller-numbers and that large seed increases yield potential only during the first few weeks of growth.

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